Help - XFIL doesn't work

[Solosko, Robert B (Bob)-2]

Hello All,

        After building almost every option that will fit into the K2 and having everything working great the first time, I finished the KPA100 over the weekend (after getting beyond the in-line fuse problem), and in the process, broke something in the K2.

        The KPA100 checked out fine but when I installed it in the K2, nothing happened - the K2 wouldn't even turn on. Measuring my power supply voltage, it was about 1 volt when plugged into the K2, but the normal 13.6 volts when not plugged in. Opening up the K2, it was evident right away that the problem was that the internal 12V wire between the K2 and the KPA100 was pinched between the KPA100 shield and the side of the K2 and apparently shorting out somewhat (but none of the fuses were blown). Taping the wires where the shield cut through the insulation and moving the wires so the wouldn't be pinched fixed that problem and now everything seemed to be working fine (or so I thought).

        Then, on CW I tuned in a strong signal, and because there was lots of QRM, hit the XFIL to a narrower filter, and the signal al shifted up a lot in frequency and almost disappeared. It did completely disappear with a still narrower filter. Going to SSB, there were lots of signals, but none of them were intelligible. Checking the XFIL menu setting, they were all still as I had set them, so this isn't a menu problem.

        I then removed the KPA100 and the XFIL problem was still there. The next step was to see just what the filters were doing using Spectrogram. The broadest CW filter, which I had set to 1.6kHz, was more like 2.6 kHz (which explains the QRM). The other filters, which I had set to 1.0, 0.6 and 0.3 kHz were also about 30% broader and were all centered around 1.4kHz. For these filters, changing the BFO down to a setting of 0 moved them down only to about 750Hz and there was no way to get them down to 600Hz. The LSB filters were similarly messed up, with really messed up filter shapes. I adjusted them as I could. Plugging in my antenna, CW signals were a little more readable, but not much, and SSB was still unintelligible.

        So, it appears that something broke, possible as a result of the pinched 12 wire (but maybe not). Everything else besides the XFIL filters seems to work. What controls the shape and center frequency of the XTAL filters and where do I start looking for what's broken?

        Thank you for any help and suggestions that you can offer.

Bob

W1SRB
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[Darwin, Keith]

I wonder, once this gets figured out, if we'll find that having the
Rework Eliminators (so as to avoid pulling the K2 board out once it is
done) would have avoided the problem ...

Just thinking.  Enjoy it as I'm not always known to do it :-)

- Keith N1AS -

-----Original Message-----
From: Solosko, Robert B (Bob)
Sent: Monday, November 13, 2006 10:43 AM

... I finished the KPA100 over the weekend ... and in the process, broke
something in the K2.

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[Solosko, Robert B (Bob)-2]

Keith,

        I did add the Rework Eliminators when I built the K2, and it made adding all of the internal options a breeze (KDSP2, KNB2, K160RX, KSB2 and now the KPA100) - I highly recommend them when building a K2. The problem I encountered with the KPA100 was my own inattentiveness when installing the KPA100 into the K2 and not watching where the 12V power wire from the KPA100 was (it just plugs into the K2 - nothing related to the REs).

Bob

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]]On Behalf Of Darwin, Keith
Sent: Monday, November 13, 2006 2:33 PM
To: [hidden email]
Subject: RE: [Elecraft] Help - XFIL doesn't work


I wonder, once this gets figured out, if we'll find that having the
Rework Eliminators (so as to avoid pulling the K2 board out once it is
done) would have avoided the problem ...

Just thinking.  Enjoy it as I'm not always known to do it :-)

- Keith N1AS -

-----Original Message-----
From: Solosko, Robert B (Bob)
Sent: Monday, November 13, 2006 10:43 AM

... I finished the KPA100 over the weekend ... and in the process, broke
something in the K2.

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[Don Wilhelm-3]

Robert,

Did the base K2 receive OK before you added the KPA100? - note that the
KPA100 has nothing to do with the base K2 receive, but I would like to know
if it worked fine at one time in the past.

The most likely thing that would cause the filter settings to fail is a
failure of the BFO or a failure in the IF filter itself.  My vote is on the
BFO - go back to page 62 of your manual and re-do the BFO range test.  If
that is OK, then try to re-do the filter alignment using Spectrogram.
Should you notice strange results with the filter alignment, then check all
the components in the lower center portion of the schematic sheet 2 of 4 for
proper soldering and proper component placement.

The most probable cause of failure is a bad solder connection.  First thing
is to check the soldering, then re-check the soldering.  When you have
completed that, check the soldering!  Often another pair of eyes will see
something that you have overlooked numerous times - if you can find someone
else to review your work, that may prove revealing.

73,
Don W3FPR

> -----Original Message-----
>
> Then, on CW I tuned in a strong signal, and because there
> was lots of QRM, hit the XFIL to a narrower filter, and the
> signal al shifted up a lot in frequency and almost disappeared.
> It did completely disappear with a still narrower filter. Going
> to SSB, there were lots of signals, but none of them were
> intelligible. Checking the XFIL menu setting, they were all still
> as I had set them, so this isn't a menu problem.
>
> I then removed the KPA100 and the XFIL problem was still
> there. The next step was to see just what the filters were doing
> using Spectrogram. The broadest CW filter, which I had set to
> 1.6kHz, was more like 2.6 kHz (which explains the QRM). The other
> filters, which I had set to 1.0, 0.6 and 0.3 kHz were also about
> 30% broader and were all centered around 1.4kHz. For these
> filters, changing the BFO down to a setting of 0 moved them down
> only to about 750Hz and there was no way to get them down to
> 600Hz. The LSB filters were similarly messed up, with really
> messed up filter shapes. I adjusted them as I could. Plugging in
> my antenna, CW signals were a little more readable, but not much,
> and SSB was still unintelligible.
>
>

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