Hi-- This is mainly for Web in Myrtle Beach, S.C. I tried sending this to
Web direct, but not sure I understand AOL email yet.
In my Omni-C the ALC is developed on the SWR-TR board by diode D2. Replacing
both D1 and D2 would be worthwhile as long as you are in there. D1 creates
the SWR voltage for metering. These diodes are nothing special, you can use
any of the following: NTE519, ECG519, GE 514, SK3100, or any other Selenium
switching diode. It is not unusual for four diodes to be bad on this board,
D1, D2, D4 and D5.
Of course there are other possible places to look, but I'd sure start there.
One thing I always do is mark the board before taking it out of the rig. Most
of them can be switched end-for-end, and with my luck, I'd do just that when I
put a board back in.
While working on the SWR-TR board, I would also replace D4 and D5 which are
across the receive antenna. Often these go bad and the receive sensitivity
suffers.
The SWR-TR board on my Omni-C is accessed from the top of the rig. Looking
from the front panel, the SWR-TR board is mounted vertically in a small square
compartment at the very back left corner of the rig. It is the board which is
closest to the center of the radio, and NOT the one closest to the side panel.
You can unplug the board to remove it for service.
In my rig, D1 is mounted next to a potentiometer. D2 is mounted next to a
variable capacitor. D4 and D5 are side-by-side just next to one end of the
relay coil.
Hope this helps. 73 de Mike
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