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Author Topic: Drake tr-4c freq dial is off 9kc from actual tx freq  (Read 1181 times)
KE7TZ
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Posts: 19




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« on: November 18, 2017, 09:09:47 PM »

Have tried to adjust using skirt of vfo knob but it comes up against a stop and won't adjust any further. Appreciate any help. Thanks 73 Jim ke7tz
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WB0CJB
Member

Posts: 131




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« Reply #1 on: November 19, 2017, 08:06:17 PM »

The crystal calibrator could be off frequency. However my own TR4C is off on several bands. 40m is off 6-7khz, etc. It is probably a crystal that is getting old. After all these rigs are 40 or so years old.

80 and 20 meters do not require a crystal besides the 9 MHz one. 40, 15, and 10 meters require a crystal besides the 9 MHz one and the VFO.

WB0CJB
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WW3QB
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Posts: 812




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« Reply #2 on: November 20, 2017, 06:17:49 PM »

My TR-3 PTO was not set correctly. I followed this procedure from some Drake resource, but I cannot remember exactly where I got it from.
Edit: I got this procedure from Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs <www.k4oah.com>

PROCEDURE FOR ADJUSTMENT OF STOP
MECHANISM ON PTO DIAL TR3/TR4
1. Adjust red dial cursor to middle of its range.
2. Align dial at 3.5 MHz with cal. Signal.
3. Turn main tuning knob clockwise 6 kHz.
4. Temporarily disengage nylon idler gear (this gear will move sideways far enough to
disengage teeth)
5. Rotate plastic dial until stop pin drops into groove on rear of metal gear.
6. With idler gear still disengaged rotate main tuning shaft clockwise until shaft pin
hits stop pin, thus locking the dial. Be sure the shaft pin protrudes far enough to
make positive contact with stop pin. (The shaft pin should stick farther thru the
shaft in one direction than in the other.)
7. Re-engage plastic idler gear.
8. Rotate main tuning dial counter-clockwise until 3.5 MHz is reached and check
alignment with cal. Signal. If necessary, slip plastic dial on shaft for proper
alignment.
9. Check high end of dial for 4 or more kc travel beyond 4.1 MHz marker after zeroing
at the 4.1 MHz point. Stop should hit as before.
This completes the procedure.
« Last Edit: November 20, 2017, 06:26:30 PM by WW3QB » Logged
KE7TZ
Member

Posts: 19




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« Reply #3 on: November 21, 2017, 11:12:11 PM »

THANKS FOR INFO AND HELP. TIME TO GET TO WORK. 73 JIM KE7TZ
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