Hello, im have a problem getting a proper range check with my radio system. I have a Futaba 9c (dont say it im not switching brands after 20 years, I do like their sevos though lol) the receiver is a 9 channel brand new less than 6 months old. receiver is at least 12!QUOT! away from fuel pump, solenoids and ecu. The antenna is run on the opposite side of all the servos leads and goes out the bottom of the fuse then run along a wing leading edge. With the Tx antenna collapsed I get about 45 paces with the turbine not running. Just a side note if I get a little too far away from the model with the tx annt collapsed and deflect the elevators, ( they are on separate channels 2 and 8) the one on channel 2 will deflect before the ch 8 one deflects. I dont know why this is happening. Some one told me channel 2 and 5 only for a two servo set up.

Back to the main problem, when I run the turbine up and do a range check I can only get about 10 paces away before I have absolutely no radio contact. One step in it works, one step out it doesnt. Im going to try a base loaded anntenna now. any suggestions thanks in advance John

Hi John,

Just one thing to try... You don’t make mention of the turbine used here, but some ECU's are not intended to be flown with the Data terminal attached. If that’s the case, try disconnecting after the start is complete it and see what the test result is... I'd try this before changing to a base loaded antenna.

Good luck,
Kelly

You say 'Tx antenna collapsed......' Try it w/ one section pulled out (IOWs, about 7" of antenna external). Then, you oughta get 600' min w/o engine running; not more than a 10% loss w/ all running. This w/ model at table height on a wood or plastic stand. And I apologize to Lee De, AKA Silver, if I got this at all wrong !

Ray

Try to do a range check with the antenna out of the fuse and pulled up like a base loaded antenna to see if you get a better range check.

I run Futaba and I'm also not changing, I also like the JR servos, my radio is a 9C and have the same receiver. I haven't had that problem before, just yesterday I did a range check on my new Viperjet and end up with the turbine off, at 100 + paces ( I quit walking away ) with the the engine running, at 105 paces before the fail safe went on and stopped the engine, I'm running the base loaded antenna made by Dean's, this is the second time I get to use it on a jet with very good success and both install.

Here are some pic.

get a wip antena

HUmmmmmmmmmmmmmmmmmm. This is a head scratcher for sure. The turbine is an artes 50 bee. the battery lead for the ecu does run parallel to a section of the antenna, but I shielded it with aluminum tape ( I think) It may just be the location where im performing my range check, (street 4 lanes plus median in an industrial park area), do you have the one piece deans or the two peice. I have a deans 2 piece and a revolution one piece in my posseion that I can try tonight. Yes when I pull up the first extension of the Tx antenna the problem go away, but I did not try a range check with it up. I will try that just for kicks. Thank you guys for the ideas. I will try and post a pic of what I have going on in the fuse. DelGato my bird is too pretty to put a toy looking whip on it, so that option is out, ive thought about that though. John

We have had some guys at our flying site off load their gear and put there plane or jet together in the pits next to their car or truck. They then try to do a range check with everything right there in the pits and then can't figure out why they can't get 40 ft of range. You have to make sure your aircraft is away from the cars/trucks and other items like metal canopy's/EZ Ups to do a proper range check. As soon as they move the plane out into the taxi way and away from the heavy metal, then they get good range checks. If your in an area that has hydrants and metal street lights with your aircraft in the driveway next to the car, you won't get a very good range check. Just a suggeston.

Very nice looking jet!

RH

Thanks I will try that. here are some pics of my intsall, its not the best but.........not much room.

I have the two piece Dean's antenna, at the joining pin I put a piece of shrinking tube to stop it from separating in case I pull the cables by mistake and I hold the antenna cable against the airplane skin by gluing a piece of fuel tubing cut in half with ca, you can see it in the previous pictures.

Nice airplane.

Band new means nothing with any type radio.. in fact they are nothing but big question marks! What is your Baseline range..ECU un-plugged.. just receiver and servos operating? Airplane up off the ground >< 3 feet, trans ant. @ 7 inches. You should be able to walk out about 200 paces (600 feet) IF not your NEW receiver or transmitter module is poorly tuned and or weak.

With turbines we must start out with a normally strong RF link! Then after you know your rec or trans is not in question.... Begin the powered up checks changing rec. ant location & type for the least lost distances. Do not fly with more than a 20% loss in range between powered up & Baseline. Nothing wrong with a 10% standard of loss between powered up & Baseline.... but a 20% degradation is safe to fly with.
Lee

I'm not sure why; but, Futaba does not recommend base loaded antennas. Sometimes it is a pain to run the standard antenna wire but I do it because I'm not educated on the risks. Why does Futaba not endorse any other way?
Chris

Thanks Lee and Chris for the info. I will check it out with all those things in mind and post the results in a few weeks. Thanks John

Not only does Futaba NOT recommend base loaded antennas... the last time I checked they will not tune & align one to your receiver even if you are willing to pay for them to do it. My guess is they won't do the conversion nor recommend it because Father / Mother Futaba says nope!

The loaded antenna's really have little advantage over a full whip or creative routing of the original wire antenna, other than being an easy way to get the antenna out of the fuse. The fact is if you do a good range check after installation.... use the type that works best! Generally the loaded type antenna will work fine if it is tuned & aligned properly to your receiver. Routing the wire antenna out the leading edge of the wing is a great way to conceal the wire while at the same time getting it out of the fuse area quickly.
Lee H. DeMary
AMA 36099

Thanks Lee. The wing leading edge worked great on my Boomerang so I'll keep trying to use that.
Chris

Jedi,
Take your jet to a wide open area to range check it. I did the same as you and ranged checked a model in an industrial park area and could only get 5 paces (15-20 ft) before lockout. I took it to my local flying field and I got 200 paces (600-650 ft) and still had control. I think your surroundings might be causing your problems. I was using a Futaba 9Z at the time with the biggest section of antenna only extended.

patrick

I will check it out this weekend in the desert, (nothing around) thanks guys for your input

The biggest thing around is the ground.... remember 3 feet above the ground or pavement surface fairly well gets you out of most ground effect. Doing range checks with the aircraft on the surface / ground for the most part is a waste of time. The effects of being close to the ground can sometimes increase or decrease the measured distances a surprising amount. Approx 3 feet above the ground neutralizes most ground effect but at the same time doesn't increase the range like 10 or 15 feet above the ground would.
Lee H. DeMary
AMA 36099

I fly Futaba and I would recommend sending the radio back to Futaba and asking them to check the tuning of the radio. I do this whenever I buy a new radio (and also test fly it in another cheap airplane) and I also send all my radios back annually to be tuned. I think it's an easy way to ensure a good RF link along with range checking each time I fly.
With my plane on the ground, I get no less than 120 (120-140) pases with the ECU plugged in. Initially I checked it like Lee said to, and I'm glad I did.

Good Luck

Does anyone know if there is a capacitor between the pos, and neg. wires on turbine fuel pumps to reduce RF noise. This i know is done in RC Cars. I cant see the end of the fuel pump on my Artes as it has a heat shrink cover over it. thanks again.

The radio works great in all my other models.

i have a jr pcm 9x and 900s pcm reciever. Im running a twin elevator servo setup and when im findng that just before failsafe kicks in, both servos are NOT moving in unison! Can one channel be out of sync with the other, or can one channel be going into failsafe before another channel does?

Secondly at the field the other day, i could only get 12 ft away with the model 30ft from the flightline with other transmitters on. If i moved the model 100ft away, i could get about 150ft away before failsafe occured.

Take a look at this info.. spark surpression from Dr. Robert Suding

The first picture shows a SPEED 600 motor with the spark surpressor on it. The two inductors are each 18" of #22 enamel coated wire wound on a 22K 2Watt resistor. The resistor value and the number of turns are not that important. A .01mfd 100v or higher disk capacitor from my junque box is soldered across the voltage input lines, and an pair of .01 disk capacitors are across the motor terminals with the inner leads soldered to the motor frame.

The 2nd picture shows the oscilloscope pattern taken without the filter. Notice the short little pulses that occur when the brushes loose contact as the motor spins. I did not measure the frequency, but I am sure it contains 36 MHz energy that would reduce your jet's effect range.

The 3rd picture shows the oscilloscope pattern after I attached the filter as shown in picture 1. Notice that the short spikes have completely disappeared. But be sure to verify that you have full range by turning the motor on and off while someone holds the airplane.

Robert W0LMD

I will assume you had the transmitter antenna fully collapsed or removed. I'm not familiar with the 9x transmitter configuration does the antenna come off or just collapse completely. Either way 150 foot range is very poor. I'll also assume the other transmitters antennas were fully extended. From the information you've given us it sounds like you've got a transmitter module & receiver that need a serious tuning & alignment.

With proper receiver / transmitter tuning you should be able to have other transmitter antennas 1 foot or closer to your receiver antenna and be able to get at least 10 - 15 feet away (NO antenna on your transmitter) before failsafe occurs. I call that test a swamp test... your swamping your receiver with full power R/F at close range. This check is a good way to know quickly if your receiver is tuned and aligned properly for sideband rejection. In fact this test will quickly cull out bad receiver / transmitter over all tuning & alignment.

A 1 to 10 ratio is the minimum that I consider acceptable. The very best receiver / transmitter combo's that I have seen you can walk out just about 30 feet with your receiver antenna wrapped around the interfering transmitters fully extended antenna. I tried this swamp test with a 2.4 gig Spectrum radio and found the R/F link is unaffected during the swamp test.

I'll bet your receiver will not pass the swamp test at all. Your failsafe distance is 1/2 of what it should be. Send your radio back to the Service center and tell them not to send it back until it will pass a swamp test and have at least a 250 foot range check. Actually the best way to do the range check is to have your transmitters antenna adjusted to 7 inches extended. At that antenna length tell the Service Center to tune it up well enough to get at least 570 feet of range.

NOTE: Quality control these days is really getting poor.... I would not trust any brand of new radio until it passes several tests. Vibration, temp, swamp, and of course a good range check.
Lee H. DeMary
AMA 36099

im going to do more checking today, but i also tried swamping checks. I left my jr 3810 on ch 72 ( im using ch 73 on the model) beside the aircraft and could ony get 12ft away. I could get further if the aerial was actually left lying as if it was within the wing! Any other posn wouldnt work.

Silver, so if i can get 30ft away before failsafe occurs, with the interfering tranny 1ft away from the model, is that a good check?

I was considering buying a JR synth module. Would that avoid the need to get tuning/alignment done by JRs service centre?

Not 1 foot from the model... 1 foot from the receiver antenna, parallel and or angled any relational position from the receiver antenna for the interfering trans. For the trans & receiver being checked the minimum is 10 feet, if you can get more than 10 feet away with your transmitters antenna removed / fully collapsed and with the interfering transmitter at full power, i.e. fully extended antenna and 1 foot or closer to your receivers antenna... then your sideband rejection / receiver blocking circuits in that receiver are tuned and working properly. Actually this test also checks your transmitters module for normal output, because it must be fairly strong to pass this test failsafe free. Obviously if you can get 30 feet away and or closer with the interfering transmitter all the better.

Keep in mind this swamp test is just a quick and dirty way to cut the wheat from the shaft...so to speak. When you get the feel of this test you can check many radios out in just a few minutes. You rarely will find any two with the same exact results. The swamp check does not take the place a proper range check especially with all on board EMI / RFI devices operating in your airplane. The swamp check just tells me if the transmitter & receiver are worth wasting any more time on.

You can buy the Synthesized transmitter & receiver modules JR, Futaba, or for that matter from any manufacture... sorry to say NO that doesn't insure a good R/F link. Buy whatever you like.. but you still must check them out. Actually the Synthesized modules must also be checked out on several channels as the range will vary from the low channels to the higher ones. Fact is I check my synth R/F modules out completely on whatever channels I plan to use.

One year at Superman I changed channels 3 times to find one no one else was on... each time I change channels I did a range check ECU operating to make sure it was OK.

NOTE: I have checked out three different JR Synth transmitter modules and have found their output to be higher than the crystal controlled versions. Why I'm not sure.. just noting what I have observed.
Lee H. DeMary
AMA 36099

I'm using a Futaba 9CAP radio with a Futaba R149DP receiver in my Reaction54. I had the same issues until I purchased a Revolution whip antenna and the problems went away.

My 2 cents...