[Elecraft] KSB2 bandwidth - 1.9 kHz?

[John, KI6WX]

Kevin;
Ordering another set of crystals can make a big difference even though the
motional inductance is not tested by Elecraft.  The spec for the motional
inductance of the crystals is 70+/-5mH.  If you happen to get an Xtal at
65mH and another one at 75mH and you are unlucky enough to install them in
the wrong Xtal positions, the filter response can look pretty ugly at the
2.5kHz bandwidth.  The problem will show up as excessive ripple in the
filter passband or non-monotonicity in the response as the filter
transitions from its passband to its stopband.  It is not likely at another
set of Xtals will have the extreme variation in motional inductance, so
ordering another set will probably fix the problem.

I want to emphasize that the standard Elecraft SSB filter does not have a
problem with the variation of the motional inductance, and Monte Carlo
analysis shows that the 2.2 kHz bandwidth option should also not have an
issue due to the variation in motional inductance.
-John
 KI6WX

----- Original Message ----- 
From: "Kevin Cozens" <kcozens@interlog.com>

>
> If the motional inductance of the crystals aren't measured by Elecraft and
> is important for a good response at the 2.5kHz bandwidth, I would think
> ordering another crystal set from Elecraft isn't any more likely to make
> the mod work properly than the set one already has.
>