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Electrical Noise onboard

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Hi, I´m thinking on lowing my electrical noise onboard but not sure whitch way could be better. My main idea is to use the o-scope to measure all VPK-PK and try to low them down as far as I can. But what about frecuencies? It´s it posibble to use the Scope to view the fundamental one and try to figure out if it´s getting on 35 mhz?

Another question I got in mind, which impedance is used in the futaba standar TX antenna? 50 omh?

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Spectrum analyzers sometimes come cheap on ebay

if you dont need the latest model.

Radio amateurs sometimes own one, and RF design companyes own alot of them,

if you know the right kind og people they can be lent or rent cheap.

Also to fully understand their use and to be able to fight noise the right way,

you need hardcore know-how, many years experience wil help you to win the fight.

you need to say what frequency band and what length antenna

on the futaba you mention.

on 35Mhz they are end-feed too short quarterwaves,

so there is mounted a longer coil on the board in there,

the antenna it self is hi impedance 150-250 ohm depending on length and coil value to compensate.

if you take away antenna and coil you get back to 50 ohm.

Edited by ThomasScherrer

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What you really need is a spectrum analyzers but those things are expensive.

Daniel

Sure the spectrum analizer should be the best, but expensive equipment too. I was trying to find some cheaper way to improve noise levels.

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I have found no way to test for problem noise apart from flying the plane and testing the range, change something and fly again. I aim to use good practice and avoid known problems.

Terry

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Is it possible to use the Scope to view the fundamental one and try to figure out if it´s getting on 35 mhz?

Sadly, an o-scope won't help much for EMI/RFI testing. The responsible signals you need to measure are not readily seen with such an instrument. As mentioned, this is the job for a decent Spectrum analyzer.

Spectrum analyzers sometimes come cheap on ebay if you don't need the latest model.

If it were only so easy. :) I'm more interested in a Network analyzer than a Spectrum analyzer. They are similar, but the Network analyzer will certainly have a useful tracking generated in it, whereas that is not always the case for the other. I've been watching ebay for a couple years looking for a decent model of either that has had a recent calibration. Because bench space is at a premium, the usual 25 year old massive beast won't work for me. There are a lot of fair deals in the $5K to $15K USD range, but that is beyond my budget. So, I am still on the hunt ...

I have found no way to test for problem noise apart from flying the plane and testing the range, change something and fly again. I aim to use good practice and avoid known problems.

Although my usual tests are done without flying, I agree that this is a great way to check for EMI/RFI noise. It is quite effective too, but not as convenient and absolute as using engr test equipment. But without a spectrum analyzer, and the experience to use it, this is not a bad way to test and resolve the noise issues.

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The emi noise you are refering to, is it for the radio control or the camera equipment..

For radio gear, I am using with extreme success , Fiber Optic servo extension.

http://forgues-research.com

Go to products, then to accessories, and scroll down , just diagrams but I can answer all questions, its my design.

Roger

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I've been watching ebay for a couple years looking for a decent model of either that has had a recent calibration. Because bench space is at a premium, the usual 25 year old massive beast won't work for me. There are a lot of fair deals in the $5K to $15K USD range, but that is beyond my budget. So, I am still on the hunt ...

Funny, looks like we're all looking for that killer deal on eBay, I guess that's just one of those things that'll never happen, an EE's dream so to speak. When I do win some money in the lottery though, that money is going towards equipment rather than a car or something, a ~2GHz scope and a ~10GHz spectrum analyzer have been on my Christmas wishlist for quite some time now :D

Cheers,

Sander.

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>a ~2GHz scope and a ~10GHz spectrum analyzer have

>been on my Christmas wishlist for quite some time now

change job ? and borrow equipment home for the weekend ?

for free ?

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change job ? and borrow equipment home for the weekend ?

for free ?

Are you offering me a job? biggrin.gif

Cheers,

Sander.

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a ~2GHz scope and a ~10GHz spectrum analyzer have been on my Christmas wishlist for quite some time now

I know what you mean. I have a TEK Spectrum Analyzer, which is good up to 21Ghz. It works great for measuring video and R/C transmitters, which covers a lot of ground for me. But I'm jones'n for a Network Analyzer of better caliber. Given the budget issues, I think I will just find a tracking generator for my TEK instead. But it would be nice to avoid the additional workbench clutter, so I still keep one eye on eBay for a killer deal.

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