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?
