[Elecraft] Rev A to Rev B Upgrade

[Don Brown]

Hi

I thought I would flesh out the list of mods required to bring a Rev A K2 to
Rev B status. In case some of you were wondering what may need to be done on
your K2


1  PLL - remove X2 and add R19 220 ohm
2  BFO - change out L33 with new toroid
3  D10 - replace with low drop diode
4  ALC - change R16 100K, R10 470 and add D8
5  10/12 meter - change value of C42 330 pf, 45 1 pf and 48 330 pf
6  RFC15 - add 100 uH choke to U4 supply line
7  RFC11 - change to 100 uH toroid choke 20 turns on FT37-43
8  add C28,29 - 12 pF across C21 and 23
9  change value C30,36 to 470 pF
10 add C224 - in series with P6 AUX RF .047 uF
11 change value C225 390 pf, 226 680 pF, 227 330 pF, L25 14 turns, L26 12
turns
12 audio pot mod - several cut runs and jumpers on front panel, RF and
control boards
13 sine wave side tone - add R11 47K and L1 82 mH
14 AGC threshold - add 50K pot at R1
15 voltmeter switch - remove and replace with jumper
16 added filtering on voltage sense - add cap at C17 .01 uF change value C42
.1 uF
17 D19,20 and C71 for future 60 meter option - add varactor diodes and
change value C71 82 pF
18 change R60 to fixed 100 ohm resistor
19 new crystals for CW and SSB - replace 14 crystals with more closely
matched set
20 AUX BUSS filtering - change value R6 100 ohm, R64 100 ohm and C12 .0027
uF

Don Brown
KD5NDB