[TenTec] Omni VI instability, TCXO worth it?

[Greg S]

Soooooo...... maybe I am totally off BASE, but if the "master"  oscillator is the issue, wouldn't he be noticing the problem on all bands, with going higher in frequency getting worse?? 

73-
Greg, KC8HXO
--------------------------------------------
On Mon, 7/4/16, Peter Klein <pklein at threshinc.com> wrote:

 Subject: [TenTec] Omni VI instability, TCXO worth it?
 To: tentec at contesting.com
 Date: Monday, July 4, 2016, 8:14 PM
 
 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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