[Elecraft] K2 Troubleshooting

[Ron McCurdy]

My reason for troubleshooting is there is NO SOUND.  I can hear the sidetone
when I turn it on.  I cannot hear the 7000hz tone.

 

1.   My reference oscillator output is 0.511.a little low.

2.   VCO output is okay.

3.   BFO output is okay.

4.   Mixer, I.F. amplifier, & Crystal filter = 0.00 vdc.

 

So, I started with the control board.  U1 voltages are okay.  U3 voltages
are okay.  U4 is a little low at 7.80 vdc.  U5 is perfect. U6-U10 are okay.
The problems:

 

1.   U2 voltages are around 3.27 vdc instead of 6.9 vdc  input voltage is
7.80 on pin 8.

 

I didn't want to move on to the RF board without finding the problem with
the Control Board.  Do you have any suggestions for finding where the U2
voltages are dropping off.

 

When I adjusted the AGC in step 5 page 48, I was only able to get 3.71 vdc.

 

Ron, KE5QDA

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