[Elecraft] K2 #4913 160m issue?

[W3FPR - Don Wilhelm]

Ken,

I really can't underatand why adding only C75 to the circuit (the only
change to the VCO for 160 meters) would throw off your prior adjustments, so
you might want to look for something else.

Actually the only thing I can think of right now is the possibility that T5
is mounted a bit loose and something (your hand maybe) shifted the turns on
T5 slightly - stranger things have happened.

73,
Don W3FPR

> -----Original Message-----
>
> > Ken,
> >
> > It is the VCO - not the bandpass filters.  The VCO will stop changing
> > frequency when the voltage at the left end of R30 goes much above 7.7
> > volts
> > and becomes unstable below 1 volt.
> >
> > It would appear that you need to re-investigate the entire VCO range
> > adjustment and adjust L30 to get everything within range on all bands.
> > See
> > the VCO alignment section of the manual (page 61 in the Rev F manual).
> >
> > If you cannot get 160 meters within range C75 may be at the
> lower edge of
> > its tolerance, a small padder capacitor can often be added across C75 to
> > bring things in line.
> >
> > 73,
> > Don W3FPR
>
> Bingo! I actually woke up last night with that idea but I decided
> to wait until I heard from the list before messing around.
>
> 2000 kc was 8.89v and all my values that I had written down
> in the manual were off.
>
> I found I had to make a compromise between 2000 (7.3v) and
> 3500 (1.83v) when tweaking L30 but all the other bands were
> well in range.
>
> The only changes to the rig since I first did the VCO alignment
> are the addition of the KAT2, KIO2 and K160RX. Could adding
> the 160m module be the culprit? My guess is yes but I could
> not find anything in the 160 manual talking about re-aligning the
> VCO after installing the module.
>
> Maybe a good candidate for an errata sheet?
>
> Thanks for the help, Don!
>
> Ken
> --
>
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