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Old 11-10-2002, 09:27 AM   #1
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Default Using 40 mhz transmitter in U.S.?

Hello. I know this thread really does not pertain to nitro on-road, and it might be somewhat off-topic for this forum, but since I predominantly race nitro touring I will ask this question in here.

I have a question regarding radio MHZ's. I am in the market to purchase a Futaba 3PK PCM Radio system. I would like to purchase one in Hong Kong since the prices are alot cheaper than here in the U.S. I notice the only frequencies available there are 27 mhz and 40 mhz. 27 mhz is out for me due to the small selection of crystal choices. 40 mhz is literally my only other choice. In my 6 years of RC-racing I have only had radios that run on 75 mhz, so I am somewhat confused on what to do.

I have heard that 40 mhz is illegal here in the U.S. On the other hand I have heard alot of "big-shot racers" here use 40 mhz since it is a clearer, less used, channel. Is this true? A fellow I used to race with use to use a 40 mhz system and I believe for that reason. Now is there any advantages using a 40 mhz system over a 75 mhz system?

Also, does ROAR/IFMAR really enforce the 40 mhz restriction? I do not want to go to a major race and be banned due to using a 40 mhz system.

If a 40 mhz system has no advantages over a 75 mhz system, and if its truly ROAR/IFMAR illegal, I will wait til' Tower Hobbies receives the 3PK PCM radios and purchase one from them. But if a 40 mhz system does have some advantages over a 75 mhz system, and the MHZ rules are not enforced, I will purchase one from Hong Kong. Thanks in advance!

Last edited by racer rich; 11-10-2002 at 09:31 AM.
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Old 11-10-2002, 09:59 AM   #2
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If the Fed's find out about it the fine is horrendous... like 5 or 10 thousand... i wouldn't risk it.
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Old 11-10-2002, 11:05 AM   #3
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I don't think there's any technical advantage going to 40 Mhz when compared to 75 Mhz.

Where I come from, we use 26, 27, 29, 40, 41 and 75 MHz bands. The 26, 29 and 41 Mhz bands are actually illegal ones but still many people use them.

It's actually not really proven but over here, we tend to avoid the 75 Mhz bands. There were 4 to 5 cases where walkie talkies were in the vicinity and a glitch happened to a 75 MHz band PCM fail safe type of controller. Apparently some walkie talkies that we use here are very near the 75 MHz frequency range and once you glitch with a more powerful walkie talkie, even a PCM fail safe will not be able to protect you from a runaway... Don't know why...
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Old 11-10-2002, 11:15 AM   #4
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same thing with some pagers and florescent lighting. Some other stuff, but pagers is main one I hear about.
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Old 11-10-2002, 02:13 PM   #5
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A: You are required to have an FCC approved license to operate on the 40MHz band.

B: Where are you at InitialD? The only bands that I can find made are 27,40,50,72,75. Realizing, however, that those numbers are approximations - the actual frequencies span outside of that actual MHz number, but are used as references. 50 and 72 are aircraft, 27 and 75 are surface and 40 requires a license in the US (legal in Japan).

This is all the info I can find, could be more, but I can't find it.. . .

C: I've never had any significant interferance that wasn't directly attributable to someone on my freq (or me just being stupid and having the wrong freq vs. clip. . . ) and never from phones or pagers. . . all the cell phones around here are nowhere near 75MHz.
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Old 11-10-2002, 02:26 PM   #6
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A funny thing that happens at tracks in the US with a lot of "pros" around is that they never seem to coordinate who’s on what 40MHz frequencies. Watching two “pros” yelling “40-band, 40-band” while they’re trying practice is always good for a chuckle.
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Old 11-10-2002, 07:24 PM   #7
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why dont you just pick up the 27mhz one from HK and switch the module to a 75mhz one? then again i could be wrong, i dunno if u can switch the module on a 3PK.
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Old 11-10-2002, 08:12 PM   #8
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I know you can on an M8.

Just make sure you match the module with the receivers. . .
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Old 11-10-2002, 10:53 PM   #9
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oh yeah, that too. you'll need a matching reciever. otherwise you could have some radio issues.
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Old 11-10-2002, 11:50 PM   #10
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Quote:
Originally posted by Boomer
50 and 72 are aircraft, 27 and 75 are surface and 40 requires a license in the US (legal in Japan).
27 can also be used with aircraft if i am correct. I remember this used to be a big fit, how aircraft has a larger band, yet also uses a band that is "reccomended" for surface only... although I beleive that 27 was setup as the universal water air and land.
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Old 11-10-2002, 11:53 PM   #11
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http://www.wcflyers.com/reference/radio_freq_chart.htm

After doing some research.
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Old 11-11-2002, 02:27 PM   #12
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I know a guy who uses 40mhz.. i should blackmail him..
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Old 11-11-2002, 02:59 PM   #13
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Default 27 Mhz

Another problem with 27 mhz is that so many other R/C "Toys" come on this band.
40 Mhz sounds good, but where do you get more crystals easily.
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Old 11-11-2002, 03:09 PM   #14
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As I said and as TRS6 showed very clearly with the frequency chart (thanks ), you can't use 40 mhz radios in America... its illegal. If someone finds out in the FAA, you're not gonna be able to do much except pay big bucks to them... not worth it.

They use 27 mhz for everything, but if you're at the race track, it is actually the best b/c of the space between frequencies 50-60 microhz, compared to 75 which is only 20 microhz.
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Old 11-11-2002, 03:49 PM   #15
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Quote:
Originally posted by Im2lazy
As I said and as TRS6 showed very clearly with the frequency chart (thanks ), you can't use 40 mhz radios in America... its illegal. If someone finds out in the FAA, you're not gonna be able to do much except pay big bucks to them... not worth it.

They use 27 mhz for everything, but if you're at the race track, it is actually the best b/c of the space between frequencies 50-60 microhz, compared to 75 which is only 20 microhz.

20KHz is quite a bit. If I remember correctly, the min. requirement is 3KHz on both sides.
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