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Is metal to metal interference on 2.4GHz a real thing?


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Was it ever a real phenomenon anyway? I honestly don't recall anyone having the problem other than blaming a crash on some spurious ideas and guesses. During one of the panics about this back in the day, I recall trying to reproduce some sort of malfunction using various methods both at close and long range from a TX within a model and with a RX and servos set up on a board and never ever got even a twitch from the servos. The only reaction I could cause reliably was to run a metal  comb down the extended TX aerial and then that would give the servos a twitch or two but not the same thing at all.

If you're worried Andy, just electrically bond the metal parts together.

 

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12 minutes ago, Cuban8 said:

If you're worried Andy, just electrically bond the metal parts together.

 

Piano wire & metal throttle arm?

 

I'd go with one of these doodahs

 

https://www.ebay.co.uk/itm/Wire-Rod-Quick-Adjustable-For-RC-Airplane-Push-Link-Plug-Servo-Connector/274441989506?hash=item3fe6046d82:g:tR8AAOSwImBfIE8R

 

Of course one nut doesn't mix with vibration - add a locknut or use threadlock... Drop of threadlock on the set screw as well.

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Off topic a bit, but I would use a ball link. I don’t think 2.4 radio cares a jot about metal to metal interference, but IC engines do care about slop free linkages.

I can attest it did exist back in the day. I remember an entertaining maiden. Anything round half throttle, and it was near uncontrollable [extra type from memory). Full chat OK, tick over, twitchy. 
Turned off the motor off, landed it. Reproduced symptoms on the bench. Replaced the metal link, to engine metal arm with a plastic link. 
Never an issue thereafter. Met its end with an ill judged low inverted pass. When I dared to do such things.

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The only problem I have is that I have to trim quite a lot more off the cowl to allow the sleeve of a ball link or clevis not to catch when closing the throttle. This may however, end up being the only solution. I looked at bonding but this would add enough stuff to the mechanism as using a ball link.

I have personally seen metal to metal interference on MHz radio so this isn't an imaginary effect.

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One of those plastic links work. A way round any fear of failure, or slop, is to put a small spring in the circuit, closing the throttle. Removes slop, and if the plastic link fails, you get a dead stick. Not likely, or the end of the world.

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I'm not prepared to compromise on a throttle linkage and especially not on a pattern-ship. After a lot of trial and error I found a ball link that will fit on the inside of the arm which I had to bend slightly.  With a chamfer on the sleeve of the ball link I am satisfied I have found a solution that will work satisfactorily and I won't have to test the theory that metal-to-metal interference is a thing on 2.4.

 

Thanks for all the suggestions.

IMG_20210304_184219819.jpg

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I have never experienced any Metal to metal interference while using 2.4 but have experienced interference being picked up by the servo or the servo leads when placed at front near the ignition unit and making servos go wild especially at lower rpm. This is very similar to metal to metal interference we experienced when using 35 meg radio. I now fit the throttle servo further back away from the ignition system and use a plastic snake for the run . Never had an issue since . 

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Nigel,

 

The cowling would have been even tighter if I hadn't cheated with the dimensions and widened the fuz a few mm and the cowling won't even go on unless I remove the cylinder head first and the whole thing was made worse because the engine has an enormous heli carb.

 

A.

Edited by Andy Stephenson
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John,

 

It's an OS 61 RF which was sold off by Just Engines at the Sandown show a few years ago. I bought it for spares but have recently pressed into into service. I believe it was originally a heli engine but how a rear exhaust engine would work in heli orientation, I'm not sure. The prop driver doesn't quite fit as some of the keyed shaft is exposed and the thread on the shaft is only 1/4" as opposed to the proper aero version which used 5/16". It's a strange one at it has an aero head. I suspect they were bitzas put together from spares so they could sell them off.

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