NPC-RC for Cherokee NR-150

Step 1. Remove the internal heatsink by unsoldering the final transistor along with the heat sensing diode
wires (D-88) which is held against the final within the white nylon shroud over the final. Take out the 2 screws that hold the heat sink to the chassis. Then using the original screw and white nylon 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 the diode is inside the white nylon shroud or epoxy it to the final.

Step 2. Make sure that in place of L-36 is a plain piece of wire with a ferrite bead. If there is a resistor with the ferrite bead on it, remove the resistor and replace it with the plain wire and ferrite bead combination.

Step3. While you are in this area of the board, you will see a two pronged support for the mirror board at TP-7. Unsolder and remove the support. Using the hole closest to the rear of the radio at TP-7 on the bottom of the board, run at least 14 guage insulated wire from the hole to the emitter of the AM regulator transistor, TR-51. Make sure the wire at the TP-7 end does not touch the mirror board.

Step 4.Remove TR-50 and replace it with a 2SA1012 or 2SA1869 with the flat side of the transistor towards
the inside of the radio.

Step 5. Remove C-189 and lay it aside for later use.
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. Solder the short ends together. Now bend the long wire of the diode with a sharp radius towards the solder joint. Now install this in the holes vacated by C-189 with the wire end of the diode towards the front of the radio and the resistor in the rear. The holes may need to be slightly enlarged to make the wire leads fit through the holes. Flip the radio over and soder C-189 to the wire leads from the diode and resistor combination.

Step 6. Turn VR-13 fully counter clockwise.

Step 7. Remove R-237 and replace with a 100 ohm 1/2 watt resistor.

Step 8. Optional. Remove R-249 if you have a spectrum analyzer AND know how to use the mic gain correctly. Otherwise leave it in place. You won't notice much performance difference either way and leaving it in place will result in cleaner modulation.

Step 9. Set dead key to 2 watts. Radio should see at least 20 watts peak power.

Thanks to Billy Dean Ward for his help with specific steps and to Bill Eitner for help understanding the theory behind the modification.
I hope this helps some people that like this radio as
much as I do.