[Elecraft] Mic Audio Problems with K3 and DXD

[Donald Butler]

This query goes to anyone out there who might be using a K3 with a TopTen DX Doubler.

 

I recently got my new K3, and now have it and an FT1000MP connected to a DXD in a SO2R setup, using prefabricated cables purchased from TopTen, and a Heil Proset plus headset.  All is well with the MP, which has worked fine with the DXD for several months.  On the K3, ptt, key and earphones all work fine, but I'm having trouble with a  strange rumbly, gravelly hash and feedback on transmit with the mic  (also in test mode).   The mic works fine when connected directly to the K3.  It also works fine to the MP through the DX Doubler, but when I connect the mic to the DXD and then to the K3 via the cable I get hash and a rumbling windy sounding feedback, even with the monitor off.  There is no hum on keydown when I do not speak.   It's also clean when I whistle into the mic, but when I speak I get the hash and rumbling.  I've confirmed its presence with on air testing.  I've tried front and back mic connections on the K3. and both high and low mic gain settings on the menu. Bias is off.  I've also tried adjusting TX EQ on the config menu.  Again, it's perfect when connected directly to the radio, but bad when cabled through the DXD.   I get identical hash on the K3 whether I'm connected to Radio 1 or Radio 2 connectors on the DXD . and the MP works fine on both.

 

It would seem that the problem must be in the cable connecting DXD to K3, but the cable seems to check out OK.  It has good continuity on all pins and all are isolated from one another except the common shield which is as it should be.  I did note that the mic ground lead is not a shield, but just another wire inside the main cable?  I added a shielded mic line with isolated shield to rule that out as a problem resulting in no change.

 

Has anyone else experienced similar problems?   If so, any suggestions?

 

Thanks

 

Don, N5LZ
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