Topband: PSK-31

[Joe Subich, K4IK]

Jim,

> I just finished a PSK31 interface from my IBM T22 to my TS850. I'm
> running my laptop sound card at full level, with a 20 dB pad at the
> data input of the radio (it's a buffered input). Shield connections 
> are to the shell of the connector, which goes straight to the
> chassis.  There's no connection to the so-called "audio ground," 
> hence no ground loop. A signal report from a local engineer looking 
> on his spectrum display is that it's clean. I haven't done IMD on it. 

Be careful when running the sound card at full output.  The amplifier 
in many cards is marginal at full output and will generate IMD and/or 
other spurious outputs before the PSK (or RTTY, MFSK, etc.) subcarrier 
even reaches the rig.  

Folks would be better served by keeping the sound card output down 
by one third to one half and using a smaller pad (ca. 10 dB).  

73, 

   ... Joe, K4IK