[Elecraft] K2 RX not working OK

[ZarubaJr@aol.com]

Hello Chris,

Do you have an oscilloscope and signal generator available to use? That would 
make trouble shooting easier, but if you don't, here is what I would check.

40 Meter RX - Examine the pads for L25 and L26 VERY closely, with a 
magnifying glass. If you see a small black ring around the lead, that means 
there is some residue from the lead tinning process that is preventing good 
contact. Remove the leads, clean them very well, then re-install.

PREAMP - Basically, the same trouble shooting method as above, the component 
to check is T6.

I've worked on several K2's with similar troubles, and the toroid inductors 
in the low pass filter section are the first place to look for trouble. I had 
a similar problem with the K2 I own, and that was the fix for me.

If you have a scope and sig gen, set the generator for 7 MHz and inject the 
signal at the antenna connector. With the scope, verify your signal level at 
P6 pin 2. Next, look for signal at K12 pin 7, then K12 pin 8, both pads of 
L26, both pads of L25, K12 pin 3, K12 pin 4. If you have the same amplitude 
of signal to this point, then the 40 meter low pass filter is probably OK. If 
at any time you have a loss of signal, or reduced amplitude, back up to the 
last point of good signal and start verifying the components in between. If 
you follow the signal flow indicated on the schematic, you should eventually 
come to the point where your signal is lost, and that would be the area to 
check more thoroughly.

I would also recommend waiting a day or two (go to the gasthaus and sit at 
the stamtisch) before beginning the troubleshooting session, to give you a 
fresh perspective of the problem. Sometimes, we spend too much time with our 
toys, and we don't see the problems, but when we come at it after a rest, 
troubles are easier to spot.

Good Luck, and let me know how it works out. If you need more help, let me 
know.

If this does fix your K2, go to your local gasthaus and have a fine pils for 
me :)

73,

John AA2BN (ex - DA1ZJ)


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