[Elecraft] KSB2 Crystal Identification prior to 2.5KHz bandwidthbuild

[W3FPR - Don Wilhelm]

Leigh,

You don't have to order new crystals.

Check the value of C179 in your K2 - if it is 100 pf (and NOT 120 pf), then 
you have John's improved version of the 2nd Xtal Filter Mod in your K2 
already.

The 'bandwidth discrepancy' is not a real discrepancy, but is a matter of 
different points used to define the bandwidth.  John KI6WX used the -3dB 
points and Elecraft uses -6 dB.

If your operating is mainly PSK31, I would believe that you would want to 
use a more narrow bandpass rather than a wider one to increase the Signal to 
Noise ratio in the passband - but then each to his own.  I personally prefer 
using a filter of about 1 kHz for PSK31 operation so I can drop the louder 
signals out of my operating passband (yes, I use the VFO knob for tuning as 
well as clicking on the screen to select the correct signal).  The KI6WX 2.2 
kHz bandwidth is now a part of the standard Elecraft KSB2 for new builds 
(but Elecraft specs it at 2.3 kHz at -6 dB), and I would recommend that 
filter for more voice power in the passband (and it is a bit flatter than 
the 'original' filter from Elecraft).

73,
Don W3FPR


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

> My K2 is #3121 and the KSB2 adapter instructions are Rev C, May 2, 2002 
> and my board is "SSB Rev D (C) 1999 Elecraft."
> The part number on the crystal envelope is E850006 and the crystals are 
> labeled "ECS V 4.9136-S KOREA D2".
> The calibration number on the envelope is 3.7.
>
> As I do more PSK operating than SSB, I am thinking of the 2.5 KHz 
> modification, and doing it at build time since it's easier then.
> I've read KI6WX's paper of July 18, 2002, but it's not clear to me whether 
> I need to order E850006.
>
> Since my K2 is #3121 is > 3000, I think it already includes XFILMDKT* 2nd 
> Filter Upgrade for the K2, although John's paper claims an improvement 
> over that.
>
> Furthermore, my KSB2 instructions claim a 2.2 KHz bandwidth, but looking 
> at the table in the KI6WX paper, the capacitors in the parts match the 
> "original" which John says are not 2.2Khz.  I'm having a little trouble 
> sorting out legacy information from current information, and applying it 
> to my Revision D SSB Board and Revision C 2/2002 instructions.
>
> If I want to build my KSB2 board for 2.5 KHz, do I need to order a new set 
> of crystals E850006 first?
>