K2 not able to receive WWV & other signal problems

[NQ3RP]

Well after finishing the set up of my K2 I thought I'd give it a work out.  I put it on 40 meters and started listening to some code-great.  Or so I thought until I switched filters - nothing on FL2-4. Then I got to checking more.  Seems like the CW was present on some parts of the band and not on other parts.  Also a CW signal is over a 5Khz area and NEVER changes tone - just there and then later just gone.  That just doesn't sound right.

So maybe I should check calibrations again.   Hmm.. Back to the 4 mhz oscillator and let's try WWV at 10 Mz.  This is when I noticed something else really strange.  No WWV signal or it is very low even with audio and rf gain all the way up but couldn't be sure .  I just notice some bumm-bumm-bumm, like nothing at all, not the normal tones.   Set C22 back to the default location get out a signal generator and set it at 10 Mhz - nothing heard.  Set it to 10.06 and tune the K2 - hey I can zero beat it there.  The minute I try to go below 10.05 on the K2 to zero beat a generator signal set somewhere below 10.05 - it's like the K2 is on some other band or part of the 30M band.  If I come up from the bottom it does the same thing at 9995.0 is ok to zero beat but anything between  9995 and 10.05 is out in la-la land.  Appears it's happening on all the bands at various places.

I'm at a loss as to what is going on and what might be wrong.  I've checked the receive circuits and tuned them and they seem to work.  Parts of each band work on CW and SSB (no ssb module  at this time but can hear conversions).  But parts of each band seem to do this act of going to some other place and it usually happens around a 5Khz display (like 7105-7115, 9995-1005, etc.)  Any ideas on what is screwed up or where to look??

[Don Wilhelm-4]

First step - go back and check the R30 voltages when tuned to 4000 kHz
and then when tuned to 7000 kHz
At 4000 it should be close to 6 volts, and when at 7000, the voltage
should be above 1.5 - if you have installed the re-work eliminators or
the wiring for the K60XV installation, you will have problems with the
7000 kHz point unless you set D19 = y in the secondary menu.

After doing that, switch to 40 meters, put the counter probe in TP1 -
make certain you have the bottom plate in place with all screws used.
Then run CAL PLL.

You should have smooth tuning, but not necessarily at precisely the
correct frequency - it may be off by no more than 1 kHz., which will
enable you to tune to 10 MHz WWV (use SSB and use Spectrogram to tell
you when the audio tones you hear in the K2 are correct.  There is a
1000 Hz tone every minute and the normal tones alternate between 500 and
600 Hz.

After that is successful, go to the K2 Dial Calibration article on my
website www.w3fpr.com and set C22 correctly using the N6KR method.
Then re-run CAL PLL and set up the filters as described in that article
using Spectrogram (download Spectrogram 5 from Tom Hammond's website
www.n0ss.net).

You should then have good frequency accuracy (within 20 or 30 Hz) and
the filters should be set up properly.

73,
Don W3FPR

NQ3RP wrote:

> Well after finishing the set up of my K2 I thought I'd give it a work out.  I
> put it on 40 meters and started listening to some code-great.  Or so I
> thought until I switched filters - nothing on FL2-4. Then I got to checking
> more.  Seems like the CW was present on some parts of the band and not on
> other parts.  Also a CW signal is over a 5Khz area and NEVER changes tone -
> just there and then later just gone.  That just doesn't sound right.
>
> So maybe I should check calibrations again.   Hmm.. Back to the 4 mhz
> oscillator and let's try WWV at 10 Mz.  This is when I noticed something
> else really strange.  No WWV signal or it is very low even with audio and rf
> gain all the way up but couldn't be sure .  I just notice some
> bumm-bumm-bumm, like nothing at all, not the normal tones.   Set C22 back to
> the default location get out a signal generator and set it at 10 Mhz -
> nothing heard.  Set it to 10.06 and tune the K2 - hey I can zero beat it
> there.  The minute I try to go below 10.05 on the K2 to zero beat a
> generator signal set somewhere below 10.05 - it's like the K2 is on some
> other band or part of the 30M band.  If I come up from the bottom it does
> the same thing at 9995.0 is ok to zero beat but anything between  9995 and
> 10.05 is out in la-la land.  Appears it's happening on all the bands at
> various places.
>
> I'm at a loss as to what is going on and what might be wrong.  I've checked
> the receive circuits and tuned them and they seem to work.  Parts of each
> band work on CW and SSB (no ssb module  at this time but can hear
> conversions).  But parts of each band seem to do this act of going to some
> other place and it usually happens around a 5Khz display (like 7105-7115,
> 9995-1005, etc.)  Any ideas on what is screwed up or where to look??
>  

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[NQ3RP]

Just a post to tell you about the resolution of my K2 not hearing WWV and other receiver problems.  I was in e-mail contact with Don and after going through what was going on with the BFO and VFO, he suggested checking the voltages on U5 pin 7 and there was no voltage there when doing PLL.  Which was strange because I did get a Band plus reading and a - Band reading on the PLL span test.  So we went back to check U5 pins 1,2,3 to U6 on CB.  No continuity from U6 pin 24 to U5 pin 2.  I checked the soldering then pulled U6.  Pin 24 was bent over and not making contact.  

I then used Spectrogram to set C22 on WWV, did the PLL linearization in about 4.5 minutes, and set the filters with Spectrogram also.  I think this K2 is the hottest of the 3 I've built.

So I just want to thank Don for sticking in there, giving insight into how the circuitry works and suggesting the simple things I over looked (like checking signal continuity!).  Now on to the SSB and noise blanker.

Don, you're da MAN!!

73's
John
NQ3RP