[Elecraft] Andy's list of installed K1 mods

[Wallace, Andy]

Here's a list of the mods I've made to my K1 since its birth 
in January of 2002.

120K resistor between VFO pot pins 1 and 2 to improve linearity. Now 9
kHz/revolution.

Added speaker grille cloth and rubber grommets to mounting 
flange of speaker.

Added display lighting: pin 16 (12V) of front panel board to 
1.2K resistor, going to a pair of Radio Shack 276-320 3.6V "Bright White" 
LEDs and back to ground at FP pin 20 (GND). Draws 4 mA.

Added shrink tubing around RIT/ATTN LEDs to reduce 
sidelighting through button holes etc.

Changed C9 in audio section from 220 uF to 100 uF to reduce 
bass response.

Added Elecraft QSK-thunk mod: Drain of Q11 goes to 220 Ohm 
resistor, other end of resistor goes to + lead of 22uF cap, 
- lead of cap goes to GND at C10 location.

Added socket pins and jumper to OFFSET and R36 areas to 
facilitate alignment in the future.

Added 12 uH choke between relay K1 leads 3 and 8 to eliminate 
attenuator pop.

Replaced VFO pot with Bourns metal shaft 3540S-1-104 (DANGER 
do not use Hybritron 3541H-1-104, frequency jumps and is 
unstable at end  of travel).

N0RC mods: changed C31 and C67 to 1 uF to speed up AGC. I 
like this mod, however I did not like his caps-across 
filter xtals mod; it worked,  but narrowed the
passband too much for my ears. Bravo on the AGC mod, though!

Added the "RIT coarse-fine" mod found in the mailing list 
archives at
http://www.qsl.net/ve3mcf/elecraft_reflect/K1_mod_RIT_Fine-coarse_Feature.tx
t
except in my case, I added 47 pF to C7 to increase 
RIT range; also: instead of 33K resistors across the 10K RIT ones, I used 
6.8K. This gives me -7.2 to +9.2 kHz of RIT for chasing split DX.

Proceed at your own risk!
  
-Andy