>
> I recently purchased a used OMNI-V that exhibits a strange and
> annoying behavior. When keying the transceiver (either CW or SSB) a
> pronounced POP comes from the speaker or headphones. Subsequent dits and
> dashes in the same letter or within a very brief period of time do not cause
> the pop to reoccur. However, a pause of even a few (1-3) seconds before
This kind of thing keeps showing up on both the Omni 5 and 6 in different
forms and intensities. Understanding what goes on when the key is
activated may help. In the 5, all a.f. stages before the last af amp. chip
are suddenly muted, a st voltage is generated on the control board and fed
to the sidetone board which in turn produces a tone which feeds into the
input of the final af amp chip.
Clicks, pops and other strange noises seem to come from several sources.
Often, their pitch and amplitude will vary with the position of the pbt
knob and or the filter selected. Usually the s-meter will jump up when the
key is let up.
All of these symptoms seem to be related to ground loops, bad grounds,
strange power supply troubles and who know what else. I've spent hours
tracking them down in both rigs.
You really need to use a scope and see where the pops are originating if
at all possible. Let's record some information:
1. Does it happen when the RF gain is turned down?
2. Does it vary with the pbt tuning?
3. DOes it happen if the sidetone volume is at minimum?
4. ....when the af gain is min?
5. On certain bands?
6. Are you using an amplifier?
7. Does using the noise blanker help?
8. Does adding a ground strap to the power supply help?
Check for this factory mod:
Plastic washers between the brackets holding the sidetone board and the
chassis. This mod was done for reasons such as this (I think). There
should be only one path to ground for the ST board and that is via one of
the shields on one of the cables. Other shields should be cut off at the
connectors. This was done to eliminate ground loops.
Steve Ellington N4LQ@IGLOU.COM Louisville, Ky
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