Posted by
Don Wilhelm-3 on
Oct 28, 2004; 10:36pm
URL: http://elecraft.85.s1.nabble.com/KSB2-Crystal-Identification-prior-to-2-5KHz-bandwidth-build-tp371142p371143.html
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?
>