Problem With VCO Stablity

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Problem With VCO Stablity

kd1na
When I operate my K2 between 7180 and 7190 Khz the VCO seems to worble or
becomes unstable. Any other band or frequency is fine. I have removed RFC15
and replaced it with a direct wire connection then later a ferrite bead.
C91's value was increased from .001 uf to .01 uf. c*88 is still  68pf but
with the advice of Elecraft Technical support I reduced the lead length of
this component to as short as possable.  These changes seem to help reduce
the bandwidth of instablity but not totally eliminate it.

The rig works fine on all bands and puts out 10+ watts.
Any suggestions

73
Dave KD1NA

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RE: Problem With VCO Stablity

Don Wilhelm-3
Dave,

This is the old WAOF (wierd at one frequency) situation.  If you have it, it
will be found near 7167 kHz.  It is most noticible on receive but it affects
the transmitted signal too.

Reduce the lead length of everything that you can find in the general area
of the VCO and PLL - even flush cut the IC leads.

If you mounted the ICs in sockets (contrary to Elecraft's instructions),
then remove the sockets and solder in the ICs directly on the board.  Make
all leads as short as possible to minimize the leads acting like tiny
antennas.

73,
Don W3FPR

> -----Original Message-----
>
> When I operate my K2 between 7180 and 7190 Khz the VCO seems to worble or
> becomes unstable. Any other band or frequency is fine. I have
> removed RFC15
> and replaced it with a direct wire connection then later a ferrite bead.
> C91's value was increased from .001 uf to .01 uf. c*88 is still  68pf but
> with the advice of Elecraft Technical support I reduced the lead
> length of
> this component to as short as possable.  These changes seem to
> help reduce
> the bandwidth of instablity but not totally eliminate it.
>
> The rig works fine on all bands and puts out 10+ watts.
> Any suggestions
>
> 73
> Dave KD1NA
>
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