Document text
'Jnerating and Maintenance
Handbook
MARCONI INSTRUMENTS LIMITED, ENGLAND
FM/AM. SIGNAL GENERATOR
МЕРЕ ТЕ 935A/2
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OPERATING AND MAINTENANCE
HANDBOOK
for
FM/AM SIGNAL GENERATOR
ТҮРЕ ТЕ 995272
Amendments
The following amendment is included
at the commencement of the Appendices
Section of this handbook. |
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Hertfordshire, ТО Telephone: St. Albans-56161
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CONTENTS
Section Page
SCHEDULE OF PARTS SUPPLIED v
1 DESCRIPTION 1
ПЕ Е К ШКА beens ат ка» ооо гезе аге «ауе LL
PEIN DETAILS ,.............»..........45..54».4... 1
1 В.Е. Е оо ї313345444345226845248415454 1
2 Modulation Systems ‚ооо ково ково вос вв овьзеоевофое 3
I Monitoring Arrangements .........................».р 4
4 Power Unit ...........555%%.%%%.54%...9...%......../4
2 ОРЕВАТІОМ 5
INSTALLATION B60005000000000000004000900000000400000000090
5
SWITCHING ON AND WARMING UP оо ае O D OCC 5
CONNECTING TO EQUIPMENT UNDER ТЕ5Т............ 5
6
6
TUNING ооо чо оо оо ооо ооо оо .. 4. ..........kxX... еә о ое 0
General . E E E E ооо о оао ооо ее ә осо ох 9 6 0.0. Ө 000000
1
2 vera CALIDTALOT ...«ї.«............са ки как CÛ
va incremental Frequency Controls ..................... 10
4 соо ose ales 21.1
SETTING UP FOR С.М. OR MODULATED OUTPUT ...... 13
1 ОВ WENO cierre ас врея вазе сочоя Ê
2 Amplitude Modulation ,,«.«. лө», «өвч өлөалөлөөөлөөөлөө 14
43 Ereguency Modulation .... еее ооо сь ое гөө. агаааа 15
4 Brmultaneous A.M. and Ғ.М, ......4.....»..45....... 18
К.Е. OUTPUT АВВАМСЕМЕМТ5....................... 19
1 Outputs from 1 БУ to 100 mV at 52 and 75 ohms ........ 20
2 Outputs from 2 pV to 200 mV at 75 ohms only .......... 21
:3 Outputs from 0, 1 pV to 10 mV at 52 and 75 ohms ....... 22
4 Output in terms of voltage developed across
РЕ uu лг REO 22
Matching to external loads other than 52 ог 75 ohms .... 23
АС Я 1овав...:...22............:..... 26
SYNCHRONIZING SIGNAL ..........................::.2
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CONTENTS (continued)
Section Page
4 MAINTENANCE г За
GENERAL 00608. е е Ч е ееееегеееееегоегеееоеоееоеееәееееоееееее»е 32
ВАО ОЕ CASE еее, neo nen ar nennen 92
И INPUT ARRANGEMENTS „6. оъ ессе ев две» 93
ACCESS TO ENCLOSED SUB-ASSEMBLIES ............. 34
т ОБАЧЕ Е 24
Е Attenuator и ео ао esee erbe “95
OUTPUT VOLTAGE Attenuator and Monitor
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ВЕ УОТАСЕВ eed sia aeo зэаШ аа зааж... 737
БЕРТАСЕМЕМТ OF VALVES AND CRYSTALS .......... 38
PRESET AND SPECIALLY SELECTED COMPONENTS... 39
ШИШЕ Е ОК ТЕТ аа фа нож ова съв tO esie аз», 0
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ОСЕМ Е Band оона ене сез оаа innen, 54
НЭГ йлн Voltage Accuracy a зо, oec o ooo кана 4%
ЕСИ ода ив ела эхэ T ененнен 99
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Incremental Frequency .....».....».»..4.........”.ш б. 41
МӨН NEAN A A i
Deviation Range Adjustment соо. осевобовоовевоевевое 48
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CONTENTS (continued)
APPENDICES Ref, No.
VALVE REPLACEMENT DATA LE E E E E ооо фо ооо ооо ооо о ооо» VRD 995A/2
COMPONENT LAYOUT ILLUSTRATIONS
Юан ОЦЕТ .....«.,....ахэ...» cowoseceaseceeoocecnveces MP 995A/2-1
General Underside View from Rear (Case Removed) ..... MP 995A/2-2
L.F, and В.Е. Units (Top View with В.Е. Unit
Bene Cover Removed) ................:......... МР 995A/2-3
В.Е, Unit (General Underside View) .............»..... МР 995A/2-4
В.Е. Unit (Close-up of Portion of Underside) ........... МР 995A/2-5
ШРЕК (Underside View) ........................... MP 995A/2-6
nues (Covers Removed) ......4................. МР 995А/2-7
ЖЕКЕ ЕИК,................»......».................. МР 995A/2-8
SPARES ORDERING SCHEDULE(with circuit references) ...... 505/995А/2
В ПИЕСИ ТО DIAGRAM ............................. ТІС 23556/2
LOU 011 ТЛАСВАМ....:....................... TLD 23080/2
DECIBEL CONVERSION TABLE ..авв!% ооо ооо ото 49 eee ом G-SUPP DB
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SCHEDULE OF PARTS SUPPLIED
The complete equipment comprises the following items: -
1, Опе Е, М, /А.М. Signal Generator Туре ТЕ 995A/2 complete with valves,
etc., as under:-
Valves: One: ОА2 (150C 4), Voltage Stabilizer Tube,
One: 5Z4G (52KU), Full-Wave Rectifier.
Six: 6AK5 (EF95), Pentodes.
Two: 6АК6, Pentodes,
Two: 6AL5 (077), Double Diodes.
One: 6AU6 (EF94), Pentode.
One: 12АТ7 (ЕСС81), Double Triode.
One: 5651 (0583/3), Voltage Reference Tube.
Lamp: One: | 6.3-volt, 0.3-amp, M.E.S., Pilot Lamp.
Oscillator Crystal; One: 333.3 kc/s, Marconi Type 1655C.
Semiconductor: One: Туре CS2-A Silicon Diode,
2. One Terminating Unit Type TM 4308; 75 ohms in, 52 and 75 ohms out,
3, One Coaxial Free Plug, Belling-Lee Type L734/P; for Terminating
Unit outlets.
4, One Jack Plug, S. T, C. Type 4006; for Crystal Check socket.
5, One Operating and Maintenance Handbook No. ОМ 995А/2,
Тһе following accessory is ап optional item supplied only if specially ordered,
20-dB Attenuator Pad Type TM 4736; for use between Terminating Unit
and output cable.
М.І, Ltd. _ an
ОМ 995А/2
2 - 4/59
DESCRIPTION
GENERAL
The Marconi Е, М. /А, M, Signal Generator TF 995A/2 covers the
frequency range 1.5 to 220 Mc/s in five bands. Its output can be un-
modulated, frequency modulated, or amplitude modulated; if required,
both frequency and amplitude modulation can be applied simultaneously.
The modulation is obtained from either an internal 1, 000-c/s oscillator
or an external source; for f.m., the deviation is variable up to a maxi-
mum of from 25 kc/s to 600 kc/s depending on carrier frequency; for
a.m., the depth is variable up to 50%,
The open-circuit output voltage is variable by means of resistive
step attenuators from 1 ВУ to 100 mV at 52 ohms and 1 pV to 200 mV at
15 ohms. А plug-on 20-dB Attenuator Pad, available ав an optional
accessory, extends the range down to 0, | pV at both impedances. The
inclusion of à carrier on/off switch makes it possible for the generator
output to be temporarily interrupted without affecting the output
impedance,
DESIGN DETAILS
R.F, Circuits
The r.f. oscillator itself is variable only over the fundamental
frequency range of 4,5 to 9,16 Mc/s; the output bands of 13.5 to 27
Mc/s, 27 to 54 Mc/s, 54 to 108 Mc/s, and 108 to 220 Mc/s are obtained
from а chain of four ganged harmonic multipliers of x3, х2, x2, and x2
respectively. The setting of the frequency switch determines which of
the multipliers acts as the output stage.
Output over the 1. 5- to 13, 5- Mc/s band is obtained by applying
the 27- to 54-Mc/s output of the second multiplier to a single-valve
circuit which combines the functions of mixer and 30-Mc/s oscillator.
The variable-frequency output from the second multiplier is thus
heterodyned with а fixed 30-Mc/s signal, and the output from the
oscillator mixer stage contains a difference-frequency component which
is utilized - after filtering and amplification - to provide outputs between
1,5 апа 13,5 Mc/s. The main tuning dial has five scales, all direct
reading in output frequency; four of these scales are for the bands
extending upwards from 13.5 Mc/s; andthe fifth scale is for the
M,I, Ltd, T
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СМ 995A/2
2 - 4/59
1.2.1 (continued)
1.5- to 13,5-Мс/в band, This fifth scale is са! :Ъга ед directly in
terms of the difference between 30 Mc/s and the cutput frequency of
the multiplier; since the scale extends frora 1.5 to 13.5 Mc/s, it
covers ап arc which corresponds to the second multiplier being tuned
from 31.5 to 43,5 Mc/s.
Whichever r.f. band is in use, the ultimate output is derived via
two resistive 75-ohm ladder-network atteruators in cascade. The
first attenuator has а range of 80 АВ апа is variabie in 20-dB steps;
the second has a range of 20 dB in 2-dB steps. The input to the
cascade is adjustable by means of the SET Л, Е, control and is
monitored by a meter having a SET R.F. mark and, respectively
above and below this mark, plus and minus l-dB marks to allow inter-
polation between the 2-dB steps of the second attenuator. The output
from the second attenuator is applied to a coaxial cable, which is
permanently attached to the Signal Generator; the direct open-circuit
output obtainable from this cable is at a source impedance of 75 ohms
and is variable between 2 pV and 200 mV. By using the plug-on
Terminating Unit supplied, outputs within tho range 1 pV to 100 mV are
obtainable at source impedances of both 52 and 75 ohms; with the
optional Attenuator Pad interposed between tbe output cable and the
Terminating Unit, outputs down to 0,1 pV are cbtainible.
The built-in crystal calibrator - the crystal unit of which has a
fundamental frequency of 333,3 kc/s -is coupied to the variable-
frequency r.f. oscillator and provides fourteen checking points on each
of the four upper frequency bands covered by the Signal Generator.
The h.t. supply to the calibrator is automatically switched on by the
insertion of a telephone plug into the CRYSTAL CHECK jack on the
front panel; the heterodyne beats at the checking pcints may then be
heard in the head telephones or via tho receiver under test. The
cursor of the tuning dial is adjustable so that it may be set to corres-
pond exactly to the nearest crystal checking poirt,
To facilitate tuning, а siow-motion worra-and-wheel drive is
incorporated; this control is fitted with a dial marked linearly from
0 to 100 to assist the operator in sub-dividing the frequency scales of
the main tuning dial, In addition, there is а diroctly-calibrated
incremental frequency control with a total range of +50 kc/s on the
13, 5- to 27-Mc/s band, this range increasing by a íactor of 2 for each
successive band to give a cover of +400 kc/s on the 108- to 220-Mc/s
band, Оп the 1,5- to 13, 5-Mc/s band, the contro: Las a cover of +100
kc/ s,
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(continued)
Forthe application of the incremental carrier shift and for fre-
quency modulation, a reactor valve is included in the tuned circuit of
the r.f, oscillator. Movement of the incremental-frequency control
varies the а, с. bias applied to the grid of the valve, causing a change
in its mutual conductance and thus à change in the oscillator frequency.
Both the а, f, modulating signal and the d.c. shift voltage are applied
to the grid of the valve via a tracking potentiometer ganged to the main
tuning capacitor so that the deviation or carrier shift is kept constant
as the Signal Generator is tuned over any one band,
A carrier on/off switch is included to enable the r.f. signal to be
interrupted without the output circuits of the generator being affected
in any way. This is done by switching the h.t. supply to the screen of
one of the harmonic multipliers; the multiplier selected depends on the
setting of the RANGE switch.
1.2.2 Modulation Systems
Either internal or external a. f. modulation (f.m. or a.m.) may
be applied; the internal modulation is derived from а 1,000 c/s
oscillator.
For frequency modulation, the a.f, signal passes through a
cathode follower and is normally fed to the reactor, not only through
the variable tracking potentiometer, but also via а switched potentio-
meter system ganged to the range switch. By this m22ns, the ratio
of a.f, input voltage to f. m. deviation is maintained constant at ail
frequencies on every band and is independent of the setting of either
the range switch or tuning control. The normal deviation ranges on
all carrier bands are 0 to 25 kc/s and 0 to 75 kc/s. But switching is
provided so that the switched potentiometer system can be by-passed,
thus enabling the deviation to be increased proportionally with increase
in frequency multiplication and giving а maximum deviation on the
highest-frequency band of 75 x 8 = 600 kc/s. On the 1,5- to 13, 5-Mc/s
band, the maximum deviation obtainable is 150 Ккс/в,
Amplitude modulation, to а depth continuously variable со to
50%, is applied to the highest-frequency harmonic multipiier which is
operating for the particular r.f, output band in use; this method helps
to reduce the spurious frequency modulation often encountered when
modulating an r,f, oscillator directly.
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(continued)
Simultaneous amplitude and frequency modulation, of use, for
example, when investigating the performance of limiter stages іп f, m,
receivers, is obtained by setting up the instrument for internala,m,
and then applying f.m. from an external source.
12243 Monitoring Arrangements
1.2.4
А moving-coil microammeter on the front panel, used in con-
junction with a crystal rectifier, continuously monitors Ше r. f. input
to the attenuators when à spring-loaded key-switch is in the normal
position; the two alternative positions are for reading f.m, deviation
and a.m. depth respectively, the former by the measurement of the
а.ї. modulating voltage injected into the reactor valve and the latter
by similarly checking the a.f, voltage being applied via the h, $, -feed
circuit to the screen of whichever multiplier is operating ав modulator
stage, The design of the modulation monitoring circuits is such that,
with the Signal Generator set up for simultaneous а, т. and f.m., both
percentage depth and deviation can be read independently.
Power Unit
А full-wave rectifier provides positive 4, с. h,t. requirements;
in the case of the reactor and г, Е, oscillator valves, the h.t. is
stabilized by means of à gas-filled regulator tube, A negative supply
for the reactor-valve bias is drawn from a voltage-doubling circuit
employing à double-diode valve and a gas-filled stabilizer. The
primary of the transformer is tapped to allow for operation from 100
to 150 volts or 200 to 250 volts, and adequate r,f. filtering is
introduced into the а.с. input circuit.
м.І, Ltd, -4-
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2,2
2,3
ОМ 995А/2
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ОРЕВАТТОМ
INSTALLATION
Unless otherwise specified, the Signal Generator is normally
despatched with its valves in position and with its mains input circuit
adjusted for immediate use with а 240-volt, 40- to 100-c/s mains
supply. The instrument can be adjusted for operation from any other
40- to 100-c/s supply voltage in the ranges 200 to 250 and 100 to 150
volts. To check or alter the settings of the mains transformer tappings,
the user should refer to MAINTENANCE - Section 4.3.
SWITCHING ON AND WARMING UP
Before switching ON, be quite sure that the instrument is
correctly adjusted to suit the particular mains supply to which it is to
be connected, The proceed as follows:-
(1) Connect the mains lead - stowed in the left-hand case-handle
recess - to the mains supply socket.
(2 Switch ON by means of the SUPPLY switch; the red pilot lamp
should now glow.
(3) Before proceeding further, allow а short time - say five minutes
- to elapse for the internal circuits to warm up. Ifa particularly
high standard of frequency stability is required, this time should
be increased to about 30 minutes,
CONNECTING TO THE EQUIPMENT UNDER TEST
The r.f. output from the Signal Generator is derived via а
permanently-attached coaxial cable fitted with à free plug; the cable
is stowed in the right-hand case-handle recess.
The separate dual-output-impedance TERMINATING UNIT has a
fixed-socket inlet which mates with the free plug on the output cable.
The outlets of the TERMINATING UNIT are fixed sockets of the same
type s
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2.3 (continued)
The 20-dB ATTENUATOR PAD, available as an optional accessory
for insertion between the output cable and the TERMINATING UNIT when
low outputs are required, has a similar fixed socket at its input end and
fixed plug at its output end,
The free plug, Belling-Lee Type L734/P, fitted to the output
cable mates with the following types of Belling-Lee coaxial-socket
connectors; -
Free Socket, Туре L734/J
Fixed Socket, Type L604/S (ZC 29611)
Fixed Socket, Type L734/S
Free plug-to-socket adaptor, Type L616, (This item
allows the mating of two free plugs)
The fixed sockets on the TERMINATING UNIT are Belling-Lee
Type L734/S and mate with the following types of Belling-Lee coaxial-
plug connectors:-
Free Plug, Type L734/P (ZC 36219)
Free Plug, Type L781/P
2,4 TUNING
The various aspects of tuning the Generator are dealt wëh in the
following sections.
General tuning: Section 2.4.1.
Standardizing frequency against crystal oscillator; Section 2, 4,2,
Use of incremental frequency controls; Section 2, 4, 3,
Interpolation of main frequency scales: Section 2,4, 4,
2.4.1 General Tuning
The TF 995A/2 covers the range 1, 5 to 220 Mc/s in five bands
as follows:-
1,5 to 13,5 Мс/в
13.5 to 27 Mc/s
27 1054 Mc/s
54 to 108 Mc/s
108 to 220 Mc/s
М.І, Ltd, “а
ОМ 995А/2
2 - 4/59
2.4.1 (continued)
The particular band required is selected by means of the RANGE
switch. Rotation of the TUNE control varies the output frequency within
the limits of the band selected, and moves the main dial relative to its
cursor,
The Signal Generator has a built-in crystal calibrator, and the
cursor of the main tuning dial is mounted so that its angular position
relative to that of the dial is variable over a small arc by movement of
a milled boss at the centre of the dial, This movable cursor enables
the operator to standardize the frequency scale of the Signal Generator
at апу time; the cursor is used in conjunction with the crystal calibrator
in the manner described in Section 2.4.2.
In addition to the RANGE switch and the TUNE control, the
instrument is fitted with a directly-calibrated incremental-frequency
control; the method of using this control is described fully in Section
2.4.3. Section 2. 4. 4 deals with the method of interpolating between
main dialmarkings by means of the linearly calibrated dial on the
TUNE control.
2.4.2 Тһе Crystal Calibrator and its Use in Standardizing the Frequency Scale
(а) Introduction
The calibrator, or crystal oscillator, has а fundamental frequency
of 333,3 kc/s, with an accuracy of 2 parts іп 107, and is coupled to the
basic 4,5- to 9, 16-Mc/s r.f. oscillator which feeds the multiplier chain.
Plugging a pair of high-resistance head telephones into the CRYSTAL
CHECK jack socket automatically brings the calibrator circuit into use;
with the aid of the headphones, the difference frequency between the
basic oscillator and the harmonic multiples of the calibrator's 333.3
kc/s can be monitored aurally.
Because the outputs on the four higher-frequency bands are all
derived directly from the multiplier chain, their frequencies have an
exact integral relationship to the frequency of the basic oscillator, It
follows, therefore, that setting the TUNE control to bring the basic-
oscillator frequency to that of a crystal harmonic will also bring the
frequency of the outputs from the multiplier cbain to à known relation-
ship with the crystal harmonic, and allow the frequency dialto be
standardized with a high degree of accuracy.
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2.4.2 (continued)
Outputs on the lowest-frequency, 1.5- to 13, 5-Mc/s, band are
not derived directly from the multiplier chain; their generation
involves а heterodyne action between the 27- to 54-Мс/в multiplier
and a 30-Mc/s fixed oscillator which is not locked to the basic
oscillator. For this reason, although use is made of the crystal
calibrator when setting up for 1,5- to 13, 5-Mc/s outputs, the accuracy
of standardization is of a lower order than that obtained on the four
higher -frequency ranges.
(b Check-Point Frequencies
The calibrator provides a total of 56 check points between 13,5
and 220 Mc/s; these check points occur as follows: -
13.5 - 27 Mc/s band: At 14, 15, and 16 Mc/s, and every
calibration point which is a multiple of
LME sa, Чо С Метев:
21 - 54 Mc/s band: At 28, 30, and 32 Mc/s, and every
calibration point which is a multiple of
2 Mc/s, to 54 Mc/s.
54 - 108 Mc/s band: At 56, 60, and 64 Mc/s, and every
calibration point which is a multiple of
4 Mc/s, to 108 Mc/s.
108 - 220 Mc/s band: At112, 120, and 128 Mc/s, and every
calibration point which is a multiple of
8 Mc/s, to 216 Mc/s,
(с) Standardization Procedure
As shown above, the calibrator allows the frequency scale to be
checked at 14 different points on each of the above bands, and the
adjustable cursor can be set to correspond exactly with any one of
these points.
When the Signal Generator is to be used above 13.5 Mc/s to
provide an output at a single spot frequency, or over a narrow band of
frequencies, the cursor should be set up at the nearest crystal check
point,
M,I. Ltd, ий»
ОМ 995A/2
2 - 4/59
2.4.2 (continued)
When the Signal Generator is to be used over а wide range of
frequencies, and it is inconvenient to reset the cursor for each
material frequency change, or, alternatively, when using the 1.5- to
13. 5-Mc/s band, the procedure is varied to reduce the mean error to
a minimum. The method of standardizing the frequency scale for
subsequent general use is as follows:-
(1) Set the INC, FREQ, control to zero.
(2) Set the RANGE switch to 13,5 - 27 Mc/s.
(3) Using the headphones plugged into the CRYSTAL CHECK jack
socket, tune the main dial to a crystal check point near the
centre of the band; e.g., 20 Mc/s,
When using the calibrator, the MOD SELECTOR must be set to
a position other than INT MOD - F.M. or EXT MOD -F,M. This
ensures that the variable oscillator is not being frequency modulated
- a condition which prevents precise setting of the TUNE control for
the lowest-frequency beat note in the headphones, since it gives rise
to a fluctuating tone.
After using the calibrator, the Signal Generator can, of course,
be subsequently set up for f,m, without invalidating any frequency
calibration previously given by use of the calibrator.
(4) Adjust the milled boss in the centre of the dial to bring the
cursor exactly in line with the calibration mark corresponding
to the crystal check point.
If the Signal Generator has been out of use for some time, it
may be necessary to use a coin in the slot provided in order to rotate
the milled boss.
(5) Check the calibration accuracy at several crystal check points
both above and below the check point at which the cursor was
set in (4) above.
(6) ^ Readjust the cursor setting to equalize the errors over the band;
e.g», it might be found that, with the frequency scale indication
correct at 20 Mc/s, the indication was high at both 15 and 25 Mc/s
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2,4,2 (continued)
- in such a case, the errors would Бе equalized by making the
indication a little low at 20 Mc/s, and thus not so high at 15 and
25 Mc/ 8,
It will be noted that, in the above procedure, the frequency scale
is standardized on the 13,5- to 27-Мс/в band, This band is specified
since its corresponding scale calibrations occupy the longest arc on the
dial. The dial can therefore be read with a high degree of discrimin-
ation on this band and the correct cursor setting most easily determined,
Once the frequency scale has been standardized on the 13,5- to 27-Mc/s
band, the cursor is correctly set to give the minimum mean error on
the other three direct-multiple bands, It is also correctly set for the
1.5- to 13, 5-Mc/s band.
When standardized in this way, the main tuning dial indication for
frequencies above 13,5 Mc/s is accurate to at least 1%, and will
generally be within 0. 5%; for frequencies below 13.5 Mc/s, the
average error does not exceed 3%.
2.4.3 The Incremental Frequency Control
This control provides а convenient means of producing small,
accurately known changes in carrier frequency. Since it is not connected
directly to the r.f., oscillator, either mechanically or electrically, but
operates by varying the d.c, voltage at the grid of the reactor valve,
the control 18 completely free from any sort of backlash, This
attribute, together with the directly calibrated scale, renders the
control very suitable for bandwidth or similar measurements.
To use the controls proceed ав follows: -
(1) With the INC, FREQ. dial set to its centre zero position, tune
the Signal Generator to the centre frequency of the equipment
under test by means of the TUNE control.
(2) Rotate the INC, FREQ. control by the amount necessary to
produce the required frequency shift or the required change in
response depending on the method of measurement,
The scale of the INC, FREQ, dial is direct-reading on the
13.5- to 27-Mc/s band. For each of the other bands, a multiplying
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ОМ 995А/2
2 - 4/59
2.4.3 (continued)
factor must be applied, the appropriate factor for each frequency
band is engraved on the front panel adjacent to the RANGE switch
marking. The multiplying factors are also given below in TABLE 1,
TABLE 1
RANGE Multiply
switch Total coverage INC, FREQ.
Setting of INC, FREQ. dial readings
(Mc/s) control (kc/s) by
tie - 13.5 +100 2
EX 727 +50 1
21 - 54 i100 2
54 -108 +200 4
108 - 220 +400 8
2,4,4 The Interpolating Dial
The TUNE control knob is fitted with a small dial calibrated
linearly from 0 to 100 over its total circumference and makes
approximately 17 revolutions as the main dial is turned through its
complete angle of rotation.
This dial may be used to subdivide linearly any portion of the
frequency coverage оп any band in order to tune accurately to а
frequency above 13. 5 Mc/s which does not coincide with a crystal
check point. The method of using the dial for this purpose is des-
cribed in the following instructions; -
(1 Set the INC, FREQ. control to zero.
(2 Set the RANGE switch to whichever of the four higher-frequency
bands includes the required frequency.
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2.4.4 (continued)
(3)
(4)
Tune the Signal Generator to the nearest crystal check point
below the required frequency, identify the point with the aid of
the CRYSTAL CHECK oscillator and note the interpolating dial
reading. :
Tune the Signal Generator to the nearest crystal check point
above the required frequency and note the change of reading of
the interpolating dial. It is important that the total change is
noted when the dial is turned through more than one revolution,
The relationship should be determined between the crystal check
points which embrace the particular section of the frequency band over
which incremental variations are to be made. Also, the relationship
should be redetermined for each different section of the frequency band,
since it varies, not only from band to band, but also for different sections
of any one band.
(5)
(6
(7)
From the difference in frequency between the two crystal check
points, and the total interpolating dial divisions traversed,
calculate the frequency change per interpolating dial division.
With the aid of the headphones, reset the main tuning dial to the
crystal check point below the required frequency.
Rotate the TUNE control so that the interpolating dial traverses
the correct number of divisions to give the required frequency.
It is recommended that the required frequency should always be
approached from the low-frequency side in order to eliminate the
possibility of error due to backlash,
The following example illustrates the use of the interpolating dial
to obtain an output from the instrument at an accurate frequency of
74,25 Mc/s.
Example: With the TUNE control set to the crystal check point at 72
Mc/s, the interpolating dial reading was 17, With the
TUNE control set to the crystal check point at 76 Mc/s the
new reading on the auxiliary dial was 40. The total number
of interpolating dial divisions traversed was 123, the dial
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2.4.4 (continued)
having rotated through slightly more than one revolution for
the frequency change of 4 Mc/s, i.e. 4,000 kc/s. In this case,
a change of 1 division on the interpolating dial corresponded,
between 72 and 76 Mc/s, to à nominal frequency change of
$000 - 32.5 kc/s
123
Therefore, by starting from the original auziliary dial setting
at 72 Mc/s (72, 000 kc/s) the required frequency of 74,25 Mc/s
(14,250 kc/s) was obtained by rotating the auxiliary dial through
74,250 - 72,000 . 2250
32.5 32,5
= 69 divisions
The interpolating dial can also, of course, be calibrated in kc/s
per division for any portion of the 1, 5- to 13, 5-Мс/ѕ band. Crystal
check points cannot be used on this band, but the movement of the
auxiliary dial for any frequency interval can be determined against the
appropriate main dial calibration markings, and accurate interpolation
between these marks carried out as previously described for the
higher-frequency ranges,
SETTING UP FOR CONTINUOUS WAVE OR MODULATED OUTPUT
The Signal Generator includes facilities which allow the
following types of r.f. output to be obtained; -
(1) Continuous Wave (see Section 2. 5. 1)
(2 Amplitude Modulated (see Section 2.5.2), variable to 50%
depth,
(a) from the internal a.f. oscillator at 1, 000 c/s,
(b from an external sine-wave source, within the range
50 c/s to 10 kc/s,
(3 Frequency Modulated (see Section 2.5.3), variable to maximum
frequency deviations ranging from 25 kc/s to 600 kc/s,
M, LA Ltd, -13-
245,1
2.5.2
ОМ 995А/2
2 - 4/59
(continued)
(a) from the internal a.f, oscillator at 1, 000 c/s;
(b) from an external sine-wave source, within the range
50 c/s to 15 kc/s.
(4 Simultaneously Frequency and Amplitude Modulated (see Section
2.5.4), the Amplitude Modulation being obtained from the inter-
nala.f. oscillator, апа the Frequency Modulation from an
external source as (3) (b), above.
When setting up for amplitude or frequency modulation as des-
cribed in Sections 2,5,2 and 2,5,3, it may be observed that, with the
METER READS key held to either А.М. or Ғ,М., as applies, the
apparent modulation ав measured on externalapparatus is less than
that indicated on the meter, This is quite in order; the meter indicates
the modulation which will be obtained when the switch is returned to its
central position and the meter reverts to its normal function of monitor-
ing the r, f. level.
Continuous Wave
(1) Set the MOD SELECTOR switch to C. W.
(2 Adjust the SET CARRIER control to bring the meter pointer to
the SET R, F, mark.
Amplitude Modulation
(a) From the intern^l oscillator
(1) Set th; MOD SELECTOR switch to INT MOD - A. M,
(2 Adjust the SET CARRIER control to bring the meter
pointer to the SET Б,Е, mark.
(3 With the METER READS key switch held in the A, M,
position, adjust the SET MOD control to the required
modulation depth, as indicated on the top scale of the
panel meter. Amplitude modulation is variable to a
maximum depth of 50%.
м, 1, Ltd, Elda
ОА 995А/2
2 - 4/59
2.5.2 (continued)
(4 Release the METER READS key switch and, if necessary,
repeat (2) above,
(b From ап external a,f, source
(1) Set the MOD SELECTOR switch to EXT MOD - A.M.
(2 Adjust the SET CARRIER control to bring the meter
pointer to the SET В.Е. mark.
(3 Connect the external modulation source to the EXT MOD
and E terminals.
(1 With the METER READS key switch held in the А.М.
position, adjust the SET MOD control to the required
modulation depth, as indicated on the top scale of the
panel meter. With the SET MOD control at maximum,
an input of approximately 15 volts r.m.s. is required
at the EXT MOD and E TERMINALS to produce 30%
modulation depth within the modulation frequency range
50 c/s to 10 kc/s.
(5 Release the METER READS key switch and, if necessary,
repeat (2) above.
2.5.3 Frequency Modulation
In addition to the MOD SELECTOR switch, there are three other
controls concerned in setting up the carrier deviation when the output
from the Signal Generator is to be frequency modulated, These controls
are the continuously-variable SET MOD potentiometer, the DEVIATION
RANGE switch, and the DEVIATION - NORMAL/HIGH switch, When
the METER READS key switch is held to F, M., the panel meter indicates
deviation, The meter has two deviation scales: one calibrated from 0
to 25. kc/5s, and the other from 0 to 75 kc/s.
With the DEVIATION - NORMAL/HIGH switch set to NORMAL,
the meter scale appropriate to the setting of the DEVIATION RANGE
Switch is used and the deviation is ав indicated by the meter for all
settings of the carrier-frequency range switch.
M.I. Ltd, -15-
j
2,5,3
(continued)
OM 995A/2
2 - 4/59
With the DEVIATION-NORMAL/HIGH switch set to HIGH, the deviation
obtained on the 13. 5- to 27-Mc/s band is the same as with the switch set
to NORMAL, For all other carrier-frequency bands the deviation is in-
creased and the meter readings - again, taken on the scale appropriate to
the settings of the DEVIATION RANGE switch - must be multiplied in
accordance with TABLE 2 below.
TABLE 2
Carrier
frequency RANGE DEVIATION
DEVIATION - NORMAL/HIGH switch
is set to HIGH
switch setting RANGE switch Multiply meter Maximum deviation
(Mc/ s) setting (kc/ s)
( 25
> 13.5 (
(ms
ЖИА;
pus - 27 (
(75
0 25
ВТ - 54 (
(КТБ
25
54 - 108 (
( 75
Dian
108 - 220 (
( 3
reading by obtainable (kc/s)
à 50
2 150
1 25
1 5
2 50
2 150
4 100
4 300
8 200
8 600
The example given overleaf shows the method of determining the
meter reading for а required deviation which is greater than 75 kc/s and
thus necessitates setting the DEVIATION - NORMAL/HIGH switch to
HIGH,
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2.5.3 (continued)
Example:
la) E.M.
(1)
(2)
(3)
(4)
(5)
M, I, 144,
ОМ 995А/2
2 - 4/59
A deviation of 160 kc/s is required at a carrier frequency
of 80 Mc/s. The carrier frequency lies within the 54- to
110-Mc/s band. The meter multiplying factor for this
band is 4; therefore, for 160 kc/s deviation, the meter
should be set (by means of the SET MOD control) to read
160 . 49 kc/s
4
Do this on the bottom scale of the meter with the
DEVIATION RANGE switch set to 75 kc/s.
from the internal oscillator
Set the MOD SELECTOR switch to INT MOD - F.M.
Set the DEVIATION RANGE switch ав required. If, at
carrier frequencies less than 13. 5 Mc/s, or greater than
27 Mc/s, more than 75 kc/s deviation is required, set
the DEVIATION - NORMAL/HIGH switch to HIGH.
(Deviations greater than 75 kc/s are not obtainable on the
13, 5- to 27-Mc/s carrier-frequency band, the maximum
deviations obtainable on the other carrier-frequency bands
are given earlier in TABLE 2).
Adjust the SET CARRIER control to bring the meter
pointer to the SET R.F. mark,
With the METER READS key switch held їо F.M., adjust
the SET MOD control until the required deviation is
indicated on the panel meter; read the meter on its
middle scale when the DEVIATION range switch is set to
25 kc/s, and read on the lower scale when the switch is
set to 75 kc/s. If the DEVIATION - NORMAL/HIGH
switch is set to HIGH, the meter readings must be
multiplied by the appropriate factor given in TABLE 2.
Release the METER READS key switch and, if necessary,
repeat (4) above.
MT.
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ОМ 995A/2
2 - 4/59
2.5.3 (continued)
(5) Е.М, from an external source
(1) Set the MOD SELECTOR switch to EXT MOD - Е, М,
(2) Set the DEVIATION RANGE switch as required. Ifat
carrier frequencies less than 13,5 Mc/s, or greater than
27 Mc/s, more than 75 kc/s deviation is required, set the
DEVIATION - NORMAL/HIGH switch to HIGH. (Deviations
greater than 75 kc/s are not obtainable on the 13.5- to
27-Мс/в carrier-frequency band; the maximum deviations
obtainable on the other carrier-frequency bands are given
earlier in TABLE 2).
(3) Adjust the SET CARRIER control to bring the meter pointer
to the SET R, F, mark.
(4 Couple the external modulation source to the EXT MOD and
E terminals,
(5 With the METER READS key switch held to F,M., adjust the
` БЕТ MOD control until the required deviation is indicated on
the panel meter; read the meter on its middle scale when
‚the DEVIATION RANGE switch is set to 25 kc/s, and read
on the lower scale when the switch is set to 75 kc/s, If the
DEVIATION - NORMAL/HIGH switch is set to HIGH, the
meter readings must be multiplied by the appropriate factor
given in TABLE 2,
For any settings of the DEVIATION RANGE and DEVIATION -
NORMAL/HIGH switches, and within the modulation frequency range
50 c/s to 15 kc/s, approximately 25 volts г. па, 5. is required between
the EXT MOD and E terminals for full deviation. With respect to 1
kc/s, the frequency characteristic of the modulation system is flat to
within +1 dB from 50 c/s to 15 кс/в,
2.5.4 Simultaneous Frequency and Amplitude Modulation
(1) Set up the required depth of amplitude modulation as detailed
in Section De De 2 (а).
М.І, 144, -18-
ОМ 995А/2
2 - 4/59
2.5.4 (continued)
2.6
(2 Leaving the MOD SELECTOR switch at INT MOD - А, M., and
without altering the setting of the SET MOD control, set up the
required deviation in à similar manner to that detailed in Section
2,5,3(5)) in this case, adjust the amount of deviation by variation
of the audio input from the external modulation source.
R,F, OUTPUT ARRANGEMENTS
Five factors affect the output level from the Signal Generator;
these factors are:
(à) Тһе SET CARRIER control whose setting determines the
input level to the attenuator cascade.
(b The "coarse" or OUTPUT VOLTAGE attenuator,
(c) The "fine" or MULTIPLY BY attenuator.
(d) The TERMINATING UNIT which plugs on the end of the
output cable from the fine attenuator,
(e) ATTENUATOR PAD Type TM 4736, which is an optional
accessory designed for insertion between the output cable
and TERMINATING UNIT when especially low output
levels are required.
The SET CARRIER control is adjusted in conjunction with the panel
meter; with the METER READS key switch in its central position, the
panel meter íorms part of à crystal voltmeter which monitors the input
to the coarse attenuator. The panel meter has three main marks оп its
scale; these marks are minus 1 dB, SET R, F., and plus 1 dB respect-
‘ively. Normally, the SET CARRIER control should be adjusted to bring
the meter pointer to the SET Б.Е, mark.
Four 20-dB steps give the coarse or OUTPUT VOLTAGE attenuator
a totalrange of 80 dB; each setting of the attenuator control has markings
in red and in white, The red markings are in terms of decibels relative
to l pV; the white markings are directly in units of voltage.
M.L Ltd. 7195
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(continued)
Ten 2-dB steps give the fine or MULTIPLY BY attenuator a total
range of 20 dB; each setting of the attenuator control has markings іп
red and white, the red markings being in terms of decibels relative to 1
pV, and the white markings, multiplying factors for the white voltage
markings on the coarse attenuator.
Both attenuators have а characteristic impedance of 75 ohms and,
"looking into" the coaxial plug at the end of the output cable, the
instrument appears ав а generator with a source impedance of 75 ohms,
The TERMINATING UNIT is, essentially, а 6-dB attenuator pad;
"looking into" its input socket, the TERMINATING UNIT presents an
impedance of 75 ohms, while the two outlets present impedances of 52
and 75 ohms respectively.
The ATTENUATOR PAD has а characteristic impedance of 75 ohms
and provides an optional, additional, 20-dB attenuation of the output
signal.
It should be noted particularly that the r. f, output controls on the
Signal Generator are calibrated in terms of source e.m, f. or open-
circuit output voltage. The significance of quoting the output соға
signal generator in this way will be apparent when it is remembered
that one of the primary functions of a signal generator is to simulate a
received signal as it would come from an aerial.
To take а simple case - that in which а 75-ohm receiver is fed
from а 75-ohm dipole, the e. m. f, induced in the aerial is shared between
its inherent 75-ohm radiation resistance and the matched 75-ohm receiver
input. Clearly, when the same receiver is fed from a signal generator,
the corresponding signal strength is given by the source e.m, f. of the
signal generator, and not by the on-load p.d. at the receiver terminals.
Outputs from l pV to 100 mV at 52 and 75 ohms
It is intended that the Signal Generator should normally be used
with the SET CARRIER control adjusted to bring the meter pointer to
the SET В.Е. mark; with the TERMINATING UNIT coupled directly to
the output cable; and, without the ATTENUATOR PAD Type TM 4736,
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2.6.1 (continued)
Used in this way, the Signal Generator should be regarded аз а
source of zero impedance in series with à resistance of either 75 ohms
от 52 ohms, the open-circuit output level, or source e.m.f., being
variable in 2-dB steps from 1 pV to 100 mV and being given
(а) directly in terms of decibels relative to 1 рУ, by the sum
of the "red" settings of the OUTPUT VOLTAGE and
MULTIPLY BY attenuators;
(b) directly in voltage, by the product of the "white" settings
of the OUTPUT VOLTAGE and MULTIPLY BY attenuators,
The plus 1-4В and minus l-dB marks on the panel meter allow
interpolation between the 2-dB steps of the MULTIPLY BY attenuator.
Setting the meter pointer to either the plus 1-dB or minus l-dB mark
increases or decreases the input to the attenuator cascade by 1 decibel.
Thus, using the SET CARRIER control and panel meter in conjunction
with the OUTPUT VOLTAGE and MULTIPLY BY attenuators, the out-
put level from the Signal Generator can be varied in 1-dB steps over
the range 0 to +100 dB relative to 1 ВУ,
It should be noted that the "white" voltage indication given by the
attenuator controls is not directly applicable when the meter is set to
other than the SET В.Е, mark; with the meter at minus 1 dB, the
source e.m.f, at the TERMINATING UNIT outlets is 0,89 of the indi-
cated voltage; with the meter at plus 1 dB, the source е. га, Е. is 1,12
of the indicated voltage.
2.6.2 Outputs from 2 p V to 200 mV at 75 ohms only
With the TERMINATING UNIT detached and with the meter at the
SET В.Е. mark, the output level obtained directly from the plug at the
end of the r.f, output cable is variable in the range 2 БУ to 200 mV and
is derived via à source impedance of 75 chms.
Under these conditions, the open-circuit level, or source e.m. f.,
in terms of decibels relative to 1 НУ is obtained by adding 6 dB to the
sum of the meter reading and the "red" indications of the OUTPUT
VOLTAGE and MULTIPLY BY attenuators; the source e,.m.f. is
given directly in voltage by doubling the product of the "white" indi-
cations of the OUTPUT VOLTAGE and MULTIPLY BY attenuators.
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2.6.3 Outputs from 0. 1 pV to 10 mV at 52 and 75 ohms
With the TERMINATING UNIT coupled to the г. Е, output cable
via the optional 20-dB ATTENUATOR PAD and with the meter at the
SET R.F. mark, the output level from the TERMINATING UNIT is
variable in the range 0.1 pV (nominal) to 10 mV.
In this case, the source e.m.f, in terms of decibels relative to
1 БУ is obtained by subtracting 20 dB from the sum of the meter reading
and the "геа" indications of the OUTPUT VOLTAGE and MULTIPLY BY
attenuators; the source е. па, Е. is given directly in voltage by dividing
the product of the "white!" indications of the OUTPUT VOLTAGE and
MULTIPLY BY attenuators by 10.
2.6.4, Output in terms of volta ge developed across an external load
»
For some particular applications, it may be desired to work not
in terms of source e.m.f. as indicated by the meter and attenuator
controls, but in terms of actual voltage developed across the external
load, This on-load, or terminal voltage, is given by the expression
ZL
Mr = E Mi Sat Ge лд Wn es ала A ИИ,
Lo 21,
where Vy = actual voltage developed across the external load,
Е = the source e,m.f, of the Signal Generator.
21, = the impedance of the external load.
Zo = the source impedance of the Signal Generator;
(with the TERMINATING UNIT in use, 2, = 75 or 529;
‚with the TERMINATING UNIT removed, Zo = 75 Q)
The expression is based on the assumption that the external load
impedance Z, is essentially resistive. Where Z, is not essentially
resistive, it may be necessary for the user to revise the expression to
take account of the reactive component of the load.
A series of multiplying factors, which can be used to convert
from source e.m.f. to actual voltage developed across an external
resistive load, and which have been derived with the aid of the above
expression, are given in TABLE 3 for a selection of typical load values.
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2.6.4 (continued)
TABLE 3
Approximate multiplying factor to
External convert from source е, m. f., to actual
load voltage developed across an external
impedance resistive load
^ rmn 20 = 752 20 = 529
10 0, 12 0.16
20 0,21 0,28
30 0,29 0,36
40 9235 0, 43
50 0,4 0.49
52 0.41 0,5
60 0,44 0,53
10 0,48 0,57
(5 0,5 0.59
80 0,51 0, 61
100 0,57 0, 65
150 0.67 0,74
200 0.73 0.79
300 0,8 0,85
500 0, 87 0, 9
2.0.5 Matching to external loads other than 52 or 75 ohms
The TERMINATING UNIT supplied with the Signal Generator
allows r.f., outputs to be obtained from a source impedance of either
52 or 75 ohms.
If the equipment under test has an input impedance of other than
52 or 75 ohms, and if it is required to present the equipment with a
signal derived from а matched source, then it is necessary to modify
the output arrangements of the Signal Generator. The simple modifi-
cations required are described in sub-sections (a) and (b) which
follow.
In these sub-sections it is assumed that the TERMINATING UNIT
is in circuit, and that the 20-dB ATTENUATOR PAD is out of circuit.
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2.6.5 (continued)
(а)
External load less than tbat of the TERMINATING UNIT outlet
in use.
The impedance presented to the load can be made equal to the
load impedance by shunting the TERMINA TING UNIT outlet with
а single resistor, Е where
LANZ
R = HOLD USA TEC E FACE A LR VIRES IR TB
5 20 - 21,
and where Zo = the source impedance of the Signal Generator
at the TERMINATING UNIT outlet in use.
the impedance of the external load,
Z1,
Under these conditions, the relationship between Esq the
e.m.f, indicated by the attenuator controls on the Signal
Generator, and Еш, the effective source e. m. f. presented
to the external load, is given by the expression
Rp 2o (Э)
В.
р
Example: 1615 required to provide а signal of 25 рУ effective
source e.m.f, ata source impedance of 20 ohms,
Esq = En х
Since the new source impedance is to be 20 ohms, the output is
taken from the 52-ohm outlet on the TERMINATING UNIT, the
52-ohm outlet being chosen in preference to the 75-ohm outlet
to obtain the minimum reduction from Egg to Ep»
From expression (2), the value of R,, to be connected in parallel
with the 52-ohm outlet of the TERMINATING UNIT is
52x20
52 - 20
32,598
From expression (3), the attenuator controls оп the Signal
Generator should be set to indicate
32,5 + 52
с
AD x 3225 5 pV
м, 1, 144, -24-
OM 995A/2
2 - 4/59
2.6.5 (continued)
The attenuators cannot be set to indicate exactly 65 pV and they
should therefore be set to 63 pV - the setting nearest to the
required value for Egg. 63 ВУ is approximately -0.3 dB
relative to 65 pV and, if desired, the user may obtain ап Есс
nearer to 65 pV by adjustment of the SET CARRIER control to
bring the meter pointer to an estimated + 0, 3 ав.
As а result of shunting the cutput of the TERMINA TING UNIT with
32, 5 ohms and setting the attenuator controls in the manner
described, the equipment under test is fed from à source whose
effective output impedance is 20 ohms and whose effective source
e.m.f, is 25 uV; the actual voltage developed across the input
impedance of the equipment under test is, of course, 12.5 p V.
(b External load greater than that of the TERMINA TING UNIT outlet
in use.
The impedance presented to the load can be made equal to the
load impedance by connecting а single resistor, Rg, in series
with the Signal Generator output, The value of Rg is given by
the expression
Кс = 21, y Zo A A важи (63
where “т = the impedance of the external load,
Zo Ше source impedance of the Signal Generator
at the TERMINATING UNIT outlet in use,
Under these conditions, the effective source е, m. f. (Ep) of
the Signal Generator and series resistor combined, equals the
source e,m, f. (Egg) of the Signal Generator alone,
і.е., Esa = ЕЕ Фофовосволосвавовевововсавозвоа (5)
Example: It is required to provide a signal of 10 цу effective
source e,m.f, ata source impedance of 300 ohms.
Since the new output impedance is greater than
either 52 or 75 ohms, there is no advantage to be
gained by using one of the TERMINATING UNIT
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2.6.5 (continued)
outlets in preference to the other; in this example
it is assumed that the 75-ohm outlet is used.
From expression (4) the value of Rg to be connected
in series with the "live!" connection between the
Signal Generator and the equipment under test, is
300 145 0225 0
From expression (5), the attenuators on the Signal
Generator should be set to indicate
10 юу |
In this way, the equipment under test is fed from а
source whose effective impedance is 300 ohms and
whose effective source e.m,f. is 10 pV; the actual
voltage developed across the input impedance of the
equipment under test is, of course, 5 LV.
2.6.6 Matching to balanced loads
The preceding Sections dealing with г, f. output arrangements are
based on the supposition that the equipment being fed from the Signal
Generator has an unbalanced input circuit.
With certain types of equipment, the input circuit is in the form
of à balanced winding; such equipment can be fed from the unbalanced
output of the Signal Generator by interposing two loading resistors
between the TERMINA TING UNIT outlet and the ends of the balanced
input winding.
One resistor, R,, is connected in series between the earth
connection of the TERMINATING UNIT outlet in use and one side of
the balanced winding; the other resistor, Ко, is connected in series
between the "Пуе" connection of the TERMINATING UNIT outlet in use
and the other side of the balanced winding.
Values for Rj and R, may be computed from the following
expressions
ZLB
Кү = >
4.%4.0%сцө% е Өө 94 ооо ооо с 0.40 6.0. (6)
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2 - 4/59
2.6.6 (continued)
сінен са - Zo %%%%%е%ғеееегочвевеееоеееоееееееееа (7)
Boer
where “ір = the total line-to-line impedance of the balanced winding.
2, = the source impedance of the Signal Generator at the
TERMINA TING UNIT outlet in use.
With the equipment under test and the TERMINATING UNIT of
the Signal Generator interconnected via Rj and R, as described above,
the source e, m. f. (Egg) indicated by the Signal Generator controls is
equal to the effective line-to-line source e.m.f. (Er) seen by the
equipment under test,
Example Itis required to match the 75-ohm outlet to a balanced
winding whose total line-to-line impedance is 200 ohms.
From expression (6), the value of Ry is
200 - 1000
2
From expression (7) the value of Ко is
200 . 75 - 250
2
Бү is connected in series with the earth connection
of the TERMINATING UNIT and one side of the
balanced winding; R2 is connected in series with
the "live!" connection between the TERMINATING
UNIT 2nd the other side of the balanced winding.
SYNCHRONIZING SIGNAL
А 1,000-c/s sine wave signal, derived from the internal a, f.
oscillator, is available between the SY NC and E terminals of the
instrument when the MOD SELECTOR switch is set at either of the
INT MOD positions, This signal has an open-circuit level of the
order of 100 volts and is derived via а source impedance of
approximately 250 КО,
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(continued)
When an output from the equipment under test is being viewed
on а cathode-ray oscilloscope, it will often be found convenient to lock
the с.г.о. time base directly with the SYNC signal rather than with the
actual signal being viewed,
The SYNC output can, of course, also be used when an audio
frequency signal is required for the equipment under test.
M, % 144, -28-
ОМ 995А/2
2 - 4/59
ABRIDGED OPERATING INSTRUCTIONS
When the user is familiar with the principles and techniques of
operation detailed in Section 2 of this handbook, the following abridged
operating instructions may be found convenient.
Carrier Frequency Range: 1,5 to 220 Mc/s
Source Impedance: Without TERMINATING UNIT, 752
With TERMINATING UNIT, 52 and
15 0
Open-circuit Output Voltage: Without TERMINATING UNIT, 200 mV
With TERMINATING UNIT, 100 mV
Modulation Frequency Range: Internal Е, М. and А. М., 1,000 с/з.
External F,M., 50 c/s to 15 kc/s.
External A.M., 50 c/s to 10 kc/s.
Modulation Range: Е,М,, DEVIATION switch at NORMAL,
0 to 25 kc/s and 0 to 75 kc/s;
DEVIATION switch at HIGH, varies
with frequency range up to 600 kc/s
on 108 to 220 Mc/s band,
А,М., 0 to 50%,
Power Supply: 100 to 150 volts, 40 to 100 c/s;
200 to 250 volts, 40 to 100 c/s,
Check correctness of mains transformer tappings before use
STANDARDIZING THE FREQUENCY SCALE
Switch mains ON and set RANGE MC/S switch to 13.5 - 27;
with MOD SELECTOR switch set to other than INT MCD - F, M.
or EXT MOD - F,M,, and using headphones plugged into
CRYSTAL CHECK socket, tune main dial to crystal check point
near centre of band, Bring movable cursor in line with dial
calibration corresponding to crystal check point. Check accuracy
of frequency indication above and below point to which cursor was
originally set, equalize errors over band by readjusting cursor.
For further details, refer to Section 2, 4.2.
м,1, Ltd. -29-
ОМ 995A/2
à - 4/59
(continued)
г. |. TUNING
me
Í
Nro Set RANGE MC/S switch to band roquired; rotate TUNE control
until cursor indicates required frequency. For higher
| Írequency-accuracy, compute rolationship of frequency change
Ws to change in auxiliary dial setting between crystal check points
| or scale markings embracing required frequency, Starting
2) from selected point below required frequency, rotato TUNE
Ne control so that incremental dial traverses calculated number of
| divisions,
For further details, refer to Sections 2,4,1 and 2, 4,4,
INCREMENTAL FREQUENCY ADJUSTMENT
Make small carrier changes by means of INC FREQ control,
using multiplying factors as shown on front panel,
Др For further details, refer to Section 2.4, 3.
C, W, OPERATION
p^ With MOD SELECTOR switch set to C, W, , adjust SET CARRIER
to bring meter pointer to SET R,F,; adjust step attenuators to
obtain required output level,
y For further details, refer to Section 2, 5, 1,
Me AMPLITUDE MODULATION
INTERNAL:
With MOD SELECTOR switch at INT MOD = A, М. , adjust SET
CARRIER to bring meter pointer to SET К.Е, With METER
READS switch at A, M, , adjust SET MOD to bring meter pointer
(0 to required modulation depth. Release METER READS switch
) W and, if necessary, readjust SET CARRIER; adjust step attenua -
ми, tors to obtain required output level.
M, I, Ltd, -30-
ОМ 995А/2
2 - 4/59
(continued)
EXTERNAL:
As for internal, except that MOD SELECTOR switch is set to
EXT MOD - А, M., and external signal injected between EXT
MOD and E terminals, Approximately 15 volts r. m. s, (50
c/s to 10 kc/s) is required to produce 30% modulation.
For further details, refer to Section 2.5.2.
FREQUENCY MODULATION
INTERNAL:
With MOD SELECTOR switch at INT MOD - F.M., adjust SET
CARRIER to bring meter pointer to SET В.Е. With DEVIATION
- NORMAL/HIGH switch at NORMAL, and METER READS switch
at F.M., adjust SET MOD to bring meter pointer to required
deviation on meter scale appropriate to DEVIATION RANGE
switch setting. (For deviations greater chan 75 kc/s, set
DEVIATION - NORMAL/HIGH switch to HIGH and multiply
meter readings by factor given in TABLE 2, Section 2.5.3).
Release METER READS switch and, if necessary, readjust
SET CARRIER; adjust step attenuators to obtain required output
level,
EXTERNAL:
As for internal, except that MOD SELECTOR switch is set to
EXT MOD - Е, М, and external signal injected between EXT
MOD and E terminals, Approximately 25 volts rem. 5. (50 c/s
to 15 kc/s) is required to produce full deviation.
For further details, refer to Section 2,5.3.
SIMULTANEOUS FREQUENCY AND AMPLITUDE MODULATION
Set up as for AMPLITUDE MODULATION, INTERNAL, Then,
with MOD SELECTOR switch, still set at INT MOD - A.M.,
apply external signal (50 c/s to 15 kc/s) between EXT MOD and
E terminals. Adjust level cf external signal to produce required
deviation; do not readjust SET MOD control.
For further details, refer to Section 2, 5, 4,
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ОМ 995A/2
2 - 4/59
MAINTENANCE
GENERAL
The following items (for details see CONTENTS, page iv) are
included in this handbook to assist in the maintenance of the Signal
Generator Type TF 995A/2:-
Block Schematic Diagram,
Complete Circuit Diagram.
Component Layout Illustrations,
Spares Ordering Schedule with Circuit References,
Valve Replacement Data Sheets.
Section 1, DESCRIPTION, of this handbook deals with the internal
circuits of the Signal Generator and is intended to be read in conjunction
with the Block Schematic Diagram; it is strongly recommended that the
user should familiarize himself with the principles described in Section
1, and illustrated in the Diagram, before commencing the adjustment or
replacement of component parts of the instrument,
The complete Circuit Diagram shows all the electrical components
contained in the instrument, The description of these components -
their type, value, rating, etc. - is given in the Spares Ordering
Schedule; the Schedule also lists certain selected mechanical
components.
The physical location of the electrical components is shown on
the Component Layout Illustrations.
REMOVAL OF CASE
To remove the Signal Generator case:-
(1) Remove the screw securing the small plate in the left-hand side
pocket*; the mains lead is cleated to the case by means of this
plate.
(2) Extract the eight screws from around the edge of the front panel,
ж On earlier models, this plate is not fitted апа, instead, the
mains lead should be fed through the hole in the back of the
pocket as the instrument is withdrawn from its case,
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(continued)
(3) Pullthe instrument clear of its case and disconnect the six-way
interconnecting cable from the power unit chassis.
(4 Detach the screw, from the inside of the case, which holds the
cleating plate for the r.f. output cable to the right-hand side
pocket.
MAINS INPUT ARRANGEMENTS
The instrument is fitted with à mains transformer which has a
double-wound primary; each primary section is tapped and the two
sections can be connected in series-parallel for 100- to 150-volt
operation or in series for 200- to 250-volt operation.
The 100- to 150-volt or the 200- to 250-volt range is selected by
links on the coil of the transformer. Selection of intermediate voltages
within either range is made by means of fly leads on the transformer
tags. These tags are common to both ranges and are, therefore,
annotated with two voltages; the applicable voltage depends on the
position of the range links,
One fly lead must always be connected to either the 10! or the
110! tag; the other is connected to the tag whose voltage, added to 0
or 10 ав appropriate, equals the mains supply voltage. Do not
connect the fly leads to the tags marked TAP A or TAP E.
In order to examine the connections to the transformer and, if
necessary, make adjustments, the instrument must be removed from
its case in the manner described in section 4.2. With the instrument
out of its case, the transformer (Reference T4 on the Circuit Diagram
and Component Layout Illustration MP 995A/2-8) is immediately
accessible.
For Supply Voltages within the Range 200 to 250 volts, the tags
on the transformer MUST be linked in the following manner:-
ШАР АФ to "ТАР B"
For Supply Voltages within the Range 100 to 150 volts, the tags
on the mains transformer MUST be linked in the following manner:-
10! to 'TAP В!
1100/200! to "ТАР A!
M. I, Ltd, -33-
ОМ 995А/2
2 - 4/59
4,3 (continued)
On earlier models, the mains transformer is of slightly different
mechanical construction. It is identified by having a mains-tapping
plate fixed to its rear edge, Attached to this panel is a pierced refer-
ence plate which is reversible and marked with a selection of voltages,
On one side of the plate, the voltages are applicable to the 100- to 150-
volt range; on the other side, to the 200- to 250-volt range.
The two sections of the primary are connected together by means
of links soldered between tags, numbered 1-2-3-4, onan insulated
strip at the front of the transformer,
For 200- to 250-volt operation, link tag 2 to tag 3.
For 100- to 150-volt operation, link tag 1 to tag 2 and tag 3 to
tag 4,
4,4 ACCESS TO ENCLOSED SUB-ASSEMBLIES
General tests or some peculiarity in the performance of the
Signal Generator may suggest the desirability of inspecting the interior
of one of the enclosed sub-assemblies which form part of the instrument.
Any of these sub-assemblies can be dismantled by the appropriate
procedure as detailed in the following sections,
4.4.1 В.Е. Unit
То remove the screening cover from the r.f, unit;
(1) With the instrument removed from its case, lay it on its face,
(2) Extract the two screws which secure the screening cover of the
r.f, unit in position.
(3) Grip the sides of the screening cover and draw it off; the cover
is held by earthing contact springs and will consequently offer
some resistance to removal,
м. 1, Li, -34-
ОМ 995A/2
2 - 4/59
4,4,2 MULTIPLY BY Attenuator
A view of the MULTIPLY BY (fine) attenuator with the screening
cover removed is shown in the Component Layout Illustration MP 995A/2-7.
To dismantle the attenuator:
(1) Remove the attenuator screening cover after extracting the single
Securing screw,
(2 Remove the front-panel control knob after slackening the two grub
screws which secure it to its associated spingle.
(3 Detach the main body of the attenuator from the front panel by
extracting five screws; three of these screws are visible on
removal of the control knob ав in (2) above; the two remaining
Screws are located immediately above the 8-dB and 12-dB panel
markings respectively.
With the attenuator thus detached, it remains coupled to the body
of the instrument by two coaxialleads; these leads are normally long
enough to permit inspection and, if necessary, replacement of the
attenuator resistors without completely disconnecting the attenuator.
Reassemble the attenuator in the reverse order to that detailed
above,
4,443 OUTPUT VOLTAGE Attenuator and Monitor Crystal X2
In addition to the actual attenuator components, the r.f. monitor
crystal, X2, and its associated filter components are mounted in the
OUTPUT VOLTAGE attenuator casing. When dismantling the attenuator,
the user should refer to Component Layout Illustration MP 995A/2-7,
Access to the crystal, X2, resistors R71 апа R72, and capacitors C88,
C89 and C90 can be obtained by removing the cover of the attenuator in
the following manner:
(1) Disconnect R70 from the small insulated spigot projecting through
the cover of the attenuator,
(2 Remove the central securing screw and lift the screening cover
clear of the attenuator body.
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4.4.3 (continued)
To obtain access to the attenuator resistors, R73 to R82, detach
the attenuator from the front panel of the Signal Generator in the
following manner:-
(3) Remove the control knob by slackening the two grub screws
securing it to its spindle,
(4) Extract the five fixing screws securing the attenuator to the
front panel; three of these screws are immediately visible on
removing the control knob as in (3) above; the two remaining
screws are located immediately above and to the right of the
coarse-attenuator panel markings.
With the attenuator detached as in (4) above, it remains coupled
to the body of the instrument by two coaxial cables. These cables are,
however, long enough to permit inspection and, if necessary, replace-
ment of the attenuator-resistors without completely disconnecting the
attenuator,
Reassemble the attenuator in the reverse order to that detailed
above.
4.4.4 Mains Input Filter Unit
To gain access to the components comprising the mains input
filter:
(1) Remove the nut and screw which secure, atthe open end, the
two halves of the mains filter unit screening cover.
(2 Separate the push-fit screening channel from the fixed half of
the screening cover,
Reassemble the screening cover in the reverse order to that
detailed above,
M, I. Ltd. -36-
ОМ 995А/2
2 - 4/59
4,4,5 Power Unit
To remove the power unit from the instrument case:
(1) Remove, from the underside of the instrument case, the five
screws which engage with nuts along the front and left-hand
flanges of the power unit chassis,
(2) Holding the power unit with one hand, remove the remaining two
screws which engage with the tapped bushes on the right-hand
flange of the power unit,
Replace the power unit in the reverse order to that detailea above.
WORKING VOLTAGES
The voltages given in this section for guidance when servicing
the instrument were obtained from measurements ona representative
Signal Generator Type TF 995A/2; the voltmeter used hada resistance
of 20, 000 ohms per volt,
Mains Transformer, h.t. secondary: 250-0-250 Уа, с,
Mains Transformer, l.t. (rectifier); 5 V a.c.
Mains Transformer, l.t. (main): 6.3 MEC
Positive H,T.:-
Rectified (V11, pin 8): 300 N а. в.
Smoothed, НТІ, (across C62): 230 V d.c.
Stabilized, HT3, (V9, pin 5): 159 V dic.
Negative Н.Т, (junction of R 117)
and R118): 85 V d.c.
Valve electrode voltages are given in Table 4,
All voltages listed are with respect to chassis, and, except where
alternative instructions are given, should be measured with the MOD
SELECTOR switch set to INT MOD - A, M. , the RANGE МС/5 switch
to 108-220, the SET CARRIER controlto maximum, and the SET
MOD control to minimum.
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Valve No.
V1
V2
V3
v4
V5
V6
V7 (amp)*
У7(овс) *
V8
У10
V12
TABLE 4
Va
250
150
150
25
250
83
250
250
100
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100
ОМ 995А/2
2 - 4/59
* When checking V7 voltages, set
the RANGE MC/S switch to 1.5
T 13. 8,
** The cathode potential of V5 increases
to 40 volts when the MOD SELECTOR
switch is set to INT MOD - Е, М,
REPLACEMENT OF VALVES AND CRYSTALS
The types of valve used in the instrument, their base connections,
and some guidance as to suitable alternatives if the types originally
fitted are not readily available are given in the Valve Replacement Data
Sheets.
The valves and crystals may normally be replaced without
special selection.
Valves VI, V5, V9, У11, and V13 to V15 are
immediately accessible on removing the instrument from its case,
То gain access to the 333. 3-kc/s oscillator crystal, ХІ, and to the
remaining valves, remove the R, F, Unit screening cover, The
crystal rectifier, X2, forms part of the OUTPUT VOLTAGE attenuator
assembly and сап be removed by the procedure detailed in Section 4. 4, 3.
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(continued)
Replacement of valves or crystals may necessitate either the
reselection of associated components or readjustment of associated
preset controls; aspects о this reselection and readjustment are
discussed in Section 4,7 - Preset or Specially Selected Components.
PRESET OR SPECIALLY SELECTED COMPONENTS
In the manufacturing data for the TF 995A/2, certain of the
components are either specified as being of the preset type or
designated for individual selection, the setting or selection of the
components being carried out during the factory calibration of the
instrument; this is necessary since the operating characteristics of
the instrument have to conform to а quantitative specification including
maximum and minimum limits of permissible error.
The Description column of the Spares Ordering Schedule shows
which of the components are of the preset type; components which are
individually selected are distinguished in that column by a single
asterisk mark.
If, in servicing a ТЕ 995А/2, it is necessary to replace any of
these components, it is also necessary, if the performance or accuracy
of the instrument is not to be impaired, to repeat the factory calibration
procedure by which the components were originally selected.
Section 4,8 gives a range of tests by which the main points of the
performance of the instrument can be checked; this section also deals
with the adjustment of preset components and with the choice of value
for individually selected components.
It will be appreciated that it may sometimes be necessary to
reselect à selected component even though that component itself has
not been found faulty and replaced in initial servicing operations, То
take an example - the internal modulation oscillator is tuned by Т and
C6, In mamfacture, Сб is selected to give an oscillator frequency of
1,000 c/s %5%. In servicing the instrument it might be found that Tl
was faulty but that C6 was not. If Tl was replaced then it would be
quite likely that with the original C6, the oscillator frequency would be
outside the specified limits of +5% and that à new value of capacitance
would have to be chosen.
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It therefore follows that, in all servicing involving replacement of
components, the user should consider carefully the possible effects on
the performance of the stage or stage^ involved,
The table which follows lists the circuit reference numbers of both
types of component together with the numbers of the sections in which
their adjustment or selection is described,
TABLE 5
Section Describing Section Describing
Component Adjustment or Selection Component Adjustment or Selection
R2 4.8.12 R69 4.8.14
R5 4.8.10 R70 4.8.8
R6 4,8,10 R114 4.8.11
R7 4.8.10 R116 4,8,10
R8 4. 8.10 R124 4, 8, 20
R9 4.8.10 се 4.8.9
Ril 4, 8.10 G35 4.8.5
R12 4. 8.10 C40 4.8.7
R13 4,8,10 C47 4. 8.6
R14 4,8,10 C59 4.8.7
R19 4, 8.11 С66 4.8.6
R24 4.8.13 C76 4.8.6
R39 4.8.18 C83 4. 8.6
R50 4,8,11 Т2 4.8.5
R63 4, 8, 17 E3 4,8,6
R65 4, 8.14 L18 4. 8. 6
R66 4.8.14 122 4. 8.6
R67 4.8.14 1-23 4, 8,6
R68 4.8.14
SCHEDULE ОҒ TESTS
The following information, based on abstracts from the internal
Factory Test Schedule, is included to enable the user to carry outa
series of tests by which the main points of performance of the instru-
ment can be checked; it also gives details concerning the adjustment to
preset components and the choice of value for individually selected
components.
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2 - 4/59
4,8,1 Apparatus Required
4. 8.2
BN. D.
750-volt Insulation Tester,
Avo Meter, model 8,
Wave Analyser; Marconi Type TF 455 (Series).
Signal Generator, with standardized output;
Marconi Types TF 801 (Series) or TF 995 (Series).
Valve Voltmeter; Marconi Types TF 428 (Series),
TF 958, TF 1041 (Series), TF 1100, or TF 1300,
A.M, Communication Receiver, covering the range 1,5
to 220 Mc/s,
Not required.
1-MQ and $-MQ resistors,
Audio-Frequency Oscillator; Marconi Types TF 195
(Series), ТЕ 885 (Series), TF 894 (Series), or ТЕ 1101.
Cathode-Ray Oscilloscope.
Deviation Meter; Marconi Type TF 791 (Series).
For the F,M. оп C, W, check (Section 4, 8.20), where deviations
of less than 50 c/s have to be measured, it is essential that the
deviation meter should be modified to operate from battery
supplies or, incorporate facilities allowing its local oscillator
to be brought under crystal control.
Insulation (Apparatus required:- Item a)
Test the insulation between each pin of the supply plug апа
chassis with SK1 engaged with PL1. The reading should be not less
than 40 MQ,
M,I, Ltd. -41-
ОМ 995А/2
2 - 4/59
4.8.3 Hum Level (Apparatus requircd:- item c)
Measure the 100-c/s hum level using a weve anziyser isolated
from the TF 995А/2 by means of a suitable capacitor. The hum level
should not exceed 20 mV as measured at the H, T, 1 point.
4.8.4 Crystal Oscillator (Apparatus requimd:- Item е)
Plug head telephones into the CRYSTAL CHECK socket and turn
the TUNE control until an audio beat is heard; acjust tne core of LS
for maximum intensity of the audio beat note.
Measure the voltage across R27 witha valve voltmeter: it should
be between 8 and 10 volis
4.8.5 Basic Oscillator (Apparatus required:- Items e and f
Set the MOD SELECTOR switch to C, W, and the main tuning
dialto 27 Mc/s. Using 2 receiver as indicator, adjust C35 until the
circuit oscillates at 2,2 Mc/s. Set the main tuning dial to 13,5 Mc/s,
and adjust the core of TZ until the circuit oscillates г: 4.5 Mc/s,
Repeat these two adjustments.
Measure the r.f. voltages at the grid ard aroae of ¥3 using a
valve voltmeter. These should Бе of the following orders: -
4,5 Mc/s 0.0 Mc/s
Grid 2.2 wolts 4.9 volts
Anode 22 volts 35 volts
Recheck the tuning adiustments against f
of high-resistance headphones plugged into the СЕТ STAL CHECK
socket. Fourteer check points should be heard. Check that the
3
oscillator output: is maintained when the dial is set to 27.5 Mc/s.
4.8.6 Frequency Multipliers (Apparatus required:- Items!
(1) 13.5- to 27-Mc/s band
Set the МСО SELECTOR switch to С. W., the P ANGE switch to
13.5 - 27 Mc/s, ard the SET CARRIER control fiiy cicckwise:
3 E |
M,i. Ltd. Las
ОМ 995А/2
2 - 4/59
4.8.6 (continued)
Set the main dial to 13. 5 Mc/s, and adjust the core of T3 for
maximum deflection on the panel meter.
Set the main dial to 27 Mc/s,and adjust C47 for maximum
deflection on the meter.
Use the receiver to check that, at these two points, the stage is
operating at 13, 5 and 27 Mc/s respectively, and that the Signal
Generator tunes to 27. 5 Mc/s at the appropriate dial reading.
(2 27- to 54-Mc/s band
Set the RANGE switch to 27-54, and adjust C66 and the spacing
of the turns cf L18 at 54 and 27 Mc/s respectively for maximum
deflection on the panel meter.
Use the receiver to check that, at these two points, the stage
is operating at 54 and 27 Мс/в respectively, and that the Signal
Generator tunes to 55 Мс/в at the appropriate dial reading.
(3 54- to 108-Mc/s band
Set the RANGE switch to 54-108, and adjust C76 and the spacing
of the turns on L22 at 108 and 54 Mc/s respectively.
Use the receiver to check that, at these two points, the stage is
operating at 108 and 54 Мс/в respectively, ard that the Signal Generator
tunes to 110 Mc/s at the appropriate dial reading.
(4) 108- to 220-Mc/s band
Set the RANGE switch to 108-220, and adjust C83 and the spacing
of the turns on L23 for maximum reading on the TF 995A/2 output
meter at 216 and 108 Mc/s respectively.
Use the receiver to check that, at these two points, the stage is
operating at 216 and 108 Mc/s respectively, and that the Signal
Generator tunes to 220 Мс/в at the appropriate dial reading.
M.I. Ltd. xa ie
ОМ 995A/2
2 - 4/59
4.8.7 1,5- to 13.5-Мс/в Band (Apparatus required:- Item f)
This test must be made with the к,{. unit cover in position,
By means оға suitable jack plug, connect a pair of head tele-
phones to the CRYSTAL CHECK socket.
Set the RANGE switch to 1.5 - 13,5, and adjust the TUNE control
to bring the 30 Mc/s main dial marking (on the 27 - 54 Mc/s arc) to
the cursor; then, using the crystal calibrator, tune for zero beat,
With the SET CARRIER control in its fully clockwise position
adjust C40 and C59 alternately to give minimum deflection on the panel
meter. These capacitors are accessible through two holes, slightly
larger than the ventiletion holes, in the top of the r.f, unit cover.
Connect the output of the Signal Generator to à receiver, and
tune the receiver to some convenient accurately -known frequency
between 1. 5 and 13.5 Mc/s.
Set the main dial of the ТЕ 995A/2 to this frequency, and adjust
C40 for maximum receiver response.
In the absence of any other frequency standard, the receiver
tuning may be standardized at frequencies between 4.5 and 9 Mc/s by
loosely coupling its input to the basic oscillator of the TF 995A/2.
This oscillator should first be standardized against the internal crystal
calibrator, the basic-oscillator frequency being given by dividing by
three the indication on the 13,5 - 27 scale.
4.8.8 R,F, Output Voltage Accuracy (Apparatus Required:- Items d, е,
and 9)
This test should be carried out with the instrument in its case,
Using а receiver аз indicator, compare the output voltage with
that of a standardized signal generator. Ша constant error exists,
itis probably due to а faulty monitor diode X2. This diode should
have à backward resistance of 8 КО or greater when checked with а
Sensitive multi-range test meter, e.g., AvoMeter Model 8. If X2 is
replaced, it will be necessary to select a new value for R70 in order
to bring the output level within the limits of 0,89 to 1, 12 of nominal
up to 100 Mc/s, and 0.795 to 1.25 of nominal up to 220 Mc/s.
M,I, Ltd. | ae
ОМ 995А/2
2 - 4/59
4.8.8 (continued)
Check at the following frequencies and levels: 25 Mc/s, 100
Mc/s, and 220 Mc/s; 100 mV and 10 юу,
4,8,9 Modulation Oscillator (Apparatus required:- Items e, i, and j)
Set the MOD SELECTOR switch to INT MOD - A.M., connect
the output from the slider of the SET MOD potentiometer to the Y
plates of a cathode-ray oscilloscope ¿nd the output of an a, Е, oscillator
to the X plates, Check the frequency of oscillation by the lissajous-
figure method, and, if outside the limits of 950 to 1,050 c/s, selecta
new value for the tuning capacitor C6,
Measure the cutput voltage at the SY NC terminal with а valve
voltmeter, It should not be less than 100 volts.
4,8,10 F.M, Deviation (Apparatus required:- Item k)
Set the DEVIATION - NORMAL/HIGH switch to NORMAL, the
DEVIATION RANGE switch to 75 kc/s, the MOD SELECTOR switch to
INT MOD - F.M., and the SET CARRIER control to give a convenient
deflection on the TF 995A/2 output meter. Connect the output cable
directly to à carrier deviation meter; set the TF 995A/2 attenuator
controls to give maximum output; апа tune both instruments to 13,5
Mc/ s.
Depress the METER READS switch to F, M. , and adjust the SET
MOD controlto give à meter indication of 75 kc/s deviation. By
means of the carrier deviation meter, check that the deviation at 13,5
Mc/s is 75 kc/s +5% and that this accuracy is maintained at 27. 5 Mc/s,
If the deviation is outside this accuracy, retune the Signal Generator and
the deviation meter to 13.5 Мс/в, and select a value for R6 to give 75
kc/s deviation at this frequency.
Check that the deviation is within the limits stated at 27. 5 Mc/s.
If itis not, make slight adjustment to the angular position of the slider
of R7 (relative to that of the tuning gang) to obtain equal deviations at
13,5 Mc/s and 27,5 Мс/в. Subsequent slight re-adjustment of R6 may
then be necessary in order to maintain deviation accuracy.
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4, 8. 10 (continued)
Check the deviation on the 27- to 54-Mc/s band to the same
limits of accuracy as for the lower band. If it is outside these limits,
measure the values of resistors R6, R115, and R116; let their sum be
termed Кт.
Select values for R13 and R14, equal іс Вт and 2Е 1 respectively,
and make smalladjustments to these values to obtain 75 kc/s deviation
at 27 Mc/s. Check that this deviation is maintained at 55 Mc/s.
Check the deviation accuracy on the 54- to 108-Mc/s band, If
it is outside the limits stated select a value for R11 equal to 3&т anda
value for БЭ equal to 1, ЗВт to bring the deviation at 54 and 110 Mc/s
to the required accuracy.
Check the deviation accuracy on the 108- to 220-Mc/s band. If
it is outside the limits stated, select a value for R5 equal іс 7R y and
a value for R12 equal to 1,2Ңт to bring the deviation at 108 and 220
Mc/s to the required accuracy.
If à deviation meter is not available, the following method may
be used to determine the frequency deviation. This method - the
disappearing carrier method - depends upon the fact that the carrier,
аз opposed, of course, to the sidebands, disappears vhen the modulation
index н (the ratio of the frequency deviation 5F to the modulation
frequency f) has values of 2.4, 5.52, 8,65, 11.79, etc. Therefore, if
the modulation frequency, f, is known, since deviation, СХ, is equal to
Бі, deviation can be simply calculated when p is known - ie., ata
carrier disappearance point, For example, if the applied modulation
has a frequency of 10 kc/s and the deviation is progressively increased
until the carrier disappears, the deviation must be 2,4 x 10 = 24 kc/s,
and again 5.52 x 10 = 55,2 kc/s.
A deviation check at 75 kc/s can be obtained at the second
disappearance with à modulation frequency of 13.6 кс/в.
To determine these points, apply the output of the TF 995A/2
to а narrow-band (communication) a.m. receiver and tune the latter
to the unmodulated output frequency of the TF 995A/2. Set the beat
oscillator of the receiver to give an audio note; then frequency
modulate the Signal Generator at à fairly high frequency outside the
passband of the a.m. receiver - such as 10 kc/s - starting from zero
deviation and increasing the deviation until the beat with the carrier
disappears. Atthis point, the actual deviation can be calculated as
described above.
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4,8.11 Incremental Frequency (Apparatus required:- Items i and j)
Check the calibration of the INC FREQ dial in the following
manner: -
(1)
(2)
(3)
(4)
(5)
(6)
(7)
By means of à suitable jack plug, connect a pair of head
telephones to the CRYSTAL CHECK socket; set the MOD
SELECTOR switch to C, W.,; then set the INC FREQ control
to its centre-zero position and short-circuit the slider of its
potentiometer, K112, to chassis,
Adjust the TUNE control to bring the frequency of the г. f,
oscillator to some convenient crystal check point near the
low-frequency end of the range, and tune carefully to zero
beat,
Disconnect the short-circuit between the slider of R112 and
chassis, and check that zero-beat occurs when the INC FREQ
control is within 2 kc/s of its centre zero position,
If zero beat does not occur with the control within 2 kc/s of
its zero setting, check that the dial is positioned on its spindle
so that tho 0 coincides with the cursor when the potentiometer
is atits mid-travel position; then select а value for R50 to
. bring the frequency to zero beat with the INC FREQ dial reading
Zero.
Having obtained satisfactory operation at zero frequency -shift
position, disconnect the telephones and connect in their place
the Y input of à cathode-ray oscilloscope. Connect an а, f
oscillator to the X input of the oscilloscope, and adjust the
frequency of this oscillator to exactly 3,33 kc/s.
Using the lissajous-figure method, check the accuracy of the
incremental dial at each calibration point. A calibrated
movement of 10 kc/s on the incremental dial corresponds to
an actual shift of the r.f. oscillator frequency of 3, 33 kc/s.
If necessary, select а value for R114 to bring the calibration
of the INC FREQ dial to ап accuracy of 10%,
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4, 8. 12 Е.М. Distortion (Apparatus required:- Items c and К)
Set thc DEVIATION NORMAL/HIGH switch to NORMAL, the
DEVIATION RANGE switch to 75 kc/s, the MOD SELECTOR switch
to INT MOD -Е.М,, and the RANGE switch to 13,5 - 27; then
adjust the SET CARRIER control to give а convenient deflection on the
TF 995A/2 panel meter.
Connect the output cable directly to à carrier deviation meter,
tune both instruments to 20 Mc/s, and adjust the TF 995A/2 attenuators
for maximum output,
Adjust the SET MOD control to produce 75 kc/s deviation, and
check that the positive and negative deviations as indicated on the
deviation meter are equal, If they are unequal, select а value for
R19 to produce equal positive and negative deviations.
Apply the demodulated #, па, signal from the deviation meter to a
wave analyser, апа measure the total distortion at carrier frequencies
of 13,5, 27, 90, and 220 Mc/s. The total f.m. distortion should not
exceed 2%,
4, 8.13 Deviation Range Adjustments (Apparatus required: Item К)
Set the DEVIATION - NORMAL/HIGH switch to NORMAL, the
DEVIATION RANGE switch to 75 kc/s, the MOD SEIECTOR switch to
INT MOD - Е, M. , and adjust the SET CARRIER control to bring the
meter pointer to SET К.Е, Set the OUTPUT VOLTAGE and
MULTIPLY BY attenuators to 100 dB, connect the output cable directly
to à deviation rneter, and tune both instruments to the same frequency.
Adjust the SET MOD control to maximum and select a value for
R2 which will produce а deviation of approximately 85 kc/s, as measured
on the deviation meter,
Set the DEVIATION RANGE switch to 25 kc/s and select a value
for R24 so that à deviation of approximately 28 kc/s is obtained with the
SET MOD controlat its maximum position.
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2 - 4/59
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4,8,14 Deviation Monitor Circuit (Apparatus required:- Item К)
Check the accuracy of the deviation reading on the TF 995А/2
meter using a deviation meter or the disappearing carrier method
described in section 4,8,10, И the indication of the TF 995A/2 is not
accurate, adjust R65. If adjustment of R65 does not correct the error
on both ranges, proceed as follows.
Turn the SET MOD control to zero апа the preset control R65 to
mid-travel; set the DEVIATION RANGE switch to 25 kc/s and hold the
METER READS switch to F, M. Select R69 to give zero reading on the
TF 995А/2 meter.
Set the METER READS switch to C, W, 2nd rotate the SET MOD
control until 25 kc/s deviation is indicated on the deviation meter.
Hold the METER READS switch to Е.М, and select R67 sc that the
TF 995A/2 meter indicates the 25 кс/в deviation,
Set the DEVIATION RANGE switch to 75 kc/s, rotate the SET
MOD control to zero, and hold the METER READS switch to F,M,
Select R68 to give zero reading on the TF 995A/2 meter. Return the
METER READS switch to C, W., and rotate the SET MOD control until
75 кс/в deviation is indicated on the deviation meter. Hold the
METER READS switch to F, M, and select R66 to give full scale reading
on the TF 995A/2 meter.
Finally, re-check the deviation calibration at several points on
each band,
4,8.15 High Deviation (Apperatus required:- Item k)
Connect the output of the TF 995А/2 to 2 deviation meter and
check that, when the TF 995A/2 is set for 9 kc/s deviation with the
DEVIATION - NORMAL/HIGH switch set to NORMAL, the deviation,
indicated on the deviation meter, rises to approximately the
following values when the DEVIATION - NORMAL/HIGH switch is
set to HIGH,
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2 - 4/59
4. 8,15 (continued)
4. 8, 16
4, 8.17
HIGH Deviation
RANGE Mc/s for 9 kc/s
NORMAL
1,5-13,5 18 kc/s
13. 5-7 9 kc/s
27-54 18 kc/s
54-108 36 Кс/з
108-220 72 Кс/в
External К, М. (Apparatus required:- Items i and К)
Connect the output of a beat frequency oscillator to the EXT
MOD and E terminals and set it to deliver 30 volts г. па, в, at | kc/s,
Set the MOD SELECTOR switch to EXT MOD - F,M,, the DEVIATION
- NORMAL/HIGH switch to NORMAL, hold the METER READS switch
to Е, M., and adjust the SET MOD control for 75 kc/s deviation. Tune
the beat frequency oscillator over the range 50 c/s to 15 kc/s and
check that the input required for 75 Кс/в deviation does not vary by much
more than +1 dB,
Feed the output of the TF 995A/2 to the deviation meter and
repeat the operation using the deviation meter as indicator; check that
not more than +1 dB variation in input is required to maintain the
deviation at 75 kc/s.
InternalA, M. (Apparatus required:-- Items c, f, and j)
Apply the output of the TF 995A/2 to à frequency changor circuit
which is followed by an i.f. amplifier and cathode ray oscilloscope;
the 1,1, amplifier should have а centre frequency which will allow its
output to be viewed directly on the с.г, o, Set the MOD SELECTOR
switch to INT MOD - A. M. апа adjust the SET MOD control for 30%
modulation as measured on the c, р, о. screen using the formula; =
M. m Ltd. -50-
OM 995A/2
2 - 4/59
+
|
|7 4,8, 17 (continued)
|
| x D max - D min
|" М%) ---------- х 100
Е D max + D min
|
|
where D max - the pe2k-to-pe2k dimensions of the c.r.o. display.
D min = the trough-to-trough dimensions of Ње с.г.с. display.
Hold the METER READS switch to А,М. 2nd check that the meter
reading is correct. Н not, select а new value for R63.
Using the wave analyser check that the total distortion of the
detected output appearing across КТО does not, in general, exceed 5%
at 30% moduletion.
4.8.18 External A. M. (Apparatus required:- Items f, i, and j)
Connect the cutput of а beat fre equency oscillator to the EXT MOD
and E terminals, and adjust it to produce pira duc 30 volts r.m. 5.
Set the MOD SELECTOR switch to EXT MOD - A.M. and adjust the
SET CARRIER control so that the meter reads SET Б,Е, Adjust the
SET MOD control to pr cris 30% modulation depth at 1.000 c/s, as
measured on ап oscilloscope in the manner outlined in Section 4. 8.17.
Tune the beat frequency cscilletor from 50 c/s іс 10 kc/s and check
thet the input required to produce 30% modulation is flat within 1 СВ
relative to 1,000 c/s. If not, select a value for R39 which fulfils
these conditions.
4.8.19 Spurious A.M. (Apparatus reguired:- Item e)
Set the TF 995A/2 for 109% 2.m. at 20 Mc/s and measure the
а.с. voli2ge арреггїпр across R70. Set to 75 kc/s deviation and check
| that the voltage across R70 is not greater then before.
-4.8.20 Spurious F.M. са С.Я. (Apparatus required:- Items с and К)
When making this check, the instrument should be removed
from its case but should be bonded to the power unit by 2 length of
copper braid or heavy-gauge wire.
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4. 8.20 (continued)
(1)
(2)
(3)
(9
(5)
(9)
(7)
(8)
Connect the generator output to the deviation meter. Note
that since the deviation to be measured is as low ав 50 c/s, it
is essential that the deviation meter itself generates negligible
spurious f,m. This can be achieved either by modifying the
deviation meter to operate from batteries or by using a
deviation meter whose local oscillation can be brought under
crystal control,
In order to detect the small amount of deviation accurately,
connect the Wave Analyser to the "L,F, Output" terminals of
the deviation meter.
Set up the Signal Generator for, say, 10 kc/s internal f, m.
deviation at a carrier frequency of 10 Мс/в,
Peak the wave amlyser reading by tuning the deviation meter
in the normal manner for а 10 Mc/s input and by tuning the
Wave Analyser to the modulating frequency. From this reading,
the Wave Analyser can be calibrated in terms of mV per kc/s
deviation,
Set the modulation selector to C. W, and, with the Carrier
Deviation Meter still tuned to the 10 Mc/s carrier frequency,
tune the Wave Aralyser to the frequency of the power supply.
Adjust R124 until the Wave Analyser indication is at a minimum,
This resistor is accessible through a small hole in the side of
the r.f, unit cover.
Measure the levels of the hum and ripple componerts and, from
the geometric sum, calculate the deviation. The deviation
should be less than 50 c/s.
Repeat operations (5), (6), and (7) for а selection of frequencies
up to 220 Mc/s. Below 100 Mc/s, the spurious deviation should
be less than 50 с/в; between 100 and 220 Mc/s, the deviation
should be less than 100 c/s,
M.L Ltá, -52-
2.
3.
OM 995A/2
2 - 4/59
AMENDMENT NO, AM4
TO
OPERATING AND MAINTENANCE HANDBOOK МО, ОМ 995А/2
A two-pole toggle switch, S7, designated CARRIER ON/OFF has
been added, It is situated at the right-hand side ofthe front panel be-
tween the SET MOD control and the MULTIPLY BY attenuator, On
Circuit Diagram TLD 23080/2, one pole is interposed between the anode,
pin 5, of voltage stabilizer V9 and the junction of C12 and L4, i.e,, in
the HT3 line; the other pole is interposed between the slider of the
SET CARRIER potentiometer, R44, and the junction of C57 and R47,
i.e., in the screen supply to the harmonic multipliers,
А low-pass R-section filter has been added to improve the
suppression of unwanted components in the output when the Signal
Generator is set to the 1,5 to 13.5 Мс/в band, Тһе filter consists of
an inductor, L26, and two capacitors, C94 and C95, These components
are situated to the right of the screening plate mounted over V12 valve
base; V12 is shown on MP 995A/2-5, Оп Circuit Diagram No,
TLD 23080/2, L26 is connected in series with the lead joining the high
end of T5 secondary and tag 7 of switch S2g. | C94 is connected between
earth and the junction of L26 and T5; C95 is connected between earth
and the other side of L26.
A variable resistor, R124, and a fixed resistor, R123, have been
added so that any spurious f.m, on c. w, due to power-supply hum can
be adjusted to a minimum. They are situated at the end of the r.f., unit
chassis adjacent to valve V2, and are mounted on à bracket attached to
the side of the chassis; this chassis shown on МР 995A/2-4,
А capacitor, C96 has been added in parallel with L15 which is
itself in series with pin 7 of V7.
ML Lb АМ4: One Sheet
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VALVE REPLACEMENT DATA
F.M./A.M. SIGNAL GENERATOR Туре TF 995A/2
FOR
VRD 995A/2
3 - 3/59
Any valve which becomes faulty should preferably be replaced by a valve of the type originally supplied in the
instrument and designated in the following table. If this is not possible, the additional data given by the table
may be used as a guide to suitable alternatives.
British
Commercial
Equivalent
British
Services
Equivalent
УІ, V2
POWER
PENTODE
BRIMAR
6AK6
CV1762
Base
Us.
Equivalent
MINIATURE 7-PIN (B7G)
V3, V4, V6,
V8, VIO, У12
Н.Е.
PENTODE
MULLARD
ЕЕ95
У5
PENTODE
BRIMAR
6AU6
MARCONI INSTRUMENTS LIMITED
C.P. 2c. 10/59
CV2524
CV4023
Sheet | of 2 sheets
VRD 995A/2
3-3/9
British | British |
Valve Commercial Services | Roce U.S.
Equivalent | Equivalent | Equivalent
v7 MINIATURE 9-PIN (B9A)
DOUBLE
TRIODE ЕССВ1 CV455 12AT7
BRIMAR |
12AT7
v9
VOLTAGE QS1200* 227
STABILIZER OA2* CV1832* ОА?“
MARCONI CV4020*
QS150/15 |
УП Tur
FULL-WAVE GZ30
RECTIFIER ЕТІ СУ1863 5246
BRIMAR U50 |
5Z4G |
VI3, VIS 6А15
DOUBLE 6D2
DIODE D152 CV140 6AL5
MARCONI DD6
D77 EB91
У14
VOLTAGE QS1209
STABILIZER | 0583/3 CV449 5651
MULLARD
85A2 |
«Тһе base connections for these voltage stabilizers are different from those of the суре О5150/15 (CV287).
The holder for V9 in the TF 995A/2 has been specially wired so that, without rewiring, any of the voltage
stabilizers listed on this sheet can be used.
MARCONI INSTRUMENTS LIMITED Sheet 2 of 2 sheets
С.Р. 2c... 10/59
E
LS
C.P. 2c 10 59
C34 C46 C65 C75 C81 AND R7
ЫК О ШТЕР АМЕР
R112
FM/AM SIGNAL GENERATOR
р
55
R25
PLP1
52
54
2-dB STEP
S6 ATTENUATOR
20-dB STEP
S3 ATTENUATOR
CRYSTAL CHECK TERMINATING UNIT 20-48 ATTENUATOR
S1 PHONES PLUG TYPE TM 4308 SPARE PLUG PAD TYPE TM 4736 OUTPUT PLUG
FRONT PANEL
MARCONI INSTRUMENTS LIMITED
DRN D.H. DATE 6.7.56 CHKD J.F.G. ISSUE 2
STOCK LIST TF 995A/2 DRG No. MP 995A/2- | | MP 995А/2- |
СШ ЕВ АШ
ШИМ 0018 RES ШӘ Ж ҮЛЕ МУ
ВВК Е АК
(CASE REMOVED)
MARCONI INSTRUMENTS LIMITED
DRN
STOCK LIST TF 995А/2 DRG No. MP 995A/2-2
S6 R24
R68
C14
R69
MAINS FILTER
L24, L25,
C84 TO C87
C8, C9 and R38
|
R.F. UNIT | L.F. UNIT
FOR DETAILS SEE FOR DETAILS SEE
MP 995A/2-3, MP 995A/2-4 AND MP 995A/2-5 | MP 995A/2-3 AND MP 995A/2-6
|
GENERAL UNDERSIDE VIEW FROM REAR (CASE REMOVED)
ATTENUATORS
FOR DETAILS
SEE MP 995А/2-7
MP 95A/2-2
С.Р. 2c 10 59
V6
ша АКИ Кг. UNITS
(ТОР VIEW WITH В.Е. UNIT
SCREENING COVER REMOVED)
V2
R8
R114
V3
Т2
С42 С45 С56 111 С51 х1 V4 L8 R12 R14 R11 v9 M1
L.F. AND R.F. UNITS (TOP VIEW WITH R.F. UNIT SCREENING COVER REMOVED)
MARCONI INSTRUMENTS LIMITED
DRN D.H. DATE | 6.7.56 CHKD J.F.G. ISSUE 2
STOCK LIST TF 995А/2 DRG No. MP 995A/2-3 | MP 995A/2-3
КЕН МТ
2
(GENERAL UNDERSIDE VIEW) |
|
|
|
FOR DETAILS |
SEE MP 995А/2-5 |
|
|
Р... — ҮЭ =
R29 13 R110 C49
(57 C25 C43 R19 C36 C38 R30 R33 C39
R.F. UNIT (GENERAL UNDERSIDE VIEW)
MARCONI INSTRUMENTS LIMITED
STOCK LIST TF 995A/2 DRG No. MP 995A/2-4 |
МР 995A/2-4
С.Р. 2с 10/59
са 122 C65 L6 | С7: С81 R
R . Б . () М | ТТ L18 | : Y 9 = 3 T" a A ЕЕ
(GDOSESUPSOESPORTION eu | JA GC Y M взе
ОЕ UNDERSIDE) 7 A: $
121 Жж DA pe
| R46 = та | T.
۷10 Soar”
| ay 2 114
| R41 "E 2
| —= | C63
| R33 175) ` |
| та C44
| |
| C60 : |
| ЯГ I1 Т5
| v8 — 8
| AP x— R42
| С77 [
| V7
| R54
| R40
| С72 Ré2,L19 R57 R61 v12 Kil
$e К.Е. UNIT (CLOSE ОР OF PORTION OR UNDERSIDE)
MARCONI INSTRUMENTS LIMITED !
DRN D.H. DATE 6.7.56 CHKD AB are ISSUE 2 |
|
STOCK LIST TF 995A/2 DRG No. MP 995А/2-5 | МР 995А/2-5
\
C.P. 2c 10/59
LAF GANAS
(UNDERSIDE VIEW)
R109
L.F. UNIT (UNDERSIDE VIEW)
MP 995A/2- 6
MARCONI INSTRUMENTS LIMITED
| РАТЕ 6.7.56 | CHKD J.F.G. | ISSUE
DRN D.H.
DRG No. MP 995A/2-6
STOCK LIST | TF 995A/2
C.P. 2c 10/59
FINE ATTENUATOR R71 C90 C89 R72 C88 x2 COARSE ATTE
ATTENUATORS
(COVERS REMOVED)
SCREENING COVER SCREENING COVER
FOR FINE ATTENUATOR R70 R121 FOR COARSE ATTENUATOR
ATTENUATORS (COVERS REMOVED)
MARCONI INSTRUMENTS LIMITED
DRN D.H. DATE 6.7.56 CHKD J.F.G. ISSUE 2
STOCK LIST TF 995А/2 DRG No. MP 995A 2-7 | МР 995А/2-7
C.P. 2c 10/59
поли РЭСМИ
MARCONI INSTRUMENTS LIMITED
T4
R120
R119
C69
R117
C58 R118
NOTE:
On current models an additional resistor, К122, is
connected in parallel with capacitor CS8.
POWER UNIT
C71 У11
С62
МР 9954/7-8
505/995А/2
2 - 4/59
SPARES ORDERING SCHEDULE МО, 805/995А/2
WITH CIRCUIT REFERENCES
for
Е,М,/А,М, SIGNAL GENERATOR ТҮРЕ ТЕ 995A/2
Applicable to Instruments
Serial Nos:-
5036001 to 5036500
5123001 to 5123500
5284001 to 5284200
5346001 to 5346200
JA103/001 to JA103/300
When ordering replacement parts, ALWAYS QUOTE THE TYPE
NUMBER AND SERIAL NUMBER OF THE INSTRUMENT CONCERNED,
To specify the individual parts required, STATE FOR EACH PART
IHE QUANTITY REQUIRED AND THE APPROPRIATE SOS ITEM NUMBER,
For example, to order replacements for the 220-kQ resistor, R4,
and the 5-ppF capacitor, C73, order as follows:-
Spares required for TF 995А/2, Serial Number 000000
1 off, SOS Item 4
1 off, SOS Item 186
It is important that the code "508" preceding each item number is
not omitted.
M, т. 144, Sheet 1
MN
y
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{ 1
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3 DANA ANI eI
Pr MS рар
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BEDS. Cir-
Item cuit
No.
Ref.
505/995А/2
2 - 4/59
Works
Description Ref,
*€60(€9€0€e€06€600€0890$006009€069*9060609$9$05820$4080069»€6909$€699€9060959906002500€66€009006(206900*900909069262*
19
20
RESIST ORS
R1 Composition, 470 КО +209, 1/4 W. 4-TM4800/2
R2 B iion, 1,5 ко, + W. PC66611/27
R3 Composition, 220 КО £109, ZW. PC66611/53
R4 Composition, 220 КО +10%, 1/4 W. РС66609/48
R5 Composition, 27 КО, 1/4 W. PC 66609/ 36
R6 Composition, 2.2 kK, 5 W. PC66611/29
R7 Wire-Wound, 50 КО Variable +10%, 3 W. 18-TM4831/2
R8 Composition, 47 КОР, +109, 1/4 W. PC66609/33
R9 Composition, 5,1 kQ*, 5 W. 7-TM4106/2
R10 Composition, 10 КО +10%, 5 W. PC66611/37
R11 Composition, 12 КОР, 1/4 W. РС66609/32
R12 Composition, 4.7 kO*, 5 М, PC66611/33
R13 Composition, 3,9 К, 1/4 W. PC66609/26
R14 Composition, 8.2 КО, 5 W. PC66611/36
R15 Composition, 4.7 КО 10%, 1/4 №. PC66609/27
R16 Wire-Wound, 4.7 КО x59, 7 W. 113-TM4826/2
R18 Composition, 220 КО 100, 1/4 W. PC66609/47
R19 Composition, 1.2 КО", 1/4 W. PC66609/20
R20 Composition, 10 КО +5%, 1/4 W. 62-TM4826/2
R21 Composition, 68 КО +10%, 1/4 №. PC66609/41
Nominal value; actual value determined during calibration
Sheet 2
M.I. Ltd.
|
SOS Cir-
Item cuit
No. Ref, Description
Ни ооо
21 R22 Composition, 68 КО +10%, 1/4 Ww.
22 R23 Composition, 56 КО +10%, 1/4 ү.
23 R24 Composition, 39 КО“, 1/4 W.
24 R25 Composition, 20 КО Variable %20%, 1/4 W.
25 R26 Composition, 15 КО 10%, 1/4 Ww.
26 R27 Composition, 2.7 МО +10%, 1/4 W,
27 R28 Composition, 220 К 10%, 1/4 W.
(28. R29 Composition, 6,8 kR 110%, 1/4 W.
E29 R30 Composition, 6.8 КО +10%, 1/4 W.
30 R31 Composition, 270 К +10%, 1/4 Уг,
3] R32 Composition, 100 2 z10%, 1/4 Ww.
| 32 R33 Composition, 2.2 КО +10%, 1/4 W.
| 33 R34 Composition, 390 9 35%, 1/4 W.
34 R35 Wire-Wound, 15 КО 15%, ТМ,
35 R36 Wire-Wound, 7.5 КО 557, TW.
36 R37 Wire-Wound, 5 КО 5505, 7 VW.
37 R38 Composition, 100 +10%, 5 W.
38 R39 Composition, 220 КО, + У.
39 R40 Composition, 15 КО 410%, 1/4 W,
m Nominal value; actual value determined during calibration
MAL Ltd,
SOS/995A/2
2 - 4/59
Works
Ref,
соо оф 06999499 9099
РС66609/41
PC66609/40
PC66609/38
74-TF 995A/2
PC66609/33
PC66609/60
PC66609/47
PC66609/29
PC66609/29
PC66609/48
PC66609/7
PC66609/23
11-ТМ4800/2
112-TM4826/2
111-TM4826/2
110-TM4826/2
PC66611/1
РС66611/53
РС66609/33
Sheet 3
~
AA ж, д. A MRD AMES а
пее ith
.......: 6.66. .3..6.6.6..2.:34 0 ne. .n..... ..
SOS Cir-
Item cuit
No. Ref.
20 R4l
41 R42
42 R43
43 R44
44 R45
45 R46
46 R47
47 R48
48 R49
49 R50
50 вы
51 R52
52 R53
53 R54
за "RES
ЭЭ R56
56 R57
57 R58
58 R59
59 R60
M.I. Ltd,
COR :
Description
RESIST ORS (continued)
Composition,
Composition,
6.8 КО +10%, 1/4 W.
2.2 КО +10%, 1/4 W.
Composition, 10 КО +1 0%, IW.
Wire-Wound, 20 КО Variable, +10%, 3 W.
Composition,
Composition,
Composition,
Composition,
Wire-Wound,
Composition,
Composition,
Composition,
Composition,
Composition,
Composition,
Composition,
Composition,
Composition,
Composition,
Composition,
100 ко 410%, 1/4 ү,
6.8 ко 5109, iw.
10 ко 210%, iw.
2.2 ко 5109, 1/4 W.
4 КО £59, 7 W.
100 ke, 1 W.
4.7 КО 5109, 1/4 W.
220 ко 410%, 1/4 W.
210 0 5109, 1/4 W.
6.8 ко 5109, 1/4 W.
68 КО 210%, 1/4 W.
47 КО £205, $ М; includes L21.
2.2 КО +10%, 1/4 М.
100 ко z10%, 1/4 W.
6.8 Ко +10%, 1/4 W.
100 kQ +10%, 1/4 W.
505/995А/2
2 - 4/59
Works
Ref.
КАКАО
PC66609/29
PC66609/23
PC66621/37
15-ТЕ995А72
PC66609/ 43
PC66611/35
PC66611/31
PC66609/23
72-ТЕ995А/2
PC66611/49
РС66609/27
РС66609/44
PC66609/12
PC66609/29
PC66609/41
TB23173/9
PC66609/23
PC66609/ 43
PC66609/29
РС66609/43
Sheet 4
NY A
ища жа = р мре ЕХ
| 505/995А /2
2 - 4/59
Eos čir-
Item cuit Works
AR В 1.0,
RESISTORS (continued)
60 561 Composition, 2.2 КО 510%, 1/4 W. PC66609/23
| 61 R62 Composition, 33 КО +20%, ZW; includes 1.19, TB23173/10
| 62 R63 Composition, 750 К" 1/4 W. 78-TF995A/2
63 R64 Composition, 470 € +10%, 1/4 W. FC66609/15
64 R65 Wire-Wound, 500 Q Variable, £209, 1/4 W. БС67401/17
65 R66 Composition, 180 kw, Zw, РС66609/46
66 567 Composition, 56 ke, 1 W. FC 66609/ 40
67 R68 Composition, 150 Ок, 1/4 W. C 66609/ 45
68 R69 Composition, 47 КФ, 1/4 W. РС66609/39
69а R70 Composition, 3,3 ОК, 1/4 W. PC66609/24
70 R71 Composition, 1 kQ +20%, 1/8 W. 39-TM4297A
71 R72 Composition, 1 Ко +20%, 1/8 W. 39-TM4297A
200: High Stability, 82.5 ко +19, 1/8 W. 36-TM4297A
73 R74 Carbon, High Stability, 742 Q +1%, 1/8 W. 35-TM4297A
74 R75 Carbon, High Stability, 742 2 +1%, 1/8 W. 35-TM4297A
75 R76 Carbon, High Stability, 742 0 41%, 1/8 W. 35-TM4297A
| 76 R77 Carbon, High Stability, 742 € 51%, 1/8 W. 35-TM4297A
77 R78 Carbon, High Stability, 2202 41%, 1/8 W. 38-TM4297A
78 R79 Carbon, High Stability, 91.69 +1%, 1/8 W. 37-TM4297A
* Nominal value; actual value determined during calibration
Имат ты. Sheet 5
ом
S. и АЗИЯ
$
505/995А/2
rb E е
E92
297
2 - 4/59
SOS Cir-
Item cuit Works
ИИИ ШИ A O. A
RESISTORS (continued)
79 R80 Carbon, High Stability, 91,6 0 +19, 1/8 W. 37-TM4297A
80 R8l Carbon, High Stability, 91,6 0 11%, 1/8 W. 37-ТМ4297А
81 R82 Carbon, High Stability, 82.5 0 +19, 1/8 W. 36-TM4297A
82 R83 Carbon, High Stability, 17.9 6 41%, 1/8 W. 24-TM4298/2
83 R84 Carbon, High Stability, 17.90 i175, 1/8 W. 24-TM4298/2
84 R85 Carbon, High Stability, 17.9 0 £195, 1/8 W. 24-TM4298/2
85 R86 Carbon, High Stability, 17,9 Q 21%, 1/8 W. 24-TM4298/2
86 R87 Carbon, High Stability, 17.9 Q 41%, 1/8 W. 24-TM4298/2
87 R88 Carbon, High Stability, 17.9 +1%, 1/8 W, 24-TM4298/2
88 R89 Carbon, High Stability, 17,9 О +1%, 1/8 W. 24-TM4298/2
89 R90 Carbon, High Stability, 17.9 Q 51%, 1/8 W. 24-ТМ4298/2
90 R91 Carbon, High Stability, 17.9 0 +1%, 1/8 W. 24-TM4298/2
91 R92 Carbon, High Stability, 17,9 Q +1%, 1/8 W. 24-TM4298/2
R93 Carbon, High Stability, 61.2 Q +1%, 1/8 W. 28-TM4298/2
93 R94 Carbon, High Stability, 332 2 +1%, 1/8 W. 26-TM4298/2
94 R95 Carbon, High Stability, 167 Я +1%, 1/8 W. 27-TM4298/2
95 R96 Carbon, High Stability, 167 Q +1%, 1/8 W. 27 -TM4298/2
96 R97 Carbon, High Stability, 1670 £195, 1/8 W. 27-TM4298/2
R98 Carbon, High Stability, 167 © 417, 1/8 W., 217 -TM4298/ 2
Sheet 6
1 И
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159425 vi E МУХ E - #1
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55 ЙОМА, fa) ОЧА WE p^ + Жек” Ru AINT y
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ER (e E Зай ща ws 5 х 5 A
agii ед 24-24 BC FE АЖ, “2
505/995А/2
2 - 4/59
505 Cir-
(item cuit Works
AAA
| ү RESISTORS (continued)
1 98 R99 Carbon, High Stability, 37.582 +1%, 1/8 W, 25-TM4298/2
{ 99 R100 Carbon, High Stability, 90 0 +2%, 1/8 W. 12-ТМ4730/2
г 100 R101 Carbon, High Stability, 900 +2%, 1/8 W. 12-ТМ4136/2
! 101 R102 Carbon, High Stability, 360 9 +1%, 1/8 W. 13-TM4736/2
N 102 R103 Carbon, High Stability, 37.5 Q 45%, 1/8 W. 10-ТМ4308/2
) 103 R104 Carbon, High Stability, 75 © +59, 1/8 W. 11-TM4308/2
Ш104 в105 Carbon, High Stability, 14.50 45%, 1/8 W. 12-TM 4308/2
105 R106 Composition, 5602 +10%, 1/4 W. PC 66609/16
1 106 8107 Composition, 22 КО 4107, 1/4 ү, РС66609/35
| 107 R108 Composition, 1 МО +10%, 1/4 W. PC66609/55
4 108 R109 Composition, 2,2 КО +10%, 1/4 W. PC66609/23
' 109 R110 Composition, 100 2 +10%, 1/4 W. PC66609/7
! 110 К111 Composition, 10 kQ +10%, 1/4 W. PC66609/31
ИУ молња, 50 КО, Variable, 2 W. 81-TF995A/2
112 R113 Composition, 68 КО +10%, 1 W. 57-ТЕ995А/2
113 R114 Composition, 100 kQ +10%, 3 W. PC 66611/49
; 114 R115 ЕЕ... 1 kR =10%, 1/4 W. PC 66609/ 33
: 115 R116 Composition, 330 2, 1/4 ү, ` PC66609/13
116a R117 Composition , 2.2 КО 10%, 1/4 W. PC66609/23
| ж Nominal value; actual value determined during calibration.
ом. Ltd, Sheet 7
SOS Cir-
Item cuit
Мо, Ref,
Description
505/995А/2
2 - 4/59
Works
Ref.
ооо ово со соо ооо ооо осо оо по об фоос ово бов оса осооо ооо ца
EXIT | вала
1184 R119
2119 R120
119/1 R121
119/2 R122
119/3 R123
119/4 R124
120 с
121 "res
122. (03
123 24102
Теа ES
1250 00
ios е”
В 127 cs
*
M.I, Ltd.
RESISTORS (continued)
Composition, 22 kR 4100, 1/4 ү,
Composition, 68 КО +10%, 1/4 W.
Composition, 33 КО +10%, 1/4 ү.
Wire-Wound, 950 0 +10%, 1 W.
Composition, 33 КО 10%, 1/4 W.
Composition, 470 2 210%, Zw.
Wire-Wound, 25 Q Variable, i w.
CAPACITORS
Paper, 0.1 pF 420%, 350V d.c.
Paper, 0,1 pF +20%, 350 V d.c.
Mica, Special Assembly, 100 uF, Nominal.
Mica, 100: pir 210%, 350 V d.c.
Mica, 100 ирЕ +10%, 350 V d.c,
Paper, 0,02 pF*, 350 V а, с,
Mica, 200 ULF +2 0%, 350 V d.c.
Mica, 100 ppF 4100, 350 V d.c.
Nominal value; actual value determined during calibration.
PC66609/35
РС66609/41
PC66609/37
82-ТЕ995А/2
PC 66609/ 43
РС 66611/23
130-TM4826/2
РС19202/14
РС19202/14
2-TM4826/2
117-TM4826/2
117-TM4826/2
12-TM4800/2
71-TM4826/2
OSS LE 5995АУ2
Sheet 8
Мо,
| 128
129
130
131
132
E33
134
135
136
137
138
139
140
141
142
143
` 144
Item
Cir-
cuit
Ref,
oo O oa в соус соо наро рос ооо ово ооо ооо ооо ee
с9
c10
C12
СЪЗ
с14
С15
C16
C17
ста
с19
C20
C21
C22
C23
C24
C25
C26
“м.т, Ltd,
1
Description
CAFACITORS (continued)
Mica, 100 pF 20%, 350 Y d,c.
Mica, SpecialAssembly, 100 ЕЕЕ, Nominal,
Mica, Special Assembly, 100 pF, Nominal,
Mica, 100 pF 4100, 350 У d.c,
Paper, 2 pF +25%, 250 V d.c.
Paper, 0,01 pF 4207, 350 V d.c.
Paper, 0.01 pF 5250, 350 V d.c.
Paper, 0,1 ҺЕ +20%, 350 V d.c.
Paper, 0.1 pF +20%, 350 V d.c,
Mica, Special Assembly, 100 pF, Nominal.
Ceramic, 0. 01 uF -20% +100%,
Ceramic, 0,001 uF +20%, 400 V d.c,
Included in Item 206,
Mica, Special Assembly, 100 upF, Nominal,
Included in Item 206,
Mica, 200 gpF +10%, 350 V d.c.
Paper, 0,001 pF «207, 600 V d.c.
Mica, 39 upF «5%, 350 V d.c.
Paper, 0.1 pF +20%, 350 V d.c.
505/995А/2
2 - 4/59
Works
Ref.
86-TF 995A/2
2-TM4826/2
2-TM4826/2
117-TM4826/2
87-TF 995A/2
13-TM4800/2
15-TM4800/2
PC19202/14
PC19202/14
3-TM4826/2
135-TM4826/2
12-TM3900/75
9-TM3900/75
86-TM4826/2
91-TM4826/2
85-TM4826/2
PC19202/14
Sheet 9
„ъъ Ss a
< -
щъ <A Th ч кс
stud red о.
-
ES = - E
“© Я 3
506/995А/2 f
2 - 4/59
505 Cir-
Item cuit Works
CAPACITORS (continued)
145 C27 Paper, 0,001 pF 420%, 600 V d,c. 91-ТМ4826/2
146 С28 Paper, 0,01 uF £20%, 350 V 4,с, 83-TM4326/2
my С29 Mica, 47 uF 20%, 350 V а, с, 9-TM3900/74
Included in Item 207,
148 C30 Ceramic, 4.7 ppF «207, 500 V а, с, 89-TM4826/2
Temperature С ompensation,
(-3000 £107) х 1079 pur /ррР/9с,
149 C31 Ceramic, 100 uF £595, 500 V а, с. 88-T144826/2
150 C32 Paper, 2 uF +259, 150 V d.c, 151-TMM24826/2
151 C33 Ceramic, 1 Е «207, 500 V 4,с, 82-TM^4826/2
152 Two-section ganged capacitor complete with ТС1478/1
trimmers; includes C34, С35, C46, and C47,
C34 Air, Variable, 14 - 200 pyr, part of Item 152.
C35 Air, Trimmer, 3 - 30 ppF, part of Item 152, |
153 C36 Ceramic, 47 ирЕ +20%, 500 V а, с, 76-TM4826/2 |
154 C37 Paper, 0.1 pF +20%, 350 уа, с, PC19202/14 |
155 C38 Ceramic, 100 pur +200, 500 V а, с, 84-TM4826/2 |
156 C39 Paper, 0.01 pF +20%, 350 V d,c. 83-TM4826/2 |
157 C40 Air, Trimmer, 1,25 - 10 pyr. 116-TM4826/2
158 C41 Ceramic, 3.3 ирЕ +10%, 750 V а, с, 75-TM4826/2
159 С42 Ceramic, 4700 pur -0+100%, 500 V d.c. 92-TM4826/2
— TIT — Sheet 10
халж
1 808 Сїк-
{Шеп cuit
| Мо, Ref.
C43
C44
C45
|| C46
| C47
лө С48
164 С49
1165 С50
0166 C51
167 C52
168 C53
169 С54
170 C55
an C56
a C57
173 C58
| С59
C60
»
C61
Description
CAPACITORS (continued)
Ceramic, 5 ppF +20%, 750 Уа, с,
Ceramic, 10 puF 220%, 750 V d.c.
Paper, 0, 5 BE +25%, 150 ү а, C,
Air, Variable, 7 - 100 uF, part of Item 152,
Air, Trimmer, 2 - 8 НАК, part of Item 152,
Ceramic, 100 Е +20%, 500 У а, с,
Ceramic, 22 дык +20%, 500 V d.c.
Ceramic, 47 pF +20%, 500 V d.c.
Mica, 100 ULE +10%, 350 V d.c.
Mica, Special Assembly, 100 uF, Nominal,
Electrolytic, 2 pF -20% +50%, 150 V d.c.
Paper, 0.1 рЕ 4250, 250 V d.c.
Ceramic, 33 ШЕ 310%, 500 V d.c.
Mica, 100 ppF +10%, 350 V d.c.
Mica, Special Assembly, 100 ppF, Nominal,
Electrolytic, 8 НЕ -20% +50%, 450 V d.c.
Ar Trimmer, 1,25 = 10 pyr,
Ceramic, Stand-Ofí, 820 pF +20%, 750 V d.c.
Ceramic, 5 Е 20%, 500 V d, c.
Works
Ref,
сое оао волов оо рос ото үрс ТОНЖОЦОН ЭГЦ
134-TM4826/2
PC18201/9
150-TM4826/2
84-TM4826/2
87-TM4826/2
73-TM4826/2
117-TM4826/2
4-TM4826/2
103-TF995A/2
93-TF995A/2
PC18202/7
117 -TM4826/2
124-127-TM 4826/2
33-TM4299/2
116-TM4826/2
79-TM4826/2
118-TM4826/2
Sheet 11
НИ? DATUR MET
ШИ 4 цул
2
SE
bp To
3 Р | 403 ЖАА Г ' az
Wa зара касае Ox Булл Ула ча Пре E АЛТЫ у
y M и ) 3
SOS
` Item
Мо.
| Cir-
cuit
Ref,
Description
505/995А/2
2 - 4/59
Works
Ref,
ооо е ес од еоФ» оов ов» өө ө ө ө ө ө о о ө ө о ө о ө ө ө ө Ф ө е э чо оо ө ө өе о ө ө э ө ә э ө эе «ө ө RE ө +
177
178
179
180
181
182
183
184
185а
186
182.
188
C62
C63
C64
C65
C66
C67
C68
(C69
(and
(С71
C70
C71
C72
C73
C74
С15
C76
C77
CAPACITORS (continued)
Electrolytic, 30 pF -20% +50%, 350V d.c.
Paper, 0.01 pF +20%, 350 V d.c.
Ceramic, 100 uF +20%, 750 V d.c.
Three-section ganged capacitor complete with
trimmers; includes C65, C66, C75, C76, C81
and C83,
Air, Variable, 7 - 100 pF; part of Item 180,
Air, Trimmer, 2 - 8 pF; part of Item 180,
Ceramic, 22 pF 20%, 500 V d.c.
Paper, 0, 01 pF +20%, 350 V d.c.
Electrolytic, Dual Section,
16 pF -20% +50%
8 HE -20% +50%, 350 V d, C,
Ceramic, 100 pF +20%, 500 Уа, с,
See Item 183,
Ceramic, Stand-Off, 820 pF 20%, 750 V d. с,
Ceramic, 5 Е 20%, 500 V 4,с,
Ceramic, 100 рыЕ +20%, 750 V d.c.
Air, Variable, 7 - 100 pF, part of Item 180,
Air, Trimmer, 2 ~ 8 НЫЕ, part of Item 180,
Ceramic, 10 ppF 4200, 500 V а, с,
13-TM4299/2
83-TM4826/2
PC18202/13
TC21478/2
87-TM4826/2
83-TM4826/2
12-TM4299/2
84-TM4826/2
79-TM4826/2
118-TM4826/2
PC18202/13
80-TM4826/2
Sheet 12
Ж
e
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jd
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ier oss
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| - 4/59
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Ш SOS 'cCir-
! Item cuit Works
li EE Әз R5 011
| CAPACITORS (continued)
I 189 C78 Ceramic, 100 Е £209, 500 V d.c. 84-TM 4826/2
190 C79 Paper, 6 F 4200), 150V d.c, 79-ТЕ99БА/2
1! 191 С80 Ceramic, 100 pF 20%, 750 V d.c. PC18202/13
| C81 Air, Variable, 7 - 75 puF, part of Item 180,
192a C82 Ceramic, Stand-Off, 820 рык +20%, 750 V d, c. 79-TM4826/2
| C83 Air, Trimmer, 2 - 9 ppF, part of Item 180
193 C84 Paper, 100 Е £209, 300 V a.c. 80-TF995A/2
194 C85 Paper, 100 uF 4200, 300 V a.c. 80-ТЕ995А/2
| 195 C86 Paper, 100 pF +20%, 300 V a.c. 80-TF995A/2
| 196 C87 Paper, l00ppF £209, 300 V a.c. 80-ТЕ995А/2
Е 197 Сав Ceramic, 820 pF +20%, 350 V d,c. 41-TM4297A
| 198 C89 Ceramic, 820 pF +20%, 350 V d.c. 41-TM4297A
| 199 C90 Ceramic, 820 Е £209, 350 V dc. 41-TM4297A
200 С91 Paper, 0.1 pr 120%, 350 V d.c, PC19202/14
Ёс 1 Paper, 0.25 pF згон, 500 Y d.c. 32-TM4299/2
f 201/1 сэз Ceramic, 5 ШЕ 20%, 500 V d.c. 118-TM4826/2
| 201/2 C94 Ceramic, 120 ШЕ 4100, 750 V d.c. 74-TM 4926/2
j 201/3 C95 Ceramic, 68 pF +10%, 750 V d.c, 90-TM4826/2
| 201/4 C96 Ceramic, 3,3 Е +10%, 750 V 4,с, 15-TM4826/2
EM. I, Ltd, Sheet 13
жле — TN х
2 - 4/
506 Cir-
Item cuit Works
No, Ref. Description Ref.
EM i лее еРопапосевевсовопововеовобеооопоовоооавортоосвбвовабвовововававо
INDUCTORS
202 bI R,F, Filter Inductor. TM4087/14
Ша 2 В.Е. Filter Inductor, TM 4087/14
204 L3 R,F, Inductor, TB16363/27
205 L4 R,F, Filter Inductor TM4087/14
206 Main portion of three-section filter TM3900/75
assembly; includes L6 and L7, and Items
138 and 139,
L6 В.Е, Filter Inductor; part of Item 206,
L7 R,F, Filter Inductor; part of Item 206,
207 1.8 Screened R,F, Inductor Assembly; TM3900/74
includes Item 146,
208 L9 Modulation Choke, TM 4159/1
209 L10 30-Mc/s Oscillator Inductor. TB23173/1
210 L11 ScreenedR,F, Inductor Assembly. TM4087/14
211 L14 В.Е. Inductor, TB23173/3
212 1.15 R.F, Inductor. TB23173/4
213 wo Shrouded H, T, Smoothing Choke (earlier models) TM4140/1A
2153/1. 32 P6 Unshrouded H, T, Smoothing Choke (later models) TM5172/31
214 L17 Shrouded Н, T. Smoothing Choke (earlier models) TM4140/1A
214/1 L17 Unshrouded Н, T. Smoothing Choke (later models) TM5172/31
215 L18 Multiplier Tuning Inductor, 27 to 55 Mc/s. TA22011
EML Ltd, Sheet 14
505/995А/2
2 - 4/59
SOS Cir-
Item cuit Works
ВИН... menu hen:
INDUCTORS (continued)
L19 В.Е. Inductor; part of Item 61, TB23173/10
1,21 В.Е. Inductor; part of Item 55, TB23173/9
217 L22 Multiplier Tuning Inductor, 54 to 110 Mc/s. TB20309/1
218 123 Multiplier Tuning Inductor, 108 to 220 Mc/s. TE23048/11
219 124 В.Е, Inductor (mains filter). TA14323/18
220 L25 R,F, Inductor (mains filter). TA14323/18
220/1 E26 Filter Inductor TB23173/39
TRANSFORMERS
221 21 А.Е, Oscillator Transformer. TM4085/2
222 T2 Master Oscillator R.F, Transformer, TM3900/ 87
4.5 to 9 Mc/s.
223 T3 Multiplier R.F, Transformer, 13.5 to 27 Mc/s. TM3900/52
224 T4 Mains Transformer with separate mains-tapping
panel (earlier models). TM4501
224/1 T4 Mains Transformer with all connections directly
to tags on transformer coil (later models) TM5150/25
225 T5 R,F, Output Transformer, 2 to 13.5 Мс/в, TB23173/5
M.I. Ltd, Sheet 15
SOS/995A/2
2 - 4/59
SOS Cir-
item. cuit Works
ARA REE
SWITCHES
226 S1 Rotary, 9 pole, 5 position, 4 wafer. TC4428/373
227 82 Rotary, 10роїе, 5 position, 4 wafer. TC4428/ 366
228 53 Lever-Actuated Rotary, 2 pole, 3 position, TC 4428/ 342
2 wafer, biased to mid-position: includes
bakelite handle,
229. 54 Toggle, 2 pole, 2 position, TB23903/2
230 S5 Rotary, 2 pole, 2 position, single wafer. 96-TM4826/2
231 56 Rotary, 4 pole, 2 position, single active wafer, TC 4428/344
with extra dummy wafer.
231/1 57 Toggle, 2 pole, 2 position, TB23903/2
VALVES, VALVE HOLDERS, AND RETAINERS
232 v1 6AK6, Pentode. 41-TF995A/2
233 Holder, for У!, TB26904/2
234 Retainer, for Vl. PC17501/2
235 v2 6AK6, Pentode. 100-TM4826/2
236 Holder, for V2. TB26904/2
231 Retainer, for V2. PC17501/2
238 УЗ 6АК5, Pentode, 101-TM4826/2
M.I. Ltd. Sheet 16
Дей
$05
Item
No,
Cir-
cuit
Ref.
Description
505/995А/2
2 - 4/59
Works
Ref,
.“е..ввеоететзеесеегееоеееоеееоеоваеетгееееоегооезгеееесеезеггеегсеегеееегееееесееегеее»е.
239
240
241
242
243
244
245
246
241
248
249
250
251
252
253
254
255
256
287
258
V4
v5
v6
V7
v8
v9
M.L Ltd.
VALVES, VALVE HOLDERS, AND RETAINERS (continued)
Holder, for V3.
Retainer, for V3.
6AK5, Pentode.
Holder,for V4.
Retainer, for V4.
6AU6, Pentode,
Holder, for V5.
Retainer, for V5.
6AX5, Pentode.
Holder, for V6.
Retainer, for Уб,
12AT7, Double Triode.
Holder, for V7.
Retainer, for V7.
6AK5, Pentode.
Holder, for V8.
Retainer, for V8.
OA2, Voltage Stabilizer.
Holder, for V9.
Retainer, for V9.
TB26904/2
PC17501/1
101-TM4826/2
TB26904
РС17501/1
49-ТЕ995А/2
TB26904/2
PC17501/2
101-TM4826/2
TB26904
РС17501/1
103-TM4826/2
TB26905/2
PC17502/2
101-TM4826/2
TB26904
PC17501/1
48-ТЕ995А/2
TB26904/2
PC17501/2
Sheet 17
505
Item
Мо.
SOS/995£.] 2
2 - 4/59
Cir-
cuit Works
Ref. Description Ref,
€89295834€a40€6€95396206«9*09949925€6998429»092459649*964995€6€4299449€«45454496€9696$9254245499924€9459595»75
259
260
261
262
263
264
265
266
261
268
269
210
211a
212
213
214
215
276
VALVES, VALVE HOLDERS, and RETAINERS (continued)
vio бАК5, Pentcde. 101-Т.М4026/2
Holder, for У10, ТВ26904
Retainer, for У10, РС17501/1
ҮЗ 52740, F.W, Rectifier. 16-TM4299/Z
Holder, for Vll. PC21214/1
Retainer, for V11, TC22744/12
V12 6AK5, Pentode, 101-TM4226/2
Holder, for V12. TB26904
Retainer, for У12, PC17501/1
V13 6AL5, Double Diode, 46-ТЕ 995A/2
Holder, for V13. TB26504/2
Retainer, for V13. PC17501/2
V14 5651, Voltage Stabilizer. 20-TM4299/2
Holder, for V14. TB26904/2
Retainer, for V14, PC17501/2
V15 ` 6AL5, Double Diode. 21-тм4299/2
Holder, for V15. TB26904/2
Retainer, for У15, РС17501/1
i M.I. Ltd. Sheet 18
505/995А/2.
2 - 4/59
SOS Cir-
Item сай Works
Мо., Ref. Description Ref,
*«*925009e60000099500Ga49230900060092906096008000a90906090000«44600009090256€9606600000090909095^5928»
CRYSTALS
271 X1 Quartz Oscillator Crystal, 333.33 кс/в, 102-TM4826/2
278 Holder, for Xl. 98-TM4826/2
279 Retainer, for Xl. 99-TM 4826/2
280. 1x2 CS2A, Silicon Rectifier. 40-TM 4291/2
281 Retaining Contact, for X2, TD20400/7
LAMP
282 PLI Pilot Lamp, 6.5 V, 0.3 A, M.E.S, 32-TF995A/2
283 Pilot Lamp Holder, with Red Lens, 42-TF995A/2
METER
284 Ml 0-100 pA, 500 € Nominal, Moving Coil, TM3970/30
including clamping brackets.
PLUGS, SOCKETS, and CONNECTING LEADS
285 Pl Plug, 6-way. 18-TM4299/2
286 5К1 Socket, 6-way. 55-ТЕ995А/2
MIL Lfd Sheet 19
шэг USD Эс ңын Ж АМА ЭРЭЭВЭР Ете Таса маже а
505/595А/2
2 - 4/59
SOS | Cir-
Item cuit Works
No. , Ref. Description Ret,
PLUGS, SOCKETS, and CONNECTING LEADS (continued)
281 Mains Lead comprising 6-ft, 3-core Flexible TM2560AQ
Cable and 3-pin plug complete with Plastic
Entry Sleeve.
288 R,F, Output Flug, coaxial, free. 30-TM 4298/2
289 Б.Е, Output Cable, coaxial, 4 ft 6 in, 38-TM 4298/2
290 Ji CRYSTAL CHECK Jack Socket, including Jack 54-TF995A/2
Plug.
291 Bush, for Item 2902, TA19742
292 R.F. Socket, coaxial, fixed. 7-TM4308/2
KNOBS, DRIVES, and DIALS
293a Knobs, for TUNE and INC FREQ controls. TB29569
294 TUNE control dial. TC20320/4
295 INC FREQ control dial, TB23220
296 Set of three Special Screws for fixing dials to TA4014
knobs.
291 Cursors, for TUNE and INC FREQ Dials. ТА20308
298a FREQUENCY DIAL. Fre-calibrated. TB23189
299 Dial Escutcheon Mounting Ring. TD20670/2
300 Dial Escutcheon (Chromium Plated), with TD20670/1
M.L Ltd,
Rubber Tubing Gasket, to fit over Item 299.
8-ТМ4357/2
Sheet 20
El m А: E UM
E Aet EL ;
.
x MAT ВА i
М г
6
A #2 ы
ne eva PS
SS Ud аж т Ж ил, даа тұ я»
88. m Гот,
SOS/ 995A] Z
2 - 4/59
SOS Cir-
Item cuit Works
Мо. де, Description Ref.
KNOBS, DRIVES, and DIALS (continued)
301 Window, including Movable Cursor Assembly, TC20735/2
to fit in Item 300. TD20670/3
TA20726
TB6775/300
6-TM4357
302 Nylon Drive Сога, 12-TM 4826/2
303 Knob, for MOD SELECTOR switch, Sl. TB25460/2
304 Knob, for RANGE MC/S switch, S2. TB25460/2
305 Knob, for DEVIATION-NORMAL/HIGH switch, TB25460/2
55.
306 Knob, for DEVIATION RANGE switch, S6. TB25460/2
307 Knob, for OUTPUT VOLTAGE attenuator. TB17848/3
308 Knob, for MULTIPLY BY attenuator. TB17848/3
309 Knob, for SET CARRIER control, R44, TB23920/1
310 Knob, for SET MOD control, R25, TB23920/1
MISCELLANEOUS
311 Cover Plate, for R, F, Output Cable exit, TA19721
in Right-Hand Handle Recess.
312 Grommet, to fit in Item 311. TA6515/1
M.L Ltd. - Sheet 21
2 - 4/59
SOS ШАР”
Item cuit Works
808/995А/2
| Мо, Ref, Description Ref,
«есееегеееоеоегеоесеееевеевеоевеегееееееесееееооееевеееегееегеоеееоееоевоеәевогееее
! MISCELLANEOUS (continued)
|
| 2213 ` Cable Saddle, to secure Item 289 to Item 311, 29-ТЕ995А/2
!
| 314а Front Panel, TD22009/2
| 315 Set of Eight Screws, complete with Black 30-TF995A/2
| Fibre Washers for fixing Front Panel to case. TB6775/183
|
| 316 Terminal, EXT МОР, TB24330/5
D^ 317 Terminal, SYNC. TB24330/5
| 318 Terminal, EARTH, TB24330/5
1. 319 Case Assembly complete with Handles and Feet. ТМ4310
| TB18258
ТА11420
|
| 320 Handle Escutcheon, Two included in Item 319, TB18258
1 321 Case Foot. Four included in Item 319, ТА11420
| 322
323 20-dB Step Attenuator Assembly; includes TM4297
Items 70 to 81 inclusive, 197, 198, 280 and
1 281.
324 2-dB Step Attenuator Assembly; includes TM4298
Items 82 to 98 inclusive,
325 | 20-dB ATTENUATOR PAD; includes Item 99 TM4736
to 101 inclusive, and Item 292.
326 52- and 75-ohm TERMINATING UNIT; TM4308
includes Items 102 to 104 inclusive, and Item
292.
NEL Lu. | Sheet 22
аа ак жу He Lahore ДИ as TV it LR AMT
SOS Cir -
Item cuit
№. , Ref,
Description
SOS/995A/2
2 - 4/59
Works
Ref.
ооо ооо ео фо ооо ооо о ос тос ово о ота ооо оо ое ооо ооо со ооо тов оо ва оо оо вас овосво
321
328
329
330
M.L Lid,
MISCELLANEOUS (continued)
R,F, Unit Screening Cover.
Contact Spring for earthing В.Е. Unit
Screening Cover.
Set of three Hexagonal Wrenches for Socket
Set Screws, sizes 2, 4, and 6BA; complete
in linen Бар,
Operating and Maintenance Handbook,
TD20318
26A -TM4826
TC -20321/3E
104-ТЕ995А/2
ОМ995А/2
Sheet 23
МАД
"ropes e AE
Хаг
Жалды ЦЕ:
A
MES сапы
м, илж
uev 6;
жау»
ЖА
DRN A.B.R.
STOCK LIST
БИЖ О КЫ О НЕМАЛО
DIAGRAM
DATE
MARCONI INSTRUMENTS LIMITED
3/59 CHKD
TF 995А/2
A.B.R.
ISSUE
TLC 23556/2
REACTOR
CRYSTAL
CHECK
O
R.F.
OSCILLATOR
4:5 — 9.16Mc/s
CRYSTAL
OSCILL ATOR
333: 33 kc/s
AF
AMPLIFIER
AND
CATHODE
FOLLOWER
MOD SELECTOR
cw
АМ ә FM
int 9 © ext
FM® 9 Ам
5|
хз X 2
MULTIPLIER MULT IPLIER
13:5-275Mcls 27-55 Mc/s
О O O
O „©
+ ge. M
RANGE Mc/s
e *
SET ө ө
— CARRIER
E s2
»
SI а
5ЕТ О о
MOD
о
на ЗА А
мор, “о SYNC
BLOCK SCHEMATIC DIAGRAM
х 2
MULTIPLIER
54—IIOM c /s |
30-Mc/s BEAT
OSCILLATOR
ANO MIXER
GIVING
+5 - 13-5 Mc/s
OUTPUT
MULTIPLIER 3
ВАЗЕ | =ош 2
| | LL.
ت а В:
С--х.
COARSE
| ATTENUATOR
LOW PASS | | FOUR
FILTER 20-db
AND STEPS
AMPLIFIER
CRYSTAL
RECTIFIER
METER READS FINE
ATTENUATOR
TEN
2-db
STEPS
DEVIATION
MONITOR
- 528. 7514.
|
TLC 23556/2
EJEA AE
DIAGRAM
Бирж
TM 4308 5 y or | — A AN
Ko DEVIATION
25 7
se
Trios MORMAL HIGH
Ам, *&— 08-220 e.
29 14-54-1080
x2—27-54 е
м ж--із5-27 ө
55 53
җг— 5-135
52.
CIRCUIT DIAGRAM
MARCONI INSTRUMENTS LIMITED
DRN D.R.H. DATE 3/57 CHKD B.R.C. | ISSUE 6
STOCK LIST TF 995A/2 DRG No. TLD 23080/2
TLD 23080/2
ОМ С-$ОРР ОВ
I - 11/57
DECIBEL CONVERSION TABLE
Ratio Down Ratio Up
VOLTAGE POWER DECIBELS VOLTAGE POWER
1-0 1-0 0 1-0 1-0
-9886 :9772 1 1-012 1-023
-9772 :9550 2 1-023 1-047
-9661 -9333 3 1-035 1-072
:9550 :9120 4 1-047 1-096
9441 :8913 5 1.059 1.122
9333 -8710 6 1-072 1-148
-9226 -8511 7 1-084 1:175
:9120 -8318 8 1.096 1.202
9016 :8128 9 1-109 1-230
-8913 -7943 1-0 1.112 1.259
48710 :7586 12 1-148 1-318
-8511 -7244 1-4 1:175 1:380
-8318 -6918 1-6 1-202 1-445
-8128 :6607 1-8 1-230 1-514
-7943 -6310 20 1.259 1.585
‚7762 -6026 22 1-288 1-660
-7586 -5754 2:4 1:318 1.738
7413 -5495 2:6 1:349 1-820
-7244 -5248 2-8 1:380 1-905
-7079 -5012 3-0 1-413 1.995
-6683 4467 3-5 1-496 2-239
-6310 -3981 40 1-585 2-512
:5957 -3548 45 1:679 2.818
-5623 -3162 5-0 1-778 3-162
-5309 -2818 5-5 1-884 3-548
:5012 2512 6 1-995 3-981
-4467 :1995 7 2-239 5-012
-3981 1585 8 2-512 6.310
:3548 :1259 9 2-818 7-943
-3162 -1000 10 3.162 10-000
:2818 07943 1 3-548 12-59
-2512 -06310 12 3.981 15-85
-2239 -05012 13 4-467 19-95
:1995 :03981 14 5:012 25.12
:1778 ‚03162 15 5-623 31-62
MARCONI INSTRUMENTS LIMITED Sheet | of 2 Sheets
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