Hitec HS-81 servo chatter ?

[Andris Golts]

Hi all installed a HS-81 as a steering servo in my micro hydro noticed it had a bad chatter .Servo is set up with a Spektrum DX3S TX and a SR300 RX tried it with another radio system same issue took the servo back to the local hobby shop they had 5 more hs-81's on the shelf 4 of the 5 chattered just as bad as mine 1 was a little better. Has anyone experienced the same problem ? Is there an issue using them with 2.4 ghz radio's? Regards Andris Golts.

[jac4412]

Hi Andris, I use an HS-81 in my DTM-X4 rc... I use a simple losi radio set... no chatter to speak of. I can try to test out a 2.4 setup and see if i can get anything to help you out

[drwayne]

Spektrum is digital Rx..HS81 is analogue.. it cannot keep up with the centering requests from Rx.. given time it will burn.
Replace with a digital

W

[Andris Golts]

Thanks jac4412 and drwayne for your input. Regards Andris Golts.

[RaceMechaniX]

Yup, the HS-81 can only be used with a analog style controller. The digital radio systems have too high of a refresh rate and will cause the servo to burn up.

[ncornacchi]

Wow, what timing......I had just bought a HiTek HS-7955TG servo for my build, and got the same chattering while using my tactic 2.4 receiver....Am I having the same problem? My Hi-Tek is a coreless digital......Do I have to change my receiver/transmitter?

[siberianhusky]

Try setting the frame rate of the Spektrum TX to 16.5 ms, this is for older analogue stuff, My hs-85's work fine on a slower frame rate, had a bit of jitter on 11ms frame rate.
It will be under the System menu.

[Flying Scotsman]

Do I understand this right, all analogue servos can not be used with a 2.4 ghz system.

Douggie

[millzee]

hi, if it's just that there noisey, I have 2x 7955's in my truck and they are quite noisey, I worried about them and did a heap of research only to find out the noise was considered normal with this type of digital servo, been bashing them for ages now and they never miss a beat, I've got used to it now and only get concerned if I can't hear them. I put another 7955 in the boat I'm building this afternoon and it is quieter but still gives a little bit of noise. I might be wrong being fairly new to rc but there working fine for now.

[siberianhusky]

I don't have any digital servos, I have futaba, Hi-tec, and JR. All have been working fine with a 16.5ms frame rate. Ran a whole season last year and the only servo that crapped out on me was the s100 Spektrum servo that came with the radio, it goes nuts when you plug it in, causes the other servo or esc to freak out as well, it got wet in a sailboat though.
I know many people who are using analogue servos with 2.4 radios.
Oh ya the futaba AQ servo in my SV works fine with both a HK 2.4 2 channel radio and my Spektrum.
My thing is I want to get a few HV servos for my nitro boats, can use a 2s lipo pack for power and not worry about the extra voltage burning up the servos and no regulator needed, the SPektrum RX will handle 9.6v

[millzee]

the 7955's handle a 2s lipos rx pack just fine, I was having a few power issues when I first converted my xxl and I used a seperate 2s lipo to run the rx and both servo's, fixed the issue and an added bonus with the added torque and speed from the extra voltage, I think from memory from 6v 333oz to 387oz torque on lipo, I can't think of the speed. I found a thread on a forum where I guy cut and pasted an email sent by a Hitec rep that say's they had tested and found no problem with running the 7955's on 2s lipo's and that the only reason they didn't state it in the marketing and on the spec's was that Hitec was in the process of producing the HV servo's. Well that's what I read anyway, I don't always belive what I read on the net but from my personal experince, there going just fine and I'll be putting the same rx lipo pack in the boat..:thumbup1:

[drwayne]

Do I understand this right, all analogue servos can not be used with a 2.4 ghz system.

Douggie

Physically larger servos are more tolerant the digital data stream harassing the analogue circuit to hold center.

Analogue Tx have ~256 steps 0% --100%.. quality digitals have 2048+ steps
The digital resolution demanded from the analogue servos is not possible, so they chatter whilst trying to achieve perfect arm position.

W

[byron]

i have that same noise on my new hs 82 servo ,can i set the rate on my futaba 3 pm radio .
any one no ?