Posted by
Don Wilhelm-3 on
May 27, 2005; 7:54pm
URL: http://elecraft.85.s1.nabble.com/K2-XTALS-tp378841p378848.html
Colin,
There are 2 separate things here - Elecraft's specs to the xtal vendor for
motional inductance were tightened on or about SN 2600. If you have a set
that is older, you will likely benefit from installing a new set of crystals
(do not mix new with the older crystals in any one filter (CW or SSB).
Secondly, yes Elecraft has widened the SSB filter bandwidth from 2.0 to 2.3
(or 2.4) kHz. Only a few capacitors in the filter are changed, and you
likely have the capacitors for the narrower filter. Weigh the pros and cons
of the wider or narrower bandwidth - the narrower filter provides a bit more
'punch' to a QRP SSB signal, but is a bit more critical in positioning the
passband correctly. The wider passband results in a more natual sounding
transmitted signal. Take your pick based on your operating desires, both
work well.
If you do decide to change the fiilter bandwidth, it is easier to install
the capacitors during initial construction - it is not really difficult to
do it after assembly, but decidedly easier to put the capacitors in before
the crystals are installed.
73,
Don W3FPR
> -----Original Message-----
>
> I am buiding a K2 sn 004149 from an earlier non built K2 sn
> 000571 up to rev 'B' on the new 'B' pc boards.
> I also have an early KSB2 SSB unit.
>
> All the above has the original XTALS for the CW filter and SSB
> unit.ie 4.195MHz -20.
> I have read lots of comments on the audio quality because of the
> tight band pass of the original SSB unit.
> I know that Elecraft have produced some modifications in the form
> of 14 new XTALs and a capacitor upgrade kit.
>
> Does anyone have experience of these mods ?
> Is there a basic capacitor upgrade that one can do first of all?
> Or is changing all the XTALs and adding new capacitors the best solution?
> Or is the original configuration ok?
>
> Regards Colin M1BNW
>
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