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Re: [TenTec] frequency adj.

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] frequency adj.
From: Ken Brown <kenradiobrown@gmail.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Wed, 23 Oct 2019 15:00:55 -1000
List-post: <mailto:tentec@contesting.com>
If you really mean 0.22 Hz you should consider yourself fortunate and not
mess with it. If it is 0.22 kHz off you can make it better, but not much.
I agree with Bob that you should check it on all bands. I expect you will
find it better one some bands and worse on others.

My experience with two Omni VIs is that even when you get the BFO
frequencies as perfect as possible, say less than 1 Hz beat with a known
accurate reference synthesizer, and get the 20 MHz reference similarly
correct, the readout will still not be perfect. Off by tens of Hertz on
some bands. And this is the case even after confirming that the band select
crystal oscillators are locked to the reference.

I have found that the offset is not necessarily proportionate to the
operating frequency, which is what you would expect if only the 20 MHz
reference was slightly off and the PLL system divide by numbers were
exactly correct. My theory is that the PLL system does not have high enough
resolution divide by numbers to really get the exact correct frequency on
every band. I think Ten-Tec rounded the numbers off to make the PLL work
faster and quieter, while still maintaining the specified +/- 50 Hz

I would love to hear from someone who knows about the PLL program running
in the Omni VI, and knows what numeric values are in the ROM.


On Wed, Oct 23, 2019 at 10:25 AM dale via TenTec <tentec@contesting.com>

> Have a OMNI VI+ ,started to set up a position for the rig today and
> noticed the frequency  readout was off about .22 hz. I remember my old
> omni V  had a simple adjustment point to tweek the readout. Same on the + ?
> if so what board and location would I find it?
>  The older I get  the more I for get. 73
> dale wt4t
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