[Elecraft] K2 - Receiver silenced

[Bill Coleman]

On 4/10/03 8:19 AM, Bill Coleman at aa4lr@arrl.net wrote:

>
>I had an odd failure of my K2 this past weekend. I had taken it camping 
>with me. While it was turned on and receiving, the S-meter slowly rose to 
>full scale, then went to zero, and I get no audio from the receiver. 
>Turning the RF gain control results in no S-meter indication.
>
>Now back home, I've done some diagnosing.
>
>I noticed that the Q2 transistor on the control board is very warm after 
>only half a minute of operation. The emitter of this transistor is at 8.4 
>volts, the base about 7 volts, but the collector is only about 3.5 volts. 
>This indicates to me that something is drawing a lot of current on the 8R 
>line.
>
>I removed all the modules until I was down to the basic K2. Still the 
>same. 8R line is about 3.5 volts, and there's no S-meter response to the 
>RF gain control. The S-meter always stays blank.
>
>The transmitter section appears to work fine.
>
>Something is happening on the 8R line. Any suggestions where I might look?

After some more troubleshooting, the problem appeared to be in the 
vicinity of U12 on the RF board.

While measuring voltage on 8R, I tapped on X6. Voltage jumped back up to 
8.4 volts.

Likely suspect is a tiny bit of desoldering junk underneath X6 is 
shorting out the pin that connects to U12 / L34. 

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901