[Elecraft] Troubleshooting a weak K2 receiver

[David Doar]

Hi guys.  I could use a little help tracking down the cause of a weak receiver on my newly built K2/10.  


All of the test and alignment procedures were satisfactory at each stage of the build. But unfortunately, when I got on the air, the receiver actually seems rather deaf.  I do hear a few signals, but rarely do they move the S-meter.  

After going through the trouble shooting section of the manual with no luck, I decided to use  the N0SS, Tom Hammond (SK) “Cheap ’N Dirty “ signal tracing method to inject a signal at the suggested  test points. I found the headphone volume drops off slightly when injecting a signal at the junction of D2 & D3, and almost totally disappears at the junction of D3 &D4. That got me checking the voltages in the T-R switch.    I found that I was only getting about 50mV at the junction of D2 and D3 (anodes). I’m also getting 0 volts at the cathode ends of D1 and D2.  Backtracking from the anodes of D2 and D3,  I get the same 50mV at RFC2.  But on the other  end of RFC2, I have the full, supplied  8 volts (receive).  


So I’m thinking that RFC2 is defective, and is the cause of the low switching voltage for the diodes.  Does it sound like I’m on the right track?






For reference, here is Tom’s “Cheap ’N Dirty Signal Tracing in the K2” article:    http://www.mmccs.com/mmarc/n0ss/k2_signal_tracing.pdf






Thanks for your help,


Dave
WB4BIN