Is a K2 Realignment Advisable

[Jim Harris-4]

Hi Folks,

My K2/100 (S/N 4787) is about 10 months old.  My
question is at what point, or ever, should all the
initial alignments be repeated?  There are several
reasons for asking the question other than electronic
components simply drifting a bit with age.

1.  Recently I've noticed when it is initially turned
on the received frequency is about 100 hz high judged
by the pitch of people's voices that I know.  After
20-30 minutes they drift to near exact frequency.

2.  When initially turned on and transmitting right
away I've had reports of distortion like I'm crowding
the mike.

3.  When doing the initial alignment I had a terrible
time with zero beating due to bad hearing.  A frequncy
counter finally helped solve that to some degree.

4.  I did not use spectrogram as it seemed confusing
and my radio seemed to play well enough without it.
It is still equal to or better than my IC746Pro.

5.  Several voltages and frequency ranges were
slightly out of tolerance but again overall it seemed
to align okay and initial performance seemed okay.

6.  I'm now using the receiving antenna port and am
trying to dig out DX and other weak signals.

I just hate to fix it if it's not broke.  But, I'm
wondering if I could squeeze a little more performance
out of it.  I hate to have my K2 on the bench for 2-3
days and not be able to use it.  Well, what does
everyone say.  Go for it or not?  

Thanks for the help and bandwidth.

Jim, AB0UK
K2/100  S/N 4787

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[Don Wilhelm-3]

Jim,

The K2 does not seem to need periodic re-alignment because there is not a
lot of drift in the component values over time and the design is on the
conservative side, so it is forgiving of minor alignment errors.

BUT - If you want optimum performance, do take whatever steps necessary to
get the alignment correct  the first time and every time you do it (usually
needed when components are changed, mods added, or other work on the
hardware inside the box).

It does not sound like you achieved optimum alignment when you initially did
it, so for that reason alone, I would say you will benefit from repeating
it.

As for your voltages that are 'out of spec' - if you measured within 10% of
the value listed in the manual, that is within spec - outside that range
usually means that you need to find the source of the anomoly and correct
it.

The 100 Hz drift that you mentioned is within the K2 spec for operating from
a cold start from 25degrees C.  If your shack ambient temperature is lower
than that, you may see more drift, but judging from peoples voices can be
problematic too, better to measure it with a known standard - how much does
it drift if you tune carefully to WWV?

I highly recommend that you use Spectrogram to set your filters.  It sounds
complicated to describe it in words maily because we try to describe what to
do in detail and anticipate any questions or stumbling bolcks that may arise
for you, but once you run through the procedure, I predict that you will
find it very easy.  Waiting through the boot process for Windows and
double-clicking the icon is a harder step than running the Spectrogram
application to align a K2 - but I have done it many, many times.

73,
Don W3FPR

> -----Original Message-----
>
> My K2/100 (S/N 4787) is about 10 months old.  My
> question is at what point, or ever, should all the
> initial alignments be repeated?  There are several
> reasons for asking the question other than electronic
> components simply drifting a bit with age.
>
> 1.  Recently I've noticed when it is initially turned
> on the received frequency is about 100 hz high judged
> by the pitch of people's voices that I know.  After
> 20-30 minutes they drift to near exact frequency.
>
> 2.  When initially turned on and transmitting right
> away I've had reports of distortion like I'm crowding
> the mike.
>
> 3.  When doing the initial alignment I had a terrible
> time with zero beating due to bad hearing.  A frequncy
> counter finally helped solve that to some degree.
>
> 4.  I did not use spectrogram as it seemed confusing
> and my radio seemed to play well enough without it.
> It is still equal to or better than my IC746Pro.
>
> 5.  Several voltages and frequency ranges were
> slightly out of tolerance but again overall it seemed
> to align okay and initial performance seemed okay.
>
> 6.  I'm now using the receiving antenna port and am
> trying to dig out DX and other weak signals.
>
> I just hate to fix it if it's not broke.  But, I'm
> wondering if I could squeeze a little more performance
> out of it.  I hate to have my K2 on the bench for 2-3
> days and not be able to use it.  Well, what does
> everyone say.  Go for it or not?
>
> Thanks for the help and bandwidth.
>
> Jim, AB0UK
> K2/100  S/N 4787
>
>

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[Bill Coleman-2]

On Feb 13, 2006, at 10:33 AM, Jim Harris wrote:

> My K2/100 (S/N 4787) is about 10 months old.  My
> question is at what point, or ever, should all the
> initial alignments be repeated?  There are several
> reasons for asking the question other than electronic
> components simply drifting a bit with age.

Old tube-type rigs required this every year or so, because the heat  
aged the components. Modern components and equipment are much better  
and don't get nearly so hot.

> 1.  Recently I've noticed when it is initially turned
> on the received frequency is about 100 hz high judged
> by the pitch of people's voices that I know.  After
> 20-30 minutes they drift to near exact frequency.

I had this sort of problem before I installed the PLL and BFO  
stability mods. Your K2 may be recent enough to have come with these  
modifications.

> 2.  When initially turned on and transmitting right
> away I've had reports of distortion like I'm crowding
> the mike.

Ditto the above.

> 3.  When doing the initial alignment I had a terrible
> time with zero beating due to bad hearing.  A frequncy
> counter finally helped solve that to some degree.

The K2 is never going to be a precise frequency meter. Due to the  
nature of the tuning mechanism, it could have an error as large as 30  
Hz.  I wouldn't sweat a re-calibration unless you find it to be a kHz  
or two off.

> 4.  I did not use spectrogram as it seemed confusing
> and my radio seemed to play well enough without it.
> It is still equal to or better than my IC746Pro.

Programs like spectrogram can really help to adjust the filters  
accurately.

> I just hate to fix it if it's not broke.  But, I'm
> wondering if I could squeeze a little more performance
> out of it.  I hate to have my K2 on the bench for 2-3
> days and not be able to use it.  Well, what does
> everyone say.  Go for it or not?
>
> Thanks for the help and bandwidth.

Wait until you want to make a mod or some other change. Enjoy it in  
the meantime.


Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901

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[Ron D'Eau Claire-2]

Jim Harris wrote:

> 1.  Recently I've noticed when it is initially turned
> on the received frequency is about 100 hz high judged
> by the pitch of people's voices that I know.  After
> 20-30 minutes they drift to near exact frequency.

And Bill, AA4LR replied:

I had this sort of problem before I installed the PLL and BFO  
stability mods. Your K2 may be recent enough to have come with these  
modifications.

--------------------------------

Bill offers excellent comments and replies. I happened to turn my K2 on
early today to check WWV at 10 MHz. Within a minute of turning it on, I was
listening to WWV and the dial read 40 Hz high: 10000.04. (See below* for my
method of finding Zero Beat in SSB mode if you're curious)

A half hour later zero beat was exactly at 10000.00 kHz

I just checked it now, about 11 hours later and it's still at 10000.00 kHz

I've found that typical since adding the BFO and PLL Reference Oscillator
(L.O.) stability mods. It isn't always 10,000.00 kHz, but within 10 or 20 Hz
of the right frequency.

If you're seeing a 100 Hz shift, I suspect you're missing one or the other
of the two oscillator mods - perhaps both. The rigs varied a lot before the
changes were made.

Ron AC7AC

*SSB "Zero Beat": Tune in WWV in  either upper or lower sideband mode so it
sounds "close" then press/hold CW RV to change instantly to the other
sideband. (That button works in SSB as well as CW). If you aren't exactly on
frequency, you'll hear the pitch of the tone jump up or down. Tune in 10 Hz
steps until you hear the direction of the jump change. For example, when I
switch from L to H, I may hear the tone go up in pitch. So I increment the
frequency 10 Hz higher, then switch from L to H again. If the pitch goes
even higher, I went the wrong way, so I tune 20 Hz lower. Change from L to H
again and see if the tone goes up or down. Now it should definitely go down.
Tune down another 10 Hz and switch from L to H again. Keep this up until
suddenly the tone jumps up instead of down in pitch. That means that I just
passed the optimum tuning point. Either zero beat was the last 10 Hz point
or it's between 10 Hz points.

Note that every time I switch sidebands the SAME direction: L or low to H or
high. You can go either way, just make sure you switch back before checking
at the next frequency!

You don't have to match tones. You only need to be able to tell that the
tone shifted direction and whether it went up or down.



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