rikhye

Just noticed lately my servos AIRTRONICS 94102 twitter when ever i turn on the rcver w/o swtictching the radio. they were fine earlier

Also is there any prefered way for the rx/tx switching pattern i feel the tx should be switched first on and then the rx and rx turned off and then the tx...what do u say?

MHawker

My Feedback: (16)

I have always been told to turn on TX then RX. And RX then TX to go off. You've got it right.

The twitching could be some tension on a servo. Do they all do it or just one?

bob_nj

My Feedback: (62)

Was the twitter noticed at the field or at home? I also agree with TX on first, and off last. Unless of course you are intentionally testing for interference_Bob

Chris 540

My Feedback: (3)

That is a common occurrence... nothing is wrong...

robert

I heard somewhere that with expensive coreless servos, they give a little jitter when turned on to check their center. I think that it was the FAQ page at www.futabarc.com
You should always turn on your TX first, then your receiver, and turn off the RX first, then TX, as if for any reason the engine should start up, your throttle will move and maybe go to full. I saw this happen to an electric once, when he turned on the RX before the TX, the throttle opened and it went full bore. It stopped in long grass, but if someone happened to be infront of the plane, it could have been bad.
Hope this helps.
Robert.

bob_nj

My Feedback: (62)

He made the statement that they didn't do that previously. Did something change

GMPheli

I have noticed that some of my FM receivers do this, and some don't. I asked before and was told that if an FM receiver is not receiveing a signal, the AGC is wide open, looking for something to lock on to. Due to variances in components, some will pick up extraneous noise and send it to the servos. Sometimes I would just turn the receiver on to check for interference.

Alan Angus

rikhye

i think it could be some abormal interference at home ... haven't noticed it on the field though. Thanks all

Rodney

Most servos will jitter if you have the receiver on and no transmitter on. there is enough rf radiation in the air that, with the automatic gain control wide open (which is what happens with no on-frequency rf is present in the area) the receiver sometime thinks it is getting a valid signal and puts out a command to the servos. That is why it is best to always have your transmitter on before turning on your receiver.

Ladyflyer

My Feedback: (2)

Normal. It is just stray RF noise. Without the signal from the TX the receiver will demodulate any spurious local RF noise and the servos are trying to respond. The main reason for turning the transmitter on before the receiver is to prevent the servos from fully driving to one extreme in the absence of a signal. The same reason for turning the TX off last. Not that any damage is likely, it is mostly one of those better safe than sorry things.

FCC

Sorry guys but this is NOT NORMAL. I lost 3 Hitec/Futaba servos with gear broken because of this problem and after that I switched to JR Radios.

The JR receivers are the only receivers available that don't show this supidity. When the Tx is off there is no way the servos will jittter because of any interference or switching and this beacuse of good circuit design.

Chris 540

My Feedback: (3)

OK..

I don't seem to have trouble with all of my Futaba controlled planes...

robert

Same here, infact, I know guys who had the receiver FLOATING on feul, and it still went fine after it was dried and cleaned. I noticed that you can get alot of interference when you don't have the radio on. Maybe its as simple as that. Try a range check, with and without the engine running, and if everything turns out fine, then there shouldn't be a problem. Also, make sure that there are know extension leads, or metal rods etc. running close to the receiver. If you have a nice clean set up, and the range check shows no problems, then I would say it should be alright. Are you using a Dual Conversion Receiver?
Robert.

Ladyflyer

My Feedback: (2)

The twitter IS normal for the NORMAL equipment you are running.
If you are concerned for your servos please reread my previous post and the posts by others regarding turn on sequence.
Once again it is common , normal and EXPECTED. I have seen it for the last 25 years . It would of course have to be very violent and extended to do harm.

Sorry FCC I have even seen JR with the same "STUPID" action :stupid:

ftomteen4cat

Yep. I agree.

Rodney

Sorry to dissagree with FCC but it is normal. Unless he has some receivers with an as yet not discovered characteristic, they will jitter anytime nearby electronic energy in range capturable by the automatic gain control (a function all good receivers have) is present. The degree and severity depend on the the strength of the unknown radiation. This can be severe or barely perceptable. Yes, JR recievers are as susceptable to this as any other good design.

FCC

You guys are just sticking to the RF section but JR filtering in the decoder section stops any servo jitter. This is simple as the interference/noise is radom but the R/C siganl time frame is 20msec, so filtering is simple and all JR RXs employs this technique.

Just read any JR radio instruction manual that clearly states that the servos will not giitter if the Tx is off and Rx is on and if you practically what to see then try this at the field. No turning on sequence required for JR, and BTW it is better if you turn your RX on first as this will show whether your channel is free or not.

I am really amazed that Futaba, Hitec, Airtronics etc. don't have this feature except JR and the new Multiplex RXs.

robert

Back to the point. What has me is that they didn't do that before, but if you did the above, I'd say you should be o.k. Try a Dual conversion if you are a little unsure.
As for turning the radios and RXs on, EVERY instruction manual I saw said to never turn on the RX first.

Ladyflyer

My Feedback: (2)

NO FCC we are STICKING to the equipment he is running. We are telling him it is normal for HIS equipment. We also told him to check it out completely and it can be due to environmental changes. We added the proper procedures can alleviate some of his concern.

I listen to my freq on a monitor.

In nearly 25 years of RC activity spurious servo movement has never been the cause for ay servo failure I have witnessed .
If the twitter being filtered were a real big deal I might go back to JR but I buy more than a filter in the decoder when I buy a receiver . Not to mention parts that aren't present cannot fail !And I don't buy JR any longer.

fiery

My Feedback: (2)

Hi LF,

I am intrigued by your comment that you don't buy JR gear any more. You must have used it in the past, but no longer. I am curious about the reason for this . I have been thinking of switching to JR. Airtronics/Sanwa equipment is not well supported by the distributor in Australia.

However, if you prefer not to elaborate, I will understand. The silly flame wars that seem to start over these types of issues can be somewhat tedious.

regards


fiery

Ladyflyer

My Feedback: (2)

It has nothing to do with the JR product. Without elaborating I found the sevice dept didn't have what I consider enough information to service what they sell.
I find HiTec receivers are sensitive (measured) selective (measured) and quality construction. The only problem is they no longer make a 50 Mhz version. The upper level Futaba are pretty good and still available on 50 Mhz. I (my hubby) am considering modifying the HiTec in the future for 50 Mhz operation. They are very good receivers

fiery

My Feedback: (2)

Thanks LF.

KB9STD

My Feedback: (1)

I could be wrong,But I have never seen a receiver that would not jitter with the transmitter off.I think FCC must be talking about the "Failsafe" in a "PCM" system.If that's the case,it has no bearing to a question about an AM or FM receiver.

FCC

No I am talking about JR PPM receivers. As I already told that the mauals of JR clealry states this property of JR RXs, so there is no ponit of argue...
If you don't believe then borrow a JR maual from someone or go the Horizon website and take a look at the mauals or ask any experienced JR user.

I lost gears of 3 servos, 2 Hitec and 1 Futaba at the field, due to the this problem with Hitec RX and this is more critical for throttle servo.

Ladyflyer

My Feedback: (2)

Quote:
"If you don't believe then borrow a JR maual from someone or go the Horizon website and take a look at the mauals or ask any experienced JR user"

I BELIEVE you. I just see no need to do whatever it is they did ,since it is NOT a problem.
If you are happy they did it ENJOY ! Tens of thousands use the OTHER radios without problem.

IF it isn't there it can't break. If it doesn't break it isn't a problem! SIMPLE HUH!