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Tech Arsenal 1
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1991-10-26
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105 lines
MOD FOR IMPROVED MONITOR VOLUME.
FOR RADIOS WITH SERIAL NUMBERS BELOW 2000
1. SET RADIO FOR 8 MHZ IN LSB
2. ADJUST C226 FOR 1 TO 1.2V AT R201.
3. VERIFY THAT IT GOES TO 3V AT 7.9999MHZ
CHANGE R85(10K) ON MAIN UNIT TO 4.7K.
........................................
PASSBAND TUNING MOD.
1. DESSOLDER AND LIFT CATHODE OF D63 FROM PCB.
2. ADD A 1N914 DIODE FROM THE CATHODE OF D63 TO THE ANODE OF D64.
3. DESOLDER AND LIFT W31 FROM PCB AND SOLDER TO JUNCTION OF THE
1N914 CATHODE AND D63 CATHODE.
AFTER MODIFICATION:
IF SHIFT BUTTON OUT = PASS BAND TUNING
IF SHIFT BUTTON IN = IF SHIFT.
..........................................
MOD TO PREVENT ANT SW UNIT FAILURE.
1. REMOVE TOP COVER
2. LOCATE ANT SW UNIT AT RIGHT REAR OF RADIO (AT ANTENNA JACK).
3. SOLDER A .0047 UF, 500V CERAMIC CAPACITOR TO BACK SIDE OF
PC BOARD AS SHOWN. (BOARD REMOVAL IS NOT NECESSARY).
4. REINSTALL TOP COVER AND CHECK FOR PROPER TRANSMITTER
OPERATION. THIS MODIFICATION PREVENTS FAILURE OF R1, R2, D1 AND L1.
-------------------------------------- TOP EDGE OF BOARD
/0\
/ \ REAR PANEL OF RADIO---->
I----0 / \
__I__ / \
.0047UF /0_______________0\
--I-- 0 /0/
I ________________________ / /
I------0________________________0 / /
/ /
/0/
VIEW: BACK ANT SW UNIT PCB.
..................................................
THE FEEDBACK CIRCUIT THAT CONTROLS THE TUNING MOTORS BECOMES SENSITIVE
AFTER A FEW MONTHS OF AGEING. IT REQUIRES A ONE TIME ADJUSTEMENT TO CORRECT.
1. REMOVE TOP COVER AND LOCATE THE ANTENNA TUNER BOARD.
2. LOCATE R5 AND R10 AND SET THEM TO THE CENTER OF THEIR RANGE.
3. SET RADIO AS FOLLOWS: TUNER ON
FREQUENCY 14.100 MHZ
MODE RTTY
4. AFTER TRANSMIT IS ENGAGED FOR 30 SECONDS,
5. ADJUST EACH CONTROL (R5 AND R10) SO NEITHER MOTOR TUNES WHILE CHANGING
FROM SSB TO RTTY AND BACK TO SSB.
-NOTE: R5 (RIGHT) CONTROLS RIGHT MOTOR AND R10 (LEFT) CONTROLS LEFT MOTOR.
6. REPEAT THIS ADJUSTMENT TO VERIFY PROPER OPERATION AND THEN CHECK ON
ALL OTHER BANDS.
7. REINSTALL TOP COVER AND RETURN TO OPERATION.
.................................................................
MODIFICATION FOR IMPROVED T/R SWITCHING TIME
(PREVENTS DAMAGE TO D45, D46, D47, Q15 ON RF BOARD)
PARTS NEEDED: 47K 1/8 WATT RESISTOR
150K 1/8 WATT RESISTOR
1SS53 DIODE
INSULATION FOR THE RESISTOR LEAD
1. REMOVE BOTTOM COVER.
2. REMOVE SCREWS FROM MAINT UNIT AND LIFT BOARD.
3. REMOVE R10 (39k) AND R11 (39K) NEAR IC-2.
4. INSTALL ONE END OF THE NEW R11 (150K) TO FOIL TRACE WICH CONNECTS TO C13.
INSULATE REMAINING LEAD OF R11 AND SOLDER IT TO PIN 3 OF IC-2.
5. INSTALL NEW R10 (47K).
6. SOLDER D159 (1SS53) BETWEEN PINS 3 AND 13 OF IC-2. CATHODE SIDE OF
DIODE (STRIPPED END) GOES TO PIN 3.
7. MODIFICATION IS COMPLETE. NO ADJUSTEMENT IS NECESSARY. REINSTALL
THE MAIN UNIT AND BOTTOM COVER.
...................................................
THESE MODIFICATIONS COME FROM ICOM EXCEPT FOR PBT .
THE MODIFICATIONS WERE MADE BY ICOM ON MY RIG EXCEPT THE PBT .
I MADE THE MOD FOR PBT MYSELF AND IT IS GREAT.
IF YOU HAVE A MOD FOR GENERAL TX (TESTED PLEASE) SEND ME ALL INFOS.
IF YOU ARE NOT FAMILIAR WITH ELECTRONIC, LIVE THOSE MODIFICATIONS
TO A TECHNICIAN.
HOPE YOU WILL ENJOY THESE MODS.
ALSO, IF YOU HAVE A PROGRAM TO RUN THE RADIO WITH THE CT-17 INTERFACE
FROM A IBM CLONE PLEASE SEND ME A COPY.
BEST 73 DE JEAN VE2KAD
JEAN-F TANGUY
P.O.BOX 931
RAWDON QUEBEC
CANADA J0K 1S0
::::::::::::::SALUTATIONS DU QUEBEC::::::::::::::::::
/EX