[Yaesu] RTTY with the 300hz filter

[Dave K6DLW]

When I was RTTY contesting I would use a 250Hz filter in my ICOM 765. I 
would tune in the signal using the 500Hz filter and tuning with a scope 
display and then switch in the 250Hz filter if needed to reduce QRM/QRN. I 
found it to be almost a necessity on 40 and 80 meters.

Dave K6DLW

----- Original Message ----- 
From: "Jeff Blaine AC0C" <keepwalking188 at yahoo.com>
To: "John Geiger" <aa5jg at yahoo.com>; <ft857 at yahoogroups.com>; 
<ft-857 at yahoogroups.com>; <ft897 at yahoogroups.com>; <yaesu at mailman.qth.net>
Sent: Sunday, September 20, 2009 12:12 AM
Subject: Re: [Yaesu] RTTY with the 300hz filter


> 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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