[Elecraft] K1 Future Improvements to VFO D3, R17, R18 any one tried??

Sun Dec 18 14:03:42 EST 2005

Hi

Don=92t get me wrong, the K1 is operating well within specs, its just =
not so
stable as the K2 or the KX1 I have in the shack. If anyone thinks theirs =
is
stable try this, feed the output of the K1 into a program that will =
allow a
waterfall display to be configured that allows about 1 hours worth of =
trace
on screen , I use a QRSS morse prog that seems to work well for this, =
use a
signal generator (I use the XG1 by Elecraft as a source). Turn on the k1
from cold and quickly tune in the signal at 7.040 for about 700Hz trace =
on
the pc. Now every 5 mins record the traces freq on the pc or just let =
the k1
run for a hour and look at the trace. After do the same test with the K2 =
or
the KX1 . I would be Very supprised if you still say the K1 has no =
drift,
one interesting thing is that the drift aways seem down in freq after =
the
first few mins, from cold the first 2-3mins produce a up drift of 10-40 =
hz
before drifting down, I find about 100Hz drift after the first 5 mins in =
one
hour. Also while doing the above test put a load on the k1 and put the =
key
down for 10 sec or so and see what happens when you go back to receive.
In practice I don=92t find it any problem at all after the first 5mins =
but
since elecraft have taken the time to print details about possible drift =
mod
im sure even they will accept that its not a defect in an individuals =
radio
but a design problem using a none DDS vfo. If you do a lot of tuning =
around
like many do in a contest and your QSO's are contest type (i.e. very =
short)
you will never notice this drift im sure! The display on the K1 still
indicates the correct freq at all times.

Regards
Paul
M0BMN

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of EricJ
Sent: 18 December 2005 17:24
To: 'Mike Morrow'; elecraft at mailman.qth.net
Subject: RE: [Elecraft] K1 Future Improvements to VFO D3, R17,R18 any =
one
tried??

I have mine set up for 80 khz and have absolutely no problems with
temperature stability. In July for the FOBB, the top of my K1 got so hot =
I
literally could not comfortably touch it. I was engrossed in the contest =
and
didn't notice the sunlight through the trees focusing on the rig. In all
that time, both heating up to sub-nuclear temperatures and cooling down =
to a
comfortable 105 degrees in the shade, the K1 sat where ever I parked =
her.

If anyone has temperature stability problems, I'd look for a defect, not =
a
design change.

Eric
KE6US
www.ke6us.com=20

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Mike Morrow
Sent: Sunday, December 18, 2005 9:13 AM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K1 Future Improvements to VFO D3, R17,R18 any =
one
tried??

Paul wrote:

>Just reading page 59 of the K1 manual and it talks about provisions for =

>improvements to the VFO temperature compensation
>
>And the use of D3, R17 and R18.
>
>Anyone tried this out and done any before and after tests.

I've heard no reports of such experiments in the five years that I've =
had a
K1 (#175) and been on this list.  Reed, K7FLY, in early 2001 reported =
some
things he did to improve temperature stability not involving any actual
circuit changes (except replacing an abnormally temperature sensitive =
VFO
votage regulator), at:

http://www.qsl.net/ve3mcf/elecraft_reflect/K1_Temperature_Freq_Drift_Mgmt=
.tx
t

My old K1 with 170 kHz VFO span (and no stability mods) is surprisingly
temperature stable, and I've not been tempted in the least to improve =
what
is already very very good.  It was recently reported that at least one =
K1
owner found VFO stability to be better with the capacitor supplied for =
the
170 kHz span than with the capacitor for the 80 kHz span.  I've never =
used
the 80 kHz option, so I can't report on a similar comparison.

73,
Mike / KK5F

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