[RTTY] 300hz or 500hz IF filter?

[Kai]

The theoretical bandwidth of 170 Hz shift 45.45 baud RTTY is just under 250 Hz.
73
Kai, KE4PT

On 8/22/2013 6:54 PM, Joe Subich, W4TV wrote:
>
> The -6 dB bandwidth of the INRAD "300 Hz" filter is shown as 340 Hz
> which is slightly less than the theoretical 370 Hz required for 170 Hz
> shift 45.45 baud RTTY.
>
> That said, performance will be a trade off between improved
> selectivity and interference rejection - up to a point.  If the
> receiver can withstand AGC effects of close in interference, a 400
> to 500 Hz filter will generally provide better copy than a 300 Hz
> filter.  Note: no amount of selectivity is useful when signals
> overlap or the interfering signal includes distortion (spurious)
> products that overlap the desired signal.
>
> 73,
>
>    ... Joe, W4TV
>
>
> On 8/22/2013 5:38 PM, David VE3VID wrote:
>> Hello everyoneI would like to outfit my FT-857D portable rig with an IF 
>> filter on its 455khz stage.  INRAD sells a suitable 500hz unit.  They also 
>> have a 300hz unit.   I am leery about the 300hz filter being too narrow.
>> Any opinions?
>> 73Davidhttp://www.ve3vid.webs.com/
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