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ssassen

Lawmate 100mW 2.4GHz Tx antenna direction?

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Alright, here's the question. I built a small camera-Tx module, using a uncased KX-131 and a Lawmate 100mW 2.4GHz Tx both powered off of the 5V BEC from the ESC. The Lawmate comes supplied with a rectangular PCB which acts as an antenna of some sort, basically a PCB with copper planes on it, I'm however unsure as how to direct it for best possible reception down below.

The below noted image illustrates how I've mounted it onto one of my smaller planes, this is using a neodynium magnet on both the camera-Tx module and the fuselage of the plane. I have the antenna pointing downwards, but would it not be better to have it pointing up? Or maybe I should replace it with something else completely?

12100.jpg

Also, as an fyi, this Lawmate module also has a ~340 ohm input impedance for composite video, as mentioned in a different topic.

Cheers,

Sander.

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Be careful with that antenna, the coax breaks before you even touch it...

On mine the ground braid was broken right after the solder point on the TX. I only noticed it when taking the TX apart to take the photos in the other thread.

I've never used that TX much as I had poor range with it. But maybe the coax was already broken when I tested it in flight a few months ago...

Edited by Kilrah

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Is that thing to the left of the camera the antenna? Because it looks like it's laying flat. BTW, powering the camera and Tx directly from the ESC's internal BEC is NOT a good idea. Those linear regulators are already very small and can just barely provide enough current for the onboard servos without burning up. I would suggest using either a separate battery for the video gear, or using an additional external regulator to power the video gear.

edit: Do you have anymore pictures? Looks like an interesting plane.

Edited by twinturbostang

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BTW, powering the camera and Tx directly from the ESC's internal BEC is NOT a good idea. Those linear regulators are already very small and can just barely provide enough current for the onboard servos without burning up.

Quite a lot of the new ESCs actually have switching regs that can supply in the range of 3A.

BTW it's pretty interesting how those slipped in the market without being noticed after all the bad that had always been told about switching regs in R/C. And if we can hope the first major makers have designed them carefully enough for that use, I'd be much more skeptic about all those who follow just to "be in the trend" like the no-name chinese makers. What I know is that the cheap no-name ESC with switching BEC I got with my small heli does manage to give me glitches at 50m on a RX that usually gives good results...

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Quite a lot of the new ESCs actually have switching regs that can supply in the range of 3A.

Haven't heard about that. I've seen some of the Castle Creations ESC's advertised w/ 3A BEC's. But I just figured they were using bigger linear regs than previously used. Still though, for maximum reliability, I think I would use an external one.

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Bigger wouldn't do a thing. It's the heat a linear reg going from 12V to 5V -AT-3A has to dissipate that would be enormous. You'd need a big heatsink in the airflow just to get rid of it.

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Twin,

BTW, powering the camera and Tx directly from the ESC's internal BEC is NOT a good idea.

Don't worry, I'm an EE, so I put some time and effort in to make sure it works without any heat related issues. It is run off of a 2S LiPo, so the ESC is able to deal with the extra heat. However the question on how to orient the antenna I have yet to see answered, nobody has any suggestions?

As for the plane, that's a design of my own, more here if you're interested (text is in Dutch, sorry) it is made from EPP foam and Depron.

Felix Extreme

http://www.modelbouwforum.nl/phpBB2/viewto...p=867771#867771

12079.jpg

Cheers,

Sander.

Edited by ssassen

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However the question on how to orient the antenna I have yet to see answered, nobody has any suggestions?

My normal setup would be to point it out the bottom but on your plane I would have it direct from the camera/tx pointing up.

Terry

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I used a Castle ESC as a 5v power supply for a 400mw lawmate, camera, osd, gps yesterday for many hours. I used it out of convenience because i couldnt be assed getting the 3A IF psu out of the other plane lol.

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Don't worry, I'm an EE, so I put some time and effort in to make sure it works without any heat related issues. It is run off of a 2S LiPo, so the ESC is able to deal with the extra heat.
Ok. Well besides making sure it has the capacity to run the extra gear, the other issue is possible interference problems by sharing the same source. But it sounds like you've got that under control.

As for the plane, that's a design of my own, more here if you're interested (text is in Dutch, sorry) it is made from EPP foam and Depron.

Very nice! Did you do all the foam cutting? Looks very clean.

Edited by twinturbostang

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I used a Castle ESC as a 5v power supply for a 400mw lawmate, camera, osd, gps yesterday for many hours. I used it out of convenience because i couldnt be assed getting the 3A IF psu out of the other plane lol.

Oh my, didn't burn any holes in your fuselage? :o

Cheers,

Sander.

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