HF distortion in audio

[OE1KBC]

Hi all,
my remote K3 with HRD via COM2 and remote Tunercontrol via COM1 is working pretty good in receive mode.
I can send up to 10-12 watt with clear audio. But over this point only extrem hiss is heard on the modulation.
A second test: When i set the K3 in tx mode and play from my internal voice recorder fine modulation up
to 100 watt is transmitted.

I set a ferrit clamp on the shielded mic/ptt cable and on the 12v power cable. nothing changed.

73 de Kurt
OE1KBC

[sm2o]

Hi

It sounds like RF-interference. Radiated RF from the antenna or probably from the antenna feeder which due to unbalance in the antenna system are radiating inside the schack, this RF are coupled back into the radio mic input.
Try with as short as possible shielded mic cables. Also try to use a separate power supply for the RRC and avoid ground loops. An RF choke on the antenna feeder preventing the RF to come into the schack is also something to think of.

73 de mike

[OE1KBC]

I found the problem by myself.
I unpluged the USB cable from the RRC-1258 - and the audio is back to normal.
When I plug the USB cable in  - the audio goes scrambled again.
Maybe the problem is, that the K3 has common MIC and PTT grouding?
I didnīt get the above problem with my second installation on the ICOM 2820.

73 de Kurt
OE1KBC

[sm2o]

OK

Good to hear that it's solved, and that you put it on the forum as a help for others also.

73 de mike