NPC-RC for Cherokee NR-100
To those that don't
know of or are unfamiliar with the Cherokee NightRider 100, it is the
AM only version of the NR-150. Features wise, it is comparable to the
Cobra 29 and Uniden PC-76 and PC-78 radios. The NR-100 has a slight advantage
over the Cobra and Uniden since no one has come up with an NPC-RC conversion
for them yet. With this conversion, the NR-100 will outperform and be
cleaner than the Cobra and Uniden models with the JP-6 mod.
It uses basically
the same board as the NR-150 but is slightly smaller and has a few minor
parts differences. Those that have seen the mod for the NR-150 will notice
that the mods are basically the same but there are some differences so
Doing the NR-150 mod on the NR-100 will not work as expected.
Here's the mod for the NR-100.
Step 1. Remove
the internal heatsink by unsoldering the final along with the heat sensing
diode wires(D-88) whic is held against the final within the white nylon
shroud over the final. Take out the 2 screws that hold the heatsink to
the chassis. Then using the factory screws and whit plastic washer mount
the final to the chassis using the factory hole. Be sure to use the insulator
and a liberal amount of heat sink compound. Carefully make sure that the
diode is inside the white nylon shroud or epoxy it to the final as a last
Step 2. Remove L-36 near VR-20. L-36 is a 2 watt resistor with a ferrite
bead on one of its wire leads.
Replace L-36 with a plain wire and the bead from the resistor.
While you are in this area of the board, you will see that there are 2
wires at TP-7 that are on the same hole. Unsolder and pull these wires
from the hole. Solder these 2 ends together making sure they are well
insulated. Remove all solder from the hole. Run at least 14 guage insulated
wire from the hole on the solder side of the board to the emitter of the
AM regulator transistor, TR-51. Double check to make sure
that the wire is in the rear hole at TP-7 since there are 2 holes at that
Step 4. Remove TR-50 and replace it with a 2SA1869 with the flat
side of the transistor towards the
inside of the radio. If you can't find a 2SA 1869, a 2SA 1012 can be used
in its place.
Step 5. Remove C-189 and lay it aside to use later. Prepare a 1N4001
diode by clipping the banded cathode end to 1/8" long. Prepare a
100 ohm 1/4 watt resistor in the same manner and solder the short ends
together. Install the diode/ resistor combination in the holes vacated
by C-189 with the resistor in the rear hole and the long wire of the diode
in the front hole. Solder C-189 on the bottom of the board to the wire
leads from the resistor/ diode combination that you just put in. Turn
VR-13 fully countrclockwise.
Step 6. Remove R-237 and replace it with a 100 ohm 1/2 watt resistor.
Step 7. Optional. For those people that have a spectrum analyzer
and know how to use the mic gain
properly, remove R-249. Those that leave R-249 in will not really notice
much of a performance difference but will have a slightly cleaner signal.
If you leave R-249 in place you will still have to experiment with the
mic gain to find the loudest signal without splatter.
Step 8. Adjust deadkey wattage to 2 watts. Radio should swing to
20 watts or better.
I hope this mod will help those that are interested in these neat radios.
I would like to thank Billy Dean
Ward for his help with this modification. This is HIS mod with minor changes
in wording and the substitutionof the 2SA1012 fo r those that can't find