Don W. W3FPR
> -----Original Message-----
>
> Hi Don and All
>
> I have used this method on 3 or 4 of the K2's I have built. I use
> a 1pF or
> 2pF NPO cap to lower the bottom end of the range to get it to
> meet the spec.
> I agree with you on pulling the crystal much with this method. I
> would not
> recommend cap values above maybe 3 or 4 pF. I have never needed
> more than 1
> pf. Padding C173 and C174 is a better method if the radio needs
> more than 1
> or 2 pf. I believe this method was suggested by Gary at Elecraft
> some time
> back. At any rate it is a little easier to do than the padding or
> change out
> of C174 and C173
>
>
> The other Don
>
> Don Brown
> KD5NDB
>
>
>
> ----- Original Message -----
> From: "Don Wilhelm" <
[hidden email]>
> To: <
[hidden email]>; <
[hidden email]>; <
[hidden email]>
> Sent: Thursday, December 08, 2005 5:03 PM
> Subject: RE: RE: [Elecraft] K2 BFO Test
>
>
> > Sverre,
> >
> > I have not tried that small capacitor from the junction of the crystals
> > and
> > L33 so I cannot comment on it from that standpoint.
> >
> > What I would like to state is that when one pulls a crystal by
> any method,
> > the stability becomes worse as the amount of pulling becomes
> greater. One
> > should be aware of this and related facts when modifying any
> circuit in a
> > way that is not 'approved and tested'. Also due to the nature of
> > crystals,
> > something that happens to work in one situation may not work
> the same for
> > all cases. Remember that I am only bringing up cautions here, I am not
> > makeing a firm statement about the operation one way or another.
> >
> > It certainly would be nice if someone (or better yet, several someones)
> > with
> > access to suitable instrumentation could try this or any other mod and
> > report the results. The fact that it worked on a sample of one does not
> > create a statement that it will work in other cases - that is simple
> > statistical knowledge - I would like to see something that says
> it works
> > in
> > at least 5 or 10 trials before drawing any firm conclusions.
> >
> > So, yes I think it should be left on your website, but you may
> want to put
> > a
> > "Use at your own peril" disclaimer on all those that are not
> 'approved by
> > Elecraft' or otherwise adequately tested (and I invite you to
> add any of
> > my
> > mods to that group as well, even though I have absolute
> confidence in my
> > own
> > work).
> >
> > 73,
> > Don W3FPR
> >
> > > -----Original Message-----
> > > >
> > > > The preferred method of padding the BFO capacitors is to
> > > > maintain the ratio between C173 and C174 by paralleling them
> > > > with capacitors. A single capacitor from the junction to
> > > > ground will be in parallel with the series combination of
> > > > C173 and the varactor D38 and could make the BFO less stable
> > > > than it should be.
> > > >
> > >
> > > Don,
> > >
> > > How about a single capacitor (1-4 pF) from the junction of the
> > > crystals and
> > > the L33 inductor as in
> > >
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