rcpete347

My Feedback: (251)

HI all, need some info, when 2.4 came out , serval years ago, It was said, their might be some issues useing anolg servos. I can remember, changeing out some mini sevos, for digidal servos.
Fact or myth
Rcpete

Randy M.

My Feedback: (38)

I believe it's likely due to the higher voltage . i've used hs635, 645 etc with no issues. With 2.4 needing at least 6v, some of the analog stuff just don't handle it well. could use an in line regulator if you need to mix them in.

FenderBean

Some of the older slower servos may have a hard time keeping up to the faster resolutions, when I went from a 9c to my 14mz I had to learn over again due to the increased speed on response.

SECRET AGENT

My Feedback: (18)

Airtronics had issues with analog servos if you used their higher resolution receiver, they resolved the issue by offering a slower resolution receiver if you wanted to run analog servos. (I fly Airtronics) I never had any issues with Futaba or Spectrum receivers running analogs and have no experience with JR.

Ron Stahl

My Feedback: (12)

Myth, what you have to watch is like Randy said, running the higher voltage that Spektrum and some others requires to avoid brown outs. I lost two JR. retract servos on my Electra until I put a 5 volt regulator inline for that channel only, problem solved. The servos are getting pulse width commands from the RX the 2.4 RF link has nothing to do with it.

Len Todd

As I understand it, digital servos can operate in parallel and analog servos operate sequentially. When each digital servo operates it can take over an amp up to 5 amps. When several Digital servos are operated the current usage is cumulative (i.e. 8 digital Servos could simultaneously draw as much as 40 amps, etc.) This caused a higher (higher than with analog servos) load on the same power supply as the Rxer. If the high load caused the voltage to drop below 4.3 VDC, then the Rxer would go into the condition we called brownout. Once the voltage recovered, the Rxer would recover. This problem was exacerbated by the people still trying to use the old 4.8 vdc NiMh packs (i.e. this low voltage pack had insufficient margin to even handle a couple good sized digital servos.)

Is this maybe what you were asking about?

RBardin

My Feedback: (27)

I remember when everyone started converting to 2.4, most of the small analog aux. servos like JR341s and 351s had a nasty habit of briefly travelling full stroke when powered up on 2.4. If you had one on your gear valve, you could find your jet unexpectedly dropped on the pavement because of this. Airframes with externally mounted turbines sometimes got dings on the bottom of the turbine cans when that happened.

So don't use any old analogs on a pneumatic air valve with 2.4!

Delta Mike

My Feedback: (18)

Interesting, I have a mixture of digitals and analog servos in my DV8R for the past 7 years, 300 plus flights with no issues. Spektrum RX using A123 unregulated batteries at 6.6 volts.

7 analog servos
4 digital servos

Boomerang1

Using an 18MZ & my analog Futaba & Hitec servos buzzed continually & started to get hot.

You can choose the resolution in the setup, once set to the lower setting the problem disappeared.

Also had a problem with digital & analog servos sharing a Y lead with the Futaba 14 channel receiver
on the first 4 channels. Solved by just using different channels & mixing them together.

Fact, there are some issues.

My experience? The issues can be simply overcome. That's for Futaba, can't speak for the other radios.

John.

Bob Paris

My Feedback: (13)

Hi Guys,
I run Airtronics gear, both -1 & -3 receivers with Analog servo's with out any issues. I use HD1501 MG, Airtronic 94102 and 94322 servo's on all my models now, with both -1 & -3 receivers with out any issues. Some say that -1 Airtronic Rx are for analog servo's and -3 for digital. But I've had no issue with the HD1501MG servo's on either Rx. All my gear is 2.4 and I made the transition several years ago, with my 72 meter gear stated to act up at our flying field. I was flying Ch. 38 with my old gear and when the new cell phone towers went up...it created havoc with my models. I do not use digital servo's and my choice after seeing to many models self destruct using them at our flying field.

Aloha,
Bobby of Maui

dbsonic

My Feedback: (3)

rcpete, please cite the source of that notion. The RF section, modulation and center frequency have nothing to do with it.

Now, Futaba 2.4G RX, R6208SB for example, only state analog cannot be used in the high speed mode(intended for higher resolution when using digital servos). They recommend running in normal mode for analog. Perhaps something like this gets taken out of context leading to that notion about analog and 2.4

And then the choice of supply voltage is separate matter. It is well known that some old Futaba servos were rated for 4.8v only and documented as such. Most others up to 6v. I dont think I ever saw specs to 6.6v or beyond until HV came along but people run them successfully on LiFe anyways. 10% overvoltage may be within the characterization window.

Dave Wilshere

if your digital servos can draw 5A you have big issues! 40A total!! The Rx would blow to pieces...

4.8v batteries are only at 4.8v when they are completely flat, they charge to 6v and operate happily around 5.6-5.7v. It's why JR '4.8v' servos are happy at 5.8-5.9v, it's the voltage they were designed to work at!!

its how the servo motor is powered/controlled that makes the difference between digital and analogue servos. Manufacturers have different ways of doing this in both types, some cope, some don't.

Meesh

My Feedback: (135)

I have a Futaba 12Z on 2.4 with a 14channel receiver. Use Hitec Digitals on rudder, elevator and ailerons. Hitec 645MG on Flaps and Steering, dual A123 6.6v packs without regulators. 2 Jets set up the same way. One has an Orbit Power Jack, the other a 12 channel SmartFly. Never a problem.

SECRET AGENT

My Feedback: (18)

My experience with Airtronics high resolution was the digitals were happy as clams but the analogs were freaking out, jittering and moving all over the place. Once I replaced the receiver with the lower resolution one everything calmed down. There is even an addendum to the Manuel that addresses this issue. Not a myth at all, just painful reality.

basimpsn

My Feedback: (5)

I almost lost my hotspot after switching from JR9303 72 MHz (100 flights) over to 2.4 futaba. HS running all Hitec 645MG. First flight on the HS with 2.4 the jet was all over the place...landing gear going in and out during flight. found out the Hitec 645MG would be ok then suddenly glitch full deflection and go back to normal. replace them with JR and it's ok.

rcpete347

My Feedback: (251)

HI all, the reason I brought this up was, when going over the Bandit, I noticed JR 2721 servos for the flaps. They have never been a problem, very quiet little boys, just doing their job.When I think about it, the JR 1221 receiver/ PB is in all my jets, and never a problem with Hitec minies for gear/ smooth stop.
Rcpete

Shaun Evans

Hi,

I just built a plane with ALL analog servos using DX-18. No problems at all. Am I going to be in trouble on the next flight?

flycatch

My Feedback: (26)

What ever happened to ops checking all equipment prior to installation? I just experienced a Hitech servo failure on the bench.

basimpsn

My Feedback: (5)

I would check and double check

ravill

My Feedback: (11)

Multiple JR 2721 and Futaba 300X servos without any issues.

Small JR servos and the cheaper Hitec servos I've had fail. But I'm not sure that was due to 2.4 vs 72 Mghz.

Those 2721's are some diehard tried and true servos. I wouldn't hesitate to continue trusting them.

Shaun Evans

Wow.

First I'm hearing of there being any issue with 2.4 and analog.

Bob Paris

My Feedback: (13)

Aloha,
I'm also building a large gas twin engine (AMR) model and bought a V2 Spectrum 18 channel radio for the model. I am using HD1501MG servo's on this model as well as Hitec 225mg's for the throttles and 85mg's for the choke control. So far, I've not witnessed any problems. I'm using Spectrum Rx's for 18 cannels I'll need for the model. Electric start takes up two channels, choke two, throttle two and engine cut off one. I'll also have one channel for my Twinsync with the new electronic ignition module (it does away with the old electric pick up system they used - no more magnets and pickups - sold by Down and Locked).

I've tested on the bench the whole system with no issues. I'm also using a Servo Power Box, to drive my flight controls - ailerons, flaps, elevator & rudder - with a yaw dampener tied into my Rudder.

This now kind of confuses me and wonder if I made a mistake with my servo choice. All the servo's I selected for this project I've used before, for years with out a problem. The HD1501 servo's have never failed on me, the Hitec HS225HD are powerful for their size and will drive the throttles with ease and the choke servo's HS85MG's will drive the choke functions-on/off only.

I guess I'll have to wait and see what happens, but if anyone is using the V2 Spectrum 18 channel radio with these servo's and have issues, please chime in and let me know.

Soft Landings Always,
Bobby of Maui

dbsonic

My Feedback: (3)

I agree with what Dave is saying. However, manufacturers are quoting nominal voltages/potentials when they issue these voltage specs.

drac1

My Feedback: (4)

I haven't had any problems with JR/Spektrum 2.4 with analogue servos.

I have a model with all older JR analogue servos and 2.4, using unregulated LiFe's. No problems at all.

drac1

My Feedback: (4)

I have had a problem when using 2 X Hitec servos on ailerons and the rest JR. They didn't like each other and the model started rolling and wouldn't stop untill it hit the ground.

The first and last time I mix brands.