[TenTec] Omni VI frequency error

[wa3fiy at radioadv.com]

Have you tried a master reset of the microprocessor?   I believe the offset 
between the 5 Mhz VFO and the display changes with modes, CW pitch, 
etc.    Maybe something got scrambled in the NVRAM.

Keep us posted.   (I have a wonderful Omni VI/3 here as well.  :-)

73,

-Lee-


On 4 Sep 2008 at 15:54, Steve Hunt wrote:

> I can't remember if I've raised this problem before; if I have, I apologise!
> 
> My OmniVI frequency readout is consistently 130Hz high on all bands and 
> all modes; in other words if I accurately tune in a station on 14,200KHz 
> the frequency read out will be 14,200.130.
> 
> I've adjusted all the BFO settings and the TCXO setting as accurately as 
> I can with a frequency meter whose calibration I checked against a DDS 
> source zero-beated to WWV.
> 
> Here's what's puzzling me:
> 
> 1) I'm reluctant to suspect the BFO frequencies - it's too much of a 
> coincidence that USB, LSB and CW are all out by exactly the same amount 
> in the same direction. In any case they are within 5 Hz as measured on 
> the counter.
> 
> 2) If the TCXO was out, I would expect the 5MHz VFO, the Xtal 
> frequencies, and the final LO frequency all to be out by the same 
> percentage. That would result in approximately 3 times the frequency 
> error on 10m as on 160m; but I see the same on all bands.
> 
> 3) Interestingly, I recently swapped the oven oscillator for the TCXO. 
> The same 130Hz shift was there before and after the change. Again it 
> seems too much of a coincidence that the two reference oscillators were 
> out by exactly the same amount. I needed to make a very small adjustment 
> to the TCXO to get it on 20 MHz, but that had no effect on the "offset".
> 
> I could always deliberately "misadjust" the BFO frequencies to 
> compensate, but that seems a retrograde step and would likely alter the 
> Tx audio characteristics by moving the carrier relative to the filter 
> skirts.
> 
> I can't think of anything that would produce the same offsets on all 
> bands and all modes. Am I missing something?
> 
> It's not a showstopper - just an annoyance.
> 
> 73,
> Steve G3TXQ
> 
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