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Old Jan 09, 2013, 01:50 PM
RIP MC
fnnwizard's Avatar
United States, CA, Midway City
Joined Dec 2003
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JR 398's?

How about some feedback on these?
Trying to search for actual specs based on 6.6v.
Also actual resolution would be nice!
TIA!
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Old Jan 09, 2013, 02:10 PM
Eggcellent...
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United States, CA, Orange
Joined Oct 2006
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They are what the 378 should have been in the first place...excellent resolution and centering.

Tom
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Old Jan 09, 2013, 10:07 PM
Registered User
United States, CA, Davis
Joined Oct 2006
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Quote:
Originally Posted by fnnwizard View Post
How about some feedback on these?
Trying to search for actual specs based on 6.6v.
Also actual resolution would be nice!
TIA!
I have 398HV as a recent replacement for worn 378HV on my Supra flaps. I use a 2S LiFe phosphate battery. Qualitatively they are definitely tighter than the 378 and they don't "sing" like the 378. Instead they sort of growl off and on at a lower volume very much like the 368.
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Old Jan 10, 2013, 11:18 AM
WINS - Winch In Nose Sailplane
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USA, NH
Joined Mar 2008
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Quote:
Originally Posted by tewatson View Post
They are what the 378 should have been in the first place...excellent resolution and centering.

Tom
What? Didn't someone call the 378 "The servo of the future"? Why, yes, I believe they did.

I'll be happy to buy some 398's after a year or two and dozens of positive feedback reports from non-company men. Just sayin'. JR lost a lot of credibility, in my eyes, on that fiasco. You make a mistake, man up, fix it and move on. It happens. You'll keep more customers than if you stonewall. Deny, deny, deny just doesn't cut it. And I'm reminded every time I turn on one of my planes that have them in it. Yes, at least I know the plane is on. Gotta look on the bright side, right.
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Old Jan 10, 2013, 11:50 AM
Eggcellent...
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United States, CA, Orange
Joined Oct 2006
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Originally Posted by jaizon View Post
I'll be happy to buy some 398's after a year or two and dozens of positive feedback reports from non-company men.
Well, you now have the first of those.

Tom
Not a JR team pilot
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Old Jan 10, 2013, 12:05 PM
F3B
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Warwickshire, England
Joined Sep 2006
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it does defy belief that the original 378 (aka graupner ds3288 etc etc) was brought to market with such poor accuracy. Especially after apparently "extensive" testing and feedback by JR team pilots, and not inconsiderable hype.

as a non JR team pilot I could see (and hear) that it was not an acceptable servo for the price by the first time I installed it in a model.

Especially when MKS brought out their range of servos it made the JR/Graupner servo look ridiculous.

They are tough servos, I will give them that. Also they had good horns and a sensible length lead and good mounting lugs.
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Old Jan 10, 2013, 12:59 PM
WINS - Winch In Nose Sailplane
jaizon's Avatar
USA, NH
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Originally Posted by tewatson View Post
Well, you now have the first of those.

Tom
Not a JR team pilot
Thanks, Tom. Just 59 to go!
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Old Jan 10, 2013, 01:20 PM
or F, J, K, or even TD
FLY F3B's Avatar
Joined Jun 2007
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58. I too can stand behind the quality of hte 398's. I am a JR pilot, but I complained loudly once I experienced the 378 problems. It took a while, but JR did finally bring the fix. I too wish the communication to the market was more open and proactive.

In these days of high end guys sealing the servos inside molded wings, it really stinks to get your new pristine wing and watch as the flaps and ailerons never really come back to center. Thankfully for one of my gliders with inaccessible servos, they did finally loosen up, and now those 378's are working well. I was about to do some seriuos surgery though.

Cheers,

Mike
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Old Jan 10, 2013, 01:33 PM
F3B
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Warwickshire, England
Joined Sep 2006
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Originally Posted by FLY F3B View Post
58. I too can stand behind the quality of hte 398's. I am a JR pilot, but I complained loudly once I experienced the 378 problems. It took a while, but JR did finally bring the fix. I too wish the communication to the market was more open and proactive.

In these days of high end guys sealing the servos inside molded wings, it really stinks to get your new pristine wing and watch as the flaps and ailerons never really come back to center. Thankfully for one of my gliders with inaccessible servos, they did finally loosen up, and now those 378's are working well. I was about to do some seriuos surgery though.

Cheers,

Mike
I still find it kind of weird. I mean did no one from JR fire up the servos and think actually they are not very good at one of the basic jobs as servo has. Actually they probably did but got too sick of the noise to carry on with it.

It's not like they were selling them to a sector of the market where the buyers didn't know what a decent servo was like (or didn't have the gift of hearing). Especially as a lot them had been using JR's own products that had perfectly normal centring.

The problem was glossed over on here by a lot of people with a vested interest. Personally I lost a lot of respect for JR.
I guess now the 398 is out everyone is allowed to say how crap the centring and accuracy* were on the 378 and how ridiculous the noise was. The gear slop was mediocre at best as well, while I am having a moan.

*they didn't just centre badly they didn't move to the same point twice in a row.
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Last edited by satinet; Jan 10, 2013 at 01:44 PM.
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Old Jan 24, 2013, 01:24 AM
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fnnwizard's Avatar
United States, CA, Midway City
Joined Dec 2003
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Thanks for the feedback Tom, JP and Mike!
Does anyone know what the resolution/deadband is for these?
Do the servos respond to each trim step of the higher end JR radios if the steps were set at minimal settings?

According to JR: The DS398 digital precison metal gear thin-wing servo offers class-leading holding torque, zero deadband and the legendary high resolution of JRŪ servos in a package that's ideal for high-performance sailplanes and electrics. By re-engineering certain internal components, the JR brand has improved upon the precision of the previous generation DS378 servo to give the DS398 servo the performance advantage JR customers demand.


Does the bold type indicate these are on par with say the DS3421and its variants? I am asking so I can hope to avoid a repeat of stupidity on my part .
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Old Jan 24, 2013, 11:28 AM
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so. cal.
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I have done a recent HV 398 install on two large scale sailplanes (16 servos just in the wings) and there is no doubt that they are MUCH more quiet than the 378, time will tell about centering and resolution.
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Last edited by s2000; Jan 24, 2013 at 07:25 PM.
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Old Jan 24, 2013, 05:05 PM
launch low, fly high
New Zealand, Hawke's Bay, Havelock North
Joined Dec 2004
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I've not used the 398, just the 181. I think that the only delta is the HV voltage capability (and the HH renumbering of the JR #). I have been impressed with the tightness of the gear train, and the centering accuracy/resolution and put this servo ahead of the 3421.

disclosure: Team JR pilot. I'd recommend checking prior postings to evaluate the probability of poster bias. This is something that one should do for any recommendation that comes from a person that you do not know!
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Old Jan 24, 2013, 06:00 PM
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United States, KS, De Soto
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Not a Team JR or HH pilot....The 398s are working well in my Aspire and I plane to get a few more for other planes.
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Old Jan 25, 2013, 12:36 AM
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New Zealand
Joined Jun 2008
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I am using the HV 398's in my Supra wing. Only had 20 flights on it before an incident that destroyed the center panel. I was really happy with the servos. Centering was excellent, very little slop. I will be using them again
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Old Jan 27, 2013, 04:31 PM
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St. Louis, MO
Joined Oct 2002
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Anyone know what the Graupner number is for the 398 servo?
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