[Elecraft] Re:K2 building problem

[Jon Perelstein]

One other possibility.
 
The symptoms you're describing sound exactly like what I was getting when I got to BFO testing on page 65.  Everything tested out perfectly (voltages, soldering, etc.) except that the frequency display was changing rapidly when I did the tests on page 65.
 
The problem turned out to be the frequency counter probe.  Although it's not emphasized in the instructions, the probe has to be built EXACTLY as shown in the manual (figure 6-14) -- especially with regard to which side of the crimp housing gets the braid and which side gets the center conductor.
 
Once I rebuilt the probe, everything tested correctly.
 
Jon
KB1QBZ


--- On Tue, 12/23/08, elecraft-request at mailman.qth.net <elecraft-request at mailman.qth.net> wrote:

Message: 12
Date: Mon, 22 Dec 2008 21:51:14 -0600
From: "Gary Auchard" <w0ebb at juno.com>
Subject: [Elecraft] K2 building problem
To: <elecraft at mailman.qth.net>
Message-ID: <8A8D929F5C4F4C63984A6003E37A36CD at GaryAPC>
Content-Type: text/plain; charset="iso-8859-1"

I've just finished the assembly of part 2 on the RF board and ran into a
BFO problem during the testing on page 65 of the manual.  All other tests have
been right on the money to this point.

When testing in the frequency counter mode the front display is changing
rapidly when using the frequency counter probe inserted in TP2.  If I tap the
Band- button the display locks in at 4.91253.  When I tap the Band+ button the
display goes back to changing rapidly.

I can measure a good solid reading at pin 6 of U11 telling me the BFO is
working and the frequency displayed is 4.91253.

I cannot get a reading for the BFO High Frequency.  I've checked L33 and
it's fine with no short caused by R116 being on top of it and has a good
continuity across the windings.

X3 and X4 are the correct crystals for that location and came from the package
marked 4.91 MHZ.

Anyone have an idea what the problem might be?

Gary Auchard - WB0MNA
K2 sn. 6506



      
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