[Elecraft] K3 160M Diversity Users

[Joe Subich, W4TV]

> The 8 poles probably have a better shape factor than the 5 
> poles, judging by my experience comparing the 5 pole stock 
> Kenwood filters with the 8 pole IRC replacements in my old 
> TS850.  With the DSP, I'm not sure you'd notice the 
> difference but as you see I went for the better filters and 
> don't regret it.

The 8-pole filters do have significantly better shape factor 
but mostly at the lowest levels on the filter skirts.  For 
the most part you will never see the difference as the DSP 
has an almost rectangular response.  

You're not likely to see any real difference between the 500 Hz 
5-pole and 400 Hz 8-pole filters in practice.  I've measured the 
-6dB bandwidth of the 500 Hz 5-pole filters in both of my radios 
at just under 500 Hz and the -30 dB bandwidth at about 760 Hz.  
This compares to the published data of 435 Hz @ -6dB and 650 Hz 
@ -30 dB for the 400 Hz 8-pole filters - see: 
www.elecraft.com/K3/K3_8_pole_plots.htm or 
www.inrad.net/product.php?productid=150&cat=140&page=1 

73, 

   ... Joe, W4TV 
 




> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Gary Hinson
> Sent: Saturday, July 25, 2009 1:43 AM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] K3 160M Diversity Users
> 
> 
> > I am about to order filters for the K3 and need some final
> > advice.  
> 
> Hi Mike.
> 
> I have a pair of 400Hz and a pair of 250Hz 8 poles in my K3.  
> I'm pretty active, 99% CW, and rarely use the 400Hz (maybe 
> once a day) and very rarely the 250Hz (once a week).  The DSP 
> works extremely well. So of these, I'd recommend the 400Hz, 
> and save up for the 250's later if you decide you need even 
> narrower bandwidth than the 400+DSP can achieve.  
> 
> The 8 poles probably have a better shape factor than the 5 
> poles, judging by my experience comparing the 5 pole stock 
> Kenwood filters with the 8 pole IRC replacements in my old 
> TS850.  With the DSP, I'm not sure you'd notice the 
> difference but as you see I went for the better filters and 
> don't regret it.
> 
> On extremely rare occasions (e.g. fishing out CW callers in 
> SSB QRM from Indonesian pirates) I have wound the filters 
> right down to the minimum 50Hz and even at that ridiculously 
> narrow setting, the K3 is a joy to copy with no appreciable 
> ringing - miles better than the TS850
> and indeed any other rig I've tried.   
> 
> I also use diversity with a 30m fullwave loop.  Works great!
> 
> I'm thinking of getting the AM and/or FM filters next so I 
> can open up the bandwidth to listen to a whole chunk of band 
> at once using an AF spectrum program: it sometimes helps to 
> listen to all the callers in a pileup and to choose a clear 
> slot to call.
> 
> 73,
> Gary  ZL2iFB
> 
> 
> 
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