Is K1 re-alignment worthwhile?

[Douglas Hagerman]

I have a K1 that I built several years ago. It seems to work fine, but I am wondering if it is worthwhile going back and doing a re-alignment. Do they drift out of adjustment over time?

Thanks.

Doug, W0UHU.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

[Mike Morrow-3]

Doug wrote:

> I have a K1 that I built several years ago. It seems to work fine,
> but I am wondering if it is worthwhile going back and doing a
> re-alignment. Do they drift out of adjustment over time?

The **most** critical adjustments on every tuned circuit of the K1 filter boards are made to peak transmitter output.  These adjustments are far more critical than any for receiver performance.

This means that the first sign of a need for filter board re-alignment is the inability to obtain 6 to 7 watts output on each band when the DC supply is about 14 vdc.

If you are getting good power output on each band, then there is **nothing** to be gained for either transmit or receive performance by re-alignment.

The only problems with drifting K1 alignment occurred with very early (2001-era) KFL1-4 four-band filter boards.  The original white-body tuning-adjustment capacitors were found to drift eith temperature change, which had great effect on the KFL1-4 sharply-peaked LC-circuits.  By 2002 superior new blue-body capacitors were supplied with with new KFL1-4 kits and also made available for back-fit in existing KFL1-4 boards.  I installed the back-fit and that permanently solved the problem.

The L-tuned KFL1-2 two-band boards never had the problem, but the circuits of the KFL1-2 are not as sharp as those of the KFL1-4 either.

Mike / KK5F
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

[Don Wilhelm]

Doug,

The answer is "maybe".  If all is working fine and you have good power
output, then I would suggest 'leave it alone'.
In any case, you will only have to peak the bandpass filters on the band
board(s) very slightly with a TUNE at a power level between 1.5 and 2
watts.  Make certain it has been powered on for at least 1/2 hour before
aligning to allow things to come up to temperature.

You do not have to do the receive alignment of the bandpass filters
first unless you have changed a band on the band board.

If you have the KNB1 installed, you will want to peak its trimmer
capacitor for a maximum response in receive mode.

After aligning the bandpass filters, you can proceed to the BFO
frequency (set it to center the FL3 passband at your desired sidetone
pitch), and set the Transmit Offset to the same pitch.

You might also want to check the frequency of the VFO when the VFO knob
is turned full counterclockwise, and also do the CAL OPF to get the VFO
Display on frequency just in case the crystals on the band board have
drifted over time.

If you are having a severe receive or transmit problem, then you may
want to resort to Receive Signal Tracing or Transmit Signal Tracing to
find the troublesome stage, but that is not usually necessary except in
problem cases.

73,
Don W3FPR

On 6/3/2018 2:36 PM, Douglas Hagerman wrote:
> I have a K1 that I built several years ago. It seems to work fine, but I am wondering if it is worthwhile going back and doing a re-alignment. Do they drift out of adjustment over time?
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]