[TenTec] No SSB TX from Omni D

[James Duffer]

I don't have an Omni D, but the fact you obtain a cw output is a good sign 
that most of your transmits circuits are working.  A lot of rigs use a  
signle sinsusoidal audio frequency to  generate a CW output. In other words 
letting the single tone unbalance the balanced modulator creating a dsf 
(double side frequency) signal which is subsequentially passed through the 
filter and one of the side frequency is eliminated thus a single frequency 
is generated and passed and amplified for the cw output.  So it would seem 
that you have a problem in the transmit audio circuits.....does your unit 
have a vox and does that work?  The suggestion on using an "scope" is a good 
one, in that you can trace the audio from the mike to the balance 
mod.....somewhere you are losing that audio.  If there is a switching point 
in this audio path, be sure and check that.

Good luck and persevere.

73, Jim, wd4air

>From: "Jay Eimer" <kd5wlx@familynet.net>
>Reply-To: tentec@mailman.qth.net
>To: <Tentec@mailman.qth.net>
>Subject: [TenTec] No SSB TX from Omni D
>Date: Mon, 29 Sep 2003 22:53:50 -0500
>
>Guys,
>
>I have recently acquired a Ten-Tec Omni D Rev B transceiver.  Everything
>seems to be working fine, except I can't get any drive on SSB.  CW power 
>out
>is fine (in fact, possibly too fine, as I can peg a 200W meter).  But when 
>I
>key the mike in sideband, the meter tweaks up to about 10W, then slowly
>fades to zero over about 1-1/2 to 2 seconds.
>
>At first I thought I might have had a bad mike, since it doesn't match the
>radio.  But I've since tried 4 others (none known to be good, but what are
>the odds....) as well as one "modern" mike, that's only 600 Ohm, but wired
>through a step-up transformer to 25K Ohm, and I do know that it is good.
>All the mikes will key the radio in VOX, and hold it keyed as long as I'm
>talking.  However, none will light the ALC light, no matter how high the
>drive is turned.
>
>Checking in the manual, I decided to check voltages on the SSB Gen board
>(part 80499).  Here's what I found (only the discrepancies noted - assume
>the rest checked normal).
>
>Pin Voltages:
>     SB-N Tx    CW 13.5 instead of 13.8 and BFO 5.0 instead of 5.7
>     SB-N Rx    BFO 5.0 instead of 5.7
>     SB-R Rx    BFO 5.5 instead of 5.9
>     CW Rx        BFO 5.0 instead of 5.9
>     Lock Rx        BFO 5.25 instead of 5.8 and T 0.7 instead of 6.6 
>(biggest
>error).  The rest are within 0.1v of the book.
>
>All of the transistors check out okay.
>
>The ICs, on the other hand:
>IC1 - Tx - pin 1, 4.4. instead of 5.4
>         pin 2, 4.4 instead of 2.3
>         pin 3, 4 instead of 0!!!!
>         pin 4, 0, normal
>         pin 5, 1.5 instead of 5.4
>         pin 6, 4.4 instead of 7.7
>         pin 7, 4.4 instead of 6.6
>and pin 8, 8.2 instead of 7.7
>
>IC1 - Rx - pin 1, 4.4 instead of 5.5v
>     pin 2, 4.4 instead of 0
>     pin 3, 4 instead of 0
>     pin 4, 0 instead of 1.6
>     pin 5, 1.3 instead of 5.5
>     pin 6, 0 instead of 8
>     pin 7, 4.5 instead of 0
>and pin 8, 8.2 instead of 8
>
>IC2 - Rx - (disclaimer, I was unable to find the "mark" for pin 1 as
>indicated by the manual, so this is a best guess based on the position on
>the board - I would have hoped the measurments would line up....)
>pin 1, 8 instead of 4.1
>pin 2, 0 instead of 4.1
>pin 3, 8 instead of 4.1
>pin 4, 5.5 instead of 0
>pin 5, 0 instead of 3.6
>pin 6, 0 instead of 4.2
>pin 7, 0 instead of 4.3 and
>pin 8, 5.5 instead of 8v
>
>Any ideas on what part might be bad?  Caps?  Somewhere else besides the SSB
>board?
>
>All help very much appreciated, as I just recently got my upgrade and I'm
>desperately trying to get on HF.
>
>Thanks,
>Jay
>KD5WLX
>
>
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