----- Original Message -----
From: "Robert & Linda McGraw (K4TAX)" <RMcGraw@Blomand.Net>
To: <johnclif@ix.netcom.com>
Sent: Friday, September 27, 2002 9:01 PM
Subject: Re: [TenTec] Omni VI calibration...
> John;
>
> I've a Omni VI+ and I use MixW software. I've not noticed any changing of
> freq during a PSK31 QSO. My Omni VI+ has the TXCO and I understand some
of
> the earlier ones had a crystal oven oscillator. Just wonder if the Omni
is
> heating up during transmit and it gets the xtal temp up higher than normal
> xtal oven temp thus the thermostat isn't effective in controlling the xtal
> freq. I'd expect a downward drift with increase temp.
>
> Just a thought.
>
> I'll watch mine a wee bit closer this evening while operating on PSK.
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message -----
> From: "John Clifford" <johnclif@ix.netcom.com>
> To: <tentec@contesting.com>
> Sent: Wednesday, September 25, 2002 4:15 PM
> Subject: [TenTec] Omni VI calibration...
>
>
> > Greetings,
> >
> > I'm sure that many of you have read the article on frequency calibration
> in
> > the latest QST. I decided to verify the calibration of my two main rigs
> > (Omni VI, Elecraft K2) to WWV and see how accurate they really were.
> >
> > Using the USB/LSB/zero beat method and MixW's spectrum display to ensure
> > both sidebands were at the same frequency, the K2 is within 20 hz
> (actually
> > 20hz above). The Omni VI is off by 10hz (above).
> >
> > But... I've noticed that, with the Omni VI, something is drifting during
> HF
> > digital mode QSOs. If I get into a PSK31 ragchew, I start sliding down
in
> > frequency. What happens is that I select the other ham's signal,
transmit
> > to him, and then when he comes back his signal is lower in frequency
than
> > mine. I have learned to 'lock' my transmit frequency in MixW so that
only
> > my receive frequency will automatically tune to the other ham's
signal...
> > hopefully this keeps my transmit signal on the same frequency. However,
> > even after locking my transmit frequency, the other ham's signal
> invariably
> > slides lower and lower down the band -- the split diamond tuning
indicator
> > ends up having the top of the diamond moving further and further to the
> > left. My rig, an Omni VI/Option 1, has the crystal oven, and this
happens
> > even if my rig has been on for an hour and I have had several QSOs to
> 'heat
> > things up.'
> >
> > Anyone else ever seen this? Anyone have any ideas as to how this can be
> > corrected? Here's another question: how certain can I be that my
> transmit
> > freq is exactly the same as my receive freq? I have a frequency
> counter...
> > I've thought of using my K2 as a reference, zerobeating my Omni to its
> > signal and measuring the K2's signal on the counter, and then measuring
> the
> > Omni's transmit signal on the counter. This should let me determine if
I
> > have a discrepancy between receive and transmit frequencies... right?
> > Anyone have a better method?
> >
> > - jgc
> >
> > John Clifford KD7KGX
> >
> > Heathkit HW-9 WARC/HFT-9/HM-9
> > Elecraft K2 #1678 /KSB2/KIO2/KBT2/KAT2/KNB2/KAF2/KPA100
> > Ten-Tec Omni VI/Opt1
> >
> > email: kd7kgx@arrl.net
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
> >
>
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