[Elecraft] Questions about new crystals

[Parker Buckley]

Ron,

EXACTLY the info I was looking for.

Thanks!
Parker

----- Original Message -----
From: "Ron D'Eau Claire" <rondec@easystreet.com>
To: "'Parker Buckley'" <pbuckley@woh.rr.com>;
<elecraft@mailman.qth.net>
Sent: Saturday, December 14, 2002 3:54 PM
Subject: RE: [Elecraft] Questions about new crystals


> I have K2 #2636.  Now that I've ordered new crystals as
part
> of the upgrade package, please tell me once again why I'm
> doing this?!  Are these better matched than what came with
> the kit?
> ------------------
>
> Newer K2's do NOT need new crystals from what I've seen.
It all started
> because, over the years, Elecraft has discovered that the
spex on the
> crystals were not tight enough to ensure that they would
all produce the
> desired filter performance. The filters in MOST K2's were
fine, but a
> few had problems. So they have progressively tightened up
the spex.
> Those who had older K2's SOMETIMES saw an improvement by
changing the
> crystals. I had a mis-matched set for the SSB OPT1 filter
in my 2+ year
> old K2. A new set of crystals fixed that, but even then
Wayne/Eric were
> very surprised that I had a mis-matched set. By then (2
years ago) they
> thought they had replaced all of the older crystal sets.
>
> I, too, have seen a few comments about the crystals
"fixing" low gain
> situations. My K2 has always had plenty of gain, so I
can't comment on
> that. My problem was a too-narrow SSB filter (OPT1) on the
SSB module.
> Fixing that with new crystals also required me to replace
all of the CW
> filter crystals on the r-f board too, in order to have a
matched set of
> filters when I was done. Changing the crystals for the CW
filters
> changed their characteristics, but did not offer any
improvement. Nor
> was any needed.
>
> The reference that you've seen to removing a crystal has
to do the a
> recent mod to improve the stability of the K2. The K2 uses
parallel
> crystals in VXO circuits and it has been found that with
better spex on
> one crystal, one crystal can be removed. That yields
better overall
> stability. If you order the BFO/PLL stability mod from
Elecraft you will
> get the proper crystal and other parts to change that will
improve the
> stability. I THINK (check their info on the reflector)
that this only
> applies to K2 BEFORE S/N 3000. I believe that these
changes were
> incorporated in newer K2 kits. So your would probably
benefit from
> adding the BFO/PLL stability mod kit. If I recall
correctly, it'll set
> you back about $10. It's a bargain.
>
> Ron AC7AC
> K2 # 1289
>
>