[Elecraft] K2 SSB mod question - parts

Sat Apr 20 16:36:05 2002

Kirby;
Several weeks ago I published a message on the reflector about an improved
version of the 2nd Xfil Mod that produces an even flatter response for the
OP1 filter.  On my K2 there is no change in the pitch of the background
noise when you switch between LSB and USB.  A frequency plot of the two
responses using Spectrogram shows that they line up on top on each other.  I
will put the full mod up on my web site in the near future, but the summary
of how to do it is below.  The 120 pF cap is replaced with a 100 pF.  You
may still use a 120 pF, but the response will not be quite as flat; do not
use a capacitor less than 100 pF (such as 82 pF) or the response will
deteriorate significantly.

1.  Install the 2nd Xfil Mod described in
http://www.elecraft.com/Apps/new_fil_docs/k2_2nd_xfil_ssb_mod.pdf

2.  Replace the 120pF capacitor in the above mod with a 100pF capacitor (10%
tolerance or better).

3.  Install a 5.6k resistor from pin 1 of U11 to pin 2 of U11 on the RF
board.

4.  Check the adjustment of L34.  In CW mode, tune to the weak birdie heard
at 7 MHz.  Set the filter bandwidth to 0.1 kHz and tune L34 for maximum
signal relative to the background noise.

-John
 KI6WX

----- Original Message -----
From: "Kirby J. Davis" <[email protected]>
To: "Elecraft Reflector" <[email protected]>; "Elecraft Support"
<[email protected]>
Sent: Friday, April 19, 2002 9:16 PM
Subject: [Elecraft] K2 SSB mod question - parts

Not sure if this question made it through the first time... my apologies if
this comes through twice...

Regarding the SSB mod...

I went to the local Radio Shack this afternoon and picked up all the parts
for the mod except for the 120 pF
capacitor. RS only had a 100 pF capacitor and a 47 pF capacitor and stated
that they could not order a 120 pF. Could either of these be used... perhaps
in parallel?

If not, where can I locate a 120 pF capacitor? Is ordering from
Radioshack.com my only choice or is there a better
source?

Thanks and 73,

.. Kirby