[Elecraft] K3 RFI in transmitted audio

[Guy Olinger K2AV]

Hi Felipe,

>> microham is being fed from K3 12v port.
>>

This is not a good idea. Repeating W4TV's warning with a different
choice of words....

The 12V at the K3 will vary up and down according to the audio current
draw, at an audio rate.  This variation in the 12V will now modulate
anything else that uses it including audio circuits in the uHam gear.
Depending on the characteristics this could cause the transmission
from one rig to appear in the other. Even without uHam or other
utility low level audio boxes, the same thing can happen with the two
rigs if they share the same power supply. It would likely be a muddled
sounding audio crosstalk, but based upon the degree of DC filtering in
a rig or device, could be quite loud.

Always run a separate small power supply to feed uHam devices and low
level audio station utility gizmo's.  Always use separate DC power
supplies for SSB transceivers operated concurrently:  one supply per
transceiver.

You can get away with mixed supply leads on CW, but NOT on SSB.

73, Guy.