This may be irrelevant to the SR-2000, I am not familiar with it. I
had a similar problem with a Drake T4XB, couldn't null the carrier. I
found, after considerable waste motion, the problem was wiring. A
previous owner had re-wired part of the balanced modulator. While the
wiring _looked_ perfectly fine, it was not. I got photographs of the
correct wiring from Garry Barrell (SK) who was the maven of Drake. Turns
out the the wires to the diode bridge were reversed. It was not the
polarity but the location of the wires that made the difference. The
stray capacitance was so different it put the trimming cap out of range.
I restored the original wiring and the null was perfect and right in the
center of the trimmer range.
Is it possible that something in this rig has changed? You might
need pix of the correct wiring to compare to yours.
Again, may be irrelevant to your problem but on my transmitter it
caused me to chase my tail for quite a while.
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On 4/2/2024 4:06 PM, W7WRX wrote:
I cleaned and tightened everything including the bracket. No change.
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
