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
>>
>>
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