[Elecraft] SSB TX signal mystery SOLVED !!!

Marinos Markomanolakis, M.D. sv9dru at hotmail.com
Tue Dec 28 19:50:08 EST 2004


First let me thank Don (w3fpr) and Garry (ab7my) for their excellent support 
and guidance for the resolution of this problem.
As posted earlier, I had a disappearance of my Tx SSB signal after 
installing the adaptor to the K2 with normal RX and normal CW Tx. Had spent 
some hours looking at the different boards without finding the culprit and 
finally started chasing the SSB signal with the oscilloscope to see where it 
was blocked.
That signal was going fine all the way past the crystal filter, exiting the 
C5 cap after the T1 transformer but then could not be found at the cathode 
of D14 !!!!
That's very strange indeed I thought, since the C5 is supposed to be 
connected to the cathode of D14 ?!?!?
And here came the realization that I had done the STUPID mistake of 
installing the D14 cathode 90deg away from its normal pad, to a similar pad 
reserved for the R10.....Of course, at a later construction step I had 
realized that one of the R10 pads was occupied, but I thought it was normal 
and had soldered it there anyway (another stupidity).

Anyway, I can go on and on about how this should never had happened, but it 
only took a 90deg rotation of this diode without even removing it from the 
board to fix this.
Now I have full SSB output and are 1/2 way done with my K2 100W amplifier 
board before I have everything up and running.
Already built the NB, AF filter and successfully passed the first alignment 
test of the 100W board....

The above story is a good example of what happens when you stay up too many 
hours building your K2. But as you know, when you start you can not easily 
contain yourself from continuing building. It is addictive !!!

73 to all,
Marinos, ki4gin




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