[Yaesu] RTTY with the 300hz filter

[Jeff Blaine AC0C]

John,

The answer to that is not easy, when you start to peel back the layers.

RTTY is 170 hz wide on paper, but in reality, the sidebands are significant. 
Extending out to 306hz wide, assuming you are capturing the 3rd which is 
generally considered the go/no go width.  The energy in the sidebands is 
important in mid to weak signal work.

I don't know what the shape of the mechanical you are referring to, but 
unless you specifically need the absolute in narrow bandwidth, the 500 is 
the way to go.  For several reasons.

You are sure to capture the signal and a good measure of it's side bands - 
meaning the signal to noise power present will offer the best chance at a 
decode (in the uncrowded band condition).

It will be much easier to tune.

And if you have a guy next to you that is really strong, his sidebands are 
going to spread over to the signal you are trying to hear and no amount of 
filtering will kill them off if the guy you are listening to is weak.

If your run into this case too many times, that's a sign that it's time to 
move up to a rig with a bit more DSP horsepower than the 857 so you can use 
the rigs DSP BPF to further tighten the BW for those few times needed.

73/jeff/ac0c


--------------------------------------------------
From: "John Geiger" <aa5jg at yahoo.com>
Sent: Friday, September 18, 2009 10:44 PM
To: <ft857 at yahoogroups.com>; <ft-857 at yahoogroups.com>; 
<ft897 at yahoogroups.com>; <yaesu at mailman.qth.net>
Subject: [Yaesu] RTTY with the 300hz filter

> Is the 300hz mechanical CW filter still wide enough to use with RTTY, or 
> would the 500hz filter work better?
>
> 73s John AA5JG
>
>
>
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