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dual convertion crystals????

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racin_38

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ok i am totally lost here ,
i just bought a truck with a 75mhz fm receiver and i am going to use my XR3i for both my savage and the mini-t i am buying
but i am lost as to what the dual convertion thing means for the RX crystal
do i just get a 75mhz channel 81-75.810 crystal or do i need a special 1?
any help would be gratefully accepted
thank you
rick
 
I think dual comversion rx's are capable of using positive shift crystals(like JR/Graupner, Airtronics/Sanwa and KoPropo), and negative shift crystals(Hitec, Futaba and everything else)

You can't use negative shft crystals in positive shift sytems, and vice versa.

If I'm wrong, somebody please correct me.
 
Actually, I believe dual vs single conversion has to do with a built in redundency in the reception. I'll see if I can find an article in a moment. Dual conversion crystals are common and should be simple to find. Most regular land and air FM receivers are dual conversion I believe. So getting a proper dual conversion crystal is cake. Just make sure you're getting a crystal that's compatible withe the Tx/Rx system you're using. JR is a positive shift system so you'll need positive shift compatible crystals. These will work with any Airtronics and JR system. You won't be able to use Futaba or Hitec crystals or receivers because they are negative shift.

Definition of "dual conversion" taken from the Futaba website:

Dual Conversion
A type of receiver that converts the incoming frequency through two intermediate stages. This tends to eliminate the type of interference known as "image". With high-precision components, it also allows the receiver to be much more precise in selecting the incoming channel it accepts. This is what helps the receiver to be very narrow-band.
 
I wasn't to shure about the dual conversion thing. Good thing candyman cleared it up.
 
thanx candyman ,
it has a novak XXL fm r/x on it now will that work with my JR radio?
if so then i wll ask him to leave it installed instead of swapping it for a hi-tec r/x
 
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the novak should work. but you will havve to make sure you have a jr crystal. same thing with my mx-3 i can use novak's but i have to have a airtronics crystal for it to work.
 
thanx guys ,the guy is leaving the novak XXL r/x on it so all i have to get is a spare channel 81 rx crystal
 

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