RF issues on 35m

[terry westrop]

Here I am on this wild weather day to report my exhaustive testing on this 35m range issue on EP & those long extension leads feading the rear end servos. The ESC was disconnected throughout testing.

Coiled leads make little difference. 6v supply no change. JR PCMZ or PCMS similar results.

Aerial placement variable, but not successful. Whip aerial (boat type 300mm length) brill; until the model/aerial is pointed away from the Tx! It then reduces dramatically! (the ext leads are then between the aerial & Tx) I suspect the problem would remain with the aerial along the wingspan.

The longer the model/ext leads the worse the issue becomes, naturally. Small models, fine.

I am now out of ideas & will revert to servos mounted traditionally (inboard) using pushrods for the larger models. 2.4 is still my last resort of course.

Thank you all for your input & I hope that any other 'lingering' 35m users will benefit from this should they find themselves in a similar situation.

TW

[Chris Bott - Moderator]

Have you tried ferrite rings yet Terry? I can't remember?
If the issue gets worse, the longer the extensions, than it may be that they are acting as an aerial and bringing in interference to the Rx.

These should be placed as close to the Rx as possible to filter out any RF.

Pop ferrite into the search box on **LINK** There are clip on ones shown as well as the wrap round type.

Edited By Chris Bott - Moderator on 10/01/2015 12:00:24

[Simon Chaddock]

Terry

This might be of interest.

35 Meg radio (where the tape measure is). The elevator servo is on the end of the boom (glass fibre) and its lead runs inside its entire length 19" (480mm) along with the aerial (too be safe from the pusher prop).

This set up does seem to suggest that the proximity of the servo lead to the aerial in itself does not generate any problems. The radio range is substantial and certainly as far as you can practically see a 40" span plane probably helped by the fact a further 18" (490mm) of aerial trails out from the back.

Just to add the ESC is close to the radio as well but it all works.

[Dickw]

I also have used the aerial inside the boom alongside the elevator servo lead on a series of relatively high power 2m electric gliders over a period of 10 years or more without any problems on 35 MHz. That was with a mixture of Fleet and Mpx Tx and Rx over the years.

I now use 2.4 GHz, but that is because of the removel of "shootdown" risk rather than any problems with 35 MHz.

Dick

[terry westrop]

Hi there again.

Yes Chris, tried ferrites early on, clip on type, no difference.

& Simon; my little Loaded Dice 30 EP is comparatively short moment also, around the 18" & no issues! It seems problems occur when the lead length increase to around 24" or more. JR also perhaps....? However, that increase in aerial exposed outside of the fuz is interesting. Maybe I'll install a new, long aerial onto an existing Rx, just to see.

Thx again.

TW

[Allan Bennett]

Is there any practical way of bringing the tail servo(s) into/onto the fuselage to shorten their leads, and using carbon pushrods? You could check if that would work, without actually making the change, by unplugging your tail servo(s) and plugging in temporary replacements, taped to the fuse, with short leads.

It would have the added benefit of lightening the tail.

[john stones 1 - Moderator]

I can't offer any help Terry you have me puzzled, I use JR and have some models with leads just as long and aerial down the fuzz, the same in large wings...never a problem. Do's your tx have xtals or synethised ? I have known dirty xtals to cause problems.

John

[Chris Bott - Moderator]

Terry have you tried the receiver from the good model, in the one that's giving trouble?

A comment above reminded me that I did have one 35Mhz rx where the aerial copper inner had broken, while the plastic insulation showed no sign of a problem at all.

There could be other issues with that Rx too, maybe.

It also bothers me that this problem is present with the ESC disconnected. Does this mean that it's nothing to do with it being an electric model?

Edited By Chris Bott - Moderator on 10/01/2015 22:43:58

[Dave Hopkin]

Depends where the ESC is disconnected from, if its just disconnected from the Motor (but still powering the RX via a BEC) then its still producing RF noise, if its disconnected from the Battery and a seperate power source for the RX then its producing no noise whatsoever - Thats what I would try (if he hasnt tried it already) run the rig with a seperate battery for the RX and the ESC NOT connected to a battery, if the problem carries on you can discount the Motor/ESC - if it stops then it would appear you have your culprit

[Chris Bott - Moderator]

That's why I was asking really, Dave.

[Dave Hopkin]

Posted by Chris Bott - Moderator on 10/01/2015 22:43:06:

That's why I was asking really, Dave.

I know, I just thought I would translate it into non-mod speak....

[kc]

All 35 Mhz gear must be at least few years old now so could it have deteriorated?

[terry westrop]

Unfortunately I have covered all points mentioned here. I've been using carbon rods + inboard servos for decades on pcmz & s modulation without any issues whatsoever.

I have tried 4 various Rx, both Z & S type with PCM10 & PCM9XII Tx, all working perfectly when used as above.

I guess the very fact that I fly precision aero models still, tends to amplify any range issues when in flight.

ESC disconnected from the Rx; no lipo either.

TW