Regency Electronics Instruction and Service Manual Model Micro Com U10r UHF FM Repeater

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ENCY _ ELECTRONICS INC. 


INSTRUCTION & SERVICE 
MANUAL 


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UHF-FM REPEATER \ 


MODEL MICRO COM U/Or 
UAPorM REPEATER 


700!1- 4001-100 PRINTED IN U.S.A, PRICE $12.50 


—————— 


UNPACKING 


Check the carton and packing material carefully for the following 
items: 


- Repeater unit 

Microphone and Connector 
- Owner's Service Manual 

= Warranty, Card 


Sl ell oeell oe 
I 


To be filled out and returned to: 


REGENCY COMMUNICATIONS, INC. 

A subsidiary of Regency Electronics, Inc. 
1227 South Patrick Drive 

Satellite Beach, Florida 32937 


MICRO-COM U1OR SERVICE MANUAL — 


CONTENTS 
SECTION 1 GENERAL INFORMATION 


l-l Description 

l-2 Specifications 

1-3 Equipment Supplied 

1-4 Equipment Not Supplied 

1-5 Installation 

1-6 ‘%peration 

1-7 Crystal Specifications 

1-8 Crystal Installation 

1-9 Crystal Heating Detail 

1-10 Crystal Location and Adjustment Diagram 


SECTION 2 REPEATER SYSTEM DESCRIPTION 


2-1 Description 
2-2 Repeater System Block Diagram 


SECTION 3 RECEIVER 


3-1 Receiver Circuit Description 
3-2 Receiver Voltages 

3-3 Receiver Block Diagram 

3-4 Receiver Board Top View 

3-5 Receiver Board Bottom View 
3-6 Receiver Schematic 

3-7 Receiver Alignment 


SECTION 4 TRANSMITTER 


4-1 Transmitter Circuit Description 
4-2 Transmitter Voltages 

4-3 Transmitter Block Diagram 

4-4 Transmitter Board Top View 

4-5 Transmitter Board Bottom View 
4-6 Transmitter Schematic 

4-7 Transmitter Tuning 


SECTION 5 POWER SUPPLY 
Regulated Power Supply Circuit Description 


Power Supply Voltages 
Power Supply Board Top and Bottom Views 


ret 
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SECTION 6 


SECTION 6A 


6A-1 
6A~2 
6A-3 
6A-4 
6A~5 


6A-6 
6A~7 
6A-8 


6A-9 
6A-10 


SECTION 7 


Pe eo 
Noor hWN FH 


MA-90 TONE ENCODER-DECODER, AND MA-95 TONE ENCODER 


General Information 

MA-90 Circuit Description 

MA-95 Circuit Description 
MA-90 Schematic and Board Views 
MA-95 Schematic and Board Views 


MA-116 TONE ENCODER-DECODER & MA~121 ENCODER 


General Information 

MA-116 Encoder=-Decoder Circuit Description 

MA-121 Encoder Circuit Description 

MA-116 & MA=-121 Tone Setting Instructions 

Adjustment Procedure (Setting Tone Receive Threshold 
on MA=-116) 

Adjustment Procedure (Setting Tone Modulation Deviation 
on MA-121) | 

Block Diagram 

Schematic 

CTCSS Tone Board Top & Bottom View 

MA-116 & MA-121 Setup Adjustment Locations, Top View 


REPEATER CONTROL SYSTEM 


Repeater Control Board 

Audio Paths 

Transmitter Activation By Noise Squelch 

Transmitter Activation By CTCSS (TONE SQUELCH) 

Operation By Local Microphone, PTT Function 

Tone Monitoring Provisions 

Three Minute Timer, Drop-Out Delay, Time-Out Warning 
Oscillator 

Repeater Control Board Top View 

Repeater Control Board Bottom View 

Repeater Interconnection Schematic, Including Power 
Supply and Control Board 

Auxiliary Tone Board Top View 

Auxiliary Tone Board Bottom View 

Auxiliary Tone Board Schematic 

LED Board Top and Bottom Views 

Repeater Control Board and Auxiliary Tone Board 
Voltages 


SECTION 8 


oon nuk WD bE 


SECTION 9 


REPEATER SETUP INSTRUCTIONS 


Preparation for Noise Squelch Operation 
Audio Level Setting, Noise Squelch 
Preparation for Tone Squelch Operation 

Audio Level Setting, Tone Squelch Operation 
Squelch Control Setting 

Final Listening Tests of Audio Level Setting 
Setup Adjustment Locations, Top View 

Setup Adjustment Locations, Bottom View 
Setup Adjustment Locations, Rear View 


ANTENNA SYSTEM REQUIREMENTS AND TESTS 


Isolation Requirements of External Antenna Systems 
and Duplexers 

Special Repeater Tests 

Test for Transmitter-Receiver Interference Within the 
Repeater 

Test for Transmitter-Receiver Interference in the 
Antenna System 

Test for Transmitter-Receiver Interference Within the 
Repeater Diagram 

Signal Injection Fixture Diagram 

Calibration of Signal Injection Fixture Diagram 

Test for Transmitter-Receiver Interference Within the 
Antenna System Diagram 


SECTION 10 PARTS LIST 


10-1 
10-2 
10-3 
10-4 
10-5 
10-6 
10-7 
10-8 
10-9 


Receiver Board 
Transmitter Board 

LED Board 

Power Supply Board 

Control Board 

Auxiliary Tone Board 

Tone Encoder-Decoder Board 
Tone Encoder Board 

Chassis Assembly 


10-10 MA-116 & MA-121 Tone Boards 


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GENERAL INFORMATION 


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SECTION 1 GENERAL INFORMATION 
1-1 DESCRIPTION 


The Regency MICRO-COM U1OR is an FM repeater for use in the 
450-470 MHz Land Mobile Communications Band. It is equipped with 
facilities which permit local control of the repeater, for use by 
a dispatcher and/or for use by maintenance personnel in making 
tests on the repeater. 


As supplied, the repeatermay be mounted on a desk or shelf. 
When equipped with Option MA-109 brackets, it may be mounted in 
relay rack structures. 


The repeater control system provides for the following func- 
tions: 


1. Operation of the transmitter by tone squelch or noise 
squelch control. 


2. Provisions for plugging in up to seven tone squelch fre- 
quencies, for use on community repeater systems. Addi- 
tional tone squelch frequencies may be added outboard, 
if desired. 


3. Three minute cutoff timer, with warning tone. 
4. Transmitter drop out dalay. 


5. Provisions enabling operationof the repeater by a local 
operator. These provisions also enable maintenance tech- 
nicians to receive and transmit test transmissions using 
each of the installed tone squelch frequencies. 


The receiver section is certified under Part 15, Subpart c 
of the FCC Rules. The transmitter is Type Accepted under the fol- 
lowing FCC Rules parts: 


21 Demestic Public Radio Services 

89 Public Safety Radio Services 

91 Industrial Radio Services 

93 Land Transportation Radio Services 
95 Citizens (Class A) Radio Services 


mcu r “|= SECTION lL 


1-2 SPECIFICATIONS 


RECEIVER 
Antenna Impedance. .......---.2---e0e- 5S etat et eenaae siete 50 Ohms 
Frequency Ringe. obred. Sool seasnamne: Pay dee cur NA: 450-470 MHz 
SeneLtivLeyet sss . HPSS PP SIS. sate ces 3 s .35uV, 12 DB Sinad 
.50uV, 20 DB Quieting 
.25uv, Carrier Squelch Opening 
.25uvV, Tone Squelch Opening 
SEOLEGCCLVLEY «io. 6 ws 6 0 2 cis win tele 01s whejeisie cities ~ eles 75 DB @ 25 KHz 
Spurious and Image........--screceccreeereecs wolee st 75 DB 
Intermodulation Rejection. .....--. cee cece reer ececes 70 DB 
Modulation Acceptance.......--- cece eee eee e reece +7.5 KEZ 
Frequency Stability............-. +.0C025%, -30°C to +60°C 
Audio Response ) Within plus 2 and minus 8 DB 


from a standard 6 DB per oc- 
tave de-emphasis curve over 
the frequency range of 300 to 
3000 Hz with a 1,000 Hz ref- 
erence frequency 


Audio Output Power, Rated 


VAIO cic sion olete se.0 sce omens Cope ai biels 4 watts @ 5% distortion 
Maximum Audio Output Power...... 5 wetts @ 10% distortion 
I.F. System..... atten Double Conversion 10.7 MHz - 455 MHz 


Part 15 FCC Certified 


TRANSMITTER 
Antenna Impedance. ...-....eeee sec ccccrercecccens 50 Ohms 
Frequency Range...... seers ceccecccccceccs e 450-470 MHz 


mcu r =2= SECTION Il 


Power Output le)... 0%. 2, SR ee gle Meats ee ahs 10 Watts (minimum) 


P) Output Frequency Stability...... +.00025%, -309C to +60°C 
Spurious & Harmonic Rejection. ..........ccececccees 60 DB 
Power *Uni C Protection eae te.. eraicreee Temperature Limiting 


Power Control Circuit 


EMLSSi LON ss". ois oe Sarah avatatet, doses san Ere tate Susieel Todas gta ceatehens eke 16F3 
MECFODNONO) sais. Sanyo ettreigiet ns High Impedance Plug-in Ceramic 
Modulationeye. eyesore. pret ete ose ta Fate Frequency Modulation with 


Automatic Deviation Limiting 


Be ALOT cteterete ani et uate Factory Adjusted to +5 KHz (max.) 
Audio Frequency Distortion.............. AOI ERE GROEN SRE 10% 
PM O@HUN cI NO LSS PIA VEL. ests cto Ste wtarera ai aleres davatars eeslals -60 DB 


Audio Frequency Response... From 300 to 3000 Hz, within +1 
; and -3 DB of a 6 DB per octave 
@ pre-emphasis characteristic as 
. referred to the 1,000 Hz level 


POWER 
Power Requirements....... etodenst st she icles siete WIV eV neG OU LH 
Receive Condition....... Peed oaks tehstenoeial ei oisl elerenelaietele -15 amps 
ipransmit CONALELOM try retets a seats s bere. Oe Sater eres a et .8 amps 
FUSO"OLZeSe. wee Ce eT we eS sate ltl e Seeks ns Ae 2 Amp. 3AG 


GENERAL FEATURES 


Outside Dimensions (Excluding 
Knobs and Connectors)........... Dyer x Lise x Oentoh 


Vertical Rack Space 
Requirements........... 11%", plus a recommended 8" for 


access to controls and connectors 


@ Weight. cocaorcestereerseereoeoe ese eee go oeeoeeesee ee SECON 50 FC 1A TOS 12 lbs Mg 


mcu r ai- dee SECTION 1 


1-3 EQUIPMENT SUPPLIED 


1 - Repeater Unit 


1 - Test Microphone and Connector 

1 - Receive Channel Crystal, installed to customer specified 
frequency . 

ai Transmit Channel Crystal, installed to customer specified 
frequency. 


1 - Control Board with connectors to accept three receive 
and three transmit CTCSS (Continuous Tone Coded Squelch 
System) modules. 

1 - Auxiliary Tone Board, to accept four receive and four 
transmit CTCSS modules. 

1 - cTCSS receive module, installed to customer specified 
frequency. 

1 - CTCSS transmit module, installed to customer specified 
frequency. 


Up to six additional CTCSS receive modules and up to six ad- 
ditional CTCSS transmit modules, installed per customer spec— 
ified frequencies, supplied at extra cost if ordered. 


1-4 EQUIPMENT NOT SUPPLIED 


Because of the many varied antenna arrangements possible for 
repeater use, antennas, antenna connecting cables, and duplexer/ 
cavity accessories are not supplied as a part of the repeater. 


‘Rack mounting adaptors are not supplied as a part of the re- 
peater. 


1-5 INSTALLATION 


Mechanical Mounting 


The U1LOR is supplied for mounting on a desk, shelf, or other 
flat surface. For those cases where it is desired to mount the 
repeater in standard relay racks, mounting brackets are available. 
The mounting brackets may be attached to the repeater chassis to 
permit the "top" or equipment side to be located in front of the 
rack panel surface, or to the rear of the rack panel surface. If 
space will permit, the front surface mounting is recommended for 
easy access to the technician adjustments. 


mcu r -4- SECTION lL 


° 


In some cases, it is desired that a local operator have ac- 
cess to control of the repeater. For these applications, the re- 
peater may be mounted on the operator's desk top. 


The microphone hang-up clip must be mounted so it is elec- 
trically grounded to the metal case of the repeater. .Mountsitsin 
a convenient location, accessible to the technician, or the local 
Operator (if any). 


1-6 OPERATION INSTRUCTIONS FOR LOCAL CONTROL POSITION 


The operator at the local control position should realize 
that the unit is a repeater, and that it performs repeater func- 
tions for various mobiles, independently of the local control op- 
erator's actions, unless interrupted by the local operator when 
making a transmission over the repeater transmitter. 


Volume Control 


This control varies the audio volume level to the local loud- 
speaker, and should be set to a comfortable listening level. It 
has no control over the volume of the repeating function, and it 
has no control over the volume of transmissions made over the lo- 
cal microphone. 


Power Indicator Lamp 


A green indicator lamp is located on the front panel. It is 
used to show that the power to the repeater unit is "on." 


Transmit Indicator Lamp 


A red indicator lamp is located on the front panel. When 
this lamp glows, it indicates that the repeater transmitter is 
turned on. This lamp will glow whether the repeater transmitter 
is activated by the local microphone or by a distant mobile. 


Tone Squelch Monitoring Function: (For units equipped with 


Tone Squelch) 


When the microphone is placed in its hang-up hook, the Tone 
Squelch System is effective and only signals from stations having 
the appropriate tones will be heard in the local loudspeaker. 


On shared radio channels, it is considered good manners to 


listen in on the channel before transmitting. When the microphone 
is removed from the hook, the Tone Squelch circuits are placedin 


mcu ¢ 25= SECTION 1 


the MONITOR condition, and any signal on the channelwill be heard 
regardless of whether it has. the appropriate tone coding. 


If the operator attempts to transmit a message by merely 
pressing the microphone button while the microphone remains in 
the hang-up hook, the tone squelch tone will. not be transmitted, 
and. the message will not get through (unless the listening sta- 
tion just happens to be in the MONITOR position at the time). 


Microphone 


A hand-held microphone is supplied with the unit. To trans-— 
mit a message, remove the microphone from its hang-up hook, press 
the push-to-talk button on the side of the microphone, and speak 
into the microphone. The Transmit Indicator will glow to signify 
that the transmitter is operating. 


‘ults are obtained by holding the microphone about 
one inch from the lips, inclined at about a 30 degree angle away 
from the face. Speak clearly in anormal tone of voice across 
the face of the microphone. 


1-7 CRYSTAL SPECIFICATIONS 


Miniature plug-in crystals are utilized in both the receiver 
and transmitter sections. 


The following Regency Part Number crystals are used: 


Transmit Crystals: 302-539 
Receive Crystals; 302-540 


Crystals should be ordered by specifying the above part num- 
bers and the exact channel frequency required. 


Installation of crystals requires the services of a competent 
technician with appropriate test equipment. Instructions for the 
necessary adjustments are included in the receiver alignment and 
transmitter tuning procedures later in this manual. 


1-8 CRYSTAL INSTALLATION 


Special care must be taken to install the crystals correctly. 
The conduction type crystal heaterwhichis used to warm the crys- 
tals at low ambient temperatures relies on having proper physical 
contact between the heater element and the crystal for effective 
operation. The Crystal Heater Detail, (Figure 1-9) demonstrates 


mcu r =-6= SECTION | 


C 


the correct method of crystal installation. The crystal must be 
pressed down into the socket pins far enough for the rim around 
the bottom of the crystal to clear the heating element and allow 
good contact between the side of the crystal and the element. 


mcu r ot Maes SECTION | 


HEATING ELEMENT 


THERMISTOR 


P.C. BOARD 


1-9 CRYSTAL HEATING DETAIL 


mcu r -8- SECTION | 


TRANSMIT CRYSTAL 


O 
NETTING INDUCTOR 


RECEIVE 
NETTING GC [)CRYSTAL 
INDUCTOR 


|-10 CRYSTAL LOCATION AND ADJUSTMENT DIAGRAM 


mcu r -9- SECTION | 


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SECTION 2 
REPEATER SYSTEM DESCRIPTION 


mcu rr SECTION 2 


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SECTION 2 REPEATER SYSTEM 
2-1 DESCRIPTION 


A block diagram of the repeater system is shown in Figure 
2-2. The block diagram shows the major functions of the various 
portions of the repeater. To make explanation of'the diagram eas- 
ier to follow, the operating frequencies have been assumed to be 
469.50 MHz receive and 464.50 MHz transmit. This follows the 
pattern of frequency assignments in the 450-470 MHz band in the 
United States. Mobiles functioning with this system would trans- 
mit on 469.50 MHz (so they will be received by -the repeater re- 
ceiver) and would receive on 464.50 Muz (so they will "hear" the 
repeater transmitter). 


As the block diagram shows, signals received on 469.50 are 
demodulated by the receiver, and the audio intelligence is sent 
to the tone squelch system. If the received Signal has the same 
tone squelch frequency as one of the installed tone squelch boards, 
the tone squelch system, acting with the repeater control system 
turns the transmitter on, and retransmits the original intelli- 
gence, 


Additionally, as the block diagram shows, an operator at the 
repeater location can transmit through the local microphone and 
can hear incoming mobiles through the local loudspeaker. Features 
within the tone squelch system and the repeater control system 
permit the operator at the repeater location to transmit one of 
the tone squelch frequencies, and also enable the loudspeaker to 
be silent except when a signal with that tone. squelch frequency 
is received. 


mcu r | oa) SECTION 2 


INCOMING SIGNALS OUTGOING SIGNALS 
(e.g. 469.500) (¢.g. 464.500) 


464.500 MHz 
TRANSMITTER 


469.500 MHz 
RECEIVER 


AUDIO FREQUENCIES 


REPEATER CONTROL 
SYSTEM 


TONE SQUELCH 
SYSTEM 


LOCAL CONTROL 
MICROPHONE 


LOUDSPEAKER 


2-2 REPEATER SYSTEM BLOCK DIAGRAM 


mcu r =—e= SECTION 2 


mcu r 


SECTION 3 
RECEIVER 


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SECTION 3. RECEIVER 
3-1 RECEIVER CIRCUIT DESCRIPTION 


The entire receiver is mounted on the receiver circuit board. 
The antenna is connected to a 2 Section RF Helical Filter, L109 
and L110, which acts as a preselector for incoming signals. 


Q105 is a grounded gate, low noise, J-FET amplifier. Its 
output is fed through an additional 2 Section Helical Filter, L112 
and L113 and delivered to the gate of Q106, a J-FET mixer. 


L.O. (Local Oscillator) injection for the J-FET mixer Q106 
is a frequency of 10.7 MHz lower than the incoming signal frequen- 
cy. It is obtained from a crystal oscillator-multiplier chain, 
consisting of Q10l, Q102, Q103, and Q104. Q101 is a crystal os- 
cillator, using a third overtone crystal in the 48.8 to 55.7 MHz 
range. The output circuit of Q101 oscillator is tuned to the 
third harmonic of the crystal frequency, and this harmonic is am- 
plified by a buffer-amplifier consisting of Q102 and Q103. Q103 
drives Q104, which operates as a frequency tripler, providing the 
wanted local oscillator injection frequency. This wanted injec- 
tion frequency is separated from various harmonics and subharmon- 
ics by the L114 and L115 section of the helical filter and deliv- 
ered to the source of the mixer, Q106. 


The output of Q106 consists of a 10.7 MHZ IF signal which is 
fed to a Six-pole monolithic crystal filter, Consistingvof FLO). 
FL102, and FL103. This filter Provides most of the adjacent chan- 
nel selectivity of the receiver. The Signal is then amplified by 
integrated circuit, IC102, which contains another amplifier for 
10.7 MHz, the second mixer circuitry and the second L.o. circuitry, 
operating at 10.245 muz. 


The 455 KHz output CLpLClLo2 (terminal 5) is coupled through 
a tuned circuit to the input of the ceramic filter, FL104. FL104 
is a narrow-band filter centered at 455 KHz, and it provides ad- 
ditional adjacent channel rejection. The output of FL104 is am- 
plified and coupled througha tuned circuit to the input of inte— 
grated circuit ICl103. ICl03 is a series of amplifiers providing 
approximately 60 DB gain at 455 KHz. Also included in ICl03 is 
the limiting circuitry and a quadrature detector circuit. 41123, 
connected between terminals 2 and 12 of Ic103, is the adjustable 
quadrature coil. 


mcu r l SECTION 3 


The audio output from IC103 (terminal L) is coupled to the 
input of the audio amplifier circuit and to the input of the 
noise-operated squelch circuit. 


Transistor Q110 is an amplifierwhose frequency response ex- 
tends from approximately 4 KHz to 25 KHz. Q110 amplifies the 
noise occurring in this frequency range. The noise is coupled to 
the base of Ql1ll. Q11l is used as a detector which rectifies the 
amplified noise and produces a DC voltage at its collector. When 
the DC voltage at the collectorof Ql1l1l is positive and of suffi- 
cient value to provide essentially a short circuit between the 
base of Q113 and the audio output from the receiver is squelched 
(muted). When a signal carrier arrives, the noise input to the 
detector (Ql111) is reduced to the point where the DC voltage at 
the base of Q112 is no longer sufficient to cause Q112 to conduct. 


At this time, Q113 is allowed to conduct normally and the au- 
dio ou-pue -. the unit is heard. With the audio preamplifier, 
(Q113) operating normally, audio is applied through the volume 
control to the input of the audio amplifier, IC104. Q113 supplies 
a Signal to the audio amplifier ICl104, which amplifies the audio 
to loudspeaker level. 


mcu r : ay a SECTION 3 


3-2 RECEIVER VOLTAGES 


NOTE: All voltages are nominal and are measuredwith a VTVM, 
at 13.0 VDC supply voltage. 


VOLTAGE DATA 


Receiver Transistors: 


Emitter Base ‘Collector 
Ql01 aba Le. 5 9 
Q102 4.2 5.0 9 
Q103 0 On? Bae 
Q104 0 : 4 -0.15 Sig 
Ql105 (FET) 1.7 (Source) 0 (Gate) 9 (Drain) 
Q106 (FET) 0.9 (Source 0 (Gate) 9 (Drain) 
Q107 (PNP) 8.7 832 520 
Ql08 3.6 4.2 8.2 
Q109 3.6 4.2 8.2 
Q110 1.0 L6G 68 
Qlll 2 Bosh 9.1 0 (Unsquelched) 
o.1 9.5 9.0(Tight Squelch) 
Qui2 0 0 2.6 (Unsquelched) 
0 See O(Tight Squelch) 
Ql113 bes 2.6 6.4(Unsquelched) 
Bef) 0 9.1(Tight Squelch) 
Ql1l4 0.4 0.8 13.0 @ 25°C 
Ql15 0 0.4 13.0 @ 25°C 


Receiver Integrated Circuits: 


EoiNO L662) 13 | ee eo ce oeelO) 11 12 13.1 


Ic10l 7 1 O. 0 POs Ome Bes 7 ees OF ato se - - = = os 
IC102 2,2 ,0.650N6) 2. one OO Base 173 sO = - - - = = 
Ic103 4278 3. 2h Lie Set ences GO 0 0.14 - ~ ede a) Wea 
Icl04 13.0 - =i) L259 RRO eeOe on 0 0 @) 0 0 ~ Or0 - ~ 


mcu r ee SECTION 3 


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3-3 RECEIVER BLOCK DIAGRAM 


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3-4 RECEIVER BOARD TOP VIEW 


meu r -5- SECTION 3 


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RECEIVER BOARD 


3-5 RECEIVER BOARD BOTTOM VIEW 


SECTION 3 


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TBABIOS 
AUDIO POWER 
AMP 
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NOTES 


aohkwn 


ALL RESISTOR VALUES NOT SPECIFIED OTHERWISE ARE OHMS. 
ALL RESISTORS NOT SPECIFIED OTHERWISE ARE 4 w. 


[-__] DENOTES ADJUSTABLE COMPONENTS. 


(CJ DENOTES CIRCUIT JUNCTION POINTS. 
HEAVY LINE DENOTES APPARENT SIGNAL FLOW. 
ALL VOLTAGES ARE NOMINAL VALUES AS MEASURED WITH A 


VTVM, SUPPLY VOLTAGE = 13,8 VOC AT INPUT 
LETTER FOLLOWING A VOLTAGE INDICATES THE FOLLOWING 
CONDITIONS: 
u = UNSQUELCHED 


Ss 
t 


SQUELCHED - THRESHOLD 
SQUELCHED - TIGHT 


3-6 RECEIVER SCHEMATIC 


SECTION 3 


RECEIVER BOARD 501-236 


3-5 RECEIVER BOARD BOTTOM VIEW 


mcu r =67 SECTION 3 


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NOTES 
, | ALL RESISTOR VALUES NOT SPECIFIED OTHERWISE ARE OHMS 
ALL RESISTORS NOT SPECIFIED OTHERWISE ARE 4 w 
[J] DENOTES ADJUSTABLE COMPONENTS 
(CI DENOTES CIRCUIT JUNCTION POINTS 
HEAVY LINE DENOTES APPARENT SIGNAL FLOW 
ALL VOLTAGES ARE NOMINAL VALUES AS MEASURED WITH A 
VTVM, SUPPLY VOLTAGE = 13.8 VDC AT INPUT 
LETTER FOLLOWING A VOLTAGE INDICATES THE FOLLOWING 
CONDITIONS 
u = UNSQUELCHED 
s = SQUELCHED - THRESHOLD 
t = SQUELCHED- TIGHT 


aroun 


3-6 RECEIVER SCHEMATIC 


mcu r i SECTION 3 


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alignment. 


Preliminary I.F. 


Final discrim- 


if radio has not been badly misaligned. 


Final touch up for 


vo 
G, 
« 
2 
uM 
° 
2 
© 
c 
cal 


optimum sensitivity 


REC; 
During the receiver alignment procedure, set 


(i.e., umsquelched). Set volume control to c 
cycle tone during the alignment procedure hel 


Signal Source Observe 


10.7 MHz Signal Generator, TP103, using DC V 
unmodulated. Connect Signal 

Generator to Drain of 9106, 

using a series 10,000 ohm 

resistor. 


Measure DC voltag 

of R154, using DC C) 
(R154 is a 39 ohm 

resistor mounted CD 


close to the rear 


haan reve. 


TP104, using DC 


pz) 
TP105, using DC . 


e) 
None Required TP101, using DC V b9 Ge 


TP102, using DC 2 Op] 
b L123 © 


odes 


Signal generator source cap- TP105, using DC S @: () ED 
able of being set to within 

+.00025% of channel frequen- 

cy. Set signal generator out- 

put channel frequency. Modu- } 
late generator with a 1000 Hz 


tone, with +3 KHz peak modu- TP103, using DC 
lation deviation. On multiple 

channel radio, do alignment 

on channel #1. 


oot fof 


S 


Reduce signal generator out- TP104, using DC v¥ C) D 

put to zero signal. If gen- 

erator attenuator does not | 

permit signal to be reduced d q b 


below receiver noise level, 


S 
| 
disconnect signal generator TP105, using DC vy 
from antenna jack. ) OOD 
| 


Bring signal generator atten- TP105, using DC v4 
uator up to a level that gives 
a good, quieting, signal. Be S) 


sure signal generator is ac- ae) 
curately set to channel fre- RIS2 WD) 


quency. 4 

. Jong 
Signal generator, as above, Distortion meter, () —se— 
tuned to exact channel fre- to loudspeaker te QQ 
quency, and modulated by a Follow usual distq S) 
1000 Hz tone, with peak mod- meter procedures ok ae) 
ulation deviation of 3 KHz. ting null and lev @) 

trols. If a disto 

ter is not availa 
step may be accom 
observing the 1,0 


signal on the lou¢ LlO¥®) 


e 


terminals with an 
loscope, and tuni 
least noise on th 
trace. Do NOT att 
touch up the tuni 
an unmodulated si 
tuning for silenc 
will result ina 
sponse from the c 
ter and poor weak 
performance. 


Signal generator, as above, 
be sure it has not drifted 
off channel. 


LIGNMENT CHART 


oe SECTION 3 


= ee 


. 
~ antune amg 
i t 
d Lan: 
Ww e 
? 
ive aed poe bie, 
rs ‘o- * 
7 Pe, 


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3 - © 
Li 


ote a 
Be ae 


ie 


alignment. Not necessary 


if radio has not been badly misaligned. 


Preliminary I.F. 


Final discrim- 
inator & AFC 


Final touch up for 
optimum sensitivity 


RECEIVER ALIGNMENT PROCEDURE 


During the receiver alignment procedure, set the squelch control to maximum counter clockwise position, 
(i.e., umsquelched). Set volume control to comfortable listening level. 
cycle tone during the alignment procedure helps to avoid alignment errors. 


Signal Source 


10.7 MHz Signal Generator, 
unmodulated. Connect Signal 
Generator to Drain of Q106, 
using a series 10,000 ohm 

resistor. 


None Required 


Signal generator source cap- 


able of being set to within 
+.00025% of channel frequen- 


cy. Set signal generator out- 


put channel frequency. Modu- 


late generator with a 1000 Hz 


tone, with +3 KHz peak modu- 


lation deviation. On multiple 


channel radio, do alignment 
on channel #1. 


Reduce signal qenerator out- 
put to zero signal. If gen- 
erator attenuator does not 
permit signal to be reduced 
below receiver noise level, 
disconnect signal generator 
from antenna jack. 


Bring signal generator atten- 
uator up to a level that gives 


a good, quieting, signal. Be 
sure signal generator is ac- 
curately set to channel fre- 
quency. 


Signal generator, as above, 
tuned to exact channel fre- 
quency, and modulated by a 

1000 Hz tone, with peak mod- 
ulation deviation of 3 KHz. 


Signal generator, as above, 
be sure it has not drifted 
off channel. 


TP103, using DC VTVM 


Listening to received 1,000 


Expected Reading, Notes 


Adjust L119,L120,T101 (top 
and bottom slugs) for maximum 
TP103 voltage. 


Adjust signal generator output 
level to obtain a .3 volts pos- 
itive” reading at TP103. As 
alignment progresses, reduce 
signal level to maintain the 

-3 volts reading. 


Measure DC voltage at top 
of R154, using DC VTVM. 
(R154 is a 39 ohm, 2 watt 
resistor mounted on end, 
close to the rear of the 
chassis) 


No adjustments in this step. 


Measured voltage should be close 
to 8.2 volts. From this measure- 
ment, determine proper discrim- 
inator set voltage. Discrimina- 
tor set voltage will be )/2 of 
voltage at top of R154. 


using 


Adjust L123 to obtain the 
proper discriminator set 

voltage as determined by 

Step 2. 


This is a discriminator adjust- 
ment. TP104 voltage should swing 
through the discriminator set 
voltage determined in Step 2. 


using 


Adjust R132 to obtain +4,0 
volts reading at TP105. 


Tune L104 for minimum positive 
or maximum negative reading 
on TP1O1. 


This adjusts output of AFC amp- 
lifier to be at +4.0 volts when 
receiving an on-channel signal. 


0 to +.2 volts. +.3 volts in- 
dicates oscillator is not 
oscillating. 


using DC VTVM 


Tune 1107 for maximum negative 
reading on TP102. 


to -.4 volts. 


TP105, using DC VTVM 


If the channel frequency is 
below 467 MHz, set the alum- 
inum core on L1ll even with 
the top of the coil form. If 
the channel frequency is above 
467 MHz, set the aluminum core 
on Llll all the way to the 
bottom of the coil form. Once 
set, it is not necessary to 
adjust L111 during the tuning 
procedure. 


Adjust L101A to obtain +4.0 
volts reading on TP105. 


This is the receiver frequency 
adjustment. TP105 reading should 
swing through the 4.0 volts set- 
ting as L101 is adjusted. 


TP103, using DC VTVM 


TP104, using DC VTVM 


Adjust L109,L110,L112,L113, 
L114,1L115,L119,L120, and T101 
top and bottom slugs for max- 
imum reading at TP103. 


Adjust L123 to obtain proper 
discriminator set voltage as 
determined in Step 2. 


As alignment progresses, reduce 
signal generator output level 
to maintain about .3 volts out- 
put at TP103. Caution: It is 
possible to tune the slugs on 
T101 to a false peak. Correct 
peak is the one with both top 
and bottom slugs furthest out 
from the center of the trans- 
former. 


This adjusts discriminator to 
center of receiver bandpass. 


TP105, using DC VTVM 


TP105, using DC 


Distortion meter, connected 
to loudspeaker terminals. 
Follow usual distortion 
meter procedures for set- 
ting null and level con- 
trols. If a distortion me- 
ter is not available, this 
step may be accomplished by 
observing the 1,000 cycle 
signal on the loudspeaker 
terminals with an oscil- 
loscope, and tuning for 
least noise on the sine wave| 
trace. Do NOT attempt to 
touch up the tuning by using} 
an unmodulated signal and 
tuning for silencing; this 
will result in a peaked re- 
sponse from the crystal fil- 
ter and poor weak signal 
performance. 


Adjust R132 to obtain +4.0 
volts reading at TP105. 


Adjust L101A to obtain +4.0 
volts reading on TP105. On 
multiple channel receivers 
repeat this in channels 2,3, 
and 4, adjusting L101B,C, and 
D respectively. 


Adjust L109,L110,L112,L113, 
L114,L115,L119,L120,T101, 
(top and bottom). 


Repeat steps x | and 

with zero signal input. 
Repeat step 12 on each 
channel with a strong signal. 


This adjusts AFC voltage to 
center value when no signal 
received. 


This adjusts receiver local 
oscillator chain to proper 
center frequency. 


During this procedure keep 
signal level from the signal 
generator at a value sufficient 
to obtain a -12 db(25%) read- 
ing on the distortion meter. 
Remember that this is a "touch 
up" type of adjustment. None of 
the adjustments should be moved 
more than a small amount from 
the setting previously obtained 


mcu Fr 


3-7 RECEIVER 


ALIGNMENT CHART 


-8- 


rise © 
[4]u] 


SECTION 3 


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SECTION 4 
TRANSMITTER 


mcu r SECTION 4 


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SECTION 4 TRANSMITTER 
4-1 TRANSMITTER CIRCUIT DESCRIPTION 
AUDIO SECTION 


Integrated Circuit IC201 (sections A and B), constitutes the 
audio circuitry of the transmitter. IC201A provides a high im- 
pedance input for the ceramicmicrophone, and supplies pre-empha- 
Sis and amplification prior to the modulation limiting circuit 
which consists of CR210 and CR211. 1C201B provides additional 
amplification, and acts as an active filter to provide the post- 
limiter filter action. The output of IC201B is fed to a control 
potentiometer which controls the audio voltage sent to the mod- 
ulator section and, therefore, is used to set the peak modulation 
deviation of the transmitter. 


IC201B also provides an amplified input to feed tones for 
continuous tone squelch systems, or other tone systems, into the 
transmitter modulation circuits. 


CRYSTAL OSCILLATOR 


Y201 serves as the crystal oscillator, using a crystal at 
1/36 of the channel frequency. The crystal is a fundamental cut, 
in the frequency range 12.5 to 14.3 MHz. 


Direct frequency modulation of the crystal is obtained by 
applying the modulation signals from the audio section to varactor 
modulator diode, CR201A. 


FREQUENCY MULTIPLIER SYSTEM 


The output of the crystal oscillator, Q201, is tuned to three 
times the crystal frequency, and this signalis amplified by buf- 
fer-amplifier Q202, then delivered to the tripler circuit, 9203, 
then delivered to the doubler circuit Q204. Q204 drives another 
doubler, Q205, to obtain a combined frequency multiplication of 
36 to reach the channel frequencies from 450-470 MHz. The doubler 
Q205 developes about 150 milliwatts of power to drive the power 
output module IC50l. 


POWER OUTPUT SECTION 
The packaged power output module, IC501, contains three cas- 


caded stages of power amplification. Its gain, and therefore its 
power output, can be controlled over certain limits by the power 


mcu r Lan SECTION 4 


control circuit consisting of R227 and Q206, which varies the DC 
voltage input to one of the early amplifier stages. In normal 
operation, R227 is adjusted to provide the rated output from the 
transmitter, but it can be set for reduced power operation for 
special applications. In order to protect the power module from 
possib’e damage through overheating, a thermal protection circuit 
is included. RT20l1 is a thermistor that rapidly increases in re- 
sistance as its temperature reaches certain levels. RT201 is ‘at- 
tached to one of the mounting bolts on IC501. When the tempera- 
ture approaches excessive levels, RT201 increases in resistance, 
thereby reducing the voltage supplied to IC501 by the power con- 
ror veircuit. 


4-2 TRANSMITTER VOLTAGES 


Transmitter Transistors: 


Emitter Base Collector 
Q201 S0 2.0 Se 
Q202 0 0.55. 6.0 
W203 0 0.34 TO a0) 
Q204 0 0.05 12.0 
Q205 @) -0.62 13.8 
Q206 (PNP) P20 7.4 Os sing 
Q207 0.4 0.8 13.0 -@. 25°C 
Q208 @) 0.4 13..0.@. 25°C 


Transmitter Integrated Circuits: 


TC2Z01 4.0 4.0 4.0 0 4.0 
Icsol 0 Opes 0 6.6 0 -0. 


meu r -2- SECTION 4 


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4-3 TRANSMITTER BLOCK DIAGRAM 


SECTION 4 


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TRANSMITTER BOARD 


4-4 TRANSMITTER BOARD TOP VIEW 


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SECTION 4 


mcu fr 


4-5 TRANSMITTER BOARD BOTTOM VIEW 


mcu rr -5- SECTION 4 


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POWER AMP MODULE 


1C50I 5 
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NOTES 
FALL RESISTOR VALUES ta)T SPECIFIED OTHERWISE ARE OHMS, 
ALL RESISTORS NOT SPECIFIED OTHERWISE ARE '¥4 W. 


DENOTES ADJUSTABLE COMPONENTS. 


([) DENOTES CIRCUIT JUNCTION POINTS. 

HEAVY LINES DENOTES APPARENT SIGNAL FLOW. 

ALL VOLTAGES ARE NOMINAL VALUES AS MEASURED WITH A 
VTVM, SUPPLY VOLTAGE = 13.8 VDC. AT INPUT TO 
VOLTAGES INDICATED ARE MEASURED WITH TRANSMITTER IN 
OPERATION AND CONNECTED TO A PROPER LOAD. 


Opun 


4-6 TRANSMITTER SCHEMATIC 


= 6 SECTION 4 


Pape - 


- 


aie Agee 


iy 
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7 


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waiv M 


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w aa ki R229 Ci 
sakes a | 10K ol 

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8 oa 100K 


Ic201B 
V2 LM358N 


re [Reag) 


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C266 


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DEVIATION 


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TRIPLER _ C22i C223 a 
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c2is_ 10K = rag | > VE Fl Real polar Pooaz 
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of 


L220 


TP205 


R226 
10K 


C238. 
c239 SPF 


2PF 


mcu r 


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REF 
Tx ANTENNA 


5 4 3 
POWER AMP MODULE 
IC50! 
ivy 
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241 
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NOTES 

FALL RESISTOR VALUES ta0T SPECIFIED OTHERWISE ARE OHMS, 
ALL RESISTORS NOT SPECIFIED OTHERWISE ARE 14 w. 
("——] DENOTES ADJUSTABLE COMPONENTS. 

(«DENOTES CIRCUIT JUNCTION POINTS. 

HEAVY LINES DENOTES APPARENT SIGNAL FLOW. 

ALL VOLTAGES ARE NOMINAL VALUES AS MEASURED WITH*A 
VTVM, SUPPLY VOLTAGE = 13.8 VDC AT INPUT TO 
VOLTAGES INDICATED ARE MEASURED WITH TRANSMITTER IN 
OPERATION AND CONNECTED TO A PROPER LOAD. 


pun 


4-6 TRANSMITTER SCHEMATIC 


“Or SECTION 4 


> i very one co  —— NRG eet NE AM ie I « 


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ss TUNING CHART 


SECTION 4 


; 


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TRANSMITTER TUNING 


During Tune-Up Procedure, press the microphone button only when actually taking readings or making 
tuning adjustments. Until tune-up is completed, keep transmitter on time to a minimum. 


Connect a 50 ohm load and R.F. wattmeter to the antenna terminal. 


On multiple channel transmitters, conduct first tuning on highest frequency channel. 


VTVM TP201 L201,and L205. L204 for +.55 volts,no drive 

Ground lead on chassis minimum positive voltage +.4 to -.3 volts nor- 
reading (or maximum nega- mal. A false peak on 

Note: a 20,000 ohm per tive if TP2 goes negative). L205 is possible, look 

volt multimeter,on the for biggest one. 

2.5 or 5 volts scale 

may be used for these TP202 | #2] L207 and L208 for minimum +.5 volt, no drive 

Proceedings. Readings Positive (or maximum neg- +.25 to -.3 volts nor- 

will be 20% lower than ative) voltage reading. mal. 

those given here on 2.5 Then touch up L205 for 

volt scale,and 10% lowe maximum negative voltage 

on 5 volt scale. reading. 

TP203 L210,L211,L212 for nega- no drive 
tive voltage reading.Then -4 volts nor- 
touch up L208 for maximum 
negative reading. 


TP204 #4] L214,L215 and C231 for no drive 
maximum negative reading. -9 volts nor- 
Then touch up L212 for A 
maximum negative reading. 


TP205 #5 | €233,C235,C237 for max- no drive 
imum negative reading. volts normal. 
Then touch up L214,L215, 
C235 for maximum negative 
reading. 


RF power meter, con- RF power output #6 R227 to 10 watts output 10 watts normal. 
nected to antenna jack. 


In multiple channel transmitters, if spacing between highest and lowest channel 
exceeds 3 MHz go back through all but the first step and tune for a compromise 
adjustment between the highest and lowest channel. 


Frequency meter, FM mon- Switch to channel #1 and adjust L201A to exact channel frequency. Then switch to 

itor or counter, with channels 2,3, and 4, and adjust L201B, L201c, and L201D respectively to exact channel 

+ .00025% accuracy. frequency. If either L201A,B,C,D have been changed appreciably during this step, go 
back and repeat the frequency setting on all channels. 


FM Modulation Monitor 48 Inject a 100 millivolt (.1 volt) tone at 1,000 Hz into the microphone jack (pin #4 
high, pin #1 ground), and adjust R240 so modulation deviation just reaches + 5 KHz 
peak. Then, in CTCSS units, remove the 1,000 Hz tone and adjust R605 on the cTCSS 
board to obtain +.75 KHz peak modulation deviation on the CTCSS tone. Reinsert the 
1,000 Hz tone and adjust R240, so combined modulation peak deviation of the 1,000 Hz 
tone and the CTCSS tone is + 5 KHz peak. If R240 was changed much, recheck the devi- 
ation due to the CTCSS tone alone, to be sure you still have .75 KHz peak deviation 
on CTCSS tone. 


mcu 


4-7 TRANSMITTER TUNING CHART 


a7a 


SECTION 4 


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SECTION 5 
POWER SUPPLY 


mci. 6 SECTION 5 


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SECTION 5 POWER SUPPLY 
5-1 REGULATED POWER SUPPLY CIRCUIT DESCRIPTION 


The circuit diagram of the power supply is shown as a part 
of the overall repeater schematic, in Section 7. 


The power supply transformer T501 transforms the LIE VAC wine 
voltage to 38 VAC, center tapped, at the secondary. Rectifiers 
CR501, CR502, CR503, CR504 and filter capacitor c503, rectify and 
filter this secondary voltage to produce approximately 23 VDC 
which is reduced to 13.0 VDC by the series-pass regulator tran- 
sistor Q501. CR501, CR502, and C502 provide a separate 23 VDC 
supply for the Regulator Board Circuitry. 


The regulator circuitry operates as follows: 


R404, R405, and R406 divide Q501's output (emitter) voltage 
down to a sample voltage slightly higher than that of CR401. Q402 
continuously compares this sample voltage with the reference volt- 
age of CR401 and adjusts the drive through amplifier Q401 to the 
regulator transistor Q501 accordingly. 


As an example, assume that the radio set (load) increases 
the current drain on Q501, causing the output voltage, and conse- 
quently the sample voltage, to drop slightly. The reduction of 
base-emitter voltage of Q402 would cause a slight decrease in col- 
lector current which in turn would increase drive to Q401 (through 
R402). Q401 would then increase the kase current to Q501 causing 
it to supply more current to the loac and raise the output volt- 
age slightly. In this manner an equilibrium is reached. Poten- 
tiometer R405 allows adjustment of the output voltage which is 
normally set for 13.0 VDC under Receive (standby) conditions. 


mcu r ost SECTION 5 


5-2 POWER SUPPLY VOLTAGES 


Emitter Base Collector 
Q401 13.8 15.6 23 
Q402 6 6.5 16.6 
Q501 3 13.8 26 


mcu r i Ar: SECTION 5 


mcur 


REGULATOR BD 


REGULATOR BD 


ee. 


302-032 


302-032 


BOTTOM VIEW 


FIG. 5-3 


SECTION 5 


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SECTION 6 


MA-90 TONE ENCODER- DECODER, 
& 
MA-95 ENCODER 


mcu rf SECTION 6 


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SECTION 6 MA-90 TONE ENCODER-DECODER, AND MA-95 TONE ENCODER 
6-1 GENERAL INFORMATION 


The model MA-90 Tone Squelch Encoder-Decoder is used as a 
tone decoder for CTCSS (tone squelch) operation of the Regency 
MICRO-COM U1OR repeater. Since the MA-90 can serve as either an 
encoder or a decoder, it can be used in either the encoder or de- 
coder sockets of the U1LOR repeater. 


The model MA-95 Tone Squelch Encoder is a simplified version 
of the MA-90 encoder-decoder, in which only those components need- 
ed for the encoding function are installed. 


Normally, for. each tone frequency accommodated by the MICRO- 
COM U1OR repeater, one MA-90 is installed in a decoder position 
and one MA-95 is installed in an encode position. 


6-2 MA-90 CIRCUIT DESCRIPTION (TONE DECODING CONDITION) 


Refer to the Circuit Diagram, Figure 6-4. When point "D" is 
grounded, the module is in the decoding mode. 


Audio from the receiver discriminator is fed into the tone 
squelch board at terminal L, and passes through the High Pass Fil- 
ter IC601, and back to the receiver's audio amplifier circuits at 
terminal J. The high pass filter removes the CTCSS tones, which 
are below the normally utilized speech frequencies, so they will 
not be heard on the receiver loudspeaker. 


Audio from the receiver discriminator (at L) is also fed in- 
to IC602, which contains a low pass filter, and a limiter ampli- 
fier. The low pass filter removes most of the speech and higher 
frequency noise components from the signal, leaving essentially 
only the CTCSS tone frequencies and low frequency noise components. 
This filtered signal is then passed to the combination of IC603 
and Ic604, which acts as a high Q band pass filter, tuned sharply 
to the wanted cCTCSS tone. IC603 contains the tone determining 
portions of the combination, and IC604 contains the necessary amp- 
lifiers for the filter arrangement. If the received tone is the 
proper one, as determined by IC603, it will be present in the out- 
put of the IC603--IC604 combination. This tone then passes to 
IC605, which is a detector circuit that detects the presence (or 
absence) of a tone signal. 


The IC605 output, is normally high, and goes to a low voltage 
upon receipt of tone. This output appears at terminal K to signify 


mcu r sol SECTION 6 


the receipt of a signal having the designated tone squelch fre- 
quency. 


6-3 CIRCUIT DESCRIPTION, MA-95 ENCODER 


The MA-95 is an encode only version of the MA-90. Refer to 
the circuit diagram, Figure 6-5. The combination of IC603 and 
Ic604 is an oscillator, with the frequency of oscillation being 
determined by the components in IC603. 


The oscillation output of IC603, IC604 is fed to F, and thus 
to the modulation section of the transmitter. 


The amplitude of the tone voltage sent to the transmitter is 


controlled by R605, which is the control for adjusting the amount 
of modulation deviation caused by the tone. 


mcur me SECTION 6 


J eans Sonne 


RECEIVER TONE 

Mai > xO ba nO Ou oD 
Z Fh PL PSIN, PL 

nU) VUNIN 

} iva) 


AND SPEECH IN — 


BOTTOM VIEW OF ASS‘Y 


SPEECH OUT 


TONE OUT 


TO TRANS 


TONE BOARD 302-508 | 


NOT SPECIFIED OTHERWISE ARE 
NOT SPECIFIED OTHERWISE ARE 


IS FOR BASIC RADIO SCHEMATIC. 
NNECTION POINTS TO 


ENCODER -DECODER BOARD 


-3- SECTION 6 


the receipt of a signal having the designated tone squelch fre- 
quency. 


6-3 CIRCUIT DESCRIPTION, MA-95 ENCODER 


The MA-95 is an encode only version of the MA-90. Refer to 
the circuit diagram, Figure 6-5. The combination of IC603 and 
Ic604 is an oscillator, with the frequency of oscillation being 
determined by the components in IC603. 


The oscillation output of IC603, IC604 is fed to F, and thus 
to the modulation section of the transmitter. 


The amplitude of the tone voltage sent to the transmitter is 


controlled by R605, which is the control for adjusting the amount 
of modulation deviation caused by the tone. 


mcur ae SECTION 6 


TONE BOARD 


RECEIVER TONE 


AND SPEECH IN — 


C60! . 
.OIMF 
— 
602 

OIMF 7 

SPEECH OUT 


MIC 
HANG UP 
BUTTON 


+ VOLTS 


mcu fr 


st ee EERE 


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Zz Ze 
T) gj VU 


IC605 
a BOTTOM VIEW OF ASS*Y 
R6EO4 
ra | ISK RECEIVER 
C608 CONTROL 
eels 
; 
TONE C609 
R6OS} DEVIATION O.1 MF 
R6O7 
100K TONE OUT 
TO TRANS 
C6IO 


on OImr T 


NOES 


ALL CAPACITOR VALUES NOT SPECIFIED OTHERWISE ARE 


PICO FARADS. 
ALL RESISTOR VALUES NOT SPECIFIED OTHERWISE ARE 


OHMS. 


2. REFER TO DRAWING 700-215 FOR BASIC RADIO SCHEMATIC. 
3. LETTERED BOXES ARE CONNECTION POINTS TO 


DRAWING 700-2i5 


6-4 MA-90 TONE ENCODER -DECODER BOARD 


rs- SECTION 6 


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EVIATION Oe! MF 


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| mney TONE OUT 
| U 

| ap 

J oe O TRANS 


| aN 


ECEIVER TONE 
TONE ENCODE BOARD IND SPEECH IN 


__NOT SPECIFIED OTHERWISE 


NOT SPECIFIED OTHERWISE 


' ENCODER BOARD 


h- SECTION 6 


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BOTTOM VIEW OF ASSEMBLY 


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R6OS} DEVIATION O.1 MF 


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ee TONE OUT 
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C6IO 


oaks 


Alien, MF iL it 
MIC 


= SPEECH OUT RECEIVER TONE 
HANG UP AND SPEECH IN 
BUTTON 


NOTES 


1. ALL CAPACITOR VALUES NOT SPECIFIED OTHERWISE 
ARE PICA FARADS. 


ALL RESISTOR VALUES NOT SPECIFIED OTHERWISE 
ARE OHMS. 


6-5 MA-95 TONE ENCODER BOARD 


SECTION 6 


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SECTION 6A 


MA-II6 TONE ENCODER-DECODER 
& 
MA-I2l ENCODER 


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SECTION 6A MA-116 TONE ENCODER-DECODER, AND MA-121 TONE ENCODER 


6A-1 GENERAL INFORMATION 


The model MA-116 Tone Squelch Encoder-Decoder is used as a 
tone decoder for CTCSS (tone squelch) operation of the Regency 
MICRO-COM U10R repeater. Since the MA-116 can serve as either an 
encoder or a decoder, it can be used in either the encoder or de- 
coder sockets of the U10R repeater. 


The model MA-121 Tone Squelch Encoder is a simplified version 
of the MA-116 encoder-decoder, in which only those components need- 
ed for the encoding function are installed. 


Normally, for each tone frequency accommodated by the MICRO- 
COM U1LOR repeater, one MA-116 is installed in a decoder position 
and one MA-121 is installed in an encode position. 


6A-2 MA-116 ENCODER-DECODER CIRCUIT DESCRIPTION (Tone Receiving 
Condition) 


Audio from the receiver discriminator is fed into the tone 
squelch board at terminal L, and passes through the High Pass Filter 
IC601A, and back to the receiver's audio amplifier circuits at 
terminal J. The high pass filter removes the CTCSS tones, which are 
below the normally utilized speech frequencies, so they will not 
be heard on the receiver loudspeaker. 


Audio from the receiver discriminator (At L) is also fed into 
an active filter, consisting of IC601B, IC602A, and Ic602B. This 
filter is a high Q, bandpass filter, that can be tuned for operation 
on any of the CTCSS tone frequencies. The components of the filter 
which determine the operating tone are precision resistors and 
condensers; R601, R602, R603, R604, R605, R606, R607, Cé60l, and 
C602. 


If the received tone is the proper one, as determined by the 
bandpass filter, it will be present in the output O67 1C602) and 
will be amplified by IC603, and then rectified to a D.C.signal by 
the tone rectifiers CR60l1 and CR602. This D.C. signal is then 
amplified further by the D.C. amplifier, TC60SA)) Ine outpucior 
Ic603 is normally high, and goes to a low voltage upon receipt of 
proper tone. This output appears at terminal K, which connects to 
the corresponding terminal K-on the receiver chassis, and is used 
to disable the receiver audio section when no tone is being detected. 


6A-3 MA-121 ENCODER CIRCUIT DESCRIPTION 


A block diagram of the of the encode only circuit board is 
shown on Figure 6A-7, and a circuit diagram is shown in Figure 6A-8. 


The operating frequency of the tone system is controlled by 


mcu xr -l- SECTION 6A 


an Active filter, consisting of IC601B, IC602A, and Ic602B. This 

filter is a high Q, bandpass filter, that can be tuned for operation 

on any of the CTCSS tone frequencies. The components of the filter é 
which determine the operating tone are precision resistors and A 
condensers; R601, R602, R603, R604, R605, R606, R607, C601, and 

C602. 


IC603A is an integrated circuit operational amplifier, used as 
a limiting amplifier. It is connected between one of the inputs and 
one of the outputs of the active filter described above. This 
limiting amplifier thus serves as a feedback path which causes the 
total circuit to oscillate at a frequency determined by the active 
filter. The limiting action of IC603 serves to keep the level of 
oscillation from overloading the active filter, thus keeping the 
output from the active filter sinusoidal. 


6A-4 TONE SETTING INSTRUCTIONS (MA-116 and MA-121) 


The tone frequency is determined by (a) the insertion of 
jumpers to determine which of three bands of operation is desired, 
and (b’ °°¢ ridjustment of a precision potentiometer to determine 
the specific tone frequency. 


For purposes of installing the jumpers, the total CTCSS frequency 
is divided into three bands, the low band being 67.0 Hz to 110.9 Hz; 
the middle band 114.8 Hz to 192.4 Hz, and the high band 203.5 Hz to 
253 ..0°Hz: 


INSTALL JUMPERS FOR THE PROPER BAND é 


Figure 6A-9 shows the jumper locations. Determine which band 
includes the desired frequency, and insert (or remove) jumpers 
according to the following chart: 


67K 02 H2? to2210n9. 82 Low Band JU601,JU602,JU603,JU604 
are all removed. 


114.8 Hz 4o6.192.4 Hz Middle Band JU601,JU603 in place. 
JU602,JU604 removed. 


2037.5? Az. fot 255 103. AzZ High Band JU602,JU604 in place. 
JU603,JU605 removed. 


After soldering or unsoldering jumpers, at least five minutes 
should elapse before making any final frequency adjustment. This 
is necessary to permit the precision resistors and capacitors in 
the vicinity of the soldering points to stabilize in temperature. 


TONE SETTING PRECAUTIONS 
Accurate frequency setting is necessary on CTCSS (tone squelch) 


systems. When making the above frequency adjustments, be sure that 
you set the tone as precisely as possible. If the tone board is to € 


mc + -2- SECTION 6A 


operate in a system using reed type tone boards, be sure that 

your frequency setting is within .1 or .2 Hz if possible. Especially 
on reed tone systems, it is advisable to measure the tone frequency 
of several of the existing units; it is not safe to assume that 

the system is really operating on exactly the frequency stamped 

on the nameplates. 


6A-5 ADJUSTMENT PROCEDURE (Setting Tone Receivé Threshold on MA-116) 


With the receiver in the receive condition, and the micro- 
phone hang up button grounded to the transceiver chassis, inject 
a signal of the appropriate channel frequency into the transceiver 
antenna jack, and modulate this signal with the wanted CTCSS tone 
frequency, with a deviation of plus and minus 200 Hz. Then, adjust 
R612 (on the tone board) until the signal just opens the tone squelch 
system, and allows the receiver audio to function, (See Fig. 6A-10). 


After performing this adjustment of R612, check to be sure 
that the tone squelch will actually open when the tone deviation 
of the receive signal becomes as much as plus and minus 200 Hz. 
Further, check to be sure that noise bursts do not come through 
when the receiver is not receiving any incoming signal. 


6A-6 ADJUSTMENT PROCEDURE (Setting Tone Modulation Deviation on 
MA-121) 


Adjust R618, on the tone squelch board to obtain a tone 
modulation deviation of plus and minus 500 Hz. Then, insert a 
100 millivolt, 1,000 Hz tone into pin four of the microphone 
jack, and adjust R240, (the transmitter deviation control on the 
transceiver) to obtain plus and minus 5 KHz peak modulation dev- 
iation. If R240 was changed much, remove the 1,000 Hz tone, and 
readjust R618 to obtain a tone squelch modulation deviation of plus 
and minus 500 Hz. 


mcu r -3- SECTION 6A 


mcu fr 


IC603A 


AMPLIFIER 


IC601B, IC602A, IC6028 


ACTIVE FILTER 


TONE OUT TO 
TRANSMITTER 


FIG 6A-7 BLOCK DIAGRAM 


oy SECTION 6A 


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SECTION 6A 


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BOTTOM VIEW 
FIG 6A-9 


mcu r -6- SECTION 6A 


SQUELCH RS5O0Z 


RECEIVER BOARD 


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SECTION 7 REPEATER CONTROL SYSTEM 
7-1 REPEATER CONTROL BOARD 


An interconnection schematic of the repeater is shown in 
Figure 7-10. The repeater control functions are performed by the 
repeater control board, which is shown in detail on the inter con- 
nection schematic. The control board components carry 700 series 
numbers. Follow Figure 7-10 while reading the following. 


The control board is arranged to permit operation of the re- 
peater by noise squelch, or by CTCSS (Continuous Tone Controlled 
Squelch, often abbreviated as "tone squelch") tones. 


The U1OR repeater is equipped to hold seven different tone 
decoders, three of these being accommodated on the repeater con- 
trol board, and four on the auxiliary tone squelch board. Any 
number up to seven may be installed, but the first one should be 
installed in P706, located on the repeater control board. Simi- 
larly, the repeater is equipped to hold seven different tone en- 
coders, three on the repeater control board, and four on the aux- 
iliary tone squelch board. Any number up to seven may be installed, 
but the tone generator corresponding to the first tone encoder 
should be installed in P705. 


7-2 AUDIO PATHS 


Audio from the receiver is fed to Pin L of the tone receiver 
in the P706 receptacle. This audio contains both the speech and 
the CTCSS tone portions of the received signal. An active high 
pass filter removes those frequencies below about 300 Hz, which 
includes the CTCSS tones and feeds the remaining signal (now 
speech only) back to the receiver at Pin J. (In units not equipped 
with tone squelch, a jumper located on the circuit board adjacent 
to P701, provides a path between Pin J and L, and no low pass fil- 
ter action is used.) This speech-only signal is then passed through 
the noise squelch controlled amplifier in the receiver and fed to 
the front panel volume control, R501. Audio from the arm of R501 
is fed back to the receiver audio power amplifier and raised to 
loudspeaker levels to operate the local loudspeaker. Thus, R501 
controls the volume heard by the local operator and has no effect 
on re-transmitted audio. 


Receive audio, for retransmission, is taken from the high 1 
side of R501, passed through the transmitter modulation input con- 
trol, R728, and sent to the transmitter modulation circuits. Since 
this audio has passed through the high pass filter in the tone 
squelch board, it contains only speech components, and daes not 
contain any CTCSS tone. If CTCSS tone is) used, .the..CTCSS. tone 
for the retransmitted signal comes from the appropriate encoder 
board, aS will be explained later. 


sav ae DOOR -l- SECTION 7 


7-3 TRANSMITTER ACTIVATION BY NOISE SQUELCH 


When JU701 is connected to the "Squelch" contact pin, the 
transmitter will be activated by any signal that is accepted by 
the receiver's noise squelch system. When a signal is received 
and the receiver's noise squelch system causes the receiver to be- 
come unsquelched, audio amplifier Q113 in the receiver draws cur- 
rent th.ough R501, the front panel volume control. This current 
creates a drop across R727 that causes Q708 to conduct. Q708 
causes Q707 to conduct, which places an effective ground on the 
cathode of CR712, which causes Q709 to conduct, which then causes 
Q@706 to conduct. Q706 places an effective ground on the PTT term- 
inals of the transmitter, and therefore activates the transmitter. 


Squelch Hysteresis Action: 


When the transmitter is activated and Q709 is ina conducting 
condition, Q709 causes Q710 to also be conducting, placing the 
collector of Q710 near ground potential. The series combination 
of CR729 -~d R675 are connected between the K Line to the receiver 
squelc.. au. ue collector of Q710. When Q710 conducts, its collector, 
acting through CR720 and R765, pulls the receiver squelch K line 
toward ground, forcing the receiver noise squelch into a more 
"unsquelched" condition. This action prevents the dropout of weaker 
signals from mobiles when the mobiles pass through low signal areas. 
The effect of this circuit is to add a large amount of "hysteresis" 
to the operation of the squelch system. That is, the signal required 


to hold the squelch open (once enercized) is thus less than that 
required to open the squelch in the first place. 


In some systems, it may be found that this "hysteresis" action 
is excessive, and permits unduly noisy signals to hold the repeater 
transmitter on. The amount of hysteresis action may be reduced by 
increasing the size of R765. 


7-4 TRANSMITTER ACTIVATION BY CTCSS (TONE SQUELCH) 


When JU70L is connected to the "tone" contact Din, ptHeare— 
ceiver noise squelch is no longer in control of the activation of 
the transmitter. In this condition, tone decoders, tuned to spe- 
cific subaudible tones, activate the transmitter when the appro- 
priate tone is detected on a received signal. 


To follow the operation under tone squelch (CTCSS) control, 
assume that a tone decoder board for. 127.3 Hz had been installed 
in the P706 connector of the repeater control board, and that a 
tone encoder for the same frequency has been installed in. the; cor= 
responding P705 connector, also on the repeater control board. 
Also assume that JU703, a wire jumper on the circuit side of the 
circuit board adjacent to P706, has been removed. 


Unsquelched audio from the receiver is connected to Pin L of 
all of the CTCSS tone receivers. When no tone is being received, 


mcu xr -2- SECTION 7 


Pin K of all tone receivers will have a positive voltage causing 
Q702, Q705, Q706, Q802, Q804, Q806 to be conducting, and Q701, 
0703, Q705, Q801, Q803 to be non-conducting. When a signal with 
127.3 Hz tone is received, the 127.3 Hz tone receiver in P706 will 
sense the presence of the tone, and the positive voltage will dis- 
appear from its K terminal, causing Q706 to be non-conducting, 
thereby causing Q705 to be conducting. Current pulled by the col- 
lector of Q706 pulls current through LD703 and CR712, causing LD703 
to light, and causing Q709 to conduct. The conduction of Q709 
eventually causes the transmitter to be activated in the same man- 
ner as it would be in the noise squelch operation mode described 
earlier. 


The conduction of Q709 also causes Q710 to conduct, placing 
its collector near ground potential. The series combination of 
CR720 and R675 are connected between the K line to the receiver 
squelch. When Q710 conducts, its collector, acting through CR720 
and R765, pulls the receiver squelch into a more "unsquelched" 
condition. This action prevents the dropout of weaker signals 
from mobiles when the mobiles pass through low signal areas. 


When no CTCSS tones are received, the cathodes of CR709 and 
CR710 are held at a positive voltage by R719. CR709 and CR710 
constitute a diode switch. In this condition, the switch is open, 
preventing the output of the tone encoder (Pin F, P705) from reach- 
ing the transmitter tone input terminal F. Similar diode switches 
prevent the output of other tone encoders from reaching the trans- 
mitter tone input. When a 127.3 Hz tone is received, the action 
of the tone receiver board located in P706, and the action of 
9806 and Q705 cause the voltage on the cathodes of switch diodes. 
CR709 and CR710 to disappear. The diodes are then forward biased 
by current through R715 and R716, and therefore wikl.conduct.the 
tone from the P705 tone generator to reach the tone input to the 
transmitter. 


7-5 OPERATION BY LOCAL MICROPHONE, PIT FUNCTION 


The local microphone may be used for dispatching from the re- 
peater location, or for testing the repeater station during main- 
tenance procedures. The microphone supplied is a model MA-83. 
This is a ceramic type microphone with a switch section that dis- 
connects the microphone element when the PTT switch is released. 


One pole of the microphone PTT switch is connected to Pin 3 
of the microphone connector J501. Inside the transmitter, Pin 3 
goes to the coil of the PTT relay. Since the other side of this 
relay is connected to plus 13 volts, approximately 13 volts ap- 
pears at Pin 3 of the microphone jack. This voltage acting through 
CR718, causes Q718 to be conducting. When the PTT switch is closed, 
the voltage at Pin 3 drops to zero, causing Q718 to become non- 
conducting, which results in a positive voltage appearing on the 
Q718 collector. This voltage, acting through R751, is connected to 


mcu-r -3- SECTION 7 


the base of the receiver noise rectifier filter, causing the 
receiver to become squelched, and thereby preventing the retrans-~- 
mission of any received audio during the time the local micro- 
phone is depressed. : 


If the repeater is equipped with tone, the tone select test 
lead JU103 is normally connected to contact TP703. When the mi- 
crophone button is depressed, TP703 is pulled almost to ground, 
causing CR709 and CR710 to conduct, thereby permitting the tone 
generated by the tone encoder in P705 to be delivered to the trans- 
mitter tone input. Thus, the 127.3 Hz tone assumed above will be 
transmitted when the local microphone switch is operated. 


If it is desired to actuate other tones for test purposes, 
the Tone Select lead JU103 may be connected to the appropriate 
tone selection contact for the desired tone, i.e., TP701, TP702, 
TP801, TP802, TP803, TP804. When the microphone PTT switch is 
activated, the CTCSS tone associated with the selected contact 
will be » citted. After the test, be sure to return JU103 to 
TP703 for uo_mal operation. 


7-6 TONE MONITORING PROVISIONS 


Assuming that the tone select test lead is connected to TP703, 
and that a 127.3 Hz tone decoder is plugged into P706, the posi- 
tive voltage of Pin K of P702 (under the no-tone received condi- 
tion), acting through R759 and R560 causes the diode audio switch 
consisting of CR719 and CR720 to block audio from the arm of the 
front panel volume control R501, preventing audio from reaching 
the receiver audio power amplifier, and the local loudspeaker. 


When a tone of 127.3 Hz is received, TP703 is no longer pos= 
itive, and the diode audio switch CR719-CR720 is switched to the 
pass condition, permitting the received audio signal to pass from 
the arm of the front panel volume control to the receiver audio 
power amplifier and thus the signal can be heard over the local 
loudspeaker. Note that this received audio must pass through the 
noise squelch circuit of the receiver as well as audio switch 
CR719 and CR720. 


The above has described the operation when the microphone is 
in its grounded hanger. When the microphone is in its hanger, 
only signals bearing the specific tone installed in P706 will be 
heard in the loudspeaker. The microphone hang-up button is con- 
nected through the microphone cable to Pin 5 of the microphone 
connector J501, placing a ground on the base of Q717, which caus=- 
es Q717 to be non-conductive. Under this condition, only the sig- 
nals bearing the 127.3 Hz tone assumed above will be heard in the 
local loudspeaker, as described above. 


mcu r -4- SECTION 7 


When the microphone is lifted from its hanger, the base of 
Q717 is pulled positive by R749, causing Q717 to conduct, forcing 
the diode switch CR719-CR720 to be in the pass condition, regard- 
less of the voltage coming from TP703. Under this condition, re- 
ferred to as the "MONITOR" condition, all audio signals that pass 
through the receiver noise squelch system will be passed on to the 
receiver audio amplifier and the local loudspeaker. This "MONITOR" 
condition permits the operator to listen on the channel before 
transmitting, and thus avoid Basis up an ongoing communication 
on the channel. 


Summarizing the action of the microphone hang-up button, and 
its monitoring actions: 


When the microphone is in its hanger, all received signals 
with appropriate tone squelch frequencies (those for which a tone 
decoder has been installed) will be retransmitted by the repeater, 
but only those signals bearing one specific tone (selected by the 
placement of the tone-select test lead, JU703) will be heard in 
the local loudspeaker. This enables the local operator to avoid 
being bothered by transmissions over the repeater which do not 
concern him. 


When the microphone is removed from its hanger, all received 
Signals, regardless of whether they have the correct tone, or any 
tone, will be heard in the local loudspeaker. This permits the 
operator to monitor activity on the channel before transmitting. 


7-7 THREE MINUTE TIMER, DROP-OUT DELAY, TIME-OUT WARNING OSCILLATOR 


When the transmitter is not activated, 0709 is non-conducting, 
causing Q710 to be non-conducting, causing Q711 to be conducting. 


Since the collector of Q711 is shunted across timing con- 
denser C708, C708 cannot be charged tkrough R735. When the trans- 
mitter is activated by the receipt of a signal, Q710 is turned 
on which makes Q711 non-conducting, thus removing the short a- 
cross C708. C708 then is slowly charced through R735. When C708 
becomes charged to about 1.2 volts, it. causes Q713 to conduct. 
Once Q713 begins conduction, it turns on Q712 which puts more 
base current into Q713, causing it to conduct heavily and turn 
on Q714. Q714 acts as a short across the line leading to the base 
CL y07L6,. cUrninguo 7 LoToLt. @cincer On. G collector 1s connected to 
the PTT lead of the transmitter, the short it creates between 
this lead and ground is removed, and the transmitter turns off 
as soon as the drop-out delay capacitor C714 is discharged. 


When Q713 becomes conductive, it also supplies collector cur- 
rent to the time-out warning oscillator, Q715,. Q715 is connected 
as a phase shift oscillator and its output is connected into the 
transmitter modulation input. The beep from the time-out warning 
oscillator is transmitted during the few seconds of the drop-out 


mcu xr -5- SECTION” 7 


delay caused by C714. C714, in the base circuit of Q716 serves 

as a "drop-out delay." While the transmitter is turned on, C714 
becomes charged. When the received signal disappears, the charge 
on C714 holds Q716 in conduction for about two seconds. Thus, the 
transmitter remains activated for about two seconds after the re- 
ceived signal disappears. 


mcu r -6- SECTION 7 


TONE/CONTROL BOARD 


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7-8 REPEATER CONTROL BOARD TOP VIEW 


SECTION 7 


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ALL RESISTORS 4 W UNLESS OTHERWISE NOTED. 
ALL CAPACITORS ARE MICROFARADS UNLESS OTHERWISE NOTED. 
(<— DENOTES ADJUSTABLE COMPONENTS. 
HEAVY LINE DENOTES APPARENT SIGNAL FLOW. 
ALL VOLTAGES (FIGURES IN PARENTHESIS) ARE NOMINAL VALUES 
AS MEASURED WITH A VTVM. SUPPLY VOLTAGE =II7VAC 60HZ 
AT INPUT TO SUPPLY CABLE. 
6. PART DESIGNATION NUMBERS INDICATE LOCATION. 
100 SERIES Rx BOARD REF SCHEMATIC 604-OI!. 
200 SERIES Tx BOARD REF SCHEMATIC 604-010. 
BOO SERIES UNASSIGNED. 
400 SERIES 
(a) POWER SUPPLY REGULATOR BOARD 
(b) ON/OFF INDICATOR BOARD. 
500 SERIES CHASSIS MOUNTED. 
600 SERIES 
(a) TONE PLUG-IN MODULE (ENCODE /DECODE) REF SCHEMATIC 5OI-275 
(b) TONE PLUG-IN MODULE (ENCODE ONLY) REF SCHEMATIC. 304-007. 
700 SERIES TONE CONTROL BOARD. 
900 SERIES TONE MOTHER BOARD REF SCHEMATIC 604-009 


Vary 


7-10 REPEATER INTERCONNECTION SCHEMATIC 
INCLUDING REPEATER CONTROL BOARD 


meu r -9- SECTION 7 


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