Frequency Help

Old 06-24-2014, 08:19 AM
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Will a receiver with a frequency of 62(75.430), work with a transmitter of 82(75.830)? If not; how close do I have to get to the radio to get the receiver to work?
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Old 06-24-2014, 08:26 AM
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The frequencies have to match exactly for it to work.


Pass you soon...
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Old 06-24-2014, 08:36 AM
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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.
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Old 06-24-2014, 08:42 AM
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Originally Posted by Bandit13 View Post
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.
Both transmitter and receiver always have to be on the same channel. Both have to be on channel 62 or both have to be channel 82( no wiggle room). You can move up or down a channel but both transmitter and receiver have to move together and remain on the same channel.

Pass you soon...
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Old 06-24-2014, 08:49 AM
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Usually by changing to a matching set of crystals, little parts with 2 prongs that plug into each, and should have the labels on them. Or if a synthesized deal by turning dials to match.
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Old 06-24-2014, 08:51 AM
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Ok. I see what your saying. Thanx for the help. I guess I need to find an 82 receiver to go with my radio.
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Old 06-24-2014, 08:55 AM
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Or just buy the crystals, they shouldn't be very expensive. Some shops probably still have a few.
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Old 06-24-2014, 09:04 AM
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I have the 75.830 crystals. But; will those crystal work in the 75.430 receiver? that's what I'm trying to figure out. It's been so long since I've used this equipment. I can't remember what goes with what.
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Old 06-24-2014, 09:42 AM
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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.
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Old 06-24-2014, 10:33 AM
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Originally Posted by Bandit13 View Post
Ok. I see what your saying. Thanx for the help. I guess I need to find an 82 receiver to go with my radio.
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.
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Old 06-24-2014, 11:22 AM
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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.
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Old 06-25-2014, 06:54 AM
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Originally Posted by Bandit13 View Post
Will a receiver with a frequency of 62(75.430), work with a transmitter of 82(75.830)? If not; how close do I have to get to the radio to get the receiver to work?
What brands / models are involved in this?

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.
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