Do you know if the frequency drift is real or if it is only on the digital
display? That is, if you tune in a CW signal, does the audible frequency
change by 1-2 kHz along with that shown on the display? Does the same
thing happen on 80 meters when the frequency is jumping?
The reason I ask is that your frequency problems could all be explained by
a problem with the frequency counter that runs the digital display. The
Omni D uses a fairly stable 5-5.5 MHz local oscillator that is then mixed
with band-specific crystals to produce the correct frequency. The displayed
frequency is measured separately from the oscillator and I have seen
anomalous frequency readings even though the oscillator is working
perfectly.
If you want another connection to wiggle, the jumper connecting the VFO IN
and VFO OUT jacks on the back of the radio can come loose and cause
problems.
Of course, Carl N4PY knows all of this much better than me, so I might be
way off base.
-Neil N0FN
On Mon, Jan 12, 2015 at 8:43 AM, Chris Howard w0ep <w0ep@w0ep.us> wrote:
>
> Hi,
>
> A few months ago I bought an Omni-D with power supply from an e-bay seller.
>
> I have been using it, and I enjoy it.
>
> It is exhibiting a constellation of faults which I need to repair.
>
> I would like to run them by the group to see if there is some
> common wisdom about them. It may save me some time if I can target
> my efforts.
>
> 1 - frequency drifting and jumping
> This seems to happen on both transmit and receive. Multiple bands.
>
> The amount of drift is about 1-2 kHz. It will usually drift downward
> then jump up. This happens when I am not touching any controls.
>
> 2 - frequency loss
> I have only had this happen on 80 meters. The frequency will jump
> much farther and/or the display will go to 1.0000
>
> 3 - low output
> Output while transmitting will fluctuate.
>
> All of these problems seem to go away if I let the radio warm-up for an
> extended period.
>
> My main tuning knob seems to turn easily enough, and all of the other
> controls seem to work ok. I don't notice any improvement or change
> by jiggling the bandswitch knob.
>
> My only attempt at repair, so far, has been to remove the top and bottom
> covers and re-seat all of the circuit boards I could find that had
> the pin connectors. I did that yesterday, but still experienced
> drifting/jumping afterwards.
>
>
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>
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