[Elecraft] KX3 Roofing Filter Question

[Bob McGraw K4TAX]

In general, filters have little to do with sensitivity.   On the other 
hand, filters do provide selectivity.   In crowded band conditions where 
one is attempting to dig out a weak signal among stronger signals, the 
roofing reduces the likelihood that the stronger signal will impact the 
overall AGC, thus diminishing the apparent strength of the weaker signal.

Otherwise, the added roofing filter certainly can't diminish the 
receiver performance but may, under certain conditions, enhance receiver 
performance.

Conclusion:   buy it!

73

Bob, K4TAX


On 1/29/2018 3:20 PM, stan levandowski wrote:
> I am going to order another KX3 this week. Probably tomorrow.  The 
> last one I ordered in 2012 did not have the roofing filter option and 
> I do not THINK I missed it.
>
> I use ONLY CW and I do NOT contest.  I like to CASUALLY chase DX and I 
> play in low stress sprints like NAQCC but mostly I just like to RAG CHEW.
>
>
> My antenna is an EFHW installed as a "half square" in trees at 30 feet 
> (MyAntennas 4010).
>
>
> I have reviewed the Elecraft site notes, and done a fair amount of 
> Googling and I now am more confused than ever.  It seems that the real 
> value lies in dealing with strong signals, crowded bands and ferocious 
> contesting conditions.
>
>
> My bottom line question is this:  If I DO NOT get the roofing filter 
> option will my KX3 receiver be LESS SENSITIVE?  The Sherwood report 
> shows a pre-amp off sensitivity of .9 uv which improves to a very 
> impressive .09 with the preamp on.  Is this somehow related to the 
> roofing filter?
>
>
> I am especially concerned because I remember doing an A/B comparison 
> on a weak signal between my previous KX3 and my 55 year old Drake 2B 
> and the 2B beat the crap out of the factory built KX3.  I can't help 
> wondering if the roofing filter I didn't buy in 2012 had something to 
> do with this.
>
>
> I sure could use a real simple answer:  buy it or don't buy it? CW 
> sensitivity is my ultimate goal because if I can't hear 'em I can't 
> work 'em.
>
>
> Thanks and 73,
> Stan WB2LQF
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to rmcgraw at blomand.net