[TenTec] Omni VI instability, TCXO worth it?

[Clayton Brantley]

Peter:  my Omni VI rev 3 had the old logic board and it did require powerapplied 24/7 to maintain stability.  The Omni VI+ did not require power allthe time because of the TCXO on the later logic board.  There is a write upon the TneTec wiki page. 

If you could find a TCXO now, it would be a good upgrade but doubt thatTenTec still has them available.  I have heard that all kinds of parts went tothe landfill before the new owner arrived.  Might try to find a logic boardfrom a parted out 564 for your radio.
I still have my 564 and it will be on the desk until it (or I ) become a SK.  HI
73 Clayton N4EV


      From: Peter Klein <pklein at threshinc.com>
 To: tentec at contesting.com 
 Sent: Monday, July 4, 2016 8:14 PM
 Subject: [TenTec] Omni VI instability, TCXO worth it?
   
I queried service at tentec.com by email about the following issue last 
Tuesday. I have heard nothing so far, so I thought I'd get some advice here.

Background:  I live in the Seattle area. I have modest wire and vertical 
antennas. I'm not a contester or hard-core competitive DXer. I do try to 
work DX when I can, and I might jump into a contest to snag a new 
country. But mostly I do HF digital (PSK, Olivia, MFSK), casual CW, or 
occasionally SSB.

I've owned my Omni VI for 20 years. It has the Option 1 DSP upgrade. 
Over the years, the radio has several times developed a frequency 
instability issue. Over a time ranging between less than a second to a 
few seconds, the transceiver moves a few 10s of Hz off frequency, then 
"snaps" back. It's mostly done this on 30m, occasionally on 20m, and now 
on 40m. Lately, it happens on 40m, with a short "period," so if I am 
listening to a good, pure CW signal, it sounds like it has old-fashioned 
"chirp."

The frequency shift occurs on both transmit and receive.  When it 
happens, if I switch to another band, it does not happen there. It is 
intermittent. Sometimes it appears random, and sometimes appears 
temperature-related (for example after transmitting for a while, or if 
the radio has been just turned on in the last half-hour or so).

When it first happened (1997), Ten Tec Service advised me to tweak the 
trimmer coil to the 30m mixer crystal 1/8 to 1/4 turn in either 
direction until the "drift and snap" stopped, and just live with the 
slight display error. I did, and later did the same thing to the 40m 
coil when that band acted up. It worked in both cases.

When it started to do the frequency dance on 20m, I sent back to the 
factory for a tune-up. This was in October 2013. Now, it's doing it 
again on 40m.

I spoke to TenTec's service manager a few months ago. He said that the 
problem might be solved by installing a temperature compensated crystal 
oscillator (the TCXO was never suggested before).  He said that I could 
install this myself if I could solder a couple of wires. He quoted me a 
price of $200 to send me the necessary circuit board and instructions. 
He said it was up to me whether I wanted to spend $200 on "an older 
radio."  He was also dead-set against my tweaking the trimmer coils to 
the individual band crystals.

I decided to wait and see if leaving the power supply on 24/7 would 
solve the issue. Nope. And while I was waiting, Ten-Tec was sold and has 
new service policies.

I would like to install the TCXO, *IF* it is very likely that it will 
solve the problem, and I can get at least another couple of years of 
good service out of the radio.  On the other hand, the radio is 20 years 
old. So if it's just as likely that I will continue to have the problem, 
then maybe the TCXO isn't worth it, and I should think about a new radio.

So, what would you do if you were me?

Thanks and 73,
--Peter, KD7MW

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