[Elecraft] Thoughts of K2 xtal prefilter

[Stewart Baker]

Hi Benny,

Thanks for your comments on the Pre-filter.
I have put my comments in between yours.

73
Stewart G3RXQ

 On Sat, 19 Mar 2005 11:53:33 +0200, Benny Aumala wrote:
>
>
> Installing prefilter IN STEAD of KNB2 gives the possibility to
> place 5dB 140 ohm attenuator on the same board in front of the prefilter.
>
>> The Pre-filter has some loss, but if absolute MDS is not a criteria, then
>> your idea may prevent some of the IMD performance being lost.
>>
> Then the 5dB pad should be temporarily taken out of function on main rf-board.
>
>> That needs to happen anyway when fitting the noise blanker.

> Installing prefilter on top of KNB2 :

>> Might cause a height problem for those fitting KPA100 in the K2 case.

> -Input of KNB2 seems to have the necessary attenuation.
> -Output can be taken from top of C6 and L2 and noise gate also
> connected here through C8. This saves the step-up coil in xtal filter.
>
>> Yes, that might work. The terminations for the mixer are rather different
>> between 5dB pad and noise blanker input. I don't know if Elecraft have
>> published IMD figures with/without the noise blanker. 

> -Original 5dB pad off in main rf-board
> -For removal, this KNB2 + prefilter unit must be replaced with a
> simple board with that 5dB pad.
>
>> KE1L has a website with 'Un-modules' which allow various K2 modules
>> to be removed while retaining signal paths etc. There is one for the KNB2
>> which would be ideal for those not having purchased a noise blanker.
>> http://w5big.home.comcast.net/K2_Un-modules.htm
>
> Benny      OH9NB
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com