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[TenTec] Omni VI instability, TCXO worth it?

To: tentec@contesting.com
Subject: [TenTec] Omni VI instability, TCXO worth it?
From: Peter Klein <pklein@threshinc.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Mon, 4 Jul 2016 17:14:16 -0700
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
I queried service@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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