K2 Adjustment--Use of Test Instrumentation--Alternative Procedures?

[Howard W. Ashcraft]

 

The K2 Manual, and various posts to the Elecraft website or this
reflector, provide substantial information regarding K2 adjustment, c22
calibration, filters, etc.  These generally assume that one doesn't have
access to test instrumentation beyond a DMM and the frequency counter
built into the K2.  This is laudable since it has allowed me, and many
others, to build and calibrate a K2/100 without investing in an
electronics lab.  However, I have been slowly accumulating good test
equipment to pursue various design and repair interests and will soon be
going over my K2/100 and my KX1 using these tools.  It would be helpful
to have adjustment and calibration procedures available that
alternatively assume the use of test instrumentation.  Although one can
admittedly figure a lot of this out yourself, having a procedure/check
list reduces the possibility of error.  And in some instances, the
sequence of adjustment can be significant.

Since potential purchasers might be put off by reference to "set the
spectrum analyzer to...." the alternative calibration procedures could
be available on the website with the primary calibration procedures
(those currently used) being contained in the manuals.  This would
reinforce the concept that the K2 can be successfully built with a
minimum of equipment.

Howard Ashcraft, W1WF





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[Don Wilhelm-3]

Howard and all,

I must respecfully disagree.

I have built many K2s and have aligned many others, and I can state from
that experience that the test equipment required is minimal.  The techniques
in the current manual for setting the reference oscillator, especially the
technique offered by none other than Wayne Burdick himself using CAL FCTR
and alternating between TP1 and TP2 while tuned to WWV or some other known
frequency achieves superior results.

I use an accurate frequency counter, a DMM, a 'scope, and a computer loaded
with Spectrogram to accomplish all that is required for proper K2 alignment,
and even all that is not required - I consider the DMM and the computer with
Spectrogram as essential, the rest are convenience instruments (see below).
I would not use any additional equipment for the alignment tasks even if it
were available.

I happen to have acquired a frequency counter that is accurate to 10e-9 or
better, and it does the job of setting the reference oscillator easier (I do
not measure the reference directly, but compare the CAL FCTR reading
obtained at TP1 with my external counter), but is not more accurate than
checking the difference between the VFO and BFO while tuned zero beat to the
WWV carrier - I come within 20 Hz using either method.

For adjusting the bandpass filters (in transmit mode), I use my oscilloscope
to indicate the RF voltage at the antenna jack (across my dummy load).  Used
in this manner, I am only using the 'scope only as a fast responding RF
voltmeter and it allows me to see the peak more readily - this is only a
convenience for me and not any necessity - an ordinary DMM with RF Probe or
the K2 display itself would be adequate, but would not respond as quickly,
so one would have to tune the slugs and capacitors more slowly.

For aligning the filters, I have found no better or more convenient method
than Spectrogram and the N-Gen although the N-Gen is a convenience too, most
any source of wideband noise (including 'dead band noise') would suffice
just as readily.

OK, so what do I use my array of other test equipment for?  It certainly
comes in handy when I am troubleshooting a problem.  The possibilities for
the use of various types of equipment for signal injection and signal
analysis can be quite lengthy, and must be coupled with an understanding of
what is normal and what is abnormal - one could write a lengthy book on all
the possibilities, but that is the challenge of troubleshooting in a
nutshell - one must understand not only what is to be expected, but must be
capable of interpreting what is unexpected.  This is certainly not in the
league with normal K2 alignment.

The bottom line here is that additional test equipment may make the task
quicker and easier, it will accomplish no more than the procedures outlined
on the manual and on the Elecraft website - the use of substitute equipment
and techniques should be obvious to those familiar with the use of that test
gear.  So if one is contemplating the purchase of test equipment just to
align the K2, I would say "save your money for other Elecraft goodies" - the
equipment you have already is adequate to do the task.  OTOH, if you wish to
make things a bit easier and/or get involved with in-depth troubleshooting,
additional equipment may be a big assist, but you must know how to use that
equipment (and that is another chapter entirely).  Consider your needs and
goals against your ham budget and make your decisions on that basis - a
'scope will only be an instrument to display 'pretty pictures' unless you
also gain the knowledge of how to properly interpret the waveforms shown, it
is all a learnog experience.

73,
Don W3FPR

> -----Original Message-----
>
> The K2 Manual, and various posts to the Elecraft website or this
> reflector, provide substantial information regarding K2 adjustment, c22
> calibration, filters, etc.  These generally assume that one doesn't have
> access to test instrumentation beyond a DMM and the frequency counter
> built into the K2.  This is laudable since it has allowed me, and many
> others, to build and calibrate a K2/100 without investing in an
> electronics lab.  However, I have been slowly accumulating good test
> equipment to pursue various design and repair interests and will soon be
> going over my K2/100 and my KX1 using these tools.  It would be helpful
> to have adjustment and calibration procedures available that
> alternatively assume the use of test instrumentation.  Although one can
> admittedly figure a lot of this out yourself, having a procedure/check
> list reduces the possibility of error.  And in some instances, the
> sequence of adjustment can be significant.
>
>

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[Howard W. Ashcraft]

Don, thank you for your comments.  However, if you note my original message, I did not suggest purchasing test equipment for the purpose of adjusting and aligning the K2.  I indicated that I was accumulating test equipment to pursue various design and repair interests.  I agree that one can calibrate a K2 without extensive test equipment and I have calibrated my K2/100 and my KX-1 using the techniques suggested by Elecraft, Wayne Burdick, yourself and others and by all report everything works well.  (I did use a DMM, Spectrogram and an Ngen for the K2.)

And I also agreed, in my original posting, that you can figure all of this out yourself.  However, there is a benefit to having established procedures and published measurements and tolerances.  The technicians who calibrate my tek instruments presumably know what to do, but tek publishes very detailed procedures and tolerances in their manuals anyway.  Similar information is available for other equipment and radios.  Presumably there is a value to doing so.  The issue here is not whether one can successfully calibrate a K2 or KX1 without instruments, but whether it is useful to publish calibration procedures and data for use if test equipment is available.   That is all that I was suggesting.

And there doesn't appear to be any harm in having alternative approaches.  Yes, you can calibrate the frequency of a K2 by zero beating WWV.  I was able to get within 20 hz by doing so.  But it took about 6 passes on two separate evenings.  Whether this was due to my inability to recognize a perfect zero beat, thermal drift from removing and replacing the K2/100 cover, or just general ineptitude can't be known.  However, I have seen numerous posts from others who have spent significant time trying to achieve the possible frequency resolution of the K2 and have done so only after multiple passes.  It may not be more accurate to use a frequency counter(due to the granularity of the K2 digital/analog conversion), but it is quicker.  And I suspect that I could tweak some of the circuits (the KSB2 board comes to mind) by measuring existing performance and testing several of the modifications and suggestions posted or referenced on the reflector.

Finally, I find calibration data useful for troubleshooting.  This weekend I plan to work on a Tek function generator that is "a little off" in frequency stability.  One of the first steps I will take is to run through the adjustment/calibration protocol to isolate misbehaving circuitry.

So why not publish calibration data and alternative procedures?

Anyway, thanks again for your thoughts and opinions.  I appreciate all of the effort you and others put in helping to improve the Elecraft products and to assist builders with their varied problems.

Howard Ashcraft, W1WF



-----Original Message-----
From: Don Wilhelm [mailto:[hidden email]]
Sent: Thu 11/10/2005 5:42 PM
To: Howard W. Ashcraft; [hidden email]
Subject: RE: [Elecraft] K2 Adjustment--Use of Test Instrumentation--AlternativeProcedures?
 
Howard and all,

I must respecfully disagree.

I have built many K2s and have aligned many others, and I can state from
that experience that the test equipment required is minimal.  The techniques
in the current manual for setting the reference oscillator, especially the
technique offered by none other than Wayne Burdick himself using CAL FCTR
and alternating between TP1 and TP2 while tuned to WWV or some other known
frequency achieves superior results.

I use an accurate frequency counter, a DMM, a 'scope, and a computer loaded
with Spectrogram to accomplish all that is required for proper K2 alignment,
and even all that is not required - I consider the DMM and the computer with
Spectrogram as essential, the rest are convenience instruments (see below).
I would not use any additional equipment for the alignment tasks even if it
were available.

I happen to have acquired a frequency counter that is accurate to 10e-9 or
better, and it does the job of setting the reference oscillator easier (I do
not measure the reference directly, but compare the CAL FCTR reading
obtained at TP1 with my external counter), but is not more accurate than
checking the difference between the VFO and BFO while tuned zero beat to the
WWV carrier - I come within 20 Hz using either method.

For adjusting the bandpass filters (in transmit mode), I use my oscilloscope
to indicate the RF voltage at the antenna jack (across my dummy load).  Used
in this manner, I am only using the 'scope only as a fast responding RF
voltmeter and it allows me to see the peak more readily - this is only a
convenience for me and not any necessity - an ordinary DMM with RF Probe or
the K2 display itself would be adequate, but would not respond as quickly,
so one would have to tune the slugs and capacitors more slowly.

For aligning the filters, I have found no better or more convenient method
than Spectrogram and the N-Gen although the N-Gen is a convenience too, most
any source of wideband noise (including 'dead band noise') would suffice
just as readily.

OK, so what do I use my array of other test equipment for?  It certainly
comes in handy when I am troubleshooting a problem.  The possibilities for
the use of various types of equipment for signal injection and signal
analysis can be quite lengthy, and must be coupled with an understanding of
what is normal and what is abnormal - one could write a lengthy book on all
the possibilities, but that is the challenge of troubleshooting in a
nutshell - one must understand not only what is to be expected, but must be
capable of interpreting what is unexpected.  This is certainly not in the
league with normal K2 alignment.

The bottom line here is that additional test equipment may make the task
quicker and easier, it will accomplish no more than the procedures outlined
on the manual and on the Elecraft website - the use of substitute equipment
and techniques should be obvious to those familiar with the use of that test
gear.  So if one is contemplating the purchase of test equipment just to
align the K2, I would say "save your money for other Elecraft goodies" - the
equipment you have already is adequate to do the task.  OTOH, if you wish to
make things a bit easier and/or get involved with in-depth troubleshooting,
additional equipment may be a big assist, but you must know how to use that
equipment (and that is another chapter entirely).  Consider your needs and
goals against your ham budget and make your decisions on that basis - a
'scope will only be an instrument to display 'pretty pictures' unless you
also gain the knowledge of how to properly interpret the waveforms shown, it
is all a learnog experience.

73,
Don W3FPR

> -----Original Message-----
>
> The K2 Manual, and various posts to the Elecraft website or this
> reflector, provide substantial information regarding K2 adjustment, c22
> calibration, filters, etc.  These generally assume that one doesn't have
> access to test instrumentation beyond a DMM and the frequency counter
> built into the K2.  This is laudable since it has allowed me, and many
> others, to build and calibrate a K2/100 without investing in an
> electronics lab.  However, I have been slowly accumulating good test
> equipment to pursue various design and repair interests and will soon be
> going over my K2/100 and my KX1 using these tools.  It would be helpful
> to have adjustment and calibration procedures available that
> alternatively assume the use of test instrumentation.  Although one can
> admittedly figure a lot of this out yourself, having a procedure/check
> list reduces the possibility of error.  And in some instances, the
> sequence of adjustment can be significant.
>
>

*****************************
This communication, including any attachments, is confidential and may be protected by privilege.  If you are not the intended recipient, any use, dissemination, distribution, or copying of this communication is strictly prohibited.  If you have received this communication in error, please immediately notify the sender by telephone or email, and permanently delete all copies, electronic or other, you may have.

To ensure compliance with requirements imposed by the IRS, we inform you that any tax advice contained in this communication (including any attachments) was not intended or written to be used, and cannot be used, for the purpose of (i) avoiding penalties under the Internal Revenue Code or (ii) promoting, marketing or recommending to another party any transaction or matter addressed herein.

The foregoing applies even if this notice is imbedded in a message that is forwarded or attached.
*****************************

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[Rob Locher W7GH]

[Howard's well-reasoned argument snipped...]

> So why not publish calibration data and alternative procedures?
>
> Anyway, thanks again for your thoughts and opinions.  I appreciate all  
> of the effort you and others put in helping to improve the Elecraft  
> products and to assist builders with their varied problems.
>
> Howard Ashcraft, W1WF


Publishing technical data costs money.  Presumably several technicians at
Elecraft and elsewhere have their own notes which could be used as the
basis for the documentation you would like to see.  However, if Elecraft
were to officially publish them, the notes would have to be typed up,
checked for accuracy, made complete, and put on the web.  Perhaps there
would need to be different measurements for different circuit board
revisions in some places.  Elecraft would then be responsible for
publishing errata and other updates.

In short, you are asking Elecraft to spend a significant amount of money
to benefit a small group of users, when an alternative already exists.
Personally, I would rather see them concentrate on keeping the price of
their products as affordable as possible.

Perhaps interested individuals such as yourself could publish your
alternative procedures and measurements on the web.  Then those that were
interested, including perhaps people connected with Elecraft, could
collaborate to make the data as accurate and robust as possible.

I am not affiliated with Elecraft, except as a satisfied customer.

73,
- Rob KE7EAG

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[Nick Waterman]

Howard W. Ashcraft wrote:
> (I did use a DMM, Spectrogram and an Ngen for the K2.)

Sort of similar question... If I'm starting with almost zero test
equipment, and want to build a K2, what's most useful...

* DMM - presumably better than the K2's built-in one?
   may also help check capacitor and resistor values etc?
* NGEN - sounds useful for testing filters?
* DL1 - quite difficult to test transmitting without a dummy load, no?
* XG1 - for calibrating the s-meter?
* Something else I've not thought of?

--
"Nosey" Nick Waterman, G7RZQ, Senior Sysadmin.
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