[TenTec] Omni VI tracking

[Ken Brown]

Hi Doug,

I want to understand how this can be. It is not making sense to me.

Here is what I know, from the Omni VI schematics, and from reason:

In SSB modes there is no change, between transmit and receive, in the 
logic states of the control lines to the BFO. The same crystal and 
trimmer capacitors are in circuit for transmit as in receive. With RIT 
and XIT turned off and operating transceive using a single "virtual VFO" 
(that is to say not in split mode) all the other oscillators should also 
be operating on the same frequency in transmit as in receive. If the 
master reference oscillator were off frequency, then the frequency 
indicated by the readout would be incorrect, yet the transmit and 
receive frequencies would be the same.

In CW mode, there is a change in the BFO between transmit and receive, 
and there is also a change in the VFO frequency, in order to accomplish 
the adjustable sidetone feature. If either of the two BFO frequencies 
used for CW TX and RX were not right, there would be an offset between a 
received signal zero beated to the sidetone, and your transmit 
frequency. Or if the BFO frequencies were perfectly adjusted, the 
sidetone frequency and the shift in the VFO would be wrong if the master 
reference oscillator was wrong.

I see how there could be an offset in CW, due to misaligned master 
reference oscillator, and I do not see how there could be an offset in SSB.

I am not denying your experience. I just do not understand it.

Ken N6KB

 

Doug Charette wrote:
> I have an Omni VI that works real well, but seems not to be tracking the
> exmit and rec frequency correctly with my RIT off. I seem to have about a
> fifty Hz difference. I am using the RIT to correct the problem, but I wonder
> if there is a simple adjustment I can make. 
>
>                    Art WA8VSJ
>
>
> Art, I just went through this with mine.  Your master reference oscillator
> needs to be realigned.  You'll need a freq. counter to do this by adjusting
> C-31 on the logic board.  Measure at connector 88.  Adjust so you see
> exactly 10 Mhz.  C-31 is located at the upper left corner of the board with
> the front of the radio facing you.
>
>
> 73,
> Doug W5GA 
>
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