Don Well, once again you've come up trumps! I did as you suggested but have ended up finally with a 1:20 potential divider and the audio sounds much like it should do, although I feel it's not as good as it was with my TS-480HX but I am being very picky! I just got a -22dB IMD report from a DJ on 40m in a noisy band so it's at least adequate. I am (just) not showing any ALC and have set the output power control to 30W. So far I have been using LSB, now I need to set up those RTTY filters properly!
Thanks again, and have a great Christmas! 73 Stephen On 18/12/07 14:13, "Don Wilhelm" <[EMAIL PROTECTED]> wrote: > 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 >> >> >> _______________________________________________ >> Elecraft mailing list >> Post to: Elecraft@mailman.qth.net >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com >> >> >> > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
