[Elecraft] Curious -- why is KXFL3 roofing filter an option on KX3 ?

[Wayne Burdick]

Hi Phil,

The roofing filter module (KXFL3) is expensive for us to manufacture because of the extremely tight tolerances on the capacitors (0.1% in some cases). They have to be matched by hand. 

We didn't want to pass this cost on to all KX3 users, since many of them don't require the roofing filters. Even without them, the KX3's receiver performance would fall into the top 6 or so radios as measured by Sherwood Engineering (http://www.sherweng.com/table.html).

73,
Wayne
N6KR


On Apr 10, 2014, at 7:56 AM, Phil Hystad <phystad at mac.com> wrote:

> I have a curiosity question.  Why is the KXFL3 roofing filter an option on the KX3?  I mean, why is it not a built-in feature of the KX3?  First, I already own a KX3 with the KXFL3 filter so I am not asking this in order to choose to buy or not.  Caveat:  I am also a neophyte (philistine, ignorant, or troglodyte) in this sort of radio technology and still in learner mode.
> 
> But, it seems to me that the KXFL3 roofing filter is almost required with a radio as nice as the KX3.  Without it, as I understand the function, any crowded band interval like a pileup or close-in CW signals and such would render a KX3 (without the roofing filter) with less than the usual Elecraft stellar RX performance.
> 
> My guess, and this is only a wild guess, is that maybe the option leads this space open to future improved roofing filters?  Or, maybe even leave it open to a 3rd party market supplied filter (although, I think this filter is particularly different from other typical 3rd party filters).
> 
> 73, phil, K7PEH