[Elecraft] Mod for optimizing the crystal filter for narrower bandwidths

Tue May 27 11:51:01 2003

I can sort of answer my own question, after having looked at the KSB2
schematic. The SSB crystal filter has a nominal impedance of 1500 ohms
and is terminated in a transformer, T2, which supposedly transforms it
down to 150 ohms. It has a 22:4 turns ratio which actually transforms it
to about 50 ohms, so this I don't understand. To transform 1500 to 150
ohms requires a 22:7 turns ratio like the input transformer T1 in the
KSB2. 

So I guess it is a matter of changing the turns ratio of KSB2's T2, or
maybe it has already been prepared for a low termination impedance like
the 38 ohms mod of the CW filter gives?

73, 
Sverre

------------------
Sverre Holm, LA3ZA
www.qsl.net/la3za

> -----Original Message-----
> From: [email protected] 
> [mailto:[email protected]] On Behalf Of Sverre 
> Holm - LA3ZA
> 
> I wonder what the effect will be on the KSB2 from this mod?
> As far as I can tell, the input to the KSB2 crystal filter 
> will be unchanged, but the output will be terminated in about 
> 38 ohms instead of 150 ohms.