On Mon, 1 Jan 2001, Mark Adams, P.E. wrote:
> Here are the specifics:
> * One day the SWR and FWD power positions did not work. Don't know why. The
> S-meter still worked. Funny thing is, the meter in my MFJ 941E also quit.
> ESD? Lightning? Everything else worked FB. A month passed.
Sounds like static discharge when you weren't looking. Mean static
discharge.
> * Then it started to shut down whenever I turned the power up past 20W or
> so. I would hit the switch for the heil mike or hit the key and click- the
> rig would be off. It would reset no trouble. Being an avid QRPer this was
> never a REAL problem. But one that I did want to fix.
.....
> So now, everything seems to work except the radio does not receive. Just
> noise comes out of the speaker. It XMIT's OK. All controls function. I tried
> the instructions in the manual on troubleshoooting the rx section, and it
> all checks out.
General symptoms remind me of the weakest link diode problem. I'd check
diodes D7, D9 on bandpass filter board, D3 and D4 on the low pass filter
board, and others nearby. These caused similar problems in one of my OMNI
VI's. The last gentleman who had the apparent ALC problem had symptoms
similar to my other OMNI VI that failed in the same diode chain. So, as a
first shot in the dark, snoop around these diodes in the low pass and
bandpass boards.
Clark
WA3JPG
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