[TenTec] No SSB TX from Omni D

Tue, 30 Sep 2003 00:00:10 -0500

You need a sensitive AC voltmeter at the very least and an oscilloscope if
you can borrow one.

es 73 de Pete WA5JCI   EM21jv

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----- Original Message -----
From: "Jay Eimer" <[email protected]>
To: <[email protected]>
Sent: Monday, September 29, 2003 10:53 PM
Subject: [TenTec] No SSB TX from Omni D

> 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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