[Elecraft] K2 Filter question

[Don Wilhelm]

Mike,

The K2 has a built-in 5 pole filter on the RF board that you can set to 
variable widths using the CAL FIL menu - you must have the internal 
counter probe to change the filter settings.
There are 4 filter settings for each mode.

These are not "roofing filters" as used in the K3, but IF crystal 
filters.  The filter type in the base K2 is of a Cohn design and the 
width can be changed as I stated above.  Its design width is about 500Hz 
and gives a nice passband from about 1.5kHz down to about 200Hz.
It can be widened out to SSB listening levels, but the passband becomes 
quite ragged at those wider widths.  It is however suitable for SSB 
listening.  The filter on the KSB2 option board has a nice flat passband.

The KSB2 option (for SSB) has a fixed width 7 pole filter.  The early 
filters were 2.1kHz width, but more recent filters are 2.4kHz.
Elecraft has a capacitor kit which will allow you to change the filter 
width.

The crystals used in the K2 filter were upgraded to better speced 
crystals at SN 2560.  I would recommend that K2s below that SN be 
upgraded with the new crystals.  Elecraft sells a kit of matched 
crystals at a very reasonable price a set of 7 for the base K2 or a set 
of 14 for both the base K2 and the KSB2 option.

73,
Don W3FPR

On 1/8/2017 11:10 AM, Mike Smith VE9AA wrote:

> It's Mike,  VE9AA...I own a K3 but almost never use it (only for FD and
> portable ops -I've used it twice in my year of ownership)
>
> I am thinking about maybe buying a used K2/10 with many options,(no DSP
> board I don't think) but as I don't know a thing about the K2 (and after
> reviewing the Elecraft website) I had this hopefully simple question. (I
> have not yet contacted the seller)
>
>
>
> Are there optional CW filters still available for the K2 or does it come
> with them all built in ?
>
>
>
> I do mostly CW so was looking at doing most of my operating with a 200-300Hz
> filter.(and perhaps with a 1.8kHz SSB filter when I am on phone)
>
>
>
> I apologize if the answer is overly obvious !
>
>
>
> Thanks much,
>
>
>
> dit dit Mike VE9AA
>
>
>
> Mike, Coreen & Corey
>
> Keswick Ridge, NB
>
>
>
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