[TenTec] Omni VI ckicks in fast QSK

[gerd Groos]

Thanks a lot Steve for pointing this posting out to me. Re-cabling and
screening audio cables will certainly do know harm. This will be next on my
todo list.

So far I re-cabled the logic board (put caps on all ICs, ran direct 5V&GND
cables to all ICs) which helped me get the birdies way down and calm the
audio noise a bit.

73

Gerd.

2016-11-21 20:37 GMT+01:00 Steve Ellington <steven4lq at gmail.com>:

> Gerd:
> I found this in the archives. It may or may not help. 73
>
> *2/14/99*
> Several weeks ago, someone on the list indicated that they could not rid
> their Omni Six of audible "clicks" while listening with headphones. I
> suggested removing plug 52 on the AF/IF Circuit board, but apparently, this
> did not help.
>
> After making yet another mod to my Omni Six last weekend, I noticed the
> same problem for the first time: I was hearing audible clicks, to the point
> of being annoying regardless of any front panel setting, including power
> and AF loudness.
>
> This weekend, I jumped in to find the cause. On my particular Omni Six,
> several areas were contributing to the clicks. Through a combination of
> regrounding, using shielded audio cable, and rerouting cables, I have my
> Omni back to the point where no or clicks thumps are heard whatsoever. The
> following steps may be of help to those who wish to minimize clicks in
> their Omnis:
>
> 1) I'm a firm believer in removing plug 52 from the IF/AF circuit board.
> Pull it, and tie-wrap it out of harms way.
>
> 2) Ground the heatsink tab of U8, the audio power amplifier. By pushing U8
> against the side chassis, a hole can be drilled for placement of a #4 screw
> which now grounds and heat-sinks U8 to the chassis.
>
> 3) Many audio cables use ribbon cable. I replaced several of these with
> single-pair shielded cable to the AF pot, FIXED AUDIO Plug 57, and cut two
> audio circuit traces on the AF/IF Board that were running too close to
> other witching circuitry.
>
> 4) Cut the nylon tie-wrap that holds the cable bundle along side the
> chassis near U8, separate and twist the wires, finding the right
> combination that minimizes the clicks.
>
> On Mon, Nov 21, 2016 at 1:22 PM, gerd Groos <df9ts.cw at gmail.com> wrote:
>
> > Hello,
> > I friend borrowed me an Omni VI, which is producing very disturbing
> > audio-clicks in fast QSK mode, at any CW speeds, even with very slow
> > keying.
> >
> > The clicks are louder than the received signal and quite distracting.
> >
> > I am including symptoms below for those who want to read on. Any ideas,
> and
> > suggestions highly welcome.
> >
> > 73
> >
> > Gerd DF9TS.
> >
> > ===
> >
> > The TRX is click-free when connected to a dummy load. Symptoms appear
> with
> > antenna signal (or white noise) on the receiver input.
> >
> > The clicks are produced in fast QSK only on key release ("key up") only.
> > "Key down" is not producing clicks.
> > TX signal is ok and click-less and without chirp (as verified with 2nd
> > receiver). RX audio signal is with these clicks.
> >
> > I verified the "TD". "T" and "R" signals generated for internal tx/rx
> > switching with a scope. They look similar to a quick Spice simulation I
> did
> > of the circuit. I did however not see a lag between "T" going down and
> "R"
> > going up.
> >
> > Slow QSK is without such clicks.
> >
> > On "slow QSK" the RX audio comes back up  slowly on "key up".
> > On "fast QSK" the RX audio comes back immediately on "key up".
> >
> > This makes me wonder if the cause is a timing issue on "key up".
> >
> > I did align the TRX following the manual, twice. BFO is well aligned
> also.
> > The rig behaves as expected. Sensitivity and filters ok.
> >
> > Removing connector 52, extensively discussed in this list, makes no
> > difference for this OMNI VI´s clicking.
> >
> > The clicks are present on Loudspeaker as well as on "Audio Out" cinch
> > socket.
> >
> > Tnx for reading this far ;-)
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