941,
just looked at the schematic for this radio and here are some places to start modding.
for the receiver: buy the 2SC2999/ 1N6263 receive kit off of ebay. they should be easy enough to find for under 10 bucks.
replace TR2 (2SC1674) with the 2SC2999 transistor.
replace D6, D7, and D28 with the diodes that come with the kit.
as for the "NPC" mod, i think what you mean is a "swing kit" which does reduce the carrier while maintaining the max modulated wattage that the radio has when peaked.
it is indeed R49 that you want to remove and play with the value of to set the dead key where you want it.
if you want to do the variable thing that is just fine, but if you want to set the deadkey where you want it and leave it there, just increase the value of R49 until you get what you want.
the stock value is 4.7ohms. so buy a 5.6 ohm, a 6.8 ohm, and a 10 ohm 1/2 or 1 watt resistors, and see what deadkey they give you.
the trick is to tune up the radio before you do the "swing mod".
first turn up the modulation pot, then, while saying "teeeesssst" (test) into the mic, tune the tuning coils listed above for max PEP wattage on your meter.
when that is done, then play with the value of R49 and set the deadkey where you want it for your amp.
if you are not running an amp, then there is no reason to play with the deadkey.
a swing kit does not give the radio anymore modulated power, it only reduces the carrier while maintaining what the radio already has.
as for the capacitor that is used in the swing mods, im not really sure why that is used, as once the carrier is present, the anti-spiking diode is already forward biased, and the modulation comes through 1:1.
maybe someone can explain the use of the cap to me as there is lots i dont understand about this stuff yet.
after doing these mods, and giving the radio a full alignment, it should be one bad ass radio.
good luck,
LC