Fw: [TenTec] Omni VI calibration...
Robert & Linda McGraw K4TAX
Fri, 27 Sep 2002 21:02:48 -0500
----- Original Message -----
From: "Robert & Linda McGraw (K4TAX)" <RMcGraw@Blomand.Net>
Sent: Friday, September 27, 2002 9:01 PM
Subject: Re: [TenTec] Omni VI calibration...
> 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
> the earlier ones had a crystal oven oscillator. Just wonder if the Omni
> 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.
> Bob, K4TAX
> ----- Original Message -----
> From: "John Clifford" <email@example.com>
> To: <firstname.lastname@example.org>
> 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
> > 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
> > 20hz above). The Omni VI is off by 10hz (above).
> > But... I've noticed that, with the Omni VI, something is drifting during
> > digital mode QSOs. If I get into a PSK31 ragchew, I start sliding down
> > frequency. What happens is that I select the other ham's signal,
> > to him, and then when he comes back his signal is lower in frequency
> > mine. I have learned to 'lock' my transmit frequency in MixW so that
> > my receive frequency will automatically tune to the other ham's
> > hopefully this keeps my transmit signal on the same frequency. However,
> > even after locking my transmit frequency, the other ham's signal
> > slides lower and lower down the band -- the split diamond tuning
> > 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
> > even if my rig has been on for an hour and I have had several QSOs to
> > 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
> > freq is exactly the same as my receive freq? I have a frequency
> > 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
> > Omni's transmit signal on the counter. This should let me determine if
> > 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: email@example.com
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