[Elecraft] K3: R-MH2 mic problems

[Randy Moore]

I've just completed assembly of K3 #688 for a friend.  Building it was a 
joy, aside from a couple of little screw-ups of mine, and having to 
compress some turns on one torroid.  The support guys are OUTSTANDING at 
answering questions and providing solutions!!!  But they are off for the 
weekend, so I'm here asking for some help.

I have hooked up my trusty Kenwood mic that I use occasionally with my 
K2 and it works fine from the K3 front panel connector.  My friend 
bought the R-MH2 mic, so I thought I'd set it up, but I am having no 
luck.  Its like I'm getting RF feedback somehow.   I've got the menu 
entry MIC SEL set to FP.H BIAS, and the MIC gain setting set to 10 and 
CMP set to 0.  While in TEST mode (no RF), the ALC bumps up to about 5 
bars and my voice sounds more-or-less normal (I'm not used to listening 
to it) over the MON function. When I go out of TEST at 50w, my voice 
sounds very distorted and the power output indication on the K3 display 
doesn't follow my voice but seems to either go high (50w) or very low.  
Again, all of the above works just fine with my Kenwood mic.

The clincher is that if I transmit into a dummy load, the MH2 works 
fine.  Got to be RF feedback, right?  Why would it effect the MH2 and 
not my Kenwood mic?

Any suggestions?

73,
Randy, KS4L