[Elecraft] K2 8 V switching

[Masleid, Michael A.]

Hello Oleg,

In "TX" mode voltage at "+8 V / RX" line is 0,25 Volts, not "zero".
Is it correctly? Q2, Q4 transistors in Control Board are good.
Thanks for any suggests!

As near as I can figure, Q24 should pull the RX line to 0.0 volts.
But, there is 82 ohms in series.  The AGC threshold circuit will
put about 3.8 volts onto R3 in series with D1 in series with the
base collector junction of Q12 on the control board during transmit.
This will have to be discharged through the 8R line while transmitting.
This will cause a voltage drop on the 82 ohm resistor.

So you should see about 0.24 volts on 8R depending, oddly enough,
on the AGC threshold.

73, de Michael, AB9GV