Elecraft KPA100UPKT User Manual
Page 4
4
Part II: Input and Feedback Circuit Changes
i
Depending upon the age of your KPA100, the following changes to the Input and Feedback circuits may have
already been incorporated. The changed parts and their new values are shown in Figure 2. Proceed directly to Part
III if these changes have been made. Otherwise follow the procedure below to make the changes.
R39 - 22
Ω
R19 - 1.6
Ω
R20 - 1.6
Ω
R23 - Jumper
R22 - 300
Ω
L18 - Jumper
R38 - 22
Ω
C82 - Removed
Figure 2. Input and Feedback Circuit Component Changes.
Remove capacitor C82 (near where the Aux RF coaxial cable attaches to the PCB). C82 will not be replaced.
i
When replacing parts with new parts or jumpers, first remove the old part, then clear the solder pad holes of
all solder before installing the new part. (See Soldering and Desoldering on page 1 for more information.) Install the
new part, solder and trim the leads flush with the PCB.
Replace resistor R23 with a jumper (R23 is near the small binocular core transformers T1.) Ma
ke
t
he
j
umpe
r
f
r
om
a
1”
(25.4 mm) length of the #20 insulated wire. Remove insulation from each end to leave
j
us
t
s
l
i
ght
l
y
l
es
s
t
han
1/
2”
(
12
mm)
of
insulation in the center of the wire. Bend the stripped ends of the wire to fit the solder pads for R23. Solder and trim the
excess leads flush with the PCB.
Replace inductor L18 (near Q1) with a jumper. Make the jumper from a 3
/
4”
(
19mm)
l
engt
h
of
t
he
#20
i
ns
ul
a
t
e
d
wi
r
e
.
Remove
i
ns
ul
a
t
i
on
f
r
om
e
a
ch
e
nd,
l
e
a
vi
ng
1/
4”
(6 mm) of insulation at the center of the wire. Bend the stripped ends of the
wire to fit the solder pads for L18. Solder and trim the excess leads flush with the PCB.
Re
pl
a
c
e
R22
wi
t
h
a
300
ohm
(
300
Ω)
2
wat
t
r
e
s
i
s
t
or
.
Re
pl
a
c
e
R20
wi
t
h
a
1.
6
ohm
(
1.
6
Ω)
2
wa
t
t
r
e
s
i
s
t
or
.
.
Re
pl
a
c
e
R19
wi
t
h
a
1.
6
ohm
(
1.
6
Ω)
2
wa
t
t
r
e
s
i
s
t
or
.