[Elecraft] Troubleshooting a weak K2 receiver

[Don Wilhelm]

Dave,

You are on the right track - you should have near 8 volts on the anodes 
of D2 and D3 during receive.  Check RFC2 with an ohmmeter - if it is 
open, request a replacement from parts at elecraft.com.  OTOH, if it shows 
a low resistance, check that both leads are properly soldered.

73,
Don W3FPR

On 8/24/2014 2:08 PM, David Doar wrote:
> Hi guys.  I could use a little help tracking down the cause of a weak receiver on my newly built K2/10.
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> 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).
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> 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?
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> 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
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> Thanks for your help,
>
>
> Dave
> WB4BIN
>
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