[Elecraft] K3 in WPX SSB with 2.7 roofer

[Johnny Siu]

Hello Dave,

I did have the same experience with 1.8Khz filter in the past.  However, upon the guidance of my contest elmer, I played around the IF shift.  By moving the centre position of the IF passband, you will find a sweet spot where you can hear the speech with minimal degrade but excellent selectivity.

73 Johnny VR2XMC
 

________________________________
 寄件人︰ Dave Hachadorian <k6ll.dave at gmail.com>
收件人︰ Reflector Elecraft <elecraft at mailman.qth.net> 
傳送日期︰ 2014年03月31日 (週一) 4:30 AM
主題︰ [Elecraft] K3 in WPX SSB with 2.7 roofer
  

I was in the WPX SSB contest this weekend, and wanted to try 
using just the 2.7 roofing filter, using only DSP to narrow the 
response below that.  I previously have had the feeling that the 
1.8 roofer was degrading speech intelligibility.  The WPX is a 
QRM-fest of the first order.  Everybody can work everybody, so 
the whole world is doing their own thing all the time.  15 meters 
was particularly bad, with almost nobody having a clear channel.

Using only the 2.7 filter, I never experienced a case of 
adjacent-signal AGC pumping, or any other negative issue during 
the contest.  I think if an SSB signal is so close to you that it 
is pumping your agc through the 2.7 filter, the frequency is 
hopelessly splattered anyway, and you'd best be moving on.  I did 

narrow the DSP down by using HI CUT, and usually ran it at 
LOW=0.15 and HIGH=2.25.

I could be persuaded to part with my pair of 1.8 filters, if 
someone is interested in them.

Dave Hachadorian, K6LL
Yuma, AZ


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