[Elecraft] k2 test rx v.poor

[TF3KX]

Hello, Chris:

I have seen occasional references to low sensitivity of the K2 during
construction, and the reasons may vary.  During the ongoing construction of
my own K2 (#6425) I had similar symptoms as you have, and finally found out
that U12 was bad.  I started a thread on this on 17-March, and you may check
out if the symptoms of your unit, and the measurements, are the same as I
had.  Incidentally, I received all kinds of suggestions to cure the problem,
except the correct one - replacing U12.  So, I wonder how prone these chips
are to failing...

If you come to the point of removing U12, it may not be straightforward.  I
had  been given the advice of cutting the chip leads, and then solder each
"foot" individually out of the board.  In my case this did not work out
successfully, so finally I simply desoldered each pin using a vacuum pump as
far as I could.  When all of the pins were reasonably solder free I used
long nose pliers to loosen each foot in its hole (from the board bottom
side) while keeping the remaining solder molten with my soldering iron. 
This way I was able to loosen up all eight feet in the mounting holes and
then pull the chip out of its place.

73 - Kristinn, TF3KX  http://radio.tf3kx.googlepages.com


Chris-584 wrote:
> 
> hi im at the stage with k2 sno 6436 where i have done alignment & test
> part 2
> pll,vco,bfo, all tested ok with good ranges. vfo linearization ok, but
> next
> to no audio noise in my headphones on recive (audio side tone good and
> strong on test)
> if i send some v,low rf from my old icom on 40m i can hear it but verry
> week.rf pre amp
> makes it a little better .att kills it. if i have some low  rf at 5.915mhz
> on a wire and put it neer 
> u11 or u12 i can hear the signal verry strong. neer to q22 its week agc,
> fast/slow/off
> has no effect, could this be down to u4 on control board its out put is
> 7.55v i am
> waiting for a new one from elecraft my last 3 k2's worked like a dream i
> would
> be happy to recive any help thanks chris g0wfh
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