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

To: tentec@contesting.com
Subject: [TenTec] Some progress made! --Omni D low to no power
From: scottsheppard@videotron.ca
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Fri, 17 Feb 2012 23:36:43 -0500
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
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.

scott VA3IED

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