[Lowfer] KU4XR sending QRSS-10 on 160 Meters

[JD]

Ah yes, having to achieve a level match that way sounds like a recipe for 
fuzzy audio.  Volume controls at their extreme lowest position are 
notoriously unstable with regard to the level they pass.

The R.S. isolation transformer is a good thing to have, and just a few 
resistors should be enough to do the trick (see attached).  A 33 ohm in 
parallel with the computer side of the transformer will provide a reasonable 
match so far as the sound card is concerned, since a lot of devices nowadays 
accomodate 32 ohm phones.  On the radio side of the transformer, a 560 to 
1000 ohm resistor in series with one of about 1/100th of that resistance 
would provide enough attenuation (40 dB) to get you into the ballpark for 
mic level.  You can play with R3 if you need more or less level.  An audio 
taper pot or even just a trimmer pot of 1K to 10K across the small resistor 
would give you even more adjustment range...but it probably wouldn't be a 
necessity since you have the means to adjust both the soundcard output and 
the transceiver input gain.

John 
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