Hi Doug,

Sorry I lost your e-mail as soon as I read it, but I think I remember 
your questions.  Glad you are making some progress.   I did work the 
1A0C operation last week on 20 meter RTTY for a new country on that mode.

You will never get rid of 100 percent of the bad characters, since there 
is no error correction in RTTY, but you  can no doubt improve things. 
There is a squelch button on the control panel of MMTTY.   Be sure 
"control panel" is checked in the drop down menu.   I've never adjusted 
this, but I think you would need the Jaws cursor or whatever the WE 
method is.

There is a "SQ" option under the AFC tab in  the "setup mmtty" dropdown 
menu.   Here is a line from the help file:
**
SQ stands for squelch. The squelch controls the value that the AFC will 
accept to try to lock in. The default value is 32.

AFC SQ is not the same as the squelch on the control panel. The control 
panel squelch display controls how strong a signal must be to print. The 
AFC SQ setting controls how weak a signal the AFC will use to tune in.
**
Are you running the 590 in SSB data mode?   I think you can tighten the 
filters down a bit more this way, rather then just running in regular 
LSB mode.

I operate in FSK mode which allows  me to get the filter down for good 
copy.  You may want to try copying a station in FSK and see if you like 
it better.

Since I use FSK, I don't use the sound card for transmit, but here is 
what I remember hearing from others to prevent overdrive in AFSK:
Set power output to desired level and make your power adjustment via the 
sound card's output level settings. Do this in the sound card itself, 
not in the radio's menu, which only gives 8 or 9 level settings.   Bring 
the sound card level up to your desired output and then back it off a 
bit.  This should prevent overdrive.

73, have fun, Steve KW3A