[Elecraft] K3: KRX3 question

[Joe Subich, W4TV]

> That's interesting since there isn't a 250 Hz roofing filter. 
> There's a 370 Hz and a 224 Hz, but no 250 Hz.  What did you 
> use for the 250 measurement above or is that a calculated 
> result?

"250 Hz" is the label (nominal) value for the 8-pole filter.
Still the 250 Hz recommendation was based on looking at the 
slope of filter skirts and attenuation near the edges of the 
passband of the 200 Hz fitter.  

There was also some discussion about building some custom 250 
or 300 Hz 5 pole filters for testing.  Page 9 of the K3 schematic 
package shows a "250 Hz" design that would probably be 290 Hz 
wide based on the performance of the 200 Hz filters. 

73, 

   ... Joe, W4TV 
 


> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Bill W4ZV
> Sent: Monday, July 07, 2008 6:28 PM
> To: elecraft at mailman.qth.net
> Subject: RE: [Elecraft] K3: KRX3 question
> 
> 
> 
> 
> 
> Joe Subich, W4TV-3 wrote:
> > 
> > 
> > Bill, 
> > 
> >> David you may be suggesting that "in theory" but I would pay
> >> *close attention* to what W0YK says.  Ed wins many RTTY contests 
> >> including several current world records from P49X, and results 
> >> sometimes speak louder to me than theory (and I'm an engineer 
> >> if that means anything).
> > 
> > Ed and I had an extensive off-line discussion concerning the K3 
> > filter options and RTTY.  We both made multiple measurements of 
> > the composite bandwidth (roofing filter, DSP and dual passband 
> > filter) with several settings.  The consensus is that the 200 Hz 
> > DSP settings work as long as the roofing filter is more than 250 
> > Hz wide.
> > 
> 
> That's interesting since there isn't a 250 Hz roofing filter. 
>  There's a 370
> Hz and a 224 Hz, but no 250 Hz.  What did you use for the 250 
> measurement
> above or is that a calculated result?  At any rate, I'll 
> defer to Ed since
> he's forgotten more about RTTY than I'll ever know, as his 
> contest results
> demonstrate.  ;-)
> 
> 73,  Bill
> 
> 
> -- 
> View this message in context: 
> http://www.nabble.com/K3%3A-KRX3-question-tp18280281p18328080.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> 
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft    
> 
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com