K2: KAF2 Versus 2.2 kHz KSB2

[Linden, Mike (BRC-Hes)]

  I plan on building my KSB2 to KI6WX's 2.2 kHz crystal filter bandwidth
specifications (which is now the current Elecraft bandwidth). Should I shift
the KAF2's low-pass filter roll-off higher in frequency when I build it to
account for the increased bandwidth of the KSB2, or will the low-pass
roll-off be adequate as is?

  Thanks, Michael N9BDF
  K2 #4137


PS  The "Amateur Radio Emergency Communications Consistency Act" (HR 1478)
and the "Amateur Radio Spectrum Protection Act" (HR 713 & S. 537) are in
Congress. Please contact your Congressmen to ask for their support of these
bills! See the following ARRL link for details:
http://www.arrl.org/govrelations/ <http://www.arrl.org/govrelations/>


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[Don Wilhelm-2]

Michael,

I am using the 2.2 kHz filter on my KSB2 with the KAF2 and have noticed no
problems with the low pass filter.  There is a very slight difference in the
upper end of the audio when I measure the filters with Spectrogram (KAF2 in
vs. KAF2 removed), but it is not enough to cause me any concern and may even
be an advantage in actual on-the-air listening because it cuts some of the
high frequency hiss without reducing intelligibility.

73,
Don W3FPR

----- Original Message -----

>   I plan on building my KSB2 to KI6WX's 2.2 kHz crystal filter bandwidth
> specifications (which is now the current Elecraft bandwidth). Should I
shift
> the KAF2's low-pass filter roll-off higher in frequency when I build it to
> account for the increased bandwidth of the KSB2, or will the low-pass
> roll-off be adequate as is?
>


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[John, KI6WX]

The KAF2 actually starts rolling off about 1 kHz.  This is nice for reducing
the background hiss, but you do need to remove the KAF2 if you want to use
Spectrogram to measure crystal filter frequency response.
-John
 KI6WX
----- Original Message -----
From: "Linden, Mike (BRC-Hes)" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, August 26, 2004 10:43 AM
Subject: [Elecraft] K2: KAF2 Versus 2.2 kHz KSB2


>   I plan on building my KSB2 to KI6WX's 2.2 kHz crystal filter bandwidth
> specifications (which is now the current Elecraft bandwidth). Should I
shift

> the KAF2's low-pass filter roll-off higher in frequency when I build it to
> account for the increased bandwidth of the KSB2, or will the low-pass
> roll-off be adequate as is?
>
>   Thanks, Michael N9BDF
>   K2 #4137
>
>
> PS  The "Amateur Radio Emergency Communications Consistency Act" (HR 1478)
> and the "Amateur Radio Spectrum Protection Act" (HR 713 & S. 537) are in
> Congress. Please contact your Congressmen to ask for their support of

these
> bills! See the following ARRL link for details:
> http://www.arrl.org/govrelations/ <http://www.arrl.org/govrelations/>
>
>
> _______________________________________________
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> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
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> Elecraft web page: http://www.elecraft.com
>


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Hello Michael,

I like the characteristics of the passive filter used on the KAF2, so I
removed the components and used them to build the same circuit which I
placed at the output of my KDSP2 module. I am using KI6WX's 2.5 kHz
bandwidth mod, and am very pleased with the results. However, as John
himself stated, you should be sure to place switch S1 on the KAF2 into
the 'Bypass' position when using Spectrogram to make measurements, to
avoid the additional rolloff.

73, Dale WA8SRA

Linden, Mike (BRC-Hes) wrote:

>  I plan on building my KSB2 to KI6WX's 2.2 kHz crystal filter bandwidth
>specifications (which is now the current Elecraft bandwidth). Should I shift
>the KAF2's low-pass filter roll-off higher in frequency when I build it to
>account for the increased bandwidth of the KSB2, or will the low-pass
>roll-off be adequate as is?
>
>  Thanks, Michael N9BDF
>  K2 #4137
>
>
>  
>

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[Paul T. Rubin]

>I like the characteristics of the passive filter used on the KAF2, so I
removed the components and used them to build the same circuit which I
placed at the output of my KDSP2 module.

This sounds very interesting. I would like to know more. Did you have any
problems with shielding to minimize noise pickup? Where did you mount the
components? I would really like to see a picture of this if you have one
available.

Thanks,
Paul Rubin N8NOV
K1 #1494  K2 #3269


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Hello Paul,

I'll refer you to a previous post that I made concerning this. My
implementation is definitely not a pretty sight though; I quickly tossed
the circuit together, and it sort of 'lays' inside the K2 (protected
with electrical tape, of course:-)). Someday I'll get around to making a
neat job of it, but a bit too busy at the moment. However, the info can
be found here:
http://www.ac6rm.net/mailarchive/html/elecraft-list/2003-10/msg00581.html

If you have any questions, I'll try to help.

73, Dale WA8SRA

Paul Rubin wrote:

>>I like the characteristics of the passive filter used on the KAF2, so I
>>    
>>
>removed the components and used them to build the same circuit which I
>placed at the output of my KDSP2 module.
>
>This sounds very interesting. I would like to know more. Did you have any
>problems with shielding to minimize noise pickup? Where did you mount the
>components? I would really like to see a picture of this if you have one
>available.
>
>Thanks,
>Paul Rubin N8NOV
>K1 #1494  K2 #3269
>
>
>
>  
>

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