Gypsy56

I just got off of the phone with Futaba Tech support with questions about the differences between S-FHSS and FHSS.
It seems that you can only use S-FHSS with digital servos, he said that analog servos would be burned out in S-FHSS mode.
The problem with this is that in FHSS mode, your 6J or 8J transmitter is now only four channel.
If you want to use more than 4 channels, you must buy digital servos. Now, the problem with THAT is, digital servos cost more than most of the airplanes I fly! This is not meant to be a rant post, but more for information for owners or potential buyers who do not know this. I sure wish I had known it before I bought my 6J.

Thanks
Ed

P.S. I feel like this should be stated clearly on all advertisments and instructions for these two systems.

pilotpete2

Hmmm,
I took the time to actually read the manual, and found no reference to the frame rate being different when running in S-FHSS mode, or any restriction with using analog servos in S-FHSS mode. With FASST radios the refresh rate is selected at the receiver. If you can only have 4 channels available when using analog servos, that would certainly be an issue. I have a freind that has the T6J. When I have a chance to talk to him I'll see what his experience has been.
Pete

darrolair

Gypsy56

I have the T8J with 8 channel S-FHSS receiver. I've been using 5 channels with analog servos for over 2 months and no problems.

The instruction manual says this receiver "is compatible with all J-plug Futaba servos, including retract, winch, and digital servos." It does not exclude analogs servos.

The transmitter has 2 settings for receiver modulation. S-FHSS mode and FHSS. FHSS will only let a person use 4 channels on the receiver. Noted as channel restrictions.

I will be setting up my 34% Extra with analog servos this winter on the T8J. I'm expecting no problems.

I really like this radio and would recommend it.

pilotpete2

Gypsy56,
I know you talked to someone at tech support, but sometimes you just get someone who only is reading off the tech notes, which could be incorrect, or misleading in wording.
I would suggest posting your question in the Futaba support forum, just to get some clarification. If you do, be patient, as they don't work on the weekend.
These radios have been out awhile, and this is the first time I've seen this question come up, and I'm sure a very high percentage of T6J owners are using analog servos primarily.

darrolair,
Good to hear your positive experience with the 8J. A very nicely featured radio at its price[8D]
Pete

Gypsy56

Pete,
I too took time to read the manual. And it never explained the circumstances for which I would choose S-FHSS over FHSS or vice versa except for frame rate (faster with S-FHSS). This is why I called the tech line and talked with John. Now, I hope you guys are right and John is wrong, but I don't want to crash an airplane to find out.
So, my question is, why do they offer the two different modes of transmission, and why would I choose one over the other?
If S-FHSS is better, why not just make it a S-FHSS only system. And why do they only operate as 4 channel systems when in FHSS mode?
I'm just tryin' to figure this whole thing out!

Ed

darrolair

Gypsy56

The 2 receiver modulations is a good question.

I'd like to see the answer also.
I'll be watching.

Darrolair

Silent-AV8R

This chart shows what mode gives how many channels on which receivers:

http://www.futaba-rc.com/receivers/f...ss-compat.html

As I understand it the FHSS was first used in surface vehicles. They later added the S-FHSS mode and expanded the channel count because the FHSS was limited to 6 maximum. They offer both modes on the 6J and 8J to allow more flexibility with the various receivers.

I have never heard anything about not being able to use analog servos with the S-FHSS mode.

I'll check on this and get back to this forum, likely later on Monday.

falcon_56

Does anyone know if the Futaba 8j would work in S-FHSS mode with Futaba S148 analog servos?

I would hate to burn all my old servos.

Pippin

How about Hitec analog servos and S-FHSS?

Silent-AV8R

You can use just about ANY analog OR digital servo with the FHSS/S-FHSS radios. No worries. I have confirmed this with the folks at Futaba service.

All I can tell the OP was there was a bit of miscommunication.

This was what Krysta told me in an email just a few minutes ago:

Gypsy56

Not a miscommunication, I heard John perfectly clear, even asked him twice. He said using analog servos in S-FHSS mode would burn out the servos. Now someone else from Futaba Service says they will not. Who's right and who's wrong? I don't know. I would like to think Krysta is right but it sounds like someone is just guessing. I would love to see it in print from Futaba before I risk my equipment.
Silent AV8R, thanks for following up on this, but the statement " You can use just about ANY analog servo with the FHSS/S-FHSS radios" was not really the question. Can you use analog servos in S-FHSS mode without damage? Maybe I'm being too picky about it,
maybe I should just fly. Darrolair says he has'nt had any problems. Anyways, thanks for all the input.

Ed

TimBle

My understanding is that FHSS mode is about a frame rate of 14 milliseconds (similar to FASST 7Ch and Multi 1&2 Normal mode) and that S-FHSS has a frame rate of 6.7milliseconds which is roughly similar to FASST HS mode.regulator when using a 2S 7.4V LiPo pack as a power sourceNormal (FHSS) and high-speed mode, normal mode has a frame rateoutput of 13.63ms and accepts any type of servos or peripherals,peripherals, high-speed mode (S-FHSS), with an output of 6.8msaccepts digital servos including the BLS series and most peripheralequipment such as brushless ESCsCapable of 4 channels only in FHSS modeEasy-Link circuitry, frequency hopping, spread spectrum designDual Antenna Diversity"

DougV

Gypsy... What I'm reading here is that these receivers are just like the FASST receiver (for example the R6106HF) they have a normal mode (FHSS) and HS mode (S-FHSS).

Set the mode according to your servos (you can expect to run analog servos on 6ms frame rate right) and go fly.

Doug.

Silent-AV8R

So, we can either believe Krysta at Futaba service, or not.

Page 8 of the 8J manual clearly says that ALL servos will work, including winch, retract, and digital servos.

If you have a receiver that can be set to a high speed mode, then you do need to use digitals when in that (HS) mode. However, when in normal mode you can use ANY servo type. This started with the R603FS receivers and continues with all receivers capable of the 2 modes, normal and high speed.

However, the radio itself and the transmission type in particular does not care. FHSS or S-FHSS, BOTH will work fine with either servo type. S-FHSS is NOT a high speed mode, it is just a slightly different protocol.

Silent-AV8R

YES, you can absolutely use analog servos with S-FHSS mode without damage. However, if your receiver is capable of being set to either normal or high speed mode, then IF you have it set to HS mode THEN you need to use digital servos. Receivers capable of dual modes (normal and High Speed) ship with the default as Normal. I am not sure what else to tell you. BTW - I am on Team Futaba and trust Krystas info without question. When I said there was a miscommunication I meant that perhaps John did not fully understand your question. But regardless, the information I have provided is accurate.

Silent-AV8R

One more thing. The only radio that this is an issue on is the T4PL which allows normal or high speed modes. Look at this chart:

http://www.futaba-rc.com/receivers/f...ss-compat.html

If you have it set to S-FHSS (HIGH) then you MUST use digital servos. Be we are not talking about that radio. We are talking about the 6J and 8J radios, and again, you can use either analog OR digital servos with those radios with no issues.

BTW - this is the 4PL, it is a car/boat radios.

http://www.futaba-rc.com/systems/futk1400.html

Silent-AV8R

None of the receivers that are compatible with the 6J or 8J have modes that can be selected. The 4PL radio linked above CAN use a normal or HS mode, and if you set it to S-FHSS HIGH mode then you need to use digitals. But it is a car/boat radio. The mode selection is done in the transmitter.

TimBle

Silent-AV8R

There is nothing to clear up. ALL servos, analog or digital will work in EITHER mode with the 6J or 8J radios. IF you have a 4PL car/boat radio AND you set that to S-FHSS and High Speed mode then you must use digital servos.

The two transmission protocols, FHSS and S-FHSS are NOT "low" speed and "high" speed. BTW, the mode of the TX and RX must match. SO your combination of TX FHSS and RX S-FHSS will not work. Nor will the TX S-FHSS, RX FHSS.

Once again, the high speed mode does NOT apply to the 6J or 8J radios regardless of FHSS or S-FHSS.

PLEASE look at the chart I linked to above. It says nothing about "Normal" or "High" for the 6J or 8J. It ONLY says that for the 4PL. And also, PLEASE look at page 8 of the 8J manual where it clearly says that any servo with a Futaba "J-plug" (the normal plug they have) will work including, winch, retract, or digital.

Silent-AV8R

This is incorrect. Please look at the receivers in the middle column of this page:

http://www.futaba-rc.com/receivers/air.html

Transmitters can do both modes. The receivers are either FHSS OR S-FHSS, they cannot be switched between the two modes. The transmitter mode must match the receiver mode in order to work. FHSS/FHSS or S-FHSS/S-FHSS.

darrolair

Thanks Silent-AV8R for the info.

I've been using Hitec, JR, and Futaba analog servos and had no problems.

I also looked really hard at my S-FHSS receivers for some place to change the mode to FHSS. There's no place externally to do that.

I agree with everything you posted for T6J and T8J radios.

Thanks again
Darrolair

Gypsy56

WOW, this is really getting confusing. I do not have an 8J system, but here is what it says on page 24 of my 6J manual.
"The R2006GS which accompanies the T6J is compatible with either the S-FHSS or FHSS settings and adjust automatically to the
signals from the transmitter, accordingly" So, although the RX does not have a manual switch to switch modes, it looks like it still switches modes when you switch the TX. It seems that this means that if my TX is set to S-FHSS (to use more than 4 channels),
then the RX switches itself to S-FHSS???? Maybe there is a difference between the way the 6J and 8J operate?

Ed

Silent-AV8R

Sorry, I thought you had an 8J. In your case the one and only difference between FHSS and S-FHSS is you only get 4 channels in FHSS and you get the full 6 channels in S-FHSS. You also get failsafe on all 6 channels with S-FHSS. In FHSS you only get failsafe on channel 2. This R2006 works like the car receivers. It automatically detects what mode the TX is using. Nowhere in the 6J manual does it say anything about S-FHSS being a high speed mode that requires the use of digital servos. The spec page for the RX does seem to indicate that and I have brought it to their attention since it appears to be an error.

Sorry for the confusion, I had it in my head you had an 8J.

One more thing. You can buy this radio with servos, the S3004, which is an analog servo.

Gypsy56

Silent AV8R,
Does the 8J RX not automatically detect modes like the 6J?
From what you have learned, do you think that even in S-FHSS mode, the 6J system would be OK with analog servos?

Thanks
Ed

Silent-AV8R

It is not the TX that auto detects, it is the receivers. You set the TX and the R2006GS RX will detect the mode of the TX. In FHSS you get 4 channels and failsafe on a single channel. In S-FHSS you get 6 channels and failsafe on all channels. There has already been one post that analog servos work fine with S-FHSS and everything that I have read and been told by Krysta and Bax says it is not an issue. So I'm going to say that it is not an issue. But I have pointed out the information on the spec page for the 6J and R2006GS RX to the folks in Champaign. I will have more info sometime tomorrow. But I am fairly confident that the answer will be that the website is incorrect. I will report back what I hear.