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K2: No recieve/power out on 20M thru 10M

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Marc Glade

K2: No recieve/power out on 20M thru 10M

I am the proud owner of K2 #4360. When I first put the unit together
everything checked out smoothly and there were no issues. I have since
added the KSB2, KIO2, KAT2, K160RX, KNB2, K60XV, and KAF2. No issues
appeared to arise after adding the modules. I had to set the K2 aside
for a month due to other commitments and upon returning to it about a
month ago I noticed I had no power out on any band. A quick check and
replacement of R50 solved this. Except now I noticed that on 20M thru
10M with a slight exception on 15M I still had no power out and also
that even with max AF gain the signal from a connected N-gen was
barely perceptible. 15M is a little different in that I can get a max
power out of 1.5W on that band and receive is also a little better but
not by much. On 160M thru 30M the rig functions perfectly fine. I have
tried re-aligning the bandpass filters multiple times to see if that
was were the problem was but could not resolve the issue. I have spent
hours looking over the rf board with a magnifying glass and a dmm
trying to find a fault or bad solder joint but haven't found anything.
My knowledge in this area is limited and I feel like I've run into a
brick wall with this issue. If there is anyone that has any
suggestions I eagerly await them.

Thank You,
Marc W1RSC
K2 #4360
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Don Wilhelm-3

Re: K2: No recieve/power out on 20M thru 10M

Marc,

There is nothing in the bandpass or lowpass filters that would cause good
behavior below the 10 mHz band and bad performance above that.

I suggest that one of the few things that could cause such behavior is the
VCO. Use CAL FCTR with the probe in TP1 and check the VCO frequency on
those bands. The frequencies should be close to those listed in the VCO
Table of the K2 Schematic Key (appendix B of the manual). Also, build the
RF Probe and check the VCO voltage as indicated in page 10 of the
Troubleshooting section (Appendix E).

73,
Don W3FPR
----- Original Message -----
From: "Marc Glade" <[hidden email]>
To: <[hidden email]>
Sent: Wednesday, November 10, 2004 1:23 AM
Subject: [Elecraft] K2: No recieve/power out on 20M thru 10M

>I am the proud owner of K2 #4360. When I first put the unit together
> everything checked out smoothly and there were no issues. I have since
> added the KSB2, KIO2, KAT2, K160RX, KNB2, K60XV, and KAF2. No issues
> appeared to arise after adding the modules. I had to set the K2 aside
> for a month due to other commitments and upon returning to it about a
> month ago I noticed I had no power out on any band. A quick check and
> replacement of R50 solved this. Except now I noticed that on 20M thru
> 10M with a slight exception on 15M I still had no power out and also
> that even with max AF gain the signal from a connected N-gen was
> barely perceptible. 15M is a little different in that I can get a max
> power out of 1.5W on that band and receive is also a little better but
> not by much. On 160M thru 30M the rig functions perfectly fine. I have
> tried re-aligning the bandpass filters multiple times to see if that
> was were the problem was but could not resolve the issue. I have spent
> hours looking over the rf board with a magnifying glass and a dmm
> trying to find a fault or bad solder joint but haven't found anything.
> My knowledge in this area is limited and I feel like I've run into a
> brick wall with this issue. If there is anyone that has any
> suggestions I eagerly await them.
>
> Thank You,
> Marc W1RSC
> K2 #4360
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

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Marc Glade

Re: K2: No recieve/power out on 20M thru 10M

Don,

I did both of these checks as per your recommendation, all readings
came back normal for both VCO freq and voltage.

Marc W1RSC

On Wed, 10 Nov 2004 08:11:17 -0500, W3FPR - Don Wilhelm
<[hidden email]> wrote:

> Marc,
>
> There is nothing in the bandpass or lowpass filters that would cause good
> behavior below the 10 mHz band and bad performance above that.
>
> I suggest that one of the few things that could cause such behavior is the
> VCO. Use CAL FCTR with the probe in TP1 and check the VCO frequency on
> those bands. The frequencies should be close to those listed in the VCO
> Table of the K2 Schematic Key (appendix B of the manual). Also, build the
> RF Probe and check the VCO voltage as indicated in page 10 of the
> Troubleshooting section (Appendix E).
>
> 73,
> Don W3FPR
>
>
> ----- Original Message -----
> From: "Marc Glade" <[hidden email]>
> To: <[hidden email]>
> Sent: Wednesday, November 10, 2004 1:23 AM
> Subject: [Elecraft] K2: No recieve/power out on 20M thru 10M
>
> >I am the proud owner of K2 #4360. When I first put the unit together
> > everything checked out smoothly and there were no issues. I have since
> > added the KSB2, KIO2, KAT2, K160RX, KNB2, K60XV, and KAF2. No issues
> > appeared to arise after adding the modules. I had to set the K2 aside
> > for a month due to other commitments and upon returning to it about a
> > month ago I noticed I had no power out on any band. A quick check and
> > replacement of R50 solved this. Except now I noticed that on 20M thru
> > 10M with a slight exception on 15M I still had no power out and also
> > that even with max AF gain the signal from a connected N-gen was
> > barely perceptible. 15M is a little different in that I can get a max
> > power out of 1.5W on that band and receive is also a little better but
> > not by much. On 160M thru 30M the rig functions perfectly fine. I have
> > tried re-aligning the bandpass filters multiple times to see if that
> > was were the problem was but could not resolve the issue. I have spent
> > hours looking over the rf board with a magnifying glass and a dmm
> > trying to find a fault or bad solder joint but haven't found anything.
> > My knowledge in this area is limited and I feel like I've run into a
> > brick wall with this issue. If there is anyone that has any
> > suggestions I eagerly await them.
> >
> > Thank You,
> > Marc W1RSC
> > K2 #4360
> > _______________________________________________
> > Elecraft mailing list
> > Post to: [hidden email]
> > You must be a subscriber to post to the list.
> > Subscriber Info (Addr. Change, sub, unsub etc.):
> > http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/subscribers.htm
> > Elecraft web page: http://www.elecraft.com
> >
>
>

Marc Glade

Re: K2: No recieve/power out on 20M thru 10M

In reply to this post by Don Wilhelm-3

Well, after following Tom's (N0SS) Cheap 'N Dirty Signal Tracing Guide
it would seem that the problem does fall within the band-pass filter
as injecting a signal at D6 works fine but at W6 hardly anything comes
through for the aforementioned bands. Now I'm even more confused
though as I don't see how one fault can cause issues on 20M-10M, but
leave 30M-160M unaffected. That would leave me to believe that there
are multiple faults in the band-pass filter which while possible,
strikes me as very odd since everything was originally working fine
and the now affected bands all started showing problems at the same
time.

Marc W1RSC
K2 #4360

On Wed, 10 Nov 2004 08:11:17 -0500, W3FPR - Don Wilhelm
<[hidden email]> wrote:

Don Wilhelm-3

Re: K2: No recieve/power out on 20M thru 10M

Marc,

What were you using as a signal during the 'cheap and dirty signal tracing'?
If you were using an antenna lead and off the air signals, remember that the
bands have been rather dead the last couple days - and more so on 20 meters
and up in the evenings.

Now that you have done the signal tracing (I assume in receive) and have
determined that everything from D6/D7 to the audio is working, try the
reverse using the RF probe while attempting to transmit at low power (about
2 watts) into a dummy load.

You should see some drop in level from D6/D7 through the bandpass filters,
but sufficient to measure. You can easily do a comparison from band to
band. The output of the pre-driver stage (collector of Q5) is easy to reach
on the top of the RF board - the collector is connected to the case.

It is true that there is nothing in common to all those bands in the
bandpass filters. As a totally wild guess, there might be some failure in
the T/R switch that would convert something to a low pass filter (but that
is a real stretch).
Could it be that your prior efforts misaligned the bandpass filters for
those bands while attempting to align them in receive state? You should be
able to peak the bandpass filter during transmit (TUNE or TUNE/DISPLAY) with
the RF probe on the collector of Q5.
If you can find any peak at all on the bandpass filters, it is likely to be
correct and you can rule out the bandpass filter area as the problem (or
verify that is really where the problem lies).

73,
Don W3FPR

----- Original Message -----
From: "Marc Glade" <[hidden email]>
To: "W3FPR - Don Wilhelm" <[hidden email]>
Cc: <[hidden email]>
Sent: Thursday, November 11, 2004 2:59 AM
Subject: Re: [Elecraft] K2: No recieve/power out on 20M thru 10M

> Well, after following Tom's (N0SS) Cheap 'N Dirty Signal Tracing Guide
> it would seem that the problem does fall within the band-pass filter
> as injecting a signal at D6 works fine but at W6 hardly anything comes
> through for the aforementioned bands. Now I'm even more confused
> though as I don't see how one fault can cause issues on 20M-10M, but
> leave 30M-160M unaffected. That would leave me to believe that there
> are multiple faults in the band-pass filter which while possible,
> strikes me as very odd since everything was originally working fine
> and the now affected bands all started showing problems at the same
> time.
>
> Marc W1RSC
> K2 #4360
>
>
> On Wed, 10 Nov 2004 08:11:17 -0500, W3FPR - Don Wilhelm
> <[hidden email]> wrote:
>> Marc,
>>
>> There is nothing in the bandpass or lowpass filters that would cause good
>> behavior below the 10 mHz band and bad performance above that.
>>
>> I suggest that one of the few things that could cause such behavior is
>> the
>> VCO. Use CAL FCTR with the probe in TP1 and check the VCO frequency on
>> those bands. The frequencies should be close to those listed in the VCO
>> Table of the K2 Schematic Key (appendix B of the manual). Also, build
>> the
>> RF Probe and check the VCO voltage as indicated in page 10 of the
>> Troubleshooting section (Appendix E).
>>
>> 73,
>> Don W3FPR
>>
>>
>> ----- Original Message -----
>> From: "Marc Glade" <[hidden email]>
>> To: <[hidden email]>
>> Sent: Wednesday, November 10, 2004 1:23 AM
>> Subject: [Elecraft] K2: No recieve/power out on 20M thru 10M
>>
>> >I am the proud owner of K2 #4360. When I first put the unit together
>> > everything checked out smoothly and there were no issues. I have since
>> > added the KSB2, KIO2, KAT2, K160RX, KNB2, K60XV, and KAF2. No issues
>> > appeared to arise after adding the modules. I had to set the K2 aside
>> > for a month due to other commitments and upon returning to it about a
>> > month ago I noticed I had no power out on any band. A quick check and
>> > replacement of R50 solved this. Except now I noticed that on 20M thru
>> > 10M with a slight exception on 15M I still had no power out and also
>> > that even with max AF gain the signal from a connected N-gen was
>> > barely perceptible. 15M is a little different in that I can get a max
>> > power out of 1.5W on that band and receive is also a little better but
>> > not by much. On 160M thru 30M the rig functions perfectly fine. I have
>> > tried re-aligning the bandpass filters multiple times to see if that
>> > was were the problem was but could not resolve the issue. I have spent
>> > hours looking over the rf board with a magnifying glass and a dmm
>> > trying to find a fault or bad solder joint but haven't found anything.
>> > My knowledge in this area is limited and I feel like I've run into a
>> > brick wall with this issue. If there is anyone that has any
>> > suggestions I eagerly await them.
>> >
>> > Thank You,
>> > Marc W1RSC
>> > K2 #4360
>> > _______________________________________________
>> > Elecraft mailing list
>> > Post to: [hidden email]
>> > You must be a subscriber to post to the list.
>> > Subscriber Info (Addr. Change, sub, unsub etc.):
>> > http://mailman.qth.net/mailman/listinfo/elecraft
>> > Help: http://mailman.qth.net/subscribers.htm
>> > Elecraft web page: http://www.elecraft.com
>> >
>>
>>
>

Marc Glade

Re: K2: No recieve/power out on 20M thru 10M

SOLVED!!!

First I would like to thank everyone very much who responded both on
and off the list with help and suggestions, I'm not sure how long it
would have taken me to find the problem without your support.

The problem: It all did lead to one part, K2 in the BPF. K2 was in the
SET position and would not go to RESET under any condition. The
reason, pin 10 of K2 had become grounded during the installation of
the K60XV when you have to solder the ground braid of a length of
RG174 to L4. The trace from pin 10 of K2 runs right next to this
location, and right at this spot, the trace was exposed just a little
little bit, allowing a piece of solder to bridge the gap to the braid
on the RG174. In retrospect this seems like something I should have
easily seen on visual inspection, but because the exposer of the trace
was so small and masked by a tiny excess piece of the ground braid I
did not see the connection. 5 minutes at the soldering table fixed the
problem and rig immediately started functioning like normal again.

Let me just say thanks again to everyone, this was a great learning
experience for me. It allowed me to learn procedures I hadn't done
before and made me love my Elecraft K2 that much more. I can't wait to
get started on my next Elecraft project, though I'm not sure what it
is yet. :)

Marc W1RSC
K2 #4360
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