Stephen,
I believe you may be overdriving the microphone input of the K2.
Do you have any attenuation between your soundcard output and the K2
microphone input? On the output (K2) side of the transformer connect a
series resistor about 10k in value and a 1k across the wires to the
microphone. That will drop the soundcard level down to about 1/10 of
the soundcard output and keep from overdriving the microphone input.
Reduce the 1k resistor if the soundcard still overloads the mic input of
the K2.
73,
Don W3FPR
Stephen Prior wrote:
Can anyone shed any light on this please?
I have connected tx and rx audio from/to the computer via isolation
transformers on both audio in and out. Rx works fine.
However, I have hit a problem trying to get acceptable transmit audio
quality. I have the K2 stripped back to 10W at the moment so am not using
my external KPA100 in order to remove that from the equation. I am feeding
the audio from the computer via the isolating transformer straight to the
microphone header with the microphone removed. I have turned the compressor
off in all modes. I have no ALC showing and have tried the power control in
various positions. The audio is extremely rough with various artifacts
spreading widely above and below the tx frequency.
I have the K2 feeding into a 100W Bird dummy load. I have listened both
with my K1 with a few inches of wire as an antenna and my TS-480HX in the
car parked outside. Same grotty received audio.
I have checked the carrier balance on the ssb board. Although still audible
in the K1¹s receiver I have minimised it for usb and lsb. I note that I can
eliminate it almost altogether for lsb, but then the level at usb is high.
So it¹s a compromise as I have read it would be.
I have tried both my desktop pc (a mac) and my Dell laptop (XP) - no
difference. I have listened directly to the audio output from the computers
it sounds right.
I must have used psk31 on a dozen or more radios in the last ten years or
so, but never hit this severe a problem before. Listening to my ssb speech
via the HM12 microphone, it doesn¹t sound great, but yet I am using the K1
to listen to it with so that¹s not too surprising. I don¹t use ssb at all
except mobile, so have had no operating experience of the K2 in this mode.
I am wondering if the problem lies deeper somewhere. I have googled, but
hit nothing useful.
Any thoughts would be much appreciated
Thanks and 73,
Stephen G4SJP
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