[Elecraft] K3 Hum on transmit

[Ron D'Eau Claire]

Let me add to Guy's excellent advice something I ran into often when
servicing shipboard radio systems. If you have a curly "stretch" cord on
your mic, they often fail somewhere inside the cord, not at the connectors.
And the failure will often be internal to the wire's insulation, so even if
you tore off the molded exterior, you'd not see the break. But, inside, the
strands of the copper wire have torn and separated. Even high quality mics
generally use very lightweight wires with only a few strands. 

Often just pulling and releasing the tension on the cord will cause the
wires to shift so they are touching again, and they will continue to work
for a while, even if the cord is stretched somewhat. 

The only way I could identify one that "fixed itself" was to work along the
cord, one loop at a time, pulling it straight and twisting it. That will
often locate the problem. But it was seldom worth it. 

Once the problem has been isolated to the mic, as it was in this case, I'd
just replace the whole cord. And be sure the soldered connections are good,
as Vic noted. 

73 Ron AC7AC

-----Original Message-----

Microphone cords, per se, can wear out faster than socks...

Always remember, tear apart your K3 DEAD LAST after EVERYTHING ELSE is
ruled out.  Most of the things we think are wrong with the transceiver are
external.  You can learn that hard or you can learn that easy.

73, Guy