[TenTec] Some progress made! --Omni D low to no power

[scottsheppard at videotron.ca]

For those of you who have been helping along with the OMNI D low power issue, here is the update:

I dragged out the fluke scopemeter tonight and did some checking...the amount of power going into the Low Level Driver is very low as prev mentioned...on the scope it was there but not much...when compared to the output of the LLD, however,  big difference. Lots of gain on the LLD. That was some good news. I checked the output from the VFO amp and that too looked good (relative)...the next check was on the output from the SSB board--again lots of output into the TX Mixer...the output from the TX mixer, however, very low.

...I found the input from the LO into the TX Mixer which looked very good as well and even the LO going into teh TX Mixer was 150 times more powerful than the output from the TX mixer...something did not add up...

since I knew my LLD was better than first thought I decided to bypass the crystal and band pass filters and bring the LO output into the LLD to see what happened...Bingo...3 watts out of the LLD when sufficiently driven. 

Encouraged by that, I hooked up the PA again and put the power to it---80 watts out before any adjustment. Looks like everything downstream and including  the LLD is A-OK...thats great news.

Now, it would seem the TX Mixer is the culprit OR it is still not getting enough input...the relative signals into the mixer look good. One thing that has me puzzled is why the signal output from the TX Mixer would show continuity with ground??? yes, 0 ohms...it would sure explain a diminished signal. I note that the output from the SSB board is also common to ground (tx or receive) that goes through the crystal filter and eventually to the TX mixer...I looked for shorts etc, no luck...perhaps a defective component--or more likely a complex impedance through one of the transformers etc...I got too tired check>>>nice to end the evening with some progress for a change.

cheers
scott VA3IED