[RTTY] 300hz or 500hz IF filter?

[Kai]

Hi David,
Update of my previous answer ...

For reference, the specs for the Collins 300 and 500  Hz filter used with 
FT-857D and FT-817 are at:
http://www.rockwellcollins.com/Capabilities_and_Markets/More/Precision_Manufacturing/Rockwell_Collins_Filters.aspx

The 300 Hz filter has a 3 dB BW of 300 Hz, and 6 dB BW of 330 Hz, all OK for the 
250 Hz wide RTTY signal. Be aware, as others have commented here, tuning is 
touchy!  The Collins 500 Hz filter has a 3 dB BW of 500 Hz and 6 dB BW of about 
530 Hz. Both are 7-pole filters and both have steep skirts. Both filters are 
suitable for 170 Hz shift 45.45 Baud RTTY.

As I mentioned earlier, the filter is not the only tool in your arsenal for 
reducing effect of interference in crowded bands. Try also turning off the RF 
preamp, and adding RF attenuation.

73,
Kai, KE4PT








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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