[Elecraft] Question on K2 2nd Stage Xfil Mod

[Don Wilhelm]

Rick,

The 120pF is about the right value, but a bit of cut and try to find the
best value can be beneficial.
Start with the 100 pf you have and add small value caps in parallel until
you 'get it right'.
First set L34 for best response on CW, and then (using Spectogram or
equivalent) vary the capacitor value for best flatness on SSB (and best
compromise between LSB/USB).

Once you have the correct value for your K2, you can further adjust L34 for
the flattest response if you have a desire to sacrifice a wee bit of S/N
ratio on CW for better flatness on SSB.

73,
Don Wilhelm  - Wake Forest, NC   W3FPR home page: http://www.qsl.net/w3fpr/
  QRP-L # 485   K2  SN 0020   mailto: w3fpr@arrl.net

----- Original Message -----

> I have a parts question on the K2 2nd Stage Xfil Mod, for 'Flatter' SSB
> Filter Response.  In the parts lists it states components required:
>
> (1) 1/4W resistor 3.3k to 3.9k Ohms
> (1) .01uF capacitor (Low-Voltage OK)
> (1) 120pF capacitor (Low-Voltage OK)
> (1) NPN small signal transistor (2N4124, 2N3904, 2N2222, PN2222, or
equiv.)
>
> My question is how critical is the 120pF cap?  I don't see one listed in
the
> RS catalog.  Been through my junk box and some of my local friends and we
> can't find one either (YET!)  Will 100pF work or will it skew the whole
> thing? I have some time this weekend to work on it so that is why I'm
asking
> anxiously?! Tnx & 73...