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

[Eric Swartz - WA6HHQ, Elecraft]

Hi George,

This is a precision matched phase I-Q filter. Its a key component of the KX3s 
excellent performance. No different than if you were ordering a precision 
crystal as we use in the K3.

These parts are matched and selected here. We can supply matched sets if they 
ever are needed. We have yet to see one fail. (The chance of failure of these 
caps is miniscule.)

73,

Eric
elecraft.com

On 4/11/2014 9:26 AM, george fritkin wrote:
> Matching 0.1% capacitors?  What kind of a design is this that requires such tolerances ?  This make maintenance almost impossible.
>   
> George, W6GF
> On Thursday, April 10, 2014 9:31 PM, Wayne Burdick <n6kr at elecraft.com> wrote:
>    
> 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
>
>
> ______________________________________________________________
> 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 georgefritkin at yahoo.com
> ______________________________________________________________
> 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 elist_copy at elecraft.com