Newbie/Oldbie Q about AM/FM radios

I'm a (guess you would call it) reborn RC model aircrafter and I have a question about a couple of old radios I have. They are both Futabas and one is a FP-T2L and the other is a FP-T4L. My question is: How do I determine if they are AM or FM as they have no indication on the units?

As an aside, I just came back from visiting my half-brother in Florida and whilst there he gave me a Futaba FP-4NBF which I am sure is an FM because it is printed on the transmitter.

Reply to
Mark Daughtry, SR
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Mark-

They are too old to even make the discontinued list on Futaba's web site. If not marked as FM like like the 4NBF, it's a pretty safe bet they are AM. Cuppla other other questions you should be asking:

1) Do they have gold stickers on the back of the case indicating they have passed a 1990 standards RF check? If not, they aren't legal to use.

2) Are the receivers narrowband? If not, they will be interfered with by adjacent channels, which are closer than under the pre-1990 band allocation.

Abel

Reply to
Abel Pranger

| They are too old to even make the discontinued list on Futaba's web | site. If not marked as FM like like the 4NBF, it's a pretty safe bet | they are AM. Cuppla other other questions you should be asking: | | 1) Do they have gold stickers on the back of the case indicating | they have passed a 1990 standards RF check? If not, they aren't legal | to use.

According to Futaba's website, all of their FM radios are narrowband. So if it's FM, it's narrowband. If it's AM, it may or may not be, and if there's no gold sticker, it's probably not.

| 2) Are the receivers narrowband? If not, they will be interfered with | by adjacent channels, which are closer than under the pre-1990 band | allocation.

Good to mention -- people tend to forget this.

Reply to
Doug McLaren

The Futaba FP-T4NL is AM. I still have one and it works fine. I have it installed in a glider and have used it while others were flying on other channels. No interference either way.

However, because of the age of the radio I have no way of determining the difference between the -T4L and -T4NL.

You might try contacting Futaba directly, by phone or e-mail. I have found then very helpful in the past.

Ron Kelley

Reply to
OP

I happened by chance to figure out that they are both AM. I was fiddling with the case of the receiver on the two channel radio and pulled out the crystal by chance and noticed on the crystal itself was labeled AM. I pulled out the crystal on the 4 channel and it also stated AM. As I had originally stated the radios are both rather old and DO NOT have the sticker required for them to be legal to use. I read in the Futaba FAQ that neither one can be updated for legal use. Fortunately the radio my brother gave me does have the sticker so I am not radio-less.

I wish to thank ALL who responded to my question. This NG is a little better than the other one (rec.models.rockets) I frequented (sans bickering, backbiting, etc.). Once again thanks to all.

Reply to
Mark Daughtry, SR

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