Document text
%
{
% “~
as
, dena
fh, °
; ‘
f 4
f
ES -
nee Ko
ENC ELECTRONICS INC.»
aineoaH VHF EM_Te
cea ccc
MODELS B7H28%,
¥
\
ivy , )
4 PU
Mh
MES
7707 RECORDS STREET PRINTED IN U.S.A. PRICE $5.00 ~
IN DIANAPOLIS, INDIANA 46226 __ 11-74 SM - 10-515
BTH - 204 AND BTH - 204H SERVICE MANUAL
SECTION I GENERAL INFORMATION
1-1 DESCRIPTION
1-2 SPECIFICATIONS
1-3 EQUIPMENT SUPPLIED
1-4 EQUIPMENT NOT SUPPLIED
1-5 INSTALLATION
[-6 OPERATION
1-7 CRYSTAL SPECIFICATIONS
1-8 CRYSTAL INSTALLATION
SECTION Z CIRCUIT DESCRIPTIONS
2-1 RF - MODULATOR BOARD
2-2 IF - AUDIO BOARD
2-3 LED DISPLAY BOARD
2-4 TRANSMITTER BOARD
2-5 RECEIVER BLOCK DIAGRAM
2-6 TRANSMITTER BLOCK DIAGRAM
SECTION 3 ALIGNMENT AND TUNING PROCEDURES
3-] EQUIPMENT REQUIRED - RECEIVER ALIGNMENT
3-2 QUADRATURE DETECTOR ALIGNMENT
3-3 IF ALIGNMENT
3-4 RF ALIGNMENT (RECEIVER)
3-5 NOISE BALANCE ADJUSTMENT
3-6 EQUIPMENT REQUIRED - TRANSMITTER ALIGNMENT
3-7 TRANSMITTER TUNING PROCEDURE ~
3-8 CRYSTAL NETTING PROCEDURE
3-9 DEVIATION AND MIC GAIN ADJUSTMENT
SECTION 4 DIAGRAMS, VOLTAGE DATA AND SCHEMATICS
4-1 RF - MODULATOR BOARD PARTS PLACEMENT DIAGRAM
4-2 RF - MODULATOR BOARD BOTTOM VIEW
BTH - 204, BTH - 204H
4-3 IF - AUDIO BOARD PARTS PLACEMENT DIAGRAM
4-4 IF - AUDIO BOARD BOTTOM VIEW
4-5 LED DISPLAY BOARD PARTS PLACEMENT DIAGRAM
4-6 LED DISPLAY BOARD BOTTOM VIEW
4-7 TRANSMITTER BOARD PARTS PLACEMENT DIAGRAM
4-8 TRANSMITTER BOARD BOTTOM VIEW
4-9 TRANSMITTER BOARD TUNE-UP TEST POINTS |
4-10 CRYSTAL LOCATION AND ADJUSTMENT DIAGRAM
4-11 VOLTAGE DATA AND SEMICONDUCTOR LOCATION DIAGRAMS
4-12 SCHEMATIC WITH VOLTAGES - BTH - 204
4-13 SCHEMATIC WITH VOLTAGES - BTH - 204H
SECTION 5 PARTS LIST
5-1 RF - MODULATOR BOARD 500-861
5-2 IF - AUDIO BOARD 500-858
5-3 LED BOARD 302-239
5-4 TRANSMITTER BOARD 501-067
5-5 CHASSIS ASSEMBLY
BTH - 204, BTH - 204H
SECTION 1 GENERAL INFORMATION
1-1 DESCRIPTION
The Regency BTH-204 and BTH-204H are all-transistor, four -channel FM
transceivers designed for use in the VHF (150-174 MHz) Communications Band.
The BTH-204 operates in the 150-162 MHz segment of the band, while the BTH-
204H operates in the 162-174 MHz segment. The transmitter and receiver sec-~-
tions both employ band-pass circuitry for maximum RF power output and receiver
sensitivity. Receive and transmit frequencies are beth crystal-controlled.
The transmitter and receiver sections can be pre-tuned to any frequency within
the specified segment of the band (150-162 MHz or 162-174 MHz). The two sections
are independently tuned, thus either one can be tuned to a different frequency (with -
in the proper segment) than the other. However, the maximum frequency spread
for the transmitter section is 1 MHz, while the receiver frequency spread is 3
MHz. In other words, the maximum difference between the lowest and highest
frequency is 1 MHz for transmit frequencies and 3 MHz for receive frequencies.
The receiver section is a double-conversion, super -heterodyne type receiver.
Silicon transistors (13) are utilizes for dependability under widely varying ambient
conditions. Also, two Integrated Circuits are used, providing for compactness and
circuit reliability. In addition, a ceramic filter is employed in the second I.F. for
optimizing performance where numerous channels are active within the same area
of the country.
The transmitter section also utilizes silicon transistors (13) throughout. Two
ruggedized RF power transistors (BET or Balanced Emitter transistor type) are
employed for high power output, which typically is 22 watts. A large, copper heat
sink ensures that there is virtually no power drop off during lengthy transmissions.
In addition, an SWR Bridge Limiting Circuit provides the necessary protection to
the RF power transistors in the event the antenna or its coaxial feedline becomes
open or shorted.
The transmitter employs phase modulation for the ultimate in carrier stability.
Internal controls are provided for adjusting the microphone gain and for setting the
the amount of deviation. The deviation control is adjusted for a maximum of 5 KHz
deviation, in conformance with FCC regulations.
The attenuation of spurious emissions from the transmitter, RF power output,
frequency stability, performance under highly varying conditions of temperature
and battery voltage, and other specifications, all exceed the limits required for
Type Acceptance by the Federal Communications Commission.
NOTE: The Regency Type BTH-204 Transmitter is Type Accepted under
Parts 21, 81, 89, 91, and 93 of the Federal Communications Com -
mission Rules and Regulations. The Regency Type BTH-204H is
BTH - 204, BTH - 204H -1- SECTION 1
Type Accepted under Parts 21, 89, 91, and 93. The receiver sec-
tion of both units is Certified under Part 15, Subpart C as required
by the FCC Rules and Regulations.
1-2 SPECIFICATIONS
RECEIVER
Anterina inipedancteé «ics seve cea cd ae soda eens owe cece e008 sihesieere emmOUlinaE
Frequency'Ratige (BTH 204) 0. 6c e'Giseae cessed «bet e cls ec Wblerss eo) POU eM La omy ce
Frequency.Range: (BUH =-20411) 05 tite, wets stasieletclc'stulc'ss bie 9) siete elon 162.0-174.0 MHz
Channels, «5 iicedec 8s sue b se se Ws epivinelen se 9 50s eels oncie sete tCok aed Meets
Sensitivity. Fos dsie's ess cess elds sclslers satsiale cls ¥ pLU poo ULVE TORI Jy en a UceemnE
Seng ittvity Pandit. sos Ea sc diel eietele cee! eee dials cle ale pie o ulate pi s/eteletele’s coishatguytemnn ayn
SELECTIVITY S es Hetarn bo ahs ee dla te lete tides Grrtetetbie Scatter atanere osteitis . 6 DB down, +7 KHz
50 DB down, +16 KHz
Imape Rejection wos. co's co's wie we G8 16 cis 6 3 pisfo ele one Ub slate ta els) or cnacshetahe te] tometer came memne
Spurious: Rejections.) <.cb sp piece sree alvin cals cieie eivleie aie Glerele gia ecg ier e neeee Terms
Intermediate: Frequencies... 5. slsstels es oe 6 elulsic cere ed sesteltiera Mit Niat emer Creer amie
2nd 1.F. -455 KHz (ceramic filter)
ModulationzAcceptance .c5. su giciiss cles ciel tie blelele ctoheie ele gis he 6 atate ier Githere ee RL ORE
squelch System. vs ss. eae REO seis a oW whole “ole'd ald dlececlele Wie Go ote este MINOT OG mmmC mana mate
Audio Output (3-4 2 SoBe) AHN 3 Watts @ 10%, or less, distortion;
> Watts, maximum
PCE Certified ii vic cs iyi cae oe ele de cpels eo dcslote ere vic) cra siete gieherera suete caeebeel | amet Sn ras a
TRANSMITTER
Antetina Impedance site sacs sine ete eieee Sleep ele ce asatate Ciavc a eiece went c tence een .. oO Ohms
Frequency Rance (BIH -204) ie Cee weer cert cele < cee een 150.0-162.0 MHz
Frequency Ranpe (BT H=204H Ji. eect wiorerctets «so ec foueiuiens st see woeeee O23 O97 SU MiEl a
CHANNELS. 6.5 cletetelete viprs ¢ alga oterarecers wela cle Sid's eh ales elelaiite. sos alee | SNe VEC ecient
Frequency Stability.......... re re ier ee weeeees +,.0005% (-30°C to +60°C)
POWEL OULDUE J h-ccole saves ached ceeiclens pentane net essevess 20 Watts (nin?) Galo ey
Power Bandwidth. ......... AMEN TE Oh eee ERT RRR SG Noo oo oie hw erative
Power Amplifier Protection...... wisistatetetstcceterare of lersiare fimicing SWR Bridge Circuit
Spurious, G HarmonicsRe jection ie. ceus eerie ss sto -vercte anes d's eae etetate 57 DB (min.)
EMissiomDesigmatorics tiptewta ere vie ujeesest etmiaie seer. eee 0 ah siete oilete aie’, ote Cte ROI
Microphone. .ccccncresecssdeeccceeadced vies sf LUD =i) pialtiiG denis C lee come
Mike Pre-Amp...... ccetegoes oeeecsenceses tee DRY WitttlevelecOncioln ine at
Modulation os’ e's. sles s slnewrele 3 so bles tice 64 6 sle'es os FHaASe MOC at OU miei lias le
Deviation Limiting
Deviation. cis. cc cic ec osunve seuss cetestiicscoesoeeec ee PACtUL YrdlJUGlLeU Orso rmE Es
internal adjustment of 0-7 KHz
FCC Type Accepted (BTH -204). 20... csccevcecesuvs PALLS 2h mG lyn O 2 me Reman
FCG Type: Accepted.(BTH =204H ins tidied sie bane see ci sie we RDA CLG ee ee ee
BTH - 204, BTH - 204H -2- SECTION 1
POWER
Mar eCRMCUUSLEINETUS ety baci eesics sss scien s ts bees s cisviccscus Lids 8 VDC (nominal)
11.7V (min.) to 14,9V (max.)
Sena QUIT CIICTILS c'est sale sielctss sie 4s ob e's e's 6'e0.0'9:0% tres eters . @ 13.8 VDC
EN Sree eed ENE, oils ces cc sawtln Re Ree, ve 130 MA.
ReECoIVO VIER AUIGIO COUUIUL IE IiG ie 6.6 6 ores 6u.0.d a0.0 4s vee oulenecseceee CUO MA,
CTV StHTICALCl Ss AWD StALE sy cteiets 6 eles co ce ve ness ce Wie ¥t¥'s 400 bo LOOMA.) (aX,)
PIeVe TL TAT LO gra vee a oie stale o Crates else die o vb leche’ i 8.8 « bietele cate seveveees 4,0.Amps (max.)
PID MOLEC Welettia etl iis oly s eters a ietsiel er ete'e'S 614616 + Sib e'o ve tet hibGie cic Cele ewieinie , OAAIUID gd AG
SEMICONDUCTORS
RICE CEEC OLE CUILS lejatciclale oie etatelaia! cites lait .6'6's.9'y oo's\ via sla s\'e)e si s'uie 6 916.6 ole 60 ab 6 biese'eiece
ae ee OTIS O SUL oC OLA 1) cis ale viele eialele Cv oie 6 sis 8 ee-0 6 cece osbee sad esiecseccievies 2
BET RF Power Transistors....... PTI ahalte at Tei eso dpi e Geib Pies eieioteceie is GLG-E.b are te
REC UeETICCU SE LOMB IGUOLGT yivic's tele eis 'e cs 6 0 0 cio. 0.0 sle.s 0100 4 018 0 clcbs bios G0 409 8 ob 0 0s
EC UAE Ott oils oer Pec fctol ersteic ists 070 oo aicic'ols viele'a aise 60 wie) nleve eieie tials e/sitele wenn) L
Drea eum LLGe ete fete eigiatain orenereleteleiaie eso 6.s as" 6's 96 6 e/6's 0/8104 4.6 6.6 0 ¢.6.¥10 «.¥'v 0:8 9.60
Pe LOCOS ey a itise fale si elervinie dvivisls 6 6/6\6 e100 0.0. 6.018% 6.0.91 sbanatatere eiara avelaters, cleat c o(6'e
BMI Aee LOC se a rtegre etal cl sielctetar stately iets/or <fele 60 e'e)clensece uc viv.cis's'e « hishe Sib e 6 bjeldini@are
ING CULEIC Lye AOUGs eter e eisiaisie core isie tral ale’ sie 'elsie clu d wid cle 6 6 sles ojere 6 a6 0\b-olarnisl 06 ole ase
PACT ITCLOE A 100eS (EI) ingiies cs secs cv sf ssessctevcbecsecess usec eusne
wh oh WN DW bo
Ge
GENERAL
Front Panel Size so, fo. nese Te ete ceils tale vcle ce sea Oy On Rid OO
Depth (Including Knobs and Ree Panel Gonnectors)....ss0ss. bie» Win te shite PAIRED PALL «
Weigth (Including Microphone and Mounting Equipment)............+. 3 ibs. 13 oz.
Pa peTA a OMeClO Lister gists ce « Sitisatsis nie sisi 6 ois » 4.i0 6 o[é\e eidse <isitye'e 01000 s/c'e 6siein) SO LOO
POW RMGONNCCLOL I Si Ter cei ss ete aae ect vtisawsccceccecsice» 4-pin, polarized
Speaker Size........ WaT co Mes co eisis cieisiclsk bres ooh re’ eis mee 2 atch, Square
1-3 EQUIPMENT SUPPLIED
a. 1 - Transceiver unit
b. 1 - Microphone and Connector
¢. 1 - Mobile Mounting Bracket
d. 1 - Mobile Mounting Hardware
e. 1 - Security Bracket
f. 1-DC Power Cord and Fuse
g. 1 - Owner's instruction Manual
1-4 EQUIPMENT NOT SUPPLIED
a. 1 - Antenna
b. 1 - Coaxial Cable feedline
8TH - 204, BTH - 204H
eo
SECTION 1
c. 1 - Coaxial Cable Connector
d. 1 - Power Supply (battery)
e. 1 - Pad Lock (used with Security Bracket)
1-5 INSTALLATION
Mobile (12 VDC) Installation:
The BTH-204 or BTH-204H transceiver is designed for installation in any
vehicle that has a 12 VDC negative ground system. The RED lead, with the
fuse holder, must be connected to the POSITIVE (+) terminal side of the battery.
The BLACK lead should be connected to the NEGATIVE terminal side of the bat-
tery, or to a metal chassis that is grounded to the negative terminal. In the
event that the battery is remotely located, it may be necessary to install addi-
tional wires for properly connecting the radio to the battery's terminals.
THE ANTENNA USED SHOULD BE PROPERLY ADJUSTED FOR THE 50 OHM
OUTPUT OF THE TRANSMITTER, A HIGH SWR WILL REDUCE THE POWER OUT,
OR MAY EVEN SHUT OFF THE TRANSMITTER ENTIRELY.
To reduce the possibility of theft, the Security Bracket should be installed as
shown in Figure 1-1. The padlock used should be of substantial construction and
can be either a key of combination operated type. | (
An external (or remotely mounted) speaker can be used by first opening the
link between terminals No. land No. 2. Then, connect one lead of external
speaker to the terminal No. 4 (chassis ground) and the other lead to terminal
No. 1. The use of a 3 to 4 ohm speaker is recommended for optimum perfor -
mance (such as Regency's MA-8).
MOUNTING BRACKET
SECURITY BRACKET
LOCK (NOT INCLUDED)
SIDE VIEW SHOWING SECURITY BRACKET INSTALLATION FIG. 1-1
BTH - 204, BTH - 204H ; -4- SECTION 1
1-6 OPERATION.
The OFF-ON switch is an integral part of the VOLUME control. Turning
this control fully counter -clockwise until a click is heard will turn the unit off.
Maximum volume, or audio output, occurs when the volume control is turned
fully clockwise.
The receiver's audio is squelched off when the SQUELCH control is turned
COUNTER -CLOCKWISE. Turning this control counter -clockwise until the noise
just disappears (threshold squelch) permits the receiver to be "quiet" until an
actual signal is received. With the squelch control set fully counter -clockwise,
the receiver will still operate properly and will not be locked-out (prevented
from resporiding to a received signal).
The transceiver is capable of two-way communications on any one of four
discrete, crystal-controlled frequencies, or channels. Selection of the de-
sired channel is accomplished by turning the CHANNEL SELECTOR knob to
Below each channel designation (F1 for example) is an LED which glows
whenever that particular channel is selected. These lamps make it easy to
tell at a glance which channel has been selected and to also verify that the
radio is turned on. The remaining LED, labeled TRANS, is a Transmit
Indicator which glows whenever the transmitter is keyed (activated).
A high impedance ceramic microphone is supplied with the unit. To in-
stall the microphone on the unit, insert the connector plug into its socket with
the locating tab toward the bottom of the radio. The connector is then locked
into place by rotating the locking ring 1/4 turn clockwise.
To transmit a message, it is only necessary to press the push-to-talk
button on the microphone and speak into the microphone. The Transmit
Indicator will come on to signify that the transmitter is activated. Best
results are obtained by holding the microphone about one inch from the lips
and inclined at about a 30 degree angle away from the face. Speak clearly
in a normal tone of voice across the face of the microphone.
1-7 CRYSTAL SPECIFICATIONS
Miniature plug-in crystals are utilized by both the receiver and trans -
mitter sections. Because of the high accuracy (close tolerances) required,
Regency crystals are recommended. Hither receive or transmit crystals
must be ordered by specifying the Channel Frequency and Part No. 2311-
0000-000 for Receive or Part No. 2312-0000-000 for Transmit. Use of
other manufacturers’ transmit crystals may cause violation of the FCC
Rules and Regulations.
BTH - 204, BTH - 204H 5- SECTION 1
If desired, the RECEIVE crystals may be purchased from other manu-
facturers. The following specifications must be included in the order:
a. Crystal Frequency, determined as follows:
Crystal Frequency = Receive Frequency -10.7 MHz
3
EXAMPLE:
Crystal Frequency = 156.300 MHz -10.700 MHz
3
Crystal Frequency = 48.533 333 MHz
b. Frequency Tolerance of .001% @ 25°C; .002% from -10 to +60°C
c. 3rd Overtone
d. Series resonance minus 600 Hz
e. Maximum equivalent series resistance of 35 ohms
f. Drive level of 2 MW (max.)
g. Holder: HC-25/U
1-8 CRYSTAL INSTALLATION
Prior to installing a crystal, the transceiver's cover will have to be re-
moved. To remove this cover, unscrew the two large bolts located at the sides
of the unit. The cover may then be slipped off by sliding it toward the rear of
the unit.
Next, the speaker should be removed. Unscrew the two small metal screws
(one located on each side) holding the speaker mounting brackets in place. Then
carefully place the speaker assembly along side of the unit.
See Figures 1-2 and 1-3 for proper Crystal Location and Installation. Insert
the Receive crystal in the proper channel; be sure the crystal is firmly seated in
the socket pins.
Special care must be taken to install the TRANSMIT crystal, correctly. The
conduction type crystal heater, which is used to heat the crystals ata very low
ambient temperature, relies on having proper physical contact between the heat -
er element and the crystal for effective operation. The Crystal Heater Detail
(Figure 1-2) demonstrates the correct method of crystal installation. The crystal
must be pressed down into the socket pins far enough for the rim around the bot-
BTH - 204, BTH - 204H -6- SECTION 1
tom of the crystal to clear the heating element and allow good contact between the
side of the crystal and the element.
For the TRANSMIT crystal, there is a variable capacitor that is to be used for
"Netting" (adjusting to the exact frequency) purposes. This netting should be made
with an accurate frequency counter, such as Regency EC-175. See 3-8 for detailed
Crystal Netting Procedure.
NOTE: FCC Regulations require that the TRANSMIT crystal be installed
and adjusted "on frequency" under the supervision of a technician
holding either a First or Second Class FCC license.
After the crystals are installed, and netted, reinstall the speaker assembly.
Then, carefully reinstall the cover and its hardware.
R334 HEATING ELEMENT
(OR R335)
CRYSTAL CRYSTAL
P C. BOARD
CRYSTAL HEATER DETAIL
(As Viewed From the Front of the Unit)
FIG. 1-2
BTH - 204, BTH - 204H -7]- SECTION 1
BTH - 204, BTH - 204H
RECEIVE CRYSTAL
POSITIONS
ANY
MICROPHONE ®
PRE-AMP GAIN
ADJUSTMENT
DEVIATION
ADJUSTMENT
MAX. GAIN MAX. DEVIATION
CLOCKWISE C.CW, ROTATION
ROTATION
T/R RELAY
TRANSMIT CRYSTAL
NETTING CAPACITORS
CRYSTAL LOCATION DIAGRAM FIG. 1-3
SECTION 1
SECTION 2 CIRCUIT DESCRIPTIONS
2-1 RF - MODULATOR BOARD
Q201 is an RF amplifier with broad-band tuned circuits in its input and out-
put circuitry. The output of the RF amplifier is coupled to the input of the mixer,
Q202, a Field Effect transistor.
The first L.O. (local oscillator), uses third overtone crystals. (The number
marked on the crystal is the receive frequency). Oscillator injection to the mixer
is accomplished by mutual coupling between the windings of T201.
The 10.7 MHz output frequency from the FET mixer is selected by T202. This
output is link-coupled to T101, the IF input tuned circuit.
The Modulator Section of this board is described in 2-4 in conjunction with the
transmitter board.
2-2 IF - AUDIO BOARD
The IF input circuitry consists of T101 and Q101, used as an IF amplifier.
The output of this amplifier is fed to an Integrated Circuit, IC101, which con-
tains the second mixer and L.O. circuitry, operating at 10.245 MHz. In some
locations where a strong secondary Image Signal has been encountered, this os -
cillator's frequency is moved to 11.155 MHz. (The crystal frequency is stamped
on the top of the crystal).
The 455 KHz output of IC101 (terminal 5) is coupled through a tuned circuit to
the input of the ceramic filter, CF101. CF101 is a narrow-band filter centered
at 455 KHz. The excellent band-pass characteristics of CF101 provide for very
good adjacent channel rejection. The output of CF101 is coupled through another
tuned circuit to the input of Integrated Circuit IC102. 1C102 is a series of ampli-
fiers providing approximately 60 DB gain at 455 KHz. Also included in IC 102 is
the limiting circuitry and a quadrature detector circuit. L103, connected be-
tween terminals 2 and 12 of IC102, is the adjustable quadrature coil.
The audio output from IC102 (terminal 1) is coupled to the input of the audio
amplifier circuit and to the input of the noise-operated squelch circuit.
Transistor Q102 is an amplifier whose frequency response extends from
approximately 5 KHz to 25 KHz. Q102 amplifies the "noise" occuring in this
frequency range. The noise is coupled to the base of Q103. Q103 is used as
a detector which rectifies the amplified noise and produces a DC voltage at
its collector. When the DC voltage at the collector of Q103 is positive and
of sufficient value to provide base bias for Q104, Q104 turns on and provides
essentially a short circuit between the base of Q105 and ground. This action
turns off Q105 and the audio output from the receiver is squelched (muted),
BTH - 204, BTH - 204H -1- SECTION 2
When a signal (carrier) arrives, the noise input to the detector (Q103) is re-
duced to the point where the DC voltage at the base of Q104 is no longer suf-
ficient to cause Q104 to conduct.
At this time, the audio pre-amplifier (Q105) is allowed to operate nor -
mally and its audio output is applied through the volume control to the base
of the audio amplifier, Q106. Q106 supplies a signal to the audio driver
transistors, Q107 and Q108. The output transistors, Q109 and Q110, form
a quasi-complementary, transformerless stage capable of delivering 5 watts
to the speaker.
2-3 LED DISPLAY BOARD
Channel Indicator:
When a particular channel is selected, the cathode of that channel's LED
indicator (LD401, 402, 403 or 404) is grounded and voltage to the LED is pro-
vided by the transceiver's supply voltage.
Transmit Indicator:
The Transmit Indicator (LD405) functions similarly, except that the cathode
is already grounded and voltage to the LED is provided by the transmitter sup-
ply voltage.
2-4 TRANSMITTER BOARD
Q308 is in a crystal oscillator circuit operating at approximately 13 MHz.
Each crystal has a trimmer capacitor in series with it. This trimmer capac-
itor is used for fine (small) adjustments to the crystal's frequency.
The crystal heater assembly consists of R334 (or R335) and two spring clips.
R334 (or R335) is located between two crystals in such a manner that the spring
clips force the crystals into reliable physical contact with this resistor. Power
dissipation in the resistor is sufficient to cause conduction heating of the crystals
to above 0°C when the ambient temperature is -30°C. Control circuitry consisting
of Q309, Q310 and associated circuitry automatically adjusts the power delivered
to the crystal heaters. Heater turn-on is nominally between 0°C and -5°C. Both
heaters will be completely shut off at normal ambient temperatures. Refer to
Figure 1-2 for detailed drawing.
The oscillator's frequency is phase-modulated by two varactor diodes, CR302
and CR303, which are connected across a coil (L306) that is lightly coupled to the
emitter circuit of the oscillator. L306 is tuned to the crystal frequency. The
oscillator's phase-modulated output is applied to the base of Q307. Q307 isa
multiplier whose output frequency is three (3) times the crystal frequency. The
7 BTH - 204, BTH - 204H “2 SECTION 2
signal from Q307 is transformer coupled to the base of Q306. Q306 is used as a
doubler, a stage that multiplies its input signal's frequency by two. Thus, the
output frequency of Q306 is six (6) times the crystal frequency. This signal is
then applied to Q303, which is also operating as a doubler. The frequency of
the output signal from Q303 is twelve (12) times the crystal frequency. This
frequency is the ultimate transmitter output frequency.
Q302 is a power amplifier operating "straight through". Q302 provides the
drive (RF signal) required by the ‘final stage, Q301, to deliver at least 20
watts of RF power to the antenna through the impedance matching network in
its collector circuit. Q301, Q302, and Q303 operate in the Class C Mode.
The transmitter output transistor, Q301 is protected from damage due to
excessive SWR on the antenna transmission line by the SWR Bridge and Drive
Limiter circuits. In the event of a load mismatch at the antenna connector,
the SWR Bridge consisting of T301, R301, R305, and CR301 will detect the
mismatch and send a signal to the Drive Limiter. The Drive Limiter (Q304
and Q305) will then bias Q306 in an off condition, preventing possible damage
to the power amplifier (Q301). Load mismatch is detected by comparing the
phases of output voltage and current to determine if standing waves exist on
the feedline to the antenna.
The modulator section of the transmitter uses a high impedance ceramic
microphone. The microphone signal is applied to a Field Effect transistor,
Q205. The output of Q205 is applied through the microphone gain control
(R217) to Q206. The mike gain control is adjusted to compensate for the
output differences in the voice levels of various operators and will normally
be set at about 75% of maximum clockwise rotation. This control sets the
mike signal to the proper clipping level for the logarithmic clipper diode
circuitry between stages Q206 and Q207. Suitable pre-emphasis and de-
emphasis is used preceding and following the diode clippers. The deviation
control (R228) in the collector circuit of Q207 sets the level of the audio
signal voltage applied to the Varactor diode modulator circuit. This level
is adjusted for a maximum of 5 KHz deviation with the clippers driven to
full clip by a 1 KHz audio signal.
The push-to-talk (PTT) Switch in the microphone applies a ground to the
transmit -receive relay coil, which activates the relay. The T-R relay
switches the supply voltage between the receiver and transmitter and switches
the antenna between the receiver input and the transmitter output.
BTH - 204, BTH - 204H -3-
SECTION 2
AWNIOA 2
93yu Ad 8+
HO13NOS
2010 £010 bold
YAIsIId NV ¥O193130 aLVS
ASION HO13NOS
ASION
101 OL
YSALIWIT-dWV AT
YSIS IdWV ST
OD ‘6010'8010 ZOIO
M3ISIIdWY
4Y3MOd OIGNV
9010
Y3AISIIdDWV
Olanv
Ae} R= Fe)
YOLV1N93Y
ANVLIOA
AlddNS AYVWIdd
SLIOA 8°El¢
oe Pig He
3NI)
Y3yNV3dS
A +
YSLLINSNVY1 —<—o
vOcA
EOZA'ZOSA'IOZTA
¥YO1L90373S
ANVE TANNVHO
TWWLSAYS
vOcd
YOLVY1119SO
WOOT
4S |
ZOl OL
40193130 }-49 YOLVIINNOSO Keyne) 2020
Y31014 IWOOT Pu? YalalIdWV Y3aXIW
WVYSVIG 4HOO18 YSAIS03Y
bOval'€0var
c0vd1 10¢07
SYOLVOIOGNI
TANNVHO
LAdLNO
YS1LINSNVYL
<2
leY4e)
Y3151IdWV G
du
y31d
SSVd
MO7
YOLOANNOD
VNNIALNV
2-5 RECEIVER BLOCK DIAGRAM
SECTION 2
BTH - 204, BTH -204H
SOf£Y)D
YyOLV1NS3Y
39VLIOA
vOfA O1<O'60EO [Kos
EOLA ZOEA'IOEA
4¥O19314S
TANNVHO
TOYLNOOD
‘NYE
43LV3H
WLISAYD AVLSAUD
Soe 0
80¢0
poe 0
YOLVTNOSO Waar
WAS AUD SAINa
AL el+
ag3y¥3iia LNdNi au
YSAIS938
yall
P+ SSvd
MO?
log © aid 39a14Ne :
YOLY INGOW Zoe 0 30¢ 0 €OE O z20¢ 0 4 Y 2
~ -3SVHd 7] MATL ¥37enod y3enod Y3AINO Boag (35 |) and&ne [ay] SKS | YoLo3NNOO
VNNALNV
!
yoLyinoay
2 SOVLIOA poe) AqY
u/1
: |
|
- A <'el+
Yo 0343114
A+ 2 0
IN3aWisNrav 2 NIVD 4 Y3AI3034
NOILVIAZG 3yIW
LNdNI
ysis 902 DO G02 0 Yai o1any
“SS usaawy SSvd Spot ualsI dW Yad dv SS¥d
MOT o1any MOI NOILWINGOW o1any 3XIW MO71
WVYOVIG 400718
Y31LINSNVYL
2-6 TRANSMITTER BLOCK DIAGRAM
SECTION 2
BTH - 204, BTH - 204H
#<
bs ee US
ree
»
‘
;
~~)
oo
be ow
SECTION 3 ALIGNMENT AND TUNING PROCEDURES
3-1 EQUIPMENT REQUIRED - RECEIVER ALIGNMENT
FM Signal Generator
Oscilloscope
AC VTVM
Noise Generator (To Be Used In 3-5 Only)
Audio Generator -HP 200D or Equivalent
Frequency Counter - Regency EC-175 or Equivalent
: During all steps of alignment, the squelch control should be in the
maximum clockwise position (minimum squelch action).
All transceivers should be aligned to the channel nearest the center
of the frequency range over which they will operate.
Diagrams 4-1 and 4-3 show the location of all coils to be adjusted.
3-2 QUADRATURE DETECTOR ALIGNMENT
3-2-1
3-2-2
3-2-3
3-2-4
Connect the FM Signal Generator to the antenna input jack. Ac-
curately set frequency to the center of the channel being used for
alignment. Modulate Signal Generator with 1000 Hz, 3 KHz deviation.
Connect the oscilloscope to Test Point A, (Junction of C126, C128,
R113). See Diagram 4-4.
Adjust output of Signal Generator until all noise in scope pattern
just disappears.
Adjust L103 for maximum peak amplitude, while maintaining symmetry
of the detected signal.
3-3 IF ALIGNMENT
3-3-1
3-3-2
3-3-3
3-3-4
Disconnect RF Signal Generator from antenna input.
Connect AC voltmeter across speaker terminals.
Adjust volume control for 0.5 volt noise reading on AC voltmeter.
Peak T102 (bottom core and top core, in that order) for maximum
noise (maximum meter reading on AC voltmeter). If circuit is not
badly misaligned, the correct point should be within two turns of the
cores’ present position.
BTH - 204, BTH - 204H -1- SECTION 3
NOTE: Coils will have two peaks; adjust core to peak away from the center
of form.
3-3-5 Adjust volume control for 1.0 volt noise reading on AC voltmeter.
3-3-6 Connect the R.F. Signal Generator to the antenna input jack. Turn
modulation off. Set the generator to the operating crystal frequency.
3-3-7 Adjust the Signal Generator output until the voltmeter reads 0.2 volts.
3-3-8 Adjust T101, T202, T201 (bottom core) and T201 (top core), (in that
order), for maximum quieting (lowest meter reading). Adjust Signal
Generator to maintain reading on AC voltmeter between 0.1 and 0.2
volts. If two peaks occur, use the one away from the center of the
coil form. |
3-3-9 Set the generator frequency to the secondary image frequency. This
is 910 KHz BELOW the channel frequency.
NOTE: If the second oscillator is at 11.155 MHz, the secondary image fre-
quency is 910 KHz ABOVE the channel frequency. Check the frequency
marked on top of Y101 (10.245 MHz for BELOW and 11.155 for ABOVE).
3-3-10 Adjust the Signal Generator output until voltmeter reads 0.2 volts.
3-3-11 Adjust T102 (bottom core), T102 (top core), T101 and T202 (in that
order) for maximum quieting degradation (highest meter reading).
Adjust Signal Generator output to maintain voltmeter reading be-
tween 0.1 and 0.2 volts. The correct position for the cores should
be within two turns of the position in Step No. 4 and 8.
3-4 RF ALIGNMENT (RECEIVER)
3-4-1 Pre-Set the cores of L201, L202, L203 flush with the tops of the
coils forms.
3-4-2 Connect AC voltmeter across the speaker terminals.
3-4-3 With nothing connected to the antenna input, adjust the volume
control until AC voltmeter reads 1 volt of noise.
3-4-4 Connect Signal Generator to antenna input jack. Set generator
accurately to the center frequency of the channel being used for
alignment. Turn modulation off.
3-4-5 Adjust output of Signal Generator until AC voltmeter reads 0.2
volts.
BTH -2 :
04, BTH - 204H -2- SECTION 3
3-4-6 Adjust L201, L202 and L203, in that order, for maximum quieting
(lowest meter reading). Adjust Signal Generator output to main-
tain voltmeter reading between 0.1 and 0.2 volts. Repeat adjust -
ments until no further improvements can be made. If two peaks
occur on any core, use the peak with the core nearest the top of
the coil form.
NOTE: The following step may be omitted if performed in IF Alignment
section. |
3-4-7 Adjust T102 (bottom core) and T201 (top core), in that order, for
maximum quieting (lowest meter reading). Adjust Signal Generator
to maintain reading on AC voltmeter between 0.1 and 0.2 volts. If
two peaks occur, use the one away from center of the coil form.
3-5 NOISE BALANCE ADJUSTMENT
NOTE: This adjustment may be required only if excessive "ignition noise"
is encountered. Usually, the noise problem is caused by improper
or inadequate noise suppression of the vehicle's ignition system.
3-5-1 Using a "T" connector, connect the FM Signal Generator and the
Noise Generator to the antenna input jack. Ifa ‘IT connector is
not available, connect the FM generator to the antenna jack and
feed in the noise signal by means of a 3 or 4 turn loop coupled to
the input coil, L201.
3-5-2 Connect the oscilloscope to the junction of Q109's emitter and Q110's
collector, or to the speaker terminals.
3-5-3 Apply a 3 to 10 microvolt signal, as accurately as can be set to the
exact channel frequency (carrier only, no modulation), and adjust
the output of the Noise Generator until spikes are clearly seen in
the audio output as viewed on the oscilloscope. The noise spikes
will either mostly’ be positive or negative if an unbalanced con-
dition exists.
3-5-4 Tune L103 (Quadrature Detector Coil) until the noise spikes are
equally positive or negative in their amplitude. The overall am -
plitude of these spikes should be much less as balance is
achieved. Usually, only a 1/4 turn, or less, is needed to obtain
the proper adjustment for best noise balance. Ifa proper balance
can not be achieved, repeat the IF and RF alignments and then
try the noise balance adjustment again.
BTH - 204, BTH - 204H -3- SECTION 3
3-6 EQUIPMENT REQUIRED - TRANSMITTER ALIGNMENT
3-6-1 RF wattmeter (or equivalent device which provides a 50 ohm load
at the appropriate power range).
3-6-2 Frequency Counter - 170 MHz preferred; 50 MHz acceptable.
3-6-3 FM Modulation Meter - Lampkin 205A or equivalent peak reading
deviation meter,
3-6-4 Audio generator - HP 200D or equivalent.
3-6-5 VIVM
3-6-6 Oscilloscope
3-7 TRANSMITTER TUNING PROCEDURE
NOTE: The encircled numbers on diagram 4-9 correspond to the LAST
digit in the following procedure steps. The unit must be con-
nected to a suitable 50 ohm load for proper alignment of the final
transmitter stage.
3-7-1 Install crystals. For full bandwidth alignment, a center tune -up
crystal must be used. Alignment is done on the center tune-up
frequency and then the bandwidth is checked using the high and
low crystals, The total maximum bandwidth for Transmitter op-
eration is 1.0 MHz (500 KHz above and 500 KHz below the tune-up
frequency).
3-7-2 Tighten trimmer capacitor C303.
3-7-3 Set the Netting" capacitors (4 trimmers; see diagram 4-10) to
mid-range.
3-7-4 With the transmitter keyed and the tune-up frequency crystal op-
erating, voltage at this point should be 2.5 to 3.0 volts as read on
a VIVM.
3-7-5 Move the VITVM's probe to this point and adjust L306 for a maximum
reading (1.8 to 2.0 volts).
3-7-6 Move the VTVM's probe to this point. Alternately peak the upper and
lower cores of T305 for a maximum reading (normally 1.5 to 2.0 volts;
however, if T304 is completely detuned, this voltage can be as high as
_ 4.0 volts). Check this reading at the lowest and highest crystal fre -
quencies installed for proper bandpass alignment.
BTH - 204, BTH - 204H 4- SECTION 3
Repeat steps 3-7-5 and 3-7-6 until no further improvement can be
made. After these adjustments have been made, L306 and the pri-
mary (bottom core) of T305 should not be changed during the re-
mainder of the alignment procedure.
NOTE: The frequency of the oscillator will change slightly whenever L306
| and [305 are adjusted. Therefore, if the adjustment of these parts
is ever changed, it is important to perform the Crystal Netting Pro-
cedure, 3-8.
3-7-7 Set the top core (secondary) of T304 flush with the top of the coil form.
With the VIVM probe on T.P.6, adjust the lower core (primary) of
T304 for a minimum voltage. This dip will be fairly sharp and will
reduce the voltage at T.P.6 to approximately 1.5 volts. Move the
VTIVM probe to T.P.7. Adjust the top core of T304 downward until
the voltage on T.P.7 increases to 0.5 to 0.6 volts. If a peak in RF
power output is reached before this voltage is 0.6 volts, leave the
top core tuned to the power peak. Under no circumstances should
the top core of T304 be tuned further down in the coil form than the
point where T.P. 7 is 0.6 volts.
3-7-8 With VI'VM probe on T.P.8, adjust the lower core (primary) of
T303 for a minimum voltage. Adjust the top core (secondary) of
T303 for maximum power output on the wattmeter. During Power
Amplifier alignment, the secondary of T303 is retouched for max-
imum power. At that time, the voltage at T.P.7 should be re-
checked and the top core of T304 readjusted, if necessary, as in
3-7-7 above.
NOTE: If the Power Amplifier Stage (Q301) is detuned to the extent that no
power indication can be obtained, the following procedure can be
used to set the top core of T303 near its correct position: move
the VITVM's probe to Test Point 8. Adjust the top core of T303
for a MINIMUM voltage at this point. Now procede with 3-7-9
and the rest of the Tuning Procedure. With the transmitter de-
livering rated output power, the voltage drop across R329 will
normally be 0.9 to 1.2 VDC.
3-7-9 Set the core of T302 to the center of the coil winding.
3-7-10 Power Amplifier Alignment
NOTE: It is desirable, during Power Amplifier Alignment, to place the
unit, especially the transmitter section, on a sheet of steel to
simulate the presence of the unit's cover. This sheet should be
large enough so that it completely covers the bottom of the trans -
mitter board and protrudes beyond the chassis on both sides. Do
BTH - 204, BTH - 204H -5- SECTION 3
not permit this sheet to touch any part protruding below the trans -
mitter board.
a. Set C303 almost tight.
b. The following adjustments are peaked in the order listed for
maximum power output as indicated on the R.F. wattmeter.
1.) Peak C303
2.) Peak C308
3.) Repeat the above two steps until
no further improvement is noted
4,) Repeak the top core of T303 (secondary)
as in 3-7-8 above.
Check bandwidth with low and high frequency crystals. Adjust T1303
for best output compromise between high and low crystals. Adjusting
the core of T302 will sometimes help widen the bandwidth or increase
power outpuf. C308 is the final adjustment for best compromise over
the frequency range.
3-8 CRYSTAL NETTING PROCEDURE
NOTE: The following procedures should be performed with the unit at a
temperature of 70 to 80°F. The frequency of each channel must
be set to within +.0001% of the assigned channel frequency. The
crystal heater should not be in operation at this ambient temper -
ature. Check to make certain that it is turned off before proceeding
further with crystal netting. The voltage drop across R334 (or R335)
is zero volts when the crystal heater is off. A useful operational
check (after the crystals are netted) is to spray R'T-301 with a
"cold" spray, lowering its temperature below the heater's turn on _.
point of approximately 30°F, When this is done, the crystal heaters
should turn on, as evidenced by Q310 being saturated (low collector
voltage).
3-8-1 Use the following procedure if a 170 MHz Counter is available:
a. Connect the unit to the RF wattmeter or dummy load.
b. Turn transmitter on (key the mike's PTT switch or ground pin
No. 2 of J2).
c. Place an RF pick-up loop consisting of 3 or 4 turns near the final
transistor's output circuit (near L301: see diagram 4-7).
d. Read the frequency on the counter.
e. Adjust the appropriate netting capacitor (C335, C337, C339, C341;
see diagram 4-7 for their location) until the frequency being read
on the counter is ''ON"' channel.
BTH - 204, BTH - 204H -6- SECTION 3
3-8-2 Use the following procedure if only a 50 MHz Counter is available:
a. Connect the unit to the RF wattmeter or dummy load.
b. Turn transmitter on.
c. Place an RF pick-up loop near the top of coil T305.
NOTE: Due to a possible slight,"\pulling"” of the crystal's frequency, couple
the pick-up loop as lightly as possible to the top coil of T305. Coupling
to the bottom coil will prevent a proper crystal netting adjustment from
being made. FCC Regulations may be violated if an improper netting
adjustment is made. Use the maximum sensitivity available at the
counter 's input.
d. Multiply the frequency read on the counter by four (4) to find the
ultimate frequency being transmitted.
EXAMPLE: Frequency read = 39.20000 MHz
Ultimate Frequency = 4 x 39.20000 = 156.800 MHz
e. Adjust the appropriate netting capacitor until the frequency being
read is within the required tolerance at one-fourth (1/4) of the
ultimate transmitted frequency.
EXAMPLE: Ultimate Frequency = 156.800 MHz
Counter Reading = 156.800 MHz = 39.20000 MHz +.0001%
&
3-9 DEVIATION AND MIC GAIN ADJUSTMENT
3-9-1 Use the following procedure for proper adjustment of the Mike Gain
(R217) and Deviation (R228) controls (see diagram 4-10 for their
locations):
a. Connect the unit to the RF wattmeter or dummy load.
b. Connect the scope probe to the junction of C225 and CR201. See
4-1 for location. It may be more convenient to connect the probe
to the cathode lead of CR202.
c. Key the transmitter and talk into the microphone with a normal
voice level. Observe the waveform on the scope and adjust R217
(Mike Gain) until approximately 10% of the voice peaks are clipped.
d. Connect the audio generator to the mike input terminals. Set the
_ audio voltage level to 0.5 - 1.0 volts RMS at 1000 Hz.
e. Couple the FM Modulation Meter's RF pick-up to the transmitter.
f. Key the transmitter and adjust R228 (Deviation Control) so that the
maximum deviation is no greater than +5 KHz.
g. Reduce the audio input level to 0.25 volts RMS. The deviation
should not be greater than +5 KHz.
BTH - 204, BTH - 204H -7- SECTION 3
i]
el,
e F 4
)
j a a : a ‘4 \ fy hes oe
=u { ' t's le ie i¥ - ee ey Se eee
ay Wee abe, a , \ of ee ok ‘Pay ie ste cre .
hy yee ¢: >
-— & ¢
St ar : , ‘(2 oe
<a 4 ee ay ety ae i, hos 7 Ot? . © Gia as ve
, ‘he Tiered . : : ie 7
een | eli = > 4) fue ei ot
«
; aw 4 Bis
' Fae Vi wh lhe ew Ti COD wow Me ae a ibe
A y yy ;
. ’ a tas ' f ‘ i 4n , aa
x pelt ay! ; ; , Sal y “ ‘ hs Mi
, R r m ie s* pal Pan is siU by % ony a
a TERS LT on abba ne oh BO RET AE a ’ y ::
i t ba. Us bond out ‘fy AY (eee P) L i :
er ar eer ee me ee
Al Sey fer ae i AO cara bon ohpetss
oh Aga a Cpl Reta saan eh
ae lee fie ao a uta d yooh
ALS Pie cuserianip Mis, ie: eign or i
: i f N a slins PS bie
{> 7 mn OBA Claas oak :
4 os) : Hl o ve ae
a by Rae ae rT
SECTION 4 DIAGRAMS, VOLTAGE
DATA AND SCHEMATICS
4-1 RF - MODULATOR BOARD PARTS PLACEMENT DIAGRAM
4-2 RF - MODULATOR BOARD BOTTOM VIEW
4-3 IF - AUDIO BOARD PARTS PLACEMENT DIAGRAM
4-4 IF - AUDIO BOARD BOTTOM VIEW
4-5 LED DISPLAY BOARD PARTS PLACEMENT DIAGRAM
4-6 LED DISPLAY BOARD BOTTOM VIEW
4-7 TRANSMITTER BOARD PARTS PLACEMENT DIAGRAM
4-8 TRANSMITTER BOARD BOTTOM VIEW
4-9 TRANSMITTER BOARD TUNE-UP TEST POINTS
4-10 CRYSTAL LOCATION AND ADJUSTMENT DIAGRAM
4-11 VOLTAGE DATA
4-12 SCHEMATIC WITH VOLTAGES - BTH - 204
4-13 SCHEMATIC WITH VOLTAGES - BTH - 204H
BTH - 204, BTH -204H SECTION 4
a
aryl f
RF BOARD 500-86l
(s0zs)
2020 .
G@oza)
MO
@
(ee)
alt
s|C)
ay)
(e)
[vo2y}
SECTION 4
MODULATOR BOARD PARTS PLACEMENT DIAGRAM
4-1 RF
BTH - 204, BTH -204H
RF BOARD 500-86l
LNdLNO JI
(XY) NIAZ'8 +
Sa a Se
LAdNI 4u
(XL) NI
A
i i
+
LAGNI
IXIW
a ee
SECTION 4
4-2 RF - MODULATOR BOARD BOTTOM VIEW
a
+
i=)
N
28
=
a
a
i=)
N
a=
=
a
IF BOARD 500-858
TO TERMINAL STRIP
QuYVO8S 3HL JO WOLLO8G SH1 NO 3YV 819 B BOIY :ILON
2114
heel
>t
Clll
4-3 IF - AUDIO BOARD PARTS PLACEMENT DIAGRAM
SECTION 4
BTH - 204, BTH - 204H
Ee ee Se ee eee ee ee, ee ee ear ae a OO EE ELE EE EEE EEE EE EE eee — a EE
SECTION 4
OQYVOS 3H1 JO WOLLOS SHINO 3YV8EID BBOIN: ALON
Vdl
BSO1RZO IAs
say e
TO TERMINAL
STRIP
IF BOARD 500-858
4-4 IF - AUDIO BOARD BOTTOM VIEW
25
t
j=)
N
as
ke
a
R
ae
‘=
a
es <n: amity ii a a EI
PEDSBOARD 330 2:-259
NOTE: C401 1S LOCATED ON BOTTOM OF BOARD
4-5 LED DISPLAY BOARD PARTS PLACEMENT DIAGRAM
LED BOARD 302-239
4-6 LED DISPLAY BOARD BOTTOM VIEW
\
BTH - 204, BTH - 204H -5-
SECTION 4
TRANSMITTER BOARD 5OI-O067
NOTE: Q301 & C304 ARE MOUNTED ON BOTTOM SIDE OF BOARD.
é
4-7 TRANSMITTER BOARD PARTS PLACEMENT DIAGRAM
BTH - 204, BTH - 204H -6- SECTION 4
BTH - 204, BTH - 204H
4-8 TRANSMITTER BOARD BOTTOM VIEW
SECTION 4
90¢71
soel
d‘l
voEel
2e¢9
dil
seco
ecOel
dil
oe
00GB
80¢9
4-9 TRANSMITTER BOARD TUNE-UP TEST POINTS
vt
i
5
BTH - 204, BTH - 204H
SECTION
BTH - 204, BTH - 204H
T/R RELAY
RECEIVE CRYSTAL
POSITIONS
MICROPHONE
Roemer: DEVIATION
TORN ADJUSTMENT
MAX. GAIN MAX, DEVIATION
C.CW, ROTATION
TRANSMIT CRYSTAL
NETTING CAPACITORS
4-10 CRYSTAL LOCATION AND ADJUSTMENT DIAGRAM
SECTION 4
4-11 VOLTAGE DATA
NOTE:
VOLTAGE DATA — TRANSISTORS
Emitter
RF BOARD
No. 500-861
IF BOARD
No. 500-858
TX BOARD
No. 501-067
Transistor
Q201
Q202 (FET)
Q204
Q205 (FET)
Q206
Q207
~Qi01
Q102
Q103 (PNP)
Q104
Q105
Q106
Q107 (PNP)
Q108 (PNP)
Q109
Q110
Q301
Q302
Q303
Q304
Q305
Q306
Q307
Q308
Q309
Q310
(Source)
0.20
0.15-0.30
AONADROODCO
, Se
0
0
Base
(Gate)
4.5
VOLTAGE DATA — INTERGRATED CIRCUITS
Note: Both IC’s are located on the IF Board, 500-858.
IC No.
| gee ae
4
5
6
1101 4.3. 10.7 0.7" aoe sn
etO2 Ae et
BTH - 204, BTH - 204H
1.3
1.3
bo
All voltages are nominal and are measured with a VT VM.
13.8 VDC Supply Voltage at input to cable supplied with unit.
| Collector
(Drain)
4.6
6.0 *(Varies with setting of R 2
Tes
4.8
0 (Unsquelched)
1.0 (Squelched)
1.5 min. (tight squelch)
1.9 (Unsquelched)
0.30 (Squelched)
1.10 (tight squelch)
5.1 (Unsquelched)
8.2 (tight squelch)
8.2
13.8 (OFF - Ambient |
Temperature = 70° to 802
0.7 (ON - Ambient Temperatul
less than 17°F)
m 13.8 (OFF)
: 0.7 (ON)
FBO S10 WEY Cae 4
A iu7 dee ie a La
Ore O1 One cI Gaie Gato Sa Gea
SECTION 4
c202 c204
7 1.5
C201 C203
{ 10 a2 3{L202 |, ||
| padentinode Tepe ka ee id
e=S= == L201
|! =
II
I}!
| 2
é
| Deis ae a ee ra
J
| 1A 4
sw 2018 Naseem Be
| \9 Age
Wy
\ 2 3 |
L0403 (49) 00 |
Jt |
ANT 50. L402 ra CHANNEL
| INDICATORS ~—|
| LD401 a |
e | 1.6 |
| col |
1000
oe es
| R401
sik 680
Ane
| 13.8 (RX)
+ | 13.3 (Tx)
|
|
| prx e
os | NOTES:
1, ALL CAPACITOR VALUES NOT SPECIFIED OTHERWISE ARE PICO-FARAD.
TX | ALL RESISTOR VALUES NOT SPECIFIED OTHERWISE ARE OHMS.
Fy ALL RESISTORS NOT SPECIFIED OTHERWISE ARE 1/4 WATT.
a 2. © NOTED VALUES ARE FACTORY SELECTED. NOMINAL VALUES SHOWN.
WGH IMPEDANCE 3.0} DENOTES A FERRITE BEAD PLACED ON THE COMPONENT LEAD.
Sen Goi re — 4, R334 ANDR335 ARE HEATING ELEMENTS FOR Y301,Y302,Y303 AND Y304
5. ALL VOLTAGES (FIGURES INRED) ARE NOMINAL VALUES AS MEASURED
2. ~ WITH A VTVM AND SUPPLY VOLTAGE TO THE UNIT IS 13.8 VDC
a. THE LETTER FOLLOWING THE VOLTAGE INDICATES THE
% FOLLOWING CONDITIONS:
R402 U= UNSQU ED
se QUELCH
: 16
TRANSMIT
Lp40s( Y7 Jinoicator
L301
S=SQUELCHED — THRESHOLD
T=SQUELCHED— TIGHT
N= HEATER TURNED OFF,;,NORMAL AMBIENT TEMPERATURE
(70 80°F)
C= HEATER TURNED ON, COLD AMBIENT TEMPERATURE
{LESS THAN 17°F) E
b. VOLTAGES INDICATED IN TRANSMITTER SECTION ARE MEASURED
WITH THE TRANSMITTER OPERATING INTO A PROPER LOAD.
0
c304 c309
303 330 & ies
$580 3 Coy304
6341
2-8
L304
b 6340
36
2 SCHEMATIC WITH VOLTAGES - BTH - 204
- 204, BTH - 204H plas SECTION 4
j
|
H
i
}
4-11 VOLTAGE DATA
NOTE: All voltages are nominal and are measured with a VTVM.
13.8 VDC Supply Voltage at input to cable supplied with unit.
VOLTAGE DATA — TRANSISTORS
| Collector
Emitter Base
Transistor (Source) (Gate) (Drain)
RF BOARD Q201 3.8 4.5 6.9
No. 500-861 Q202 (FET) 1.0 0 6.2
Q204 4.4 5.0 Vie
Q205 (FET) 0.80 0 5.0
Q206 0.20 0.80 4.6
Q207 0.15-0.30 0.65-0.90 6.0 *(Varies with setting of R
IF BOARD
No. 500-858 Qi01 23 3.0 es
Q102 1.0 Wy 4.8
Q103 (PNP) 8.2 8.2 O (Unsquelched)
8.2 8.2 1.0 (Squelched)
8.2 8.2 1.5 min. (tight squelch)
Q104 0 0 1.9 (Unsquelched)
0 0.80 0.30 (Squelched)
0 0.80 1.10 (tight squelch)
Q105 1.4 ti 5.1 (Unsquelched)
it 0.10 8.2 (tight squelch)
Q106 We) V3 12.4
Q107 (PNP) 13.8 13:3 RAWs
Q108 (PNP) 6.9 6.6 0.10
Q109 6.9 Tee 13.8
Q110 0 0.10 6.9 i se
TX BOARD Q301 0 -0.5 13.2 3 ee
No. 501-067 Q302 0 -0.4 iat es
Q303 0.50 -0.2 12.4 .
Q304 0 0.33 Pas =
Q305 1.4 2.3 1.6
Q306 1.6 1.0 ee
Q307 1.9 1.4 Kee
Q308 2.6 2.8 82
Q309 - 0.6 13.8 (OFF - Ambient
Temperature = 70° to 80°
— 1.4 0.7 (ON - Ambient Temperatu
less than } 7°F}
Q310 0 — 13.8 (OFF)
0 - 0.7 (ON)
VOLTAGE DATA — INTERGRATED CIRCUITS
Note: Both IC’s are located on the IF Board, 500-858.
IC'No:s [3-25 6-3) es SG) Fees OO ena elit ee
16-401 64.2: 20.90 2.0:7' 4 20 SOO a oe
1O102° 4.0: 63.3.0) 0 on eS eels | OcGeg ec aa meee 30
BTH - 204, BTH - 204H -10- SECTION 4
13.8 (RX)
CHANNEL
INDICATORS
13.3 (TX)
HIGH IMPEDANCE
MICROPHONE
+8.2V REG
NOTES: :
1. ALL CAPACITOR VALUES NOT SPECIFIED OTHERWISE ARE PICO-FARAD.
ALL RESISTOR VALUES NOT SPECIFIED OTHERWISE ARE OHMS.
ALL RESISTORS NOT SPECIFIED OTHERWISE ARE |/4 WATT.
2. a NOTED VALUES ARE FACTORY SELECTED. NOMINAL VALUES SHOWN.
3.—O- DENOTES A FERRITE BEAD PLACED ON THE COMPONENT LEAD.
4. R334 ANDR335 ARE HEATING ELEMENTS FOR Y30!1,Y302,Y303 AND Y304
RT 30! 5. ALL VOLTAGES(FIGURES INRED) ARE NOMINAL VALUES AS MEASURED
WITH A VTVM AND SUPPLY VOLTAGE TO THE UNIT IS 13,8 voc
a. THE LETTER FOLLOWING THE VOLTAGE INDICATES THE
R330
22
100K l00K
FOLLOWING CONDITIONS:
U= UNSQUELCHED
S=SQUELCHED — THRESHOLD
T=SQUELCHED— TIGHT
N= HEATER TURNED OFF,;NORMAL AMBIENT TEMPERATURE
(70* 80°F)
C= HEATER TURNED ON; COLD AMBIENT TEMPERATURE
(LESS THAN I7°F) +
b. VOLTAGES INDICATED IN TRANSMITTER SECTION ARE MEASURED
WITH THE TRANSMITTER OPERATING INTO A PROPER LOAD.
+8.2V REG : 4
Ra =
2.2K
WA >
ci2t
FR .0lnt
Ril
47K
;
|
Seuz :
8.2K | hee
AN
ci23 re
Out cq bao :
= 7.5K
cw
c
047 nf |
:
' :
SPK-I <=
3.2n a
EXT
SPKR INDSENE
BTH-204
| /
13.8 (RX) )
RI37 /
66
2W :
Pe ue a +8.2V REG. :
13.8 (RX) ¥
11.5-14.5 voc :
= +
DC POWER CORD cRio2 7S 25001 /
:
zee .
= —_ = :
x
+>
DEVIATION ADu. T NS
R228 OK [ | SN R332 \
cw i Y Pe
c23i \
slut Ne
case
Olut
a WW
L_¢230
T> Olnt
4 D +82 V REG.
e WA—
T R324
"80 R319
Rae Sear’ 68K R304
100
56K ==)
cai i
15 12.2 0307 =
>t i
r303
{| Ycr30z aoe
R325 R326
wae eae
BTH - 204, BTH - 204H A1-
4-]2 SCHEMATIC WITH VOLTAGES - BTH - 204
SECTION 4
CHANNEL
INDICATORS
13.8 (RX)
x
RX
TX
RY I
16 470
TRANSMIT
WEE #2) INDICATOR
1
|
|
|
|
|
|
|
|
|
|
|
| R402
|
|
|
|
|
I
|
|
|
|
|
|
|
- eee L301
R305
470
R301
270
301
15
YCR301
NOTES:
RT301
4c CW,
@\
0.6¢
7
. 0
F4
y304
=
c34l
2-18
csse e340
5; 36
H - 204, BTH - 204H
apunr
ALL CAPACITOR VALUES NOT SPECIFIED OTHERWISE ARE PICO-FARAD.
ALL RESISTOR VALUES NOT SPECIFIED OTHERWISE ARE OHMS.
ALL RESISTORS NOT SPECIFIED OTHERWISE ARE 1/4 WATT.
™% NOTED VALUES ARE FACTORY SELECTED. NOMINAL VALUES SHOWN.
. ck DENOTES A FERRITE BEAD PLACED ON THE COMPONENT LEAD.
) R334 AND R335 ARE HEATING ELEMENTS FOR Y301, 302, Y303 AND Y304.
ALL VOLTAGES (FIGURES IN RED) ARE NOMINAL VALUES AS MEASURED
WITH A VTVM AND SUPPLY VOLTAGE TO THE UNIT IS 13.8VvDC.
a. THE LETTER FOLLOWING THE VOLTAGE INDICATES THE FOLLOWING
CONDITIONS:
U= UNSQUELCHED
S* SQUELCHED— THRESHOLD
T= SQUELCHED — TIGHT
N= HEATER TURNED OFF; NORMAL AMBIENT TEMPERATURE (70°80°F)
C= HEATER TURNED ON ; COLD AMBIENT TEMPERATURE (LESS THAN !7°F)
b. VOLTAGES INDICATED IN TRANSMITTER SECTION ARE MEASURED
WITH THE TRANSMITTER OPERATING INTO A PROPER LOAD.
-12- SECTION 4
+8.2V REG
RIO9
33
7.6
' cis abe
ut 119
, _ 2000 ¢ 47
Ri06
180
me I ee Se
FarPiios a
Cor 3 {8 14 jp} 3-5 i i
cua !
anf 270 e t |
clos mor 180 L102 | cue | icioz ’
68 Lio! cia 2ut
cips ek alle 250 |
Pint T 390 6 2 I
J =
CIT +—_4
t 3]
+ 8.2VREG
Rus
2.2K
cl2i
|
| |
0204 | 7.2 |
5.0 :
|
| |
|
| ci23
c22) |
62 | Oldut
\ R213 | | SQ.
\ 39K |
LD404) \ | H
| 1.0
(7) \ he \ z cizz
\ = C135 | 470
\ | 250ut |
| CHANNEL | RIT RUS
| INDICATORS \ | a | OK Sarat peek 10K
\ 5 | cle7
. INT. SPKR, | Sut
| \ | | t
ark ) ~204H | |
| \ wee | ta | eee as |
C401 \ | |
ee DB i Tiooo \ | |
a | R401 < \ | eee |
= : 680 | 13.8(RX)
| T
= ' 13.8 (RX) 1 RI3T
1 $8
w
ICT) Ue) +8.2 V REO.
1 x
\ + Oo ee + cr io2Z
ci3é6
1000 ut ud CI37
(SR Pa NOTES:
1. ALL CAPACITOR VALUES NOT SPECIFIED OTHERWISE ARE PICO-FARAD.
ALL RESISTOR VALUES NOT SPECIFIED OTHERWISE ARE OHMS.
ALL RESISTORS NOT SPECIFIED OTHERWISE ARE |/4 WATT.
\ 11,5-14.5 voc
ee ee Oe =~ 2. @& NOTED VALUES ARE FACTORY SELECTED. NOMINAL VALUES SHOWN
\ 3. <F DENOTES A FERRITE BEAD PLACED ON THE COMPONENT LEAD.
\ 4. R334 AND R335 ARE HEATING ELEMENTS FOR Y301,Y302, YSOS AND Y304.
Pi \ 5. ALL VOLTAGES (FIGURES IN RED) ARE NOMINAL VALUES AS MEASURED
R \ WITH A VTVM AND SUPPLY VOLTAGE TO THE UNIT IS 13.6VDC.
RT 301 a THE LETTER FOLLOWING THE VOLTAGE INDICATES THE FOLLOWING
CONDITIONS:
Us UNSQUELCHED
S* SQUELCHED— THRESHOLD
T= SQUELCHED — TIGHT
N= HEATER TURNED OFF; NORMAL AMBIENT TEMPERATURE(70°-—80°F)
C+ HEATER TURNED ON ; COLD AMBIENT TEMPERATURE (LESS THAN I7*F)
b. VOLTAGES INDICATED IN TRANSMITTER SECTION ARE MEASURED
WITH THE TRANSMITTER OPERATING INTO A PROPER LOAD.
+ 6.0V REG
\TRANSMIT
D408 (9) INDICATOR
= ~
8.2 Sw 301
OG So 0308 i 4
XY) an J 3 F4
R305 c329 Fl 2 $
halt eee ay) F3
c3l4 2.6 F2
6 Olpt
0. TOO MOOK Yy301 y302 Y303 y304
ca0l aes C335 C337 c339 C34!
2-18) 2-18) 218 2-18)
Ycrs0! 100K ee wees
C334 C336 ic33e C340
36 36 36
BTH - 204, BTH - 204H eto SECTION 4
SECTION 5 PARTS LIST
NOTE: Parts with an asterisk (*) denotes those values that are used
only in the BTH-204H. All other listed parts are common to
both units.
When ordering parts, please include the following information:
Model Number (BTH-204 or BTH -204H)
Item Number
Description
Part Number
ane fm
BTH - 204, BTH - 204H SECTION 5
5-1 RF - MODULATOR BOARD 500-861
Item Description
Part No.
RESISTORS
R201 100 ohm, 10%, “%W
R202 4.7K, 10%, %W
R203 ° 10K,10%, “ZW
R204 1K, 10%, “AW
R205 1K, 10%, YW
R206 6860 ohm, 10%, “AW
R211 33 ohm, 10%, ZW
R212 10K, 10%, “ZW
R213 39K, 10%, “4W
R214 1.5K, 10%, AW
*R214 470 ohm, 10%, “W
R215 10K, 10%, “ZW
R216 3.9K, 10%, “ZW
R217 10K, Trimmer
R218 68K, 10%, YW
R219 6.8K, 10%, %ZW
R220 18K, 10%, “AW
R221 470 ohm, 10%, %W
R222 10K, 10%, “ZW
R223 39K, 10%, “ZW
R224 120K, 10%, “W
R225 39K, 10%, “ZW
R226 27K, 10%, “ZW
R227 470 ohm, 10%, “AW
R228 10K, Trimmer
R229 10K, 10%, “ZW
R230 100K, 10%, %W
R231 2.7K, 10%, “ZW
CAPACITORS
C201 10PF, 10%, NPO, 500V (DISC)
*C201 8.2PF, 10%, NPO, 500V (DISC)
C202 .27PF, 10%, (COMPOSITION)
C203 8.2PF, 10%, NPO, 500V (DISC)
*C203 6.8PF, 10%, NPO, 500V (DISC)
C204 1.5PF, + .25PF, NPO, 500V (DISC)
C206 5.6PF, 10%, NPO, 500V (DISC)
*C206 3.9PF, 10%, NPO, 500V (DISC)
C207 001 mfd, +80 - 20%, 500V (DISC)
C208 001 mfd, +80 - 20%, 500V (DISC)
C209 .68PF, 10% (COMPOSITION)
C210 01 mfd, +80 - 20%, 500V (DISC)
C211 220PF, 5%, 50V (MICA)
C212 01 mfd, +80 - 20%, 500V (DISC)
C217 18PF, 10%, NPO, 500V (DISC)
*C217 15PF, 10%, NPO, 500V (DISC)
C218 68PF, 5%, 50V (MICA)
C219 001 mfd, +80 - 20%, 500V (DISC)
C220 01 mfd; +80 - 20%, 500V (DISC)
C221 82PF, 5%, 50V (MICA)
C222 A mfd, 20%, 12V (DISC)
C233 25 mfd, 10V, 85°C
(ELECTROLYTIC)
C224 47 mfd, +80 - 20%, 3V (DISC)
C225 1 mfd, 20%, 12V (DISC)
C226 .0033 mfd, 10%, 100V
(MYLAR FILM)
0277, 022 mfd, 10%, 100V
(MYLAR FILM)
C228 A mfd, 20%,12V (DISC)
C229 47 mfd, +80 - 20%, 3V (DISC)
C230 01 mfd, 10%, 100V
(MYLAR FILM)
C231 1 mfd, 20%, 12V (DISC)
BTH - 204, BTH - 204H
4701-0101-042
4701 -0472-042
4701-0103-042
4701-0102-042
4701-0102-042
4701-0681-042
4701-0330-042
4701-0103-042
4701-0393-042
4701-0152-042
4701-0471 -042
4701-0103-042
4701-0392-042
_ 4751-0103-001
4701 -0683-042
4701-0682-042
4701-0183-042
4701-0471-042
4701-0103-042
4701-0393-042
4701-0124-042
4701-0393-042
4701-0273-042
4701-0471-042
4751-0103-001
4701-0103-042
4701-0104-042
4701-0272-042
1500-0100-905
1500-0829-905
1510-0278-900
1500-0829-905
1500-0689-905
1500-0159-205
1500-0569-905
1500-0399-905
1503-0102-001
1503-0102-001
1510-0688-900
1503-0103-001
1506-0221-550
1503-0103-001
1501-0180-001
1501-0150-001
1506-0680-550
1503-0102-001
1503-0103-001
1506-0820-550
1502-0104-005
1513-0250-001
1502-0474-001
1502-0104-005
1508-0332-610
1508-0223-610
1502-0104-005
1502-0474-001
1508-0103-610
1502-0104-005
Description
.01 mfd, 10%, 100V
(MYLAR FILM)
47PF, 5%, 50V (MICA)
10 mfd, 10V, 85°C
(ELECTROLYTIC)
.0047 mfd, 10%, 100V
(MYLAR FILM)
COILS
Antenna Input (Brown)
RE Input (Red)
RF Output (Black)
Oscillator, emitter
Oscillator, output
Mixer, output
DIODES
Silicon, Signal
Silicon, Signal
TRANSISTORS
Silicon, NPN (Red Top)
Field Effect, Junction
Silicon, NPN
Field Effect, Junction
Silicon, NPN
Silicon, NPN
Part No.
1508-0103-610
1506-0470-550
1513-0100-001
1508-0472-610
1800-3152-001
1800-3152-002
1800-31 52-008
1801-1236-900
1800-31 70-100
1800-31 70-200
4805-1 241-200
4805-1 241-200
4801 -0000-035
481 1-0000-030
4801-0000-095
4811-0000-030
4801 -0000-010
4801 -0000-010
*Indicates values used in BTH-204H
SECTION 5
5-2 IF - AUDIO BOARD 500-858
Item
Description
RESISTORS
18K, 10%, “ZW
10K, 10%, %W
1K, 10%, “ZW
180 ohm, 10%, “AW
220 ohm, 10%, “ZW
180 ohm, 10%, “%W
22K, 10%, “ZW
47K, 10%, “ZW
33 ohm, 10% “ZW
270K, 10%, “AW
4.7K, 10%, %W
8.2K, 10%, %W
2.2K, 10%, “AW
39K, 10%, “ZW
10K, 10%, %W
5.6K, 10%, “AW
2.2K, 10%, ZW
100 ohm, 10%, %W
10K, 10%, %W
10K, 10%, “ZW
18K, 10%, ZW
5.6K, 10%, “ZW
10K, 10%, “ZW
3.3K, 10%, “ZW
180 ohm, 10%, “ZW
560 ohm, 10%, %W
1K, 10%, “AW
33K, 10%, AW
68K, 10%, “ZW
18K, 10%, %“%W
2.2K, 10%, AW
2.2K, 10%, %W
56 ohm, 10%, %W
560 ohm, 10%, “ZW
1.5K, 10%, “ZW
100 ohm, 10%, %W
68 ohm, 10%, 2W (wire wound)
CAPACITORS
220PF, 5%, 50V (MICA)
.01 mfd, 19%, 100V (Mylar Film)
.01 mfd, +80 - 20%, 500V (DISC)
01 mfd, 10%, 100V (Mylar Film)
220PF, 5%, 50V (MICA)
220PF, 5%, 50V (MICA)
.01 mfd, +80 -.20%, 500V (DISC)
.01 mfd, +80 - 20%, 500V (DISC)
68PF, 5%, 50V (MICA)
.2 mfd, +80 - 20%, 12V (DISC)
180PF, 5%, SOV (MICA)
390PF, 5%, 50V (MICA)
270PF, 5%, 50V MICA
250PF, 5%, 50V (MICA)
.2 mfd, +80 - 20%, 12V (DISC)
.2 mfd, +80 - 20%, 12V (DISC)
.2 mtd, +80 - 20%, 12V (DISC)
39PF, 10%, NPO, 500V (DISC)
.002 mfd, 20%, 500V (DISC)
.047 mfd, 10%, 100V (Mylar Film)
.01 mfd,; 10%, 100V (Mylar Fiim)
470PF, 20%, 500V (DISC)
.015 mfd, 10%, 100V (Mylar Film)
.002 mfd, 20%, 500V (DISC)
.047 mfd, 10%, 100V (Mylar Film)
1 mfd, 20%, 12V (DISC)
BTH - 204, BTH - 204H
Part No.
4701-0183-042
4701 -0103-042
4701-0102-042
4701-0181-042
4701-0221 -042
4701-0181-042
4701 -0223-042
4701-0473-042
4701 -0330-042
4701-0274-042
4701-0472-042
4701-0822-042
4701-0222-042
4701 -0393-042
4701-0103-042
4701-0562-042
4701-0222-042
4701-0101-042
4701-0103-042
4701-0103-042
4701-0183-042
4701-0562-042
4701-0103-042
4701-0332-042
4701-0181 -042
4701-0561 -042
4701 -0102-042
4701-0333-042
4701-0683-042
4701-0183-042
4701-0222-042
4701-0222-042
4701-0560-042
4701-0561-042
4701-0152-042
4701-0101-042
4710-0680-041
1506-0221-550
1508-0103-610
1503-0103-001
1508-0103-610
1506-0221 -550
1506-0221-550
1503-0103-001
1503-0103-001
1506-0680-550
1502-0204-006
1506-0181-550
1506-0391 -550
1506-0271-550
1506-0251-550
1502-0204-006
1502-0204-006
1502-0204-006
1500-0390-605
1523-0202-001
1508-0473-610
1508-0103-610
1523-0471-001
1508-01 53-610
1523-0202-001
1508-0473-610
1502-0104-005
CF101
Description
5 mfd, 50V, 85°C (Electrolytic)
.047 mfd, 10%, 100V (Mylar Film)
.047 mfd, 10%, 100V (Mylar Film)
10 mfd, 25V, 85°C (Electrolytic)
.001 mfd, +80 - 20%, 500V (DISC)
.001 mfd, +80 - 20%, 500V (DISC)
001 mfd, +80 - 20%, 500V (DISC)
.2 mfd, +80 - 20%, 12V (DISC)
250 mfd, 16V, 85°C (Electrolytic)
1000 mfd, 16V, 86°C (Electrolytic)
250 mfd, 10V, 85°C (Electrolytic)
.001 mfd, +80 - 20%, 50V (DISC)
COILS
Choke, 820 mhy, shielded
Choke, 820 mhy, shielded
Quadrature Detector
Input, 10.7 mHz IF AMP
Output, 10.7 mHz IF AMP
DIODES
Silicon, Signal
Zener, 8.2Y.5%, 1W
TRANSISTORS
Silicon, NPN
Silicon, NPN
Silicon, PNP (White Top) -
Silicon, NPN
Silicon, NPN
- Silicon, NPN
Silicon, PNP, AF Driver
Silicon, PNP, AF Driver
Silicon, NPN, AF Output
Silicon, NPN, AF Output
INTEGRATED CIRCUITS
IF Amplifier
IF Limiter/Detector
CRYSTAL
10.245 mHz (Standard)
11.155 mHz (Special)
FILTER
Ceramic, 455 KHz
Part No.
1513-0050-004
1500-0473-610
1508-0473-610
1513-0100-003
1503-0102-001
1503-0102-001
1503-0102-001
1502-0204-006
1511-0251-002
1511-0102-002
1511-0251 -001
1503-0000-008
1803-31 82-700
1803-3182-700
1860-3151-700
1800-1250-700
1800-31 68-300
4805-1241-200
4808-0000-009
4801 -0000-010
4801 -0000-010
4801 -0000-060
4801 -0000-010
4801 -0000-010
4801-0000-010
4801 -0000-135
4801 -0000-135
4802-0000-002
4802-0000-002
31 30-3167-901
3130-3157-603
2301-3151 -601
2301-3151-602
2700-0000-008
SECTION 5
-
5-3 LED BOARD 302-239
Item Description Part No.
SOR RE RT 4 eS SS
RESISTORS
R401 470 ohm, 10%, 1/3 W 4704-0471-042
R402 680 ohm, 10%, 1/3 W 4704-0681-042
CAPACITORS
C401 .001 mfd, +80 - 20%, 50V (DISC) 1503-0102-003
DIQDES
LD401_ ~—LED, Red 4810-1282-900
D402. LED, Red 4810-1282-900
LD403 LED, Red 4810-1282-900
LD404_ LED, Red 4810-1282-900
LD405 ‘LED, Red 4810-1282-900
BTH - 204, BTH -204H
SECTION 5
5-4 TRANSMITTER BOARD 501-067
Item Description
RESISTORS
R301 270 ohm, 10%, “ZW
R303 4.7 ohm, 10%, “~AW
R304 10 ohm, 10%, “ZW
R305 470 ohm, 10%, “AW
R306 100 ohm, 10%, “ZW
R308 3.9K, 10%, “ZW
R310 10 ohm, 10%, “ZW
R311 39 ohm, 10%, “~W
R312 27K, 10%, “ZW
R313 1K, 10%, “AW
R314 18K, 10%, “ZW
R315 100 ohm, 10%, “~W
R316 150 ohm, 10%, “~W
R317 56K, 10%, “AW
R318 3.9K, 10%, “ZW
R319 68K, 10%, “AW
R320 100K, 10%, %~W
R321 1.5K, 10%, “ZW
R322 27K, 10%, “ZW
R323 39K, 10%, %W
R324 180 ohm, 10%, ZW
R325 100K, 10%, %W
R326 100K, 10%, “ZW
R328 100 ohm, 10%, %W
R329 3.3 ohm, 5%, %W
R330 22 ohm, 10%, “ZW
*R330 47 ohm, 10%, %W
R332 2K, 5%, %W
R333 560 ohm, 10%, “ZW
R334 100 ohm, 5%, 2W (wire wound)
R335 100 ohm, 5%, 2W (wire wound)
RT301 Thermistor
CAPACITORS
C301 T8PF, 10%, NPO, 50V (DISC)
*C301 15PF, 10%, NPG, 50V (DISC)
C302 18PF, 10%, NPO, 50V DISC
*C302 15PF, 10%, NPO, 50V (DISC)
C303 4-60PF, Trimmer
C304 330PF, 350V, (MICA)
C305 05 mfd, +80 - 20%, 25V (DISC)
C306 10 mfd, 20%, 25V (TANT)
C307 .05 mfd, +80 - 20%, 12V (DISC)
C308 2-18PF, Trimmer
C309 100PF, 5%, 50V (MICA)
C310 1 mfd, 20%, 12V (DISC)
C311- 15PF, 10%, NPO, 500V (DISC)
C312 33PF, 10%, NPO, 50V (DISC)
C313 001 mfd, +80 - 20%, 50V (DISC)
C314 01 mfd, +80 - 20%, 25V (DISC)
C315 270PF, 5%, 50V (MICA)
*C315 100PF, 5%, 50V (MICA)
C316 47PF, 5%, NPO, 50V (DISC)
C317 .005 mfd, +80 - 20%, 50V (DISC)
C318 .005 mfd, +80 - 20%, 50V (DISC)
C319 100PF, 5%, 50V (MICA) -
*C319 82PF,5%, 50V (MICA)
C320 10 mfd, 20%, 25V (TANT)
C322 82PF, 5%, 50V (MICA)
*C322 120PF, 5%, 50V (MICA)
C323 180PF, 5% 50V (MICA)
*C323 390PF, 5%, 50V (MICA)
C324 .01 mfd, +80 - 20%, 25V (DISC)
C325 .05 mfd, +80 - 20%, 12V (DISC)
BTH - 204, BTH - 204H
Part No.
4701-0271-042
4701-0479-042
4701-0100-042
4701-0471-042
4701-0101-042
4701 -0392-042
4701-0100-042
4701-0390-042
4701-0273-042
4701-0102-042
4701-0183-042
4701-0101-042
4701-0151-042
4701-0563-042
4701-0392-042
4701-0683-042
4701-0104-042
4701-0152-042
4701-0273-042
4701-0271-042
4701-0181-044
4701-0104-042
4701-0104-042
4701-0101-042
4701 -0339-042
4701-0220-042
4701-0470-042
4701 -0202-032
4701-0561-044
4701-0101-031
4701-0101-031
5300-0000-001
1500-01 80-650
1500-0150-650
1500-0180-650
1500-01 50-650
151 7-0000-002
1522-0331 -001
1502-0503-004
1515-0100-005
1502--0503-006
151 7-0000-001
1506-0101-550
1502-0104-005
1500-0150-605
1500-6330-650
1503-0102-003
1502-0103-004
1506-0271-550
1506-0101-550
1524-0470-002
1503-0502-005
1503-0502-005
1506-0101-550
1506-0820-550
1515-0100-005
1506-0820-550
1506-0121-550
1506-0181-550
1506-0391 -550
1502-0103-004
1502-0503-006
Description
~ 1O0PF, 5%, 50V (MICA)
180PF, 5%, 50V (MICA)
75PF, 5%, NPO, 50V (DISC)
100PF, 5%, 50V (MICA)
47PF, 5%, NPO, 50V (DISC)
36PF, 5%, NPO, 50V (DISC)
4.7PF, 10%, NPO, 500V (DISC)
1 mfd, 20%, 12V (DISC)
100PF, 5%, 500V (MICA)
270PF, 5%, 50V (MICA)
36PF, 5%, NPO, 50V (DISC)
2-18PF, Trimmer
36PF;, 5%, NPO, 50V (DISC)
2-18PF, Trimmer
36PF, 5%, NPO, 50V (DISC)
2-18PF, Trimmer
36PF, 5%, NPO, 50V (DISC)
2-18PF, Trimmer
.1 mfd, 20%, 12V (DISC)
390PF, 5%, 50V (MICA)
COILS
Output, Antenna
Output, Final
Choke, RF Final (Collector)
Choke, RF Final (Base)
Input, Final ;
Modulator, Phase (13MHz)
Bridge, VSWR
Output, Driver
Output, Pre-driver (156MHz)
Output, Doubler (78MHz)
Output, Tripler (39 MHz)
Bead, Ferrite
Bead, Ferrite
Bead, Ferrite
Bead, Ferrite
DIODES
Silicon, Signal
Varactor, SMV1172
Varactor, SMV1172
Zener, 8.2V, 5%, “ZW
Zener, 6.0V, 5%, ZW
TRANSISTORS
Final RF Power (BTH - 204)
Final RF Power (BTH - 204H)
Driver, RF Power
Pre-driver, RF Power
Silicon, NPN
Silicon, NPN
Silicon, NPN
Silicon, NPN
Silicon, NPN
Silicon, NPN
Silicon, NPN
Part No.
1506-0101-550
1506-0181-550
1524-0750-002
_1506-0101-550
1524-0470-002
1524-0360-001
1500-0479-905
1502-0104-005
1504-0101-505
1506-0271-550
1524-0360-001
1517-0000-001
1524-0360-001
151 7-0000-001
1524-0360-001
151 7-0000-001
1524-0360-001
151 7-0000-001
1502-0104-005
1506-0391 -550
1801-1244-700
1801 -1284-300
1803-3189-800
1803-1245-900
1801-1276-000
’ 1800-1251-800
1800-1 244-800
1800-1244-500
1800-31 66-300
1800-31 66-200
1800-31 66-100
2502-0000-001
2502-0000-001
2502-0000-001
2502-0000-001
4805-1241-200
4809-0000-001
4809-0000-001
4808-0000-013
4808-0000-01 2
4804-31 73-304
4804-31 73-302
4804-3169-603
4804-31 69-605
4801 -0000-010
4801 -0000-005
43801 -0000-003
4801 -0000-003
4801 -0000-003
4801 -0000-010
4802-0000-002
*|Indicates values used in BTH-204H
SECTION 5
5-5 CHASSIS ASSEMBLY
Item Description
-ELECTRICAL COMPONENTS
R1 5K, Volume Control/switch SW-1
R2 7.5K, Squelch Control
R3 680 ohm, 10%, “~W
I C1 15PF, 10%, NPO, 500V (DISC))
G2 15PF, 10%, NPO, 500V (DISC)
ail C3 15PF, 10%, NPO, 500V (DISC)
C4 .05 mfd, +80 - 20%, 25V (DISC)
C5 100 mfd, 10V, 85°C (Electrolytic)
C6 .047 mfd, 10%, 100V (Mylar Film)
GT .001 mfd, +80 - 20%, 50V (DISC)
CR1 Diode, Silicon, Rectifier
RY-1 Relay, 3PDT, 12V (T/R)
SPK-1 Speaker, 3.2 ohm, 4 in. sq.
(with mounting brackets)
SW201 Switch, PC Mount (Receive)
SW301 Switch, PC Mount (Transmit)
TB-1 Terminal Board, 4-lug
Part No.
4750-3211-201
4750-3211-202
4701-0681 -042
1500-0150-605
1500-01 50-605
1500-0150-605
1501-0503-004
1511-0101-001
1508-0473-610
1503-0102-003
4806-0000-004
4500-0000-004
7011-1069-100
7011-1069-200
7011-1069-300
2103-3007-914
Y200 Crystal, Receive (Specify Frequency) 2311-0000-000
Y300 Crystal, Transmit
(Specify Frequency)
Fi Fuse, 5 AMP, 3AG
J1 Connector, Antenna (Chassis)
J2 Connector, Microphone (Chassis)
P1 Connector, Power (Chassis)
P2 Connector, Microphone (Cable)
$1 Connector, Power (Cable)
Socket Pins, Crystal Mounting
DC Power Cord Assembly
) Microphone Assembly
(with connector)
Microphone, Ceramic (no connector)
MECHANICAL COMPONENTS
Detent, 4- position (Rotary Switch)
Heat Sink, Driver Transistor
Heat Sink, Final Transistor
Bracket, Relay Mounting
Front Panel Bezel (Chrome)
Faceplate (BTH - 204)
*Faceplate (BTH - 204H)
Knob, Channel Selector
Knob, Volume and squelch
Cabinet (Wrap) Assembly
Foot, Rubber
Bracket, Mobile Mounting
Bracket, Security (less lock)
Hanger, Microphone
Hardware Kit, Mounting
2312-0000-000
5106-0000-008
2105-0000-020
2105-0000-021
2104-0000-004
2104-0000-601
2108-0000-001
2830-0000-004
7011-1037-901
701 1-1060-300
1300-5080-902
5105-1219-809
5400-0000-002
5400-3211-800 ©
1400-3211-100
1405-5081-301
2403-5106-500
2403-51 14-300
2402-1 268-900
2402-1276-202
1408-6033-301
1402-0000-001
1400-3143-100
1400-1241-500
2830-0000-003
7011-1051-300
(bolts, washers, security bracket, mic hanger)
Manual, Owner’s Instruction
(BTH - 204)
*Manual, Owner’s Instruction
(BTH - 204H)
7} Manual Service ($5.00 prepaid)
~,
BTH - 204, BTH - 204H
7001 -1051-500
7001-1063-800
SM-10-515
SECTION 5
ati ie
Faltale val
Pie = hi