[Elecraft] 8 or5 Pole cw filters

[Johnny Siu]

Hello Gentleman,
I am not a CW op.  To my knowledge, 8 pole will give more passive IMD and lower NPR (see page 6 of the report below by AB4OJ):
http://www.ab4oj.com/test/docs/npr_test.pdf

73
Johnny VR2XMC
      寄件人︰ Brian Hunt <huntinhmb at coastside.net>
 收件人︰ "<elecraft at mailman.qth.net>" <elecraft at mailman.qth.net> 
 傳送日期︰ 2015年01月14日 (週三) 12:27 PM
 主題︰ Re: [Elecraft] 8 or5 Pole cw filters
   
Remember that these are roofing filters and what they do is keep strong adjacent signals out of the DSP and AGC. The final selectivity is set by the DSP WIDTH control. As you ratchet down the WIDTH the appropriate roofing filter is switched in automagically. 

That said, when I bought my K3 I added a single 400 Hz 8 pole thinking that I could add others later. That was 4 years ago. 

I've been trying to decide between a 700 Hz and 1 KHz filter for a while. Turns out that on CW the NR is more effective at those BWs and 2.7 KHz is too wide a door to leave open when chasing weak signals. 

I'm a 95% CW op, contester and DX chaser. 

HTH & 73,
Brian, K0DTJ


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