Glowire/elwire interference?

[Michael211_2000]

Question... 2 years ago at my club's annual "night-fly" (www.Jetero.com) one of our members was trying the glowire/elwire for the 1st time on his airplanes and had heck with it. :censored:

The plane was using a 72 mhz Futaba radio with 2 inverters and when activated on the ground it would pass a range test, but as soon as it was airborn he'd start to lose control of the plane... rf interference. He gave up after 2 attempts with 2 different ariplanes that night. This past November he returned with the same planes and glowire but using a new 2.4 gig radio system and flew them with no further problems. He swore that the inverters were wreaking havoc with his 72 mhz radio equipment previously though! :censored:

So now I have a small electric heli setup with glowire (1 inverter, 2 strands of 5 foot wire) and am using 72 mhz and hovering up to 100 feet away I'm not having any problems with rf interference. This 400 sized electric heli has the long antenna lead all wound round and round the landing skids on 1 side... ergo I'd think it is a worst case scenario and would be prone to any nearby rf interference (about to change to a base loaded whip antenna though). :confused:

So does glowire/elwire cause rf interference on 72 mhz radio equipment or not? Or does "mileage vary" depending on the inverter used? I doubt I'm using the same inverter my fellow club member was having so much trouble with. :o

I intend sometime this summer to finally make the break and go 2.4 gig as well, but mostly to eliminate the frequency pin conflicts I've experience with other club members who are on my same channel at the club field (grrrrrr! :censored: ).

Thanks for you input.

- Michael

[GallopingGhost]

I have 2 3 ft runs on a foamie with a 72mhz Corona Rx and have had no problems at all. To make matters even more suspect I have a Rubber Duck TX antenna. Still no problems.
The Heli guys seem to be ok with it as well.
I like the 2.4 stuff for a silly reason, the tx antenna doesn't get in the way with close in 3d flying.

[Michael211_2000]

Holy Chit! That's what I'd call EXTREME 3D if you're that close!!! LMAO!

Just be careful not to cut something more important than your antenna off... fingers, nose, maybe put an eye out I'm thinkin. All machines have the potential to fail and I sure don't want one anywhere near me when it does!

Thanks for the info otherwise.

ps. What's a rubber duck antenna? I sure hope it's not like the little yellow bathtub rubber duckies I've seen! LOL!

- Michael

[GallopingGhost]

Holy Chit! That's what I'd call EXTREME 3D if you're that close!!! LMAO!

Just be careful not to cut something more important than your antenna off... fingers, nose, maybe put an eye out I'm thinkin. All machines have the potential to fail and I sure don't want one anywhere near me when it does!

Thanks for the info otherwise.

ps. What's a rubber duck antenna? I sure hope it's not like the little yellow bathtub rubber duckies I've seen! LOL!

- Michael

Rubber Duck is actually the real name for a product! Its a base loaded flexible TX antenna for MHZ use. Hobby Lobby sells one too that is yellow but not flexible. They call it a PowerStick.
I have nearly hit my TX antenna on several occasions! I can't dump all my 72mhz stuff with long TX antennas but I would like to.

[BEC]

EL inverters are notorious for throwing off RF noise. Where they are relative to the receiver and what receiver it is are critical. I've had mixed results in different airplanes over the years.

How they're powered and whether that's tied to the radio system power in any way is also a factor.

[Michael211_2000]

Well, on my electric heli the inverter is tied directly to the main lipo battery (via the male deans connector). I don't think you could run the inverter from the receiver power as it wouldn't have enough volts to power up the glowire.

The guy with the airplane who had so much trouble with his glowire was using 9V battery powered inverters (2 of them, each with their own 9v battery). What was really strange was that it range tested just fine on the ground with his tx antenna down, but when he got it airborne and got a little ways out the plane would just start wondering around on it's own (intermittent r/f link). However the plane wouldn't dive or do anything crazy suddenly, it was more like the r/f link was just dropping out completely for a second or 2 every 30 seconds or so... so he was able to get it back on the runway and land relatively safely, but he obviously decided to stop flying it that night.

He's since changed to a 2.4 gig radio system and flown it successfully. However my thoughts are that he must have had some other problem with his 72 mhz radio system because (as I saw it) the plane's r/f link wasn't so much as being interferred with as simply dropping out intermittently in the air. I don't recall if his ground range test was with the nitro engine running or not... I guess he could have had a short somewhere in his radio system that night and the engine vibrations were making it lose r/f link and/or radio system power. As I said, it passed a ground range check with flying colors, just couldn't fly with it. And this gentleman is a very experienced flier/builder.

With my small 400 sized electric heli with an inverted mounted on the side of the frames (around 2 inches from the antenna which is on the opposite side of the heli frames) and a full length 72 mhz antenna which is wound up between the landing skids I'd think this a worse case scenario yet I'm not seeing any r/f interference and have flown it beyond treetop level with no problems (100 to 120 feet at least). I'd think that if the inverter were to cause any problems I'd be seeing 'em. Like all inverters I've come across this one humms to itself the entire time it's powered up.

Thanks.

- Michael

[rkopka]

I made the same observations. The inverter was connected to the main batt and no chance to fly. I then added capacitors directly at the 12V input of the inverter and the problems are gone.

RK