Re: 250 Hz and 400 Hz Filter Measurements

Posted by Richard Ferch on Jul 16, 2010; 2:30pm
URL: http://elecraft.85.s1.nabble.com/250-Hz-and-400-Hz-Filter-Measurements-tp5300671p5302182.html

As someone who mainly operates during CW and RTTY contests, I draw a
slightly different conclusion from Craig's and Jim's. In the absence of
a true 270 Hz roofing filter, the existing "250 Hz" filter appears to be
the best roofing filter option on offer for RTTY contest use. Therefore,
while I agree with Ed's conclusion about these two filters, of the two
the one that is unnecessary for me is the 400 Hz filter.

 From amongst the existing choices, a 500/250 combination seems most
effective for my situation. If I were more heavily into 160 CW as
compared with RTTY, I might opt for a 400/200 combination instead. For a
single roofing filter for CW/RTTY use, you might find a 400 to be the
best single-filter compromise. Different solutions for different situations.

73,
Rich VE3KI


Craig AC0DS wrote:

> I agree with you that there is no need for the 250 Hz 8 pole
> option.

Jim Brown K9YC wrote:

> Indeed, there is no good
> reason for the EXISTENCE of this particular 250 Hz filter,
> primarily because it is NOT a 250Hz filter by any reasonable
> measure.

and Ed Muns W0YK wrote:

> Accordingly, in their application as
> roofing filters for the K3, I see no reason to have both the "250" and the
> "400" in the same receiver.

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html