Another Noob Question ..AM/FM ????? - RC Groups
Shop our Airplanes Products Drone Products Sales
Thread Tools
Apr 13, 2009, 05:11 PM
Cheif Bottlewasher
more coffee's Avatar

Another Noob Question ..AM/FM ?????

A: i dont know
B: somebody else may be thinking as well

I have a Hitec Ranger III 75Mhz channel 73 (75.650)FM transmitter /reciever

I have a chance to get a Futaba Attack 2DR 75Mhz Channel 73 (75.650)AM transmitter/reciever

Well they work together or do i have to change the crystals? The channels above are whats stamped on the crystal ..or is it a type "O"

I dont think I do given the difference between AM and FM in frequency modulation ...but thought I'd ask ..
Sign up now
to remove ads between posts
Apr 13, 2009, 05:49 PM
no wings any more, just dust!
Ghost 2501's Avatar

AM or FM...?

well in short, AM is cheaper, generally two channels and slightly more suceptible to interferrence from motor sparking and things like power lines, (ever had the radio tuned in on AM and gone under a power line that spans the road?)

FM gives you the ability to get more channels on your reciever and is generally quieter than the AM stuff regarding interferrence.

AM crystals and FM crystals are not intermixable either, however you will still get interferrence from someone else who is on the same frequency regardless of what you are on, AM or FM as 75.650 is 75.650 regardless of how its sent up the antenna.

I have ran My neptun on AM and later on FM, and to be honest, apart from interference risk, which in many cases is OVER RATED, running on just 2 channels, there isn't much of a difference operationally, you will still get a good 300 feet from each type of radio, just be careful where you run the antenna.
Apr 13, 2009, 06:46 PM
Registered User
More Coffee,

Even though they are on the same frequency they will not work together if that is what you are wondering. They don't speak the same language, so if you put one in one boat and the other in a different boat you would still need to take both transmitters to the pond with you. You would be better off seeing if you can get another FM set and change crystals the in the new receiver to match your existing transmitter that way you only have to take one transmitter with you. You can run a Hitec receiver with a Futaba transmitter or vise versa as long as they are both on the FM band.

Apr 14, 2009, 06:55 PM
Cheif Bottlewasher
more coffee's Avatar
Alright heres how it goes ..I bought the Futaba radio ..all there including servo's...
I brought it home and filled the transmitter with batteries....I then switched it on ...after that i switched Bender on ..she has a Hitec HFS-O3MM RX FM reciever and runs the same chanel though FM ..

To my disappointment I have full function control ..though a little glichy ..nothing serious ,,of Bender using my Futaba Attack 2DR TX..

Need new Xtals for Bender ..

Futaba says in the book that i cant cange its Xtal unless i sent it to the factory for calibration .. What the ????.. Anyway

I think that maybe the Attack wasnt AM as was advertised or listed in the box ..think its FM...

I dunno ..In the future I'll stick with Hitec just because i can RE & RE the crystal on the fly ..
Unless i get one of the Ghz jobbies when they get cheap..
Apr 15, 2009, 03:08 AM
no wings any more, just dust!
Ghost 2501's Avatar
the 2DR is AM

as for x-tal changes, that can be done by the home user, (just that it i think, is illegal under us law)
Apr 15, 2009, 03:45 AM
Sea Dragon-Lover
Umi_Ryuzuki's Avatar
The AM Reciever will need to be tuned. the type of signal it uses is different
than FM. It may be just as economical to buy a new FM reciver to replace any
AM equipment you are using, if you want to use the same transmitter with each boat.

Apr 15, 2009, 02:46 PM
Cheif Bottlewasher
more coffee's Avatar
Thanks for the info ..

I think i will just dedicate the AM Transmitter to a boat , leave it till it craps out or i can get a FM unit later .. and get a couple sets of Fm crystals for my Hitec gear ...

The system was new and just laying around , i got it for not much more than a couple pint's ...and tire wear to get it ..

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Another Noob Question TimmA69 Beginner Training Area (Aircraft-Electric) 2 Mar 25, 2009 10:22 AM
Discussion another noob question - Heavy air???? springer Foamies (Scratchbuilt) 3 Jul 19, 2007 12:05 PM
Discussion Another noob question, tail servo positioning? Sky_Dancer Mini Helis 2 Apr 05, 2007 08:34 PM
Discussion Another noob 2nd plane question :-s Joe2003 Beginner Training Area (Aircraft-Electric) 5 Aug 03, 2006 12:48 AM
Yet another Noob question chris8105 Beginner Training Area (Aircraft-Electric) 11 Oct 14, 2004 01:09 PM