[Elecraft] 700 Hz roofing filters

[Richard Ferch]

Ken,

You wmay get a number of different answers on this, but mine would be: 
max filter width 500 Hz while tuning around, and minimum width 250 Hz. A 
normal operating setting might be 350-400 Hz. I believe your 200 Hz 
roofing filter will be too narrow to be useful for RTTY.

More importantly, I believe you should turn AFC off in MMTTY. MMTTY does 
its own filtering, so if AFC is off, changing the filter width setting 
may not make as much difference as you might have expected, but if AFC 
is on, narrow filtering will be essential to try to stop the receive 
decoder from being pulled away by nearby signals.

In AFSK, you can simply operate with AFC off and NET on all the time. 
When you are CQing, you can use RIT to copy off-frequency callers and 
embed a clear RIT command in your CQ message, the same as you would in CW.

Alternatively, when you are CQing you can turn AFC on and NET off and 
have your CQ message invoke the HAM default (MMTTY's software equivalent 
to clearing RIT); when you are S&Ping, you would turn AFC off and NET 
on. I don't know about WinTest, but N1MM Logger has settings to automate 
all of this.

73,
Rich VE3KI


G0ORH wrote:

> Doing CQ WW RTTY as a low power multi single, this weekend as first time ever on this \
> mode have WinTest es mmtty es setup for AFSK A.
>
> What is the preferred filter width min es max in these crowded bands.
> Hopefully the P3 will give me an edge squeezing in somewhere.