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Old 08-31-2004, 09:54 AM   #1
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Default FM radios. 27Mhz or 75Mhz

I know about the basic differences between 27 and 75, 75Mhz has 30 open channels as compared to 6 for 27Mhz, the channels on 75Mhz are much narrower though. Does that make them more subseptible to interference? Are there any advantages to 27Mhz that would make up for the disparity in channels?
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Old 08-31-2004, 01:06 PM   #2
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Hey Jackhammer, we meet again!

To tell you the truth, much of what we know about this stuff we hear as rumor. I remember hearing people say that 27Mhz gets better reception and is more resistant to interferance. But here is what I have learned in my years.

-Neither one seems to work any better than another. I've stood on the stand using 72 while a person right next to me was using 71. The result......nothing, nada, zip! It just works.

-Whatever advantages that 27Mhz gives the user is lost when you take into account the fact that there aren't enough channels. At our track, we have more problems with freq. conflicts than we ever do with interferance. Many times resulting in people not even getting a chance to practice. And these are people with 2-3 sets of extra crystals!

The way I see it, maybe if your using AM, then you may have to worry about the narrow bands between the 75Mhz freq., but in FM, with these very powerful modern radios, I just don't see the need to worry about it.
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Old 08-31-2004, 05:54 PM   #3
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I've had an XR3 for a while, I've got a couple frequencies for it but like you said it's always a hassle regardless, either 'cause it's a big meet and there's a lot of people or because some jerk happens to be on the same channel as you and chooses to keep the practice freq. clip even when he's on the pits.
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Old 09-01-2004, 02:14 AM   #4
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In theory the 75Mhz channel (or any higher frequency channels) gets better reception due to less attenuation in air with higher energy waves.

But you see, the 25Mhz band only has a few channels whereas the 75Mhz band has quite a bit more. So your interference with another dude's radio who is on a channel close to yours might be worse.

But the 2nd part is only speculation so I went with a 75Mhz.
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Old 09-01-2004, 09:06 AM   #5
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Quote:
Originally posted by jackhammer74
....or because some jerk happens to be on the same channel as you and chooses to keep the practice freq. clip even when he's on the pits.
EXACTLY! Thats why its 75Mhz AND synthesized for me all the time!

Haven't had to wait for clip in two years!
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Old 09-01-2004, 01:48 PM   #6
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Here's the deal on it.................27 and 75 fm.....


27 was better about 3yrs ago. But now with the top end JR/KO/Futaba radios in 75 they have gotten better. Also there was hardly a person on 27mhz back then. So 27 was better.


Now with the intro of all the RTR that are on 27am........with only being six channels..........you really need to have the synthesized module or buy all 6 channels if you want to race.

Also lots of the pros where using Japanese freqs..........they were half channels. 1.5 , 2.5, etc. That way no one was ever interfering with them.


So what's better?...............I think now they are the same. If you can afford the synth then go 75mhz just for the sheer #'s you can change to.


As for me I run 27 and always have.
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Old 09-01-2004, 01:52 PM   #7
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Yea, that's what I thought, which brings me to the original reason I even posted, after years of frustration, I finally decided to spring for a synthesized radio. Tower has the MX3S in both 27mhz and 75mhz, when I made my choice I chose the 27mhz instead of the 75mhz, but I didn't think much of it. Tower doesn't go into explaining the difference between the two. That was Sunday, Monday afternoon I was looking through the August issue of RCCA and came upon the Airtronics add for the MX3S, and that's when I found out the difference. I called Tower but my order had already been shipped. Well, this really sucks, as soon as I get that sucker it's going back to Tower. They should provide a quick explanation of the diffence between the two. It's not as if it's obvious.
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Old 09-01-2004, 04:09 PM   #8
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Not so fast, It depends what class you are running. If you are running onroad, I think 27 is the way to go because there are very few people with either rtr or 27 band radios.
On the other hand, if you are running offroad, the rtr monster trucks will keep you busy hunting for freq clips on 27. It is really feast or famine on the offroad side.

I have been running onroad and 1/8 buggies offroad for about 5 yrs on 27mhz and have found it to be more convenient rather than a hastle.

Now I can't comment on which gets better reception, but using my hitec aggressor with dcx dual conversion receiver, I have never received any interference or hits.

One other thing I have noticed is alot of people disgruntled with their synthesized receivers going bad and not happy with the performance.
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Old 09-02-2004, 01:38 PM   #9
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Well then, it may not be such a bad idea to keep the 27mhz MX3S. I race on-road 4wd stock, and aside from maybe novice class I don't see a lot of RTRs at my track. Crap!! Decisions, decisions!!
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Old 09-02-2004, 01:56 PM   #10
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I hate to be the bearer of bad news for you guys hating
27 mhz.....
But KO Propo has in their line up Twelve channels in the
27 mhz band, thats right 12 channels.

They call it split channels.
Our "Normal" channels, i.e. 1,2,3,4,5,and 6
are now denoted in KO's line up as 02, 04,06,08,10,and 12.
And "Split" them in the middle, and you have 6 more channels
i.e. 01,03,05,06,07,09, and 11

I don't know of hand the exact frequency mhz #, but you
could go to the KO forum and ask over there, if you needed
that info.

Hope this helps
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