BJ CROW

I've started getting into jets and just finished the Starfire II. She's ready to get in the air but I'm going nuts trying to resolve my range problem! Eighty feet away and all servos go crazy with my antenna collapsed. I have a JR 8301 Tx with JR 9ch FM Rx and Hitec H225 servos except for a mini JR servo for steering.
This happens with the antenna placed outside of the jet and I just installed a brand new RX. I have a 6 volt battery which is needed to raise the torque of my servos.
I read the great thread earlier about John's range problems and the only other solutions I can think of is using a voltage regulator on battery pack or noise suppressors on servo leads.
I'm trying to reach Shaun E for some advice also. He's been a big help to this novice jet flier.
Any other ideas before I vent my frustration out on my poor, defenseless jet?
Thanks,
Bryan

JohnVH

My Feedback: (38)

Try a different battery, try unplugging one thing at a time like I did.

Change channels

Is this turbine powered?

BJ CROW

Wow, what a fast reply!
I have tried unpluging different servos but haven't tried a new battery. The current battery has been cycled and appears to be in good shape but replacement is worth a try.
John, luckily I don't have an ECU to worry about since my settup is OS .91 with Dynamax.
I just range checked again with TX antenna collapsed and RX ant. out of fuselage and with certain orientations of the TX (not pointed at RX), I can get the servos to glitch at only 40 ft.

Bryan

JohnVH

My Feedback: (38)

Try a 4 cell batt and see what happens.

I have never had any range problems ever, even using a 5cell before, except on the jet, but that will be taken care of shortly.

Steve Collins

My Feedback: (8)

Bryan,

I feel your pain. I just had an almost identical situation to yours. My servos would go nuts at only about 20 to 25 feet away. In my case, the plane is a BVM Ultraviper, BVM fan, engine, and pipe and the radio is a Futaba 8UAFS.

I tried everything and the problem defied solution. I tried three different brand new receivers, all the same make, model and channel and which were proven to have excellent range in other planes. Even tried a JR 10 channel PCM receiver on another channel. It got only about 10 feet away before the servos went crazy. I tried a different battery pack, isolated the switch, unplugged each servo one at a time, plugged them back in one at a time. Nothing worked. Next, I thought I had some excess length in some of the servo leads so I ordered new leads custom made to the exact length I needed. Still no help.

I failed to mention earlier that my servos are all Futaba high end servos and all of the servo extensions and Y harnesses are buffered and from Electro-Dynamics. The two aileron servos are digitals.

I have never discovered the source of the problem! But, I did discover a workaround solution and it is the only thing that worked. A friend of mine suggested that for one of the many range checks I bring along a long plastic tube. He ran the antenna through the tube and used some tape to hold the tube vertical. The next range check was amazing. 350 to 400' before the servos began a slight twitch. I had a couple of whip antennas that I bought in the anticipation that I might need them for my turbine planes so the next time we did a range check we had the receiver set up with one of the whip antennas. No noticeable change to the 350 to 450' range. I now have the whip permanently installed on the plane but it still bugs me that the source of the problem could not be identified. I have not flown this plane since being equipped with the whip antenna so it hasn't been proven 100% as the solution. First flight will be any day now(waiting on retract parts from BVM).

Steve Collins

My Feedback: (8)

Bryan,

I also forgot to mention that I used to have a Yellow ACFT Starfire with the exact same setup as my Ultraviper and did not have any range problems whatsoever. Same radio, same receiver, and same channel. Go figure.

rcs1313

BJ Crow,

When you try a new battery pack....substitute a 4 cell pack just for trial purposes and see what happens. If you read the thread you know that I had major problems with the 6 volt battery system. At least try it....let us know what happens with just this one change.....thanks

Rod

BJ CROW

UPDATE:

I tried a 4 cell battery in place of the 5 cell and there was no improvement. This is really frustrating because I've tried the same RX in my 1/4 scale aerobatic and the settup is rock solid!
The only variables I can think of in the Starfire is carbon fibre reinforcement(conducts electricity) and alot more servos. I'm using 10.
Horizon Hobby tech. said I may be overloading the RX but if I remove two servos(such as servos on a Y harness for flaps), the glitch remains.
Aptar,
I feel the same way. Hate to mask problems with a stronger antenna setup. With the antenna hanging out of the aircraft, I should definitely be getting good range.

Steve Collins

My Feedback: (8)

Bryan, The sum total of all of my testing proved conclusively that the radio setup is not the problem. Like I said, we never identified the exact problem but through extensive testing we removed the radio and servos and wires as having any part in it. It seems likely that you have already reached that point in the testing you have already done. Like I said before, nothing helped the range problem until I installed the whip antenna. Do the same test I did with the plastic tube and run you antenna vertical and see what happens to your next range test.

jlong34016

My Feedback: (1)

I had this problem on a roo with futaba digital servos. Problem went away when unplugged rudder servo that had a y harness and an extention. My solution was to put reciever in back so the digital servo leads were short.

Silver182

My Feedback: (2)

Have you had your aircraft mounted on a stand (non-metallic) which places your aircraft at least 2 to 3 feet off the ground . Try this with no other changes and see what happens. I have found placing the aircraft on the ground not only reduces the range, but more important produces a very unreliable and inconsistent range check. So mount it up 2 to 3 feet off the ground and do the range check again.

You also mentioned you have a JR 8301 Tx with JR 9ch FM Rx! I have found the only way to know for sure if you are getting a safe flyable range is to do the Fully extended transmitter antenna range check. There are so many different transmitter designs you can't compare apples to apples unless you do the full antenna check, besides that's the way you are going to fly it!! The distances are going to be greater so you will need a cell phone for you and your buddy. The perfect distance is 4 to 5 tenths of a mile! ( a cell phone or walkie talkie will not effect your radio) If you can get those distances you are OK. I have seen a Futaba 8UF PCM system go out as far as 8 tenths a mile!! Over 1/2 a mile is great to exceptional. Less than 3.5 tenths a mile or 1848 feet, and you've got something wrong! In an inert aircraft (No ECU, lighting systems,smoke pumps, etc., etc. ) if your range is less than 3.5 (1848 feet) tenths a mile means your receiver or transmitter is very weak!! They need realignment!!
Lee H. DeMary
AMA 36099

George

My Feedback: (57)

Hey Lee, I did your "swamp" test today with my new Rx and 2 different Tx modules. Both passed with exceptional range, but the brand new module blew the old one out of the water. Then I did an antenna down turbine off range check and got over 500' (tired of wallking) with no "lock-out". Now all I have to do is the antenna up, turbine off/turbine running checks and off I go.

Thanks for the great info. and real-world checks.

George

Silver182

My Feedback: (2)

Sounds like your doing it right ---------- one other thing that can be done to ensure a "Best case" RF link at all times is the use of dual receiver battery packs. Just plug two in with separate switches and turn both switches on before flight. Use a Y connector if your out of open receiver ports. On any port. A matched set of Batteries is nice, say two 1500ma packs or larger --------. What brand of radio are we talking about? Just curious --------
Good Luck
Lee ---------

George

My Feedback: (57)

I'm using a JR 8103 and 945s (dual conversion) Rx. Remember, I e-mailed off-line about my .5 mi. range check and weak Tx module?
I was going to do dual batteries on my Spot here shortly. My F-86 uses one 6V pack with Mini-Hobby's regulator. If I dual it out, will I need another regulator or do I just "Y" it to the regulator? (That sounds like a "not so good setup).

Thanks again,

George

Silver182

My Feedback: (2)

Probably the best way to dual your 6V regulated setup is to dual everything regulator switch and all ---------- I would tell you from my experience with my MIG you could dual it out with just a 4.8 pack and switch. The thing I'm not sure of is what effect that would have on your regulator??

My MIG is setup with one 4.8v 3000ma pack and a Duralite 6v 2400ma pack. The two differing voltages you would think might conflict. I've heard some say the 4.8 is going to draw down the 6v pack. Well so far all I've seen is voltage to spare ----- I have an I4C digital voltmeter mounted on-board and after several flights with both packs turned on, I haven't seen the voltage drop below 5.0 volts! All the while charging the ECU battery between each flight! ECU batteries need to be pumped up each flight I beleive!!
With the Jet Cat it is said don't make more than three flights before recharging the ECU pack, cause if it drops below 7.0v even during a voltage spike the turbine will shutdown. I haven't ever seen that happen, but I have witnessed a bad ECU battery that was so weak, during ramp up when the fuel pump was asking for more voltage the thing would shutdown and never complete the start sequence. I discovered what was going on because I like to watch the voltages and he happened to have an I4C in the same circuit as the ECU battery. I noticed the voltage drop quickly to 7v when the turbine was trying to ramp up! We changed out the bad ECU battery with a new one and "vola" the Jet Cat was back to it's old self again --------- started and ran like a clock!!
Lee ----------

jlong34016

My Feedback: (1)

i use an electodynamics isolator. it allows me to use a small 4.8 volt reciever pack and two 6 volt servo packs. This prevents servos drawing down voltage and locking out reciever(i have seen this twice with bad results).

Silver182

My Feedback: (2)

The isolator system in principal sounds good, I just don't trust anything between the battery and the receiver. Even a switch, thats why I use two totally separate ones.
Regulators, isolators, etc. may be OK I just like to keep it simple!! Your statement about the servos drawing down VOLTAGE is precisely why I use two receiver packs, and why I really like my Duralite setup! You put a 2400ma Duralite on line and your not going to see the voltage ever drop low enough to lockout a receiver. I did experience my first receiver lockout do to low voltage years ago. The D/F had 15 servos and at the time I only had one 2000ma 4.8 receiver pack, I learned a lesson from that day on ----------
Lee -----

I

TonyF

My Feedback: (92)

If you use two batteries of differing voltages without regulators, the batteries will "balance" each other. IOW, the system will draw off the higher voltage pack, until that pack's voltage is the same as the lower voltage pack. When the switches are on, the higher voltage pack will try to charge the lower voltage one, although the current flow is small due to the low voltage difference. With regulators, the system will still draw off the pack that has the higher voltage regulator, but it will not allow the two packs to cross-talk.

My usual system is two equal voltage packs with two equal voltage regulators. The capacity of the packs does not matter. If not using regulators, then two packs of equal type and voltage, again capacity does not matter.

My biggest reason for using dual packs is for redundancy, although there are other benefits. But if you are using a system that supplies the receiver and servos with separate power, keep in mind that the loss of a single pack will mean the loss of the model, unless you run redundant packs on each supply.

I also do not like a lot of stuff between the batteries and the receiver, but I have never heard of a voltage regulator failure, and using redundant batteries helps reduce that risk. I do not use or recommend the "battery backer" systems out there, I have seen problems with them.

BJ CROW

This is interesting.

I'm reading here that using a whip antenna (effectively raising antenna higher off ground) or raising model 2-3 feet off ground will improve my radio range problems and/or is the proper technique for range checking.
The radio manuals never recommend raising model off ground for range checking at their recommended distances. I wonder why.
One Rep. told me switching from JR PPM to JR PCM receiver will solve my problems and I've sent the PPM back for an exchange. Will the PCM just mask my problem or solve it? My understanding is that the transient servo "jitters" I get will not occur with PCM although the loss of signal during that time, remains. I guess it's still better to have neutral servos during brief signal loss than dancing servos while flying at 150 MPH!!

Bryan

JohnVH

My Feedback: (38)

I have been told that is wrong, PCM doesnt fix problems. They wont 'jitter' they just stop moving.
But with either your going to get a hit as I understand it.

jlong34016

My Feedback: (1)

No they do jitter. I was running a Futaba 9Z Syn. PCM with digital servos when i had my problem. Jumped all over the place.

Silver182

My Feedback: (2)

I'm reading here that using a whip antenna (effectively raising antenna higher off ground) or raising model 2-3 feet off ground will improve my radio range problems and/or is the proper technique for range checking.

Bryan, "Placing the aircraft in an inert stand that holds your aircraft 2 - 3 feet off the ground ------does absolutely nothing to "improve your radio range problems." All it does is place your aircraft up out of possible "re-bar, pipes, wires, anything else that may cause anomalies while your doing your range check. You must understand it is very difficult to have the same environment for testing so you can compare what I say you should get in distance, compared to some other quoted distances. The distances I have stated are just observations I've made over time. The (1848 foot distance with a fully extended trans ant.), is a distance I define as a minimum for any turbine powered model that I would fly or own!! That distance I would require regardless of type of receiver PPM or PCM!! No one person has an empirical magic distance. There are people flying turbines at over 200 miles per hour that could barely get a lockout free range check of 150 feet (JR Trans & Rec. antenna removed). One hundred and fifty feet (ant. removed) equals about 1320 feet with the antenna fully extended. And of course they had the model sitting on it's tires on a taxi-way! What they are doing is comparing other range tests they have done with other successfully flown aircraft. Not a bad standard for them as long as they stay consistent ----!!

Bryan, you have a good standard to work with, even if you don't realize it ------ if you can predictably find the range you are getting with a "known problem radio" you then know what won't work! In a way it's a measure that is good to know, because now you know for sure what is unacceptable!! I believe those guys flying with range checks of barely (150 / 1320) feet are living on the edge, to close to the edge for my pocket book ----------! The fact is you've proved the PCM / PPM thing, (see below) if I remember correct you said you were getting something more than the 150 feet, well you were using straight FM not PCM. They have been getting small Glitches all along they just don't "see them" the way you have.

I have quoted standards which I know will work universally and they are high, higher than most manufactures would ever think they had to set for every unit they sold!! That's why the distances they quote are much shorter than can be achieved!! Remember it's your 5 to 10 grand in the air not there's. If you crash because of a poor RF link you will never be able to prove it and even if you could you won't get any reimbursement from any manufacture. So work to get the best RF link you can because it's your time and money!!!!


My understanding is that the transient servo "jitters" I get will not occur with PCM although the loss of signal during that time, remains. I guess it's still better to have neutral servos during brief signal loss than dancing servos while flying at 150 MPH!! Bryan

The whole reason the radio manufactures came up with PCM was to shut us up about "Glitches" Shoot 25 years ago FM was new and supposed to be better than AM, well a Glitch is a Glitch is a Glitch AM or FM. Maybe FM was slightly better than AM cause it is not quite as susceptible to some forms of EMI. Then they were able to build in a NO movement reaction to a momentary Glitch. We call it PCM, they call it a God send -----.

If you really want to see the difference, between PCM and PPM ask your buddy with his new JR 10X to program in fail-safes in his pattern plane or Jet or racer and set fail-safe for a full throw command, lets say to an outside snap roll !! Unless he is very very confident with his RF link, and knows it's very strong, he won't do it !!!

The reason is with the JR 10X whoever wrote the software program removed the "time delay" to execution of preset fail-safe positions. The 10X transmitting to a PCM receiver will Glitch just like a PPM / FM, in the correct situation. If the RF link is strong you might not see it "Glitch to an outside snap roll very often" but if it happens to be he has a weak RF link, watch him do the "Glitch dance" kinda fun it a way --------.

Until just recently no one flying a turbine bird would ever program in fail-safe on the throttle channel to a shutdown position. They didn't want to take the chance of a "Glitch flame-out." I only did it a couple of times just for grins and then only with RF links that I new to be very very strong. Shoot now with the great new software from Jet Cat all of us are programming in fail-safe shutdowns because Jet Cat has given us the time delay back!!
Lee ----------

JohnVH

My Feedback: (38)

No, they dont. At least not on my 10X. You must have some other problems, when I get out of range they do nothing. If you get some feedback from another tx they will jitter.

jlong34016

My Feedback: (1)

On my 9Z futaba with digital servos and y harness to rudders and extentions to the elevons all servos jittered severly with antenna up and right next to the plane in my basement. Unplugging the four digital servos solved the problem. My solution was to put the reciever in the back of the plane eliminating the long runs. I have never used JR. The plane flys fine with this setup and range check is the same as all my other planes.