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

[m0bmn]

Hi Gang

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 would be most interested to see if it made any difference, if no one as
tried it anyone know a reason why not to try it or I will

Have a play

 

All the best

Paul

M0BMN

 


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[Mike Morrow-3]

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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[EricJ-2]

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

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Mike Morrow
Sent: Sunday, December 18, 2005 9:13 AM
To: [hidden email]
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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[m0bmn]

Hi

Don’t 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’t 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: [hidden email]
[mailto:[hidden email]] On Behalf Of EricJ
Sent: 18 December 2005 17:24
To: 'Mike Morrow'; [hidden email]
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

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Mike Morrow
Sent: Sunday, December 18, 2005 9:13 AM
To: [hidden email]
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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[Don Wilhelm-3]

Paul,

I would not regard 100 Hz of drift in the K1 as a design problem at all -
The K1 spec is for drift less that 200 Hz after a 5 minute warmup.

The fact that the K1 does not use a DDS vfo is not a 'design problem' as was
stated, but surely was a design decision based on price/performance with
components available at the time it was designed.  At the time the K1 was
designed, DDS units were not as available as today and were still quite
pricy - by the time the KX1 was designed, the cost of DDS had dropped
significantly.  I fail to understand how anyone could refer to this a
'design problem'.

73,
Don W3FPR

> -----Original Message-----
...snip... 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
> > possible drift modhour. 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’t find it any problem at all after the first 5mins but
> since elecraft have taken the time to print details about
> 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
>
>

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