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List:       elecraft
Subject:    Re: [Elecraft] KX3 Roofing Filter Question
From:       Barry <k3ndm () comcast ! net>
Date:       2018-01-30 17:49:00
Message-ID: em66708baf-84c2-40cb-828a-d3ef7330db20 () office-desktop-i
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Stan,
If you use the 8 KHz receive offset, you can not use the roofing filter; 
it is disables when you invoke the SHFT. So, having it will do you no 
good. And, that's the simple answer.

I have my KX3 set to the offset as it cleans up the spectrum display 
that I use; I've never looked into the performance difference of using 
the offset or not. I did use my KX3 for causal DX, contesting, and 
everything in between. It's a wonderful radio. I have since purchased a 
K3s, so the KX3 has been relegated to Field Day use only.

Be careful of system sensitivity specs. Most receivers are more 
sensitive than ambient conditions will allow. The .9 uV number you show 
is absolutely fine for the lower end of HF, but you could use a little 
more at the upper end. I live in an urban environment with power lines 
and neighbors with noisy TVs, heat pumps, and solar arrays. I'd be more 
than happy if I could use a sensitivity of a 1 uV on 80.

73,
Barry
K3NDM

------ Original Message ------
From: "stan levandowski" <sjl219@optonline.net>
To: Elecraft@mailman.qth.net
Sent: 1/29/2018 4:20:06 PM
Subject: [Elecraft] KX3 Roofing Filter Question

>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
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