RE: Futaba 617 Rx / Hitec 7955 servos - Compatible?
Curiosity got me about running digital Hitec servos on my 2.4 Futaba 617 Rx. I would not think there would not be any compatibility issues would there? I'm no expert so please correct me if neccessary but here is what I've concluded so far:
After some internet research I found some older threads about this scenario where Hitec servos were misbehaving or locking out due to the signal output voltage of some Futaba receivers being lower than the required voltage oftheservos. This would not be good, and even worse the problem would not present itself until the servo reached about a 120F operating temp (which could easily be done on a hot summer day) or is continuously under high loads at which point the servo would require a higher voltage than the receiver signal would put out. So you could easily have apotiental latent failureand never even know about it! This is one choke point I wouldn't want to have.
Good news is I think this is not a problem anymore. Some 2.4Futaba receivers would put out a max of 2.7v to the servos, while some Hitec servos required a minimum 3.0v when at max operating capacity therefore resulting in servo malfunction. If anybody knows any more or can elaborate on this please chime in.
Another similar scenario to this is not in compatibility of components but in using long servo leads, lighter guagewire,and/or y-connectors.In this casethereceiver signal voltage drops over the long leads to the servo and the result is jittering, twitching or lockout thatinmanyinstances will not be present under nomal range checks. Apparently aneasy fix for this is an in-linebuffer-amplifier; cheap insurance for boosting the voltage to the servos. I assume the Smart-Fly power boards will do this also.
So I've now given a lookand am leaning towards Futaba servos again. I don't want to start a war on the perfect servohere but the Futaba 9156 seems to be an awsome servo and comparable in perfermance and price to the Hitec 7955, yet you just don't see many Futabas on large scale aircraft? Heck, many of the larger well known internet RC retailers don't even carry Futaba servos but instead push Hitec hard. I think over the years Futaba was passed by Hitec in the large scale market due to pricebutit seems theyare catching back up. Futaba dosen't push the infamous "Titatanium Gears" like Hitec followers, but for those that have used this line ofservos,theyhave reported very long life spans with little slop ever developing and better centering over the Hitecs.