[Elecraft] New Crystals or Not

[Mike McCoy]

I just completed the xtal replacement and I can pretty much echo Pauls
observations. Not sure about the ripple but it's definately flatter,
i.e.there is less slope across the passband (previously the filter 'fell
off' about 6-8 db toward the high end). However, I now seem to have a -4
to -5 db 'notch' about 400 hz wide smack in the middle though (now two big
'ripple bumps' ? ;)  Even so it's no biggy... having an overall flatter
response across the passband is a good thing.

More importantly (at least in my case) the SSB passband is wider. The SSB
passband with the xtals I received with my kit was only about 1400-1500 hz
wide (@ -10 db) which made SSB sound umm.. 'pinched' (even after the SSB
filter mod). After installing the new matched SSB xtals it's about 2.5Khz
wide at 0 db and 1800-2K wide now @ -10 db. That improvement alone made it
worth the effort for me.

But that's not all... It's appears my problem of 'low audio' is gone. I can
only presume it's due to an increase in receiver gain. Prior to the
replacement I had to turn my audio gain pretty much fully clockwise (or use
headphones) to hear anything. Now it's about 9 o'clock to achieve the same
level.

As a point of reference my original xtals were labled ECS 4.915-0195 (K2 sn
# 2602, ordered 4/15 and finished about 5/30)

Bottom line, this retrofit certainly has my vote. While I felt the K2 was
pretty darn decent before, I now feel like I have the K2 everyone has been
raving about.

Mike - K5PU


----- Original Message -----
From: "Paul Jensen" <pj@pcrentals.com>
To: <elecraft@mailman.qth.net>
Sent: Monday, October 28, 2002 1:33 PM
Subject: Re: [Elecraft] New Crystals or Not


>
> > Has anyone who has replaced their crystals taken any before & after pics
of
> > filter shapes? They would somehow have to find their way to a web site.
> > Using spectogram, I'm not sure if I could recognize a shape that could
be
> > improved upon if I saw one. Or should I do as the tee shirt says - "just
do
> > it" and be done with it. My K2 is well over a year old.
>
> I did not take pictures before and after the crystal change out (probably
> should have) - but all I noticed was less passband ripple and a fairly
> dramatic increase in receiver gain.  Before I had the volume typically at
> 2 o'clock for average listening, now it is at almost full
> counter-clockwise at 8 o'clock.  This weekend, I could hear a cw signal
> 20 feet away even though the volume control was full off!  The agc is
> kicking in a lot more also.
>
> "Just do it"
>
> Paul Jensen
> AD5IW
>
>
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