Frequency Help
#3
Thread Starter
Tech Initiate
Joined: Dec 2013
Posts: 32
I know we use to be able to move up and down in racing in case of conflict. So there is wiggle room. But; I've also been told that as long as both are 75mhz, your ok. I'm just trying to find out what is the norm today.
#4
Pass you soon...
#9
Tech Champion

Joined: Oct 2007
Posts: 7,341
Best I can remember that should work fine. Exactly what is done, just use a matching "75MHz" set, should work on any channel within that overall range of frequencies.
There is a possible issue with negative shift vs positive shift, but best I can remember or know that was on the 27MHz band. Even then I never experienced any damage by trying the wrong setup, as far as I know it's safe to try what you have and see if it works.
Also a potential narrow band issue depending on how old the stuff is, but since you have all even number channels I don't think it is a problem.
There is a possible issue with negative shift vs positive shift, but best I can remember or know that was on the 27MHz band. Even then I never experienced any damage by trying the wrong setup, as far as I know it's safe to try what you have and see if it works.
Also a potential narrow band issue depending on how old the stuff is, but since you have all even number channels I don't think it is a problem.
#10
Joined: Sep 2009
Posts: 5,366
From: Central Wisconsin USA
No need to buy another receiver. Just need to find a matching set of crystals and you're good to go. Each set of crystals contain a receiver crystal and a transmit crystal. (marked tx and rx) Any channel in the 75 mgh band will work. I think they go channel 62 thru 90 or something like that and they come in even number channels. (62, 64, 66 etc.) But they both must match between the rec. and the radio for it to work properly. Any hobby shop may have some hanging on the peg yet.
#11
It would be safest to buy a crystal of the same brand as the transmitter or receiver it's going into. As Dave mentioned, there is the question of negative- or positive-shift for FM devices (regardless of frequency band), as well as many others such as: mode (third overtone, fifth overtone, or third overtone with doubler); intermediate frequency (usually 455kHz on single-conversion receivers, and for the second intermediate frequency on double-conversion receivers); load capacitance; etc. If you buy the crystal that the manufacturer recommends for your receiver, you don't have to know any of this.
It makes my head hurt to think that we had to think about all that stuff way back when.
It makes my head hurt to think that we had to think about all that stuff way back when.
#12
You do not just need the same frequency, but the radio and receiver need to be compatible models as well. I think more information is needed to help get this to work.
Also FWIW, if you have the option to put a 2.4ghz style radio setup in this I would work towards that end. It is better on many fronts.




