Does anyone know if it's necessary to use a Y-harness with the 603ff reciever in the FASST setup???

No idea was a FASST is ???

Can you elaborate please ......

www.futabarc.com/radioaccys/futl8926.html

I don't have one but I have been reading up on what I can find and it seems that the receivers require 6.0v supply, so they are designed to work at 6.0v and not 4.8v as older receivers...I would assume there is no regulation to 4.8v (would be odd to say the least) so they are most likely powering the servos at 6.0v. A voltmeter check will confirm. In the documentation I have found, Futaba say it will power anything and everything from a micro to a large scale servo, digital and standard. I wouldn't bother with the harness.

I dont use a Y harness with mine and it works fine, so far its a good system, just bought a second one for a backup, I do use the 603fs receivers though, too my knowledge the fs model has never gone to failsafe, but I have only used the system a couple of months, I will know more after it has been in the boats for a season or so..

I do reccomend the system and love the operation of it so far......
mike sr

My 3pks 2.4gig receiver works fine on 4.8v and 6v.

thanks guys, I will check the voltage with/without a load, for kicks and giggles, and post my findings.

I am very pleased with mine as well. I have run with and without a Y harness and can't tell the difference.