[Elecraft] SSB problem update

[Marinos Markomanolakis, M.D.]

Update 12/26/04:

Did some additional testing with the oscilloscope today and it seems that 
the balanced modulator IC may be the problem. traced the mic input from the 
pin #5 of the P1 connector, to the input (U3-pin4) and output (U3-7) of the 
speech compressor with the expected amplification. The same signal was 
traced to the input of U5 (pin1). Also the IF signal was detected at the U5 
pin 6, as expected, but no modulated RF was present at the U5 output (pin4). 
The signal at U5-pin 4 was similar in amplitude and frequency to the RF 
input signal but was not modulated by the AF.

Following these results, and given that everything at the Rx side and the 
TUNE Tx seems to work fine, I believe that the NE612 IC has been damaged. Of 
course I did observe the proper antistatic and overheating precautions, but 
one never knows what might have happened to it.

Interestingly enough, replacing the main microprocessor chip with an older 
version 1.06F that I had available, made the AUX BUS (U1-28) voltage go to 
the expected 2.4 V value in Tx but did not fix the SSB no Tx problem. So I 
tend to think that the AUX-BUS line is not the issue here.

I will order a replacement IC from Elecraft and post the results once I have 
it installed.
Thanks to all that have replied to my question.

73,
Marinos.