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RX aerials

Discussion about Tx, Rx, Servo's, Batteries, Chargers, and all the other things we like to talk about..
Moderator: VinceC
MDev
Posts: 160
Joined: 07 Oct 2018, 19:17
Location: WEYMOUTH

RX aerials

Post by MDev »

There was mention of keeping 2.4ghz aerials away from servo leads but with the FrSky Gr8X the aerials are short and channels 7, 8 come in from the other end onto the board. The result is less chance to get the aerials into clean air. I do get glitching when at short range.

I understand that the exposed aerials are shorter and designed for the RX, can other lengths be used on it to get them away from interference?

M
john greenfield
Posts: 497
Joined: 18 Mar 2015, 07:52
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Re: RX aerials

Post by john greenfield »

Futaba sells different length aerials to solve this problem. Actually, it is the same length aerial but on an extended piece of co-ax cable. It clips onto the aerial terminal on the receiver RX board so no soldering required.
I do not know if they will fit the Fr-Sky boards.
AEB
AEB = Aeronautical Energiser Bunny (with thanks to CW)
Barry_Cole

Re: RX aerials

Post by Barry_Cole »

FrSky sell their own longer aerials, they are available from T9.

They do plug on, but I think they may use 2 sizes of plug. Check with T9 before ordering.

Make sure your glitching is dot down to a dodgy servo. One bad one can make them all glitch. Been there done that.

:) :) :) :)

BC
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Peter Balcombe
Posts: 1399
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: RX aerials

Post by Peter Balcombe »

Yes, you will be pretty sure to have the RF link dropout with the Tx right next to the receiver due to swamping (overloading the receiver).
No problems when moved a couple of feet away.
My kit usually reports “telemetry lost” when the Tx is very close & recovers as soon as the Tx is moved a foot or so.

Also, always best to have the Rx itself away from the ESC in an electric power setup as radiated noise from the motor drive/BEC high power switching elements can break into the Rx circuitry, even if not directly via the aerials/front end.

Note that separate SBEC (switching BEC) regulator units may also generate significant RF noise - the ferrite ring on the output lead is there to reduce conducted interference, but it doesn’t stop radiated noise!

The noise power reduction is a square law effect, so doubling the distance reduces signal levels by a factor of 4.
MDev
Posts: 160
Joined: 07 Oct 2018, 19:17
Location: WEYMOUTH

Re: RX aerials

Post by MDev »

Thanks all, the point I was trying to get across was that the GR8X RX has different length exposed aerials (the unsheathed length is different, from a forum) and is designed so the only onboard software copes with this and due to the design of the board servo leads come onto it from both ends making it hard to get the short aerials away.

Yes I can get longer aerials but as far as I know the exposed section is also longer, Will longer length exposed aerials work the same?

M
Barry_Cole

Re: RX aerials

Post by Barry_Cole »

Frsky have been using 1/4 wave, 1/5 wave, and 1/6 wave aerials. I will check and see what you need. I have not used Ch 7 & 8 on these Txs yet so have not had your problem. If you take the aerials away to each side that should be far enough. Do you get glitching when you are outside.??

I will check about the aerials.

BC
MDev
Posts: 160
Joined: 07 Oct 2018, 19:17
Location: WEYMOUTH

Re: RX aerials

Post by MDev »

Thanks Barry, yes the glitching is when I am indoors, I’m not overally concerned it’s just annoying. The issue with the short exposed aerials and trying to distance them from the servo leads must be fairly new. I got one of the first ones, I think. Up till now I have brought the extended ones without the paddles for the other XR8 RX which work well even when I push them out through carbon fuses.

Yes I have seen your link to the longer GrX8 ones.
Barry_Cole

Re: RX aerials

Post by Barry_Cole »

Do you have florescent lamps indoors?. I used to get glitching in the workshop until I changed the tubes for LED ones.

BC
MDev
Posts: 160
Joined: 07 Oct 2018, 19:17
Location: WEYMOUTH

Re: RX aerials

Post by MDev »

Yes, but not on during the day.
Barry_Cole

Re: RX aerials

Post by Barry_Cole »

No, That is Daylight using, Electricity saving.....

:lol: :lol: :lol: :lol:

BC
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