I have a question about ko radio will after market receivers mainly novak or hitec that are made for JR or others. I know the filters in these are specific but i've heard that they will work wondering which one. Ko receivers are just to much money. My radios are an ex-11 and mars R 75mhz FM.

I use an EX-11 with a Novak XXtra (synthesized) receiver. With these receivers, one dial sets both the first digit of the channel and the radio manufacturer. The choice for KO is labelled "JR-AIR-KO_MPX."

So, I'd guess that it will work with JR receivers, but I not sure whether you'd use JR or KO crystals. I'd guess JR. If you have a buddy with a JR set, I'd test it.

I have a KO EX-1 FM 75mhz, and I use novak receivers and KO crystals and have never had a problem.

this may sound whacky but I've even gotten away with using Futaba crystals in my EX1.