[Elecraft] K2 ultimate rejection

[Martin Kratoska]

Looking at the Rob Sherwood's receiver data table

http://www.sherweng.com/table.html

I discovered a remarkable fact: the K2's weakest point is the FILTER 
ULTIMATE REJECTION. Sherwood says it is 80 dB only (and there are two 
K2s) and it was confirmed by one of our top grade contesters and 
DXpeditioners.

A closer look onto schematic awake an idea to reuse KSB2 crystal filter 
for receiving on both CW and SSB. No doubt the additional 7 crystals 
will improve this figure significantly. I had no opportunity to track 
the rather complex diode switching scheme but Sherwood's figures saying 
it clearly – there are 5+2 crystals in CW receive path only. So my 
question: is there any mod to improve the ultimate rejection using KSB2 
crystal filter? (of course, G3RXQ's filter mods are here but I don't 
plan to destroy a KSB2 board and I am not interested in SSB). Would any 
experienced K2 builder willing to play around this?

And a QSK improvement to listen between elements up to 40 wpm would made 
from the K2 a dream radio :-)

I don't own my K2 yet but a 100 dB ultimate rejection would ensure me 
that I should't lose my time with thinking if to buy or not :-)

73,
Martin, OK1RR