RE: Help - XFIL doesn't work -problem solved

[Solosko, Robert B (Bob)-2]

Don,

        Your experience, expertise and advice does it again. Since my K2 has worked fine since I built it a year ago, I didn't think that this would be a solder problem, especially since the problem surfaced when installing the KPA100. Tom, N0SS, suggested that I re-do the BFO calibration, as you did. Re-doing the BFO range check the other day showed that the lower end of the range was above the limit by several kHz and re-setting the filters with Spectrogram didn't improve things. Then last night I resoldered all of the components used in the BFO and IF filter. Doing the BFO range check again, it was now right where it should be. Running CAL PLL and resetting the filters with Spectrogram brought my K2 back to it normal operation. So, apparently there was a marginal solder joint that was loosened by all of the moving and shaking associated with installing the KPA100. Thank you so much, and to Tom also, for your help and advise.

Bob W1SRB

PS - the Rework Eliminators again showed their value. I had to remove the DSP board to get to one of the test points, and I removed the SSB and noise blanker boards to re-solder the BFO and filter components. It took all of about 15 seconds to put the unheaders back in place of these boards so I could test the BFO and filters, both before and after the re-soldering effort.


-----Original Message-----
From: Don Wilhelm [mailto:[hidden email]]
Sent: Monday, November 13, 2006 8:32 PM
To: Solosko, Robert B (Bob); [hidden email]
Subject: RE: [Elecraft] Help - XFIL doesn't work


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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