[Elecraft] K3/0 - How to enable left side mic?

[JOE]

The manual for the K3/0 says:
"It uses its internal speaker and front headphone jack for receive 
audio, and its front
microphone connector for your mic input."

In other words you need to use the front mike connector on the K3/0.  
The mike connector on the back of the K3/0 is actually an output to the 
RemoteRig box.  This is different than the back of your K3/10 K3/100 
radio, where it is an input.  You need the special E85051 (or homemade 
equivalent) cable that connects the K3/0 "SPKRS" and "PTT IN" to the 
RRC1258 "AUX/MIC" jack. BTW, the "PTT IN" on the K3/0 is actually a PTT 
output from the K3/0 to the RRC1258.

You may be able to make a direct connection to the RRC1258 "AUX/MIC" for 
your headset.  I've never done this, but it may be possible.

The HM2 mike is an Electret that needs bias on.  Both Heils are probably 
Dynamic and need bias off.  You'll have to check the Heil literature. I 
don't know how bias is controlled in the K3/0 so I don't know how bias 
on/off woks at the K3/0 but it's worth mentioning as a possible problem.

If you are using the E850511 that came from Elecraft, there is a 
possibility of a "digital noise" problem.  The pairs used for mike audio 
are split between two pairs, causing an imbalance.  This may or may not 
show up in your K3/0.

There is also a small noise problem in the E980207 speaker cable that 
goes between the K3/0 and the RRC1258.  I fixed that with isolation 
transformers.

73, Joe, K1ike