AM > FM interference
03-24-2003, 09:02 PM
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AM > FM interference
Is is possible for AM radios to interfere with FM radios on the same channel? I want to opperate an AM radio on channel 56 near an FM radio on 56 (if possible)
03-24-2003, 10:02 PM
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AM > FM interference
It doesn't matter if they're AM or FM or PCM (which is actually also FM). If two radios transmit on the same frequency at the same time they will interfere with each other.
Why do you want to use two radios on the same channel?
Why do you want to use two radios on the same channel?
03-25-2003, 02:33 AM
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AM > FM interference
FM varies the frequency slightly high and low from nominal (not much... ch 56, at 72.910 mHz would only deviate in the 4th decimal region.) The AM, being at a constant frequency would obscure the variations created by the FM system.
Am varies the signal strength.... The FM's constant signal strength would hide that from the AM RX.
That's why it won't work.
Am varies the signal strength.... The FM's constant signal strength would hide that from the AM RX.
That's why it won't work.
03-25-2003, 06:27 AM
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AM > FM interference
Thanks for letting me know. It wasn't that i wanted to use them at the same time, but my friend's FM radio is an 56 and my AM radio is on 56.
Does anyone know, is it legal to change frequencies in RF modules? I know how, but I won't if it is illegal. I know it is supposedly illegal to change a crystal in a transmitter, but OK to change RF modules. HElp!!
Does anyone know, is it legal to change frequencies in RF modules? I know how, but I won't if it is illegal. I know it is supposedly illegal to change a crystal in a transmitter, but OK to change RF modules. HElp!!
03-25-2003, 11:29 AM
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AM > FM interference
Changing the crystal in a TX module s essentially the same thing as changing the crystal in a TX which doesn't use the module.
It is not illegal IF you take it in to an electronics shop which is FCC licenced to do work on TX's and have them check the tuning. If there happens to be such a shop near you (often there is...) its not expensive... just a quick hook-up to the Oscilliscope and a verification that the frequency is within specs. (they rarely need to be retuned)
Because the modern equip is so good... there's a 90%+ chance that swapping the crystal won't cause a problem. You just don't want to be the guy who has his radio detuned by getting a crystal which is as far offfrequency as possible one direction when the original was as far off as possible the other way If that happens... YOU won't see the deviation... but it can interfere with industrial radio control systems which operate between hobby R/C frequencies.
It is not illegal IF you take it in to an electronics shop which is FCC licenced to do work on TX's and have them check the tuning. If there happens to be such a shop near you (often there is...) its not expensive... just a quick hook-up to the Oscilliscope and a verification that the frequency is within specs. (they rarely need to be retuned)
Because the modern equip is so good... there's a 90%+ chance that swapping the crystal won't cause a problem. You just don't want to be the guy who has his radio detuned by getting a crystal which is as far offfrequency as possible one direction when the original was as far off as possible the other way If that happens... YOU won't see the deviation... but it can interfere with industrial radio control systems which operate between hobby R/C frequencies.
