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Your thoughts on a 72MHz amp

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I recently saw a link to this amp posted at RCGroups.



The seller claims it's a 7W amplifier for 72MHz, and provides instructions for installing it into an R/C transmitter. I know this can open a big can of worms with regards to the legal issues, and rightfully so. There's probably a long list of reasons why it shouldn't be so readily available for purchase and use in the US.

That said, I wanted to ask about it in a technical sense. How well would something like this work? Assuming the receiver side of the plane is properly set up and was performing to reasonable expectations, would this amp make a big improvement? Would it be reasonably safe to use out in the middle of nowhere? (no other R/C activity within 20 miles for example)

Edited by KeithLuneau
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In a perfect world, this hack would increase range by about 4X. But, the legal issues make this impractical for anyone in the USA that wants to play within the FCC regulations.

I've heard that the much lower power UHF "long range" R/C systems being discussed at rcgroups have more range that this kind of setup. They may be legal for use in the USA with a ham license, but best to ask the makers about that (assuming they have confirmed knowledge on this issue).

But, a good 72MHz R/C System (highest quality R/C Rx) that is properly installed, with deliberate measures to tame model RFI issues, will give extraordinary range. So exactly what typical distance are you trying to achieve?

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Ideally I'd like to fly around 5 miles reliably. I think this amp would give me that, I'm getting at least a mile with stock gear. Given that this costs $120, runs the risk of shooting someone else down (though there's literally nobody flying R/C here but me), is illegal, etc. I think I'd be better off saving up for a UHF system instead.

I'm currently using a Corona RP8D1 receiver in one plane, and a Hitec Electron 6 in another. Maybe I'll pick up a good Futaba receiver to try in the mean time. Any suggestions on which one is the best? I do have a PCM transmitter (9CAP) but would prefer a PPM receiver. I like knowing that my signal is weak before it's dead.

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I'd like to fly around 5 miles reliably.

Five miles is pushing it with standard R/C gear. I'd suggest 2-3 miles is more likely for the average mortal.

I'm currently using a Corona RP8D1 receiver in one plane, and a Hitec Electron 6 in another.

I've heard that those two economy priced receivers are decent designs. Cyberflyer had good success with Futaba PCM on very long distances; Check his personal hobby site to see the details (don't have the link, but should be easy for you to find with Google).

Speaking of Cyberflyer, what ever happened to him? Haven't seen him on the Forums in years.

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I remember seeing his flights too. Last time I talked to him he said he was still flying but not posting as much. That was at least a year ago though. I found his site again, but didn't see much about his setups and equipment, at least the R/C gear.

Maybe I'll just stick with my current mile range and enjoy that for a little while longer, and work on other things that need attention, like my ground station, a video splitter, etc. People often say how cool it must be to live in the middle of nowhere like I do, with miles of nothing in all directions. Don't get me wrong, I do love it, but it does get boring flying around in the same little circle with all this terrain begging to be explored from the air! lol

Edited by KeithLuneau
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The record in Spain with 35mhz is 18km, and many users have made 10km without much problem. So I assume you could get 5miles out of 72mhz with a little bit of work optimizing your r/c placement fpv gear, cables, ferrites and so on.

After you do that you should try to use a 4x longer r/c receiver antenna, this usually improves a lot the quality of the reception. And after testing this mod and obtaining good results you could improve your tx antenna, on 35mhz many users have adapted 27mhz CB to use it with 35mhz, it´s not hard at all, but requires some technical knwoledge.

IMHO no amplifiers are needed almost always many times they are just a new problem, just improve your antennas and enviroment

I wonder too where cyberflyer is, was a very valuable member of this forum, he was the father of the FPV name right?

Edited by Wavess
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