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headhunter23

question about modding ar7000 receiver

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Hello, I've done a couple searches not just on this forum, but google and rcuniverse. Just a question about the ar7000 receiver for the dx7. Is it possible to swap the external antenna with a 5-6dbi circularly polarized patch antenna? Am wondering if it's possible to get more range outta the receiver. Not even sure if it's possible. Anyone see anything about modding spektrum receivers to change the antenna to something larger?

Ivan.

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Hi Ivan,

The problem with adding an aerial with gain is that it will only have gain in certain directions and the other directions will be even worse than the original aerial.

This is not good for a receiver as it usually needs to receive from all directions. Transmitters can use aerials with gain to good effect as long as you can be sure you can keep the plane is the beam.

This is the oppersite way round to the video links we use. but both ways you need an omni directional aerial on the plane.

Terry

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Hmmm... so adding even an omni directional won't work? Is there a way to boost the receiver otherwise then?

Btw your other suggestion is to change the dx7 antenna then to something that will have a wide enough beam to keep the plane in operation? Just making sure I understand you correctly.

Ivan.

Edited by headhunter23

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Thats correct, you can't get something for nothing.

I would forget boosting the receiver, just make sure the RX aerial gets a nice clear view.

Boosting the TX may be worth while if you are after long range only but is probably not legal.

Terry

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Boosting the TX power with a different aerial is easy, boosting with an amp is a little harder. Both will not be legal I suspect. Where do you live ?

Terry

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kanada eh? I'm sure there is something that says I can't do it, yet I would still like to know more about the two options. I'm only using this aircraft for going over unpopulated bush to scout rivers and lakes, specifically access to them, so I don't see how I could be affecting anyone eh?! ;) Heck I would be surprised if there was anything running 2.4ghz within tens of kilometers, even 100's in certain areas. Tis the only way to fish now, tons of places are just over fished here in Ontario, unless you like catching .5lb of anything besides carp, suckers and catfish.

Ivan.

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I'm only using this aircraft for going over unpopulated bush to scout rivers and lakes

Honestly, if that is your operating environment, then a 2.4Ghz R/C system is not going to offer any advantages. Regardless of any sane things you do to the AR7000, a high quality 72Mhz R/C system would offer more range. Just food for thought.

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That's what I've kept reading... So should I switch to a futaba 9c running on 72mhz? Was thinking of getting one and adding the 2.4ghz whutchyamakcallit to run my current receivers but put the 72mhz one on the long range plane. Would that be a good choice for 72mhz system?

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How much range are you expecting to get ??? Or needing ?

Edited by W3FJW-Ron

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I really do want three km range, the dx7 system seems to have a range of 1.2-1.5km. The 72mhz systems seem to over or around 2km. (could be wrong on numbers, have just been what I've read.) Anyways as posted in the rcuniverse forum I was looking for that range to check out bush between lakes etc. Where my bro lives it's completely bush and google earth hasn't updated the areas with high def maps, nor do I see them doing it in the near future.

I have been reading about the diydrones which are kind of an option, but would need to learn and read a lot more and test before flipping controls over to an autopilot,plus even more money. Also from what I understand I would probably need a larger plane, which I don't desire, due to landings and launchs. I guess any words of wisdom or forum suggestions would be helpful. Would have been nice to just swap antenna's similar to adding mr cams goofproofpatch etc to all the antennas used but that would constrict the flying from what I understand, but thought for any antenna's on the plane that they could be changes to omni directional higher dbi antenna's compared to the stock ones.

Ivan.

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Since it's not too practical to have gain antennas on the plane due to their size, the only option you really have is to put a good antenna up for your receiver. The path loss if I remember correctly and I can't figure it in db as it's been too long ago, but say let's use a 1000 meters as a reference for a power of 10. At 2000mtrs, you would have a gain of -5 or half the reference power, and at 3000 mtrs it would drop by another half to -2.5 and so forth. and that would be under ideal conditions. What I'm getting at, is you would run out of video range long before you run out of control range with the equipment commonly used.

If I'm wrong from not remembering this subject very well, I would appreciate comments to help refresh my memory. Not too much of that left as I'm busy exploring the other info and knowlege contained on this site..

Edited by W3FJW-Ron

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Are you sure I would lose video range? From what I've read as long as I have a good receiver antenna with the 900mhz .5w system I can have up to 5km. With rc'cam's goof proof I have the 3km from what I understand for sure. Or go with a yagi 14dbi which would be difficult to do without a second person...

Ivan.

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I really do want three km range, the dx7 system seems to have a range of 1.2-1.5km. The 72mhz systems seem to over or around 2km.

The link budgets for quality 72Mhz R/C are vastly better than the 2.4Ghz systems. In practice, I think your wilderness flight area should experience 5X better range with 72Mhz versus a similar system that uses 2.4GHz.

So should I switch to a futaba 9c running on 72mhz?

There are a few folks that have successful long range experience using stock R/C gear. Just poke around the various R/C forums to see what they are using.

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I think I've been searching, reading and asking questions since geez... october or november and to be honest I've never gotten a straight answer. Since a few of you have been essentially the fathers of aerial vids and now the emerging drones, what radio systems do you favour? Either a. store bought or b. custom? Bear in mind, not extremely heavy systems, just something that can fit in twinstar or cularis... so max receiver weight maybe a 100g or so.

Thanks.

Ivan.

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Ivan,

there is no easy answer as there are many ways to do it. A lot depends on you as you will be using it.

If you are just starting out and not into electronics much then I would say go for a good standard 72Mhz system.

What you are using now and how happy you are with it ?

Terry

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spektrum dx7 system with dsm2, I'm happy with everything but from what I understand the 72mhz would allow a longer distance. Although I really like the fact that I don't have to worry about others interfering or vice versa. Totally love that.

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If your happy with your dx7 then maybe you could look for a 500mW amp or try adding a 6dbi aerial to your TX. Remember that with the aerial you will need to keep it upright to get the range you want.

Terry

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No but there is no reason to think it won't work, you just have to track down a suitable amp. I have a tiny UHF amp that turns 100mW into 500mW but they don't have one for 2.4Ghz, maybe someone out there makes one and it will be easy.

Terry

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