futaba reciever replacements

[urbs00007]

i presently use a futaba 3pmx. are there cheaper brand receivers that will work reliably with this radio?

[NativePaul]

I use Futaba FASST 6EX and 8FG plane radios, mostly with Futaba RX but I do have one mini hydro that wont fit a side plug or cased RX and as the only end plug Futaba RXs are VERY expensive high end SBus units that I loath to run uncased, and while uncased it would just fit, I went off brand with a FrSky TR4B (not to be confused with FlySky, who are very low end), which is much smaller and lighter.

As with my genuine RXs the range is more than I need, or can use.

The failsafe (as tested by switching off the TX (as yet I've never used it for real with FASST)) is just as quick.

On removing the cheesy cardboard "case" the soldering on my example was good. I have had no issues with mine, but it is less than a year old so longevity has not been tested yet (most of my Futabas are 8 years old now with no issues from any).

Chinese quality control has a reputation of being very bad unless watched like a hawk by their customers in factory QA workers like the big names supply, so even though some of the higher end Chinese manufacturers like FrSky are getting a good reputation for quality, at the moment my peace of mind is still greater with a Futaba product. While I cant fault the functionality of the product I received and will undoubtedly buy more FrSky RX for slow boats, and Mini FEs with packaging issues. I will continue to buy Futaba RXs for all my fast models that have room for them, despite them being bigger, heavier, and more expensive.


Why am I prepared to pay a premium for the best radio link available and branded receivers? Many of my boats have a lot of time and/or money in them and I always wanted to protect my investment, and as the only thing in a boat that can fail and lose the whole lot is the radio it made sense to spend a decent amount on it, but something happened recently that had me getting much more serious about it.
A lowly P Ltd or mildly tweaked RTR weighing 6lb and doing 50mph has 682 Joules of kinetic energy, that is similar to the muzzle energy of a .357magnum or .45ACP+P. When dealing with that amount of energy which is not directly under my control, I want the best control over it that I can possibly get, in order to minimise the chances of having a runaway boat maim or kill someone. I have seen someone hit by a flying boat and I am very thankful that A, it had flipped so was flat on, B, it was a glancing blow, C, the heavy parts missed him, D, it was a fairly young and resilient chap that got hit, E, he was an understanding fellow boater that didn't sue, and F, it wasn't my boat that hit him. But for the flip of a dice any of the first 4 factors could have made it a serious or fatal injury, and if any one of them had been different how could I have justified not using the very best that is available?

As it happens the incident above was not caused by a radio issue at all, but someone losing his boat in the spray and driving the wrong boat out of it (so be careful with that, it is dangerous too. A quick lift of the throttle or twitch of the wheel can quickly tell you if you are not 100% sure which boat you are driving).

[Flying Scotsman]

Paul, a well written and thoughtful post on the topics you brought up.

Douggie

[NativePaul]

Thanks Douggie, that means a lot. I was expecting to eat some flack on this one.

[slider46]

I run nothing but Futaba radios and rx in my boats and have never had a glitch or failure.... Its cheap insurance as far as I'm concerned.... I have a genesis that runs 73 mph and a f41 stryker cat gas boat that runs hi70s to low 80s. I can't afford to loose the radio while running the boat...

[urbs00007]

I run nothing but Futaba radios and rx in my boats and have never had a glitch or failure.... Its cheap insurance as far as I'm concerned.... I have a genesis that runs 73 mph and a f41 stryker cat gas boat that runs hi70s to low 80s. I can't afford to loose the radio while running the boat...

its going to be used in a 30 mph electric mono.

[grsboats]

John I don't think there is a china generic receiver compatible with this radio..btw the same radio I've been using for years with zero issues.Gill

[JimClark]

moved to radio forum

[SweetAccord]

John I don't think there is a china generic receiver compatible with this radio..btw the same radio I've been using for years with zero issues.Gill

Really? I find there are.

Peek here: https://hobbyking.com/en_us/radios-r...ers/fasst.html

I still stand by that the smallest receiver you can get that is just as reliable as anything Futaba is the ASSAN. Way less expensive and is tested many times over in boat and planes. They still have the smallest receivers on the market with a fail safe and have beyond eye sight range and still no one has come close to copying them. Size: 36 X 14 X 3mm (1.97 X 1.02 X 0.39 inch)Weight: 3.2g
Try finding something smaller, you won't for the price and reliability.

[grsboats]

Nice.

[NativePaul]

That is not an apples to apples comparison. Assan use one of the most basic protocols out there, it is a single channel with a static frequency, it has ample range like most radios in good conditions, and the build quality is great, but it is far more susceptible to interference than FASST (and most other competitors), which uses 2 different channels simultaneously and both are constantly hopping around across the whole frequency band, it is not just as reliable. The simple protocol also needs far less complicated electronics so a smaller lighter package is the obvious result.

The FySky TR4B I said I use in post 2 is only 4 dollars more and 1.8g heavier than the admitedly tiny Assan at 5g, yet utilises the superior FASST protocol and has 2 regular length antenna. Well worth it IMO.

Assan's own FASST compatible receiver is 47x30x10.8mm and 12.8g, heavier than Futabas equivalent RX, much cheaper though.

[grsboats]

Thanks Paul..more clear impossible!

[SweetAccord]

That is not an apples to apples comparison. Assan use one of the most basic protocols out there, it is a single channel with a static frequency, it has ample range like most radios in good conditions, and the build quality is great, but it is far more susceptible to interference than FASST (and most other competitors), which uses 2 different channels simultaneously and both are constantly hopping around across the whole frequency band, it is not just as reliable. The simple protocol also needs far less complicated electronics so a smaller lighter package is the obvious result.

The FySky TR4B I said I use in post 2 is only 4 dollars more and 1.8g heavier than the admitedly tiny Assan at 5g, yet utilises the superior FASST protocol and has 2 regular length antenna. Well worth it IMO.

Assan's own FASST compatible receiver is 47x30x10.8mm and 12.8g, heavier than Futabas equivalent RX, much cheaper though.

Far more susceptible? No way no how. I been using them for 10 years now, never one glitch. Airplane guys use them too which are way more susceptible as they are closer to towers and buildings with antennas and never a glitch or lost plane. Frequency hopping is way over rated. It has no advantage over a strong locked channel.

[SweetAccord]

The dual antenna X8 are still DSSS which covers a more wider range of frequencies and are just as resilient to interference as anything FAST. Futaba FAST just hops around at different frequencies and rates, I prefer solid signal with failsafe rather than something hopping around, to me that is a good chance for a brown out as you are vulnerable while looking to find another channel and still have to keep a failing frequency to stay connected to.

I never found a reason to go to them as the single antenna with failsafe works beautifully. Sure technology gets better and better but like everything there is a point of diminishing returns. The single antenna are also DSSS and you can go with either but if you are paranoid the dual antenna is just a piece of mind option.

[TRUCKPULL]

This is all good for the FAST system.

Does anyone make a receiver to match the Futaba - 2.4GHz - S-FHSS system??

Larry

[SweetAccord]

Did you look at the links I posted? If Hobby King don't have them no one will.

[longballlumber]

This is all good for the FAST system.

Does anyone make a receiver to match the Futaba - 2.4GHz - S-FHSS system??

Larry

Why? The Futaba OEM FHSS stuff is very reasonable in cost.

[NativePaul]

Sweetaccord.
Yes, more susceptible in a lot of ways. Your never having a problem with it doesn't disprove that, my dad never crashed his car when driving home from the pub when it was legal to do so, but that doesn't make his drink driving as safe as me taking a taxi.

Frequency hopping can be overrated when applied to a small part of the band, but can also offer significant advantages implemented correctly, and it is not just the hopping that makes FASST superior.

I think you have been misinformed about FASST, while there are some hopping protocols out there that operate on limited parts of the 2.4 band Futaba's FHSS being one (along with JR/Spektrum's DSM2, WFly, FlyDream, Corona). Futaba's FASST however (along with FrSky, Sanwa/Airtronics FHSS3, Sprektrm's DSMX, JR's DMSS, Multiplex's M-link) utilises the whole of the legal 2.4ghz band.

Assan's narrower bandwidth allows for 83 channels whereas FASST uses 36 wider bandwidth channels. If there is a tight spike of interferance it is much less likely to affect the wider FASST channel. If however the interferance takes out a whole channel of each (if it is wide enough to take a FASST channel it would actually cover 2 ASSAN channels) there is a 1 in 83 chance of it hitting the channel the ASSAN is on and taking out the ASSAN's link, and a 1 in 36 chance of it hitting the FASST's channel, which sounds really bad, but the FASST's dual antennas are not just 2 antenna on the same receiving circuit to avoid getting atenuated by engines, motors, batteries, etc between than and the TX, they are attached to their own separate internal receiver and the chances of them both being on the same channel are to take out the FASST's link is 1 in 1296, a significant improvement.

Then there is the hopping, FASST doesn't hang around waiting for a bad signal like some, so it doesn't have to look to find a new channel, it constantly changes channels at 500hz whether dirty or not, so even if that 1296-1 chance comes up all is not over, as it will only lose the link for 1/500th of a second before switching to a new channel.

You seem to be using brownout is a different context to the one I know, which is when the supply voltage dips below somethings minimum operating voltage and it temporarily ceases to function. I think I addressed what you meant in my hopping paragraph, but ironically the minimum operating voltage is one area that the ASSAN does actually beat FASST. ASSAN has the lowest operating voltage that I have seen at 2.3v, whereas FASST needs 2.6v, both reboot quickly. The one that brought brownouts to the fore was Spektrum, which needed 3.5v and their older RX could take several seconds to reboot, making a crash likely if it happened (recent units boot quickly, I don't know if they need less voltage now too as there have been generational changes since, but it was not in the initial "fix"). I have not heard of any brownout issues with RX that need <3.2v.

ASSAN may be good enough for you, it may be good enough for me, and you are right about diminishing returns, But ASSAN does not offer as reliable an RF link as Futaba FASST (with the exception of their Gunther8 FASST compatible RX).

Due to the possible consequences of a failed RF link, I want the best link available whether overkill or not. Even real Futaba RXs are only a small proportion of my total boat cost, so for me it is not worth skimping on.


Larry.
All the talk is about FASST because the OP's 3PM-X is FASST not S-FHSS. There are a couple of S-FHSS compatible RX that I know of, FrSky do the Delta8, and Orange do the GR400S. There are also a few Futaba FHSS compatible RXs, and as far as I know all the S-FHSS TXs can be switched between S-FHSS and FHSS, as the protocol is nearly the same, S-FHSS just allows failsafe on all channels instead of just the throttle, and a choice of either more than 4 channels(up to 8), or high speed mode for digital servos.

[SweetAccord]

In theory and in practice, a good FHSS system will keep working long after many 2-frequency DSSS systems have locked out. However, that's not the whole story and it's not all that cut and dry.

Because the FHSS systems are using much (or all) of the band, there are situations where they can be badly affected while a DSSS system is not affected at all. I've seen it. This can occur if the band is heavily congested except for a small portion and the DSSS system chooses that portion on which to operate without any issues. The DSSS signals are allocated to the clean part of the band and thus provide faultless communications, while the FHSS one loses a good percentage of its data to noise because it's hopping through interference.

It's rare but it can happen cause I've seen it.

[NativePaul]

True, that can happen. If 35 of the 36 channels available are dirty, that FASST will be noticeably very slow slow and laggy (I don't know the protocol well enough to say if it starts skipping known dirty channels, but assuming not which is the worst case), it may only getting updated 14 times a second which is getting on for a quarter of the normal speed servos run at.

I know I would prefer a slower radio to one that doesn't work though. (JR/Spektrum seem to agree as they must have spent phenomenal amounts of money switching from a single channel with clean start (DSM), to a 2 channel DSSS (DSM2), and now to a full channel hopper (DSMX/DMSS)

Are ASSAN actually delivering a 2 channel DSSS system now? I must admit I was basing what I have said on it not being, though I still much prefer a full channel hopper to a 2 channel DSSS. It was always advertised and specified as such, but spectrum analysis of the first couple of generations showed they were only broadcasting on 1 frequency which never moved, and was always the same one whether dirty at switch on or not. I don't know anyone with a set to test it and googling brings up lots of old posts complaining about it. Maybe they fixed it so the complaints stopped, or maybe people didn't like being lied to and stopped buying it. Have you seen any recent spectrum analysis?

[SweetAccord]

True, that can happen. If 35 of the 36 channels available are dirty, that FASST will be noticeably very slow slow and laggy, as it may only getting updated 14 times a second which is a quarter of the speed analog servos run at(I don't know the protocol well enough to say if it starts skipping known dirty channels, but assuming not which is the worst case), the chances are high that ASSAN would have stopped working altogether long before the channels was that bad though.

Are ASSAN actually delivering a 2 channel DSSS system now? I must admit I was basing what I have said on it not being, though I still prefer a full channel hopper 20 a 2 channel DSSS. It was always advertised and speced as such, but spectrum analysis of the first couple of generations showed they were only broadcasting on 1 frequency that never moved, and was always the same one whether dirty or not. I don't know anyone with a set to test it and googling brings up lots of old posts complaining about it. Maybe they fixed it so the complaints stopped, or maybe people didn't like being lied to and stopped buying it. Have you seen recent spectrum analysis?

I have the first generation. I know ASSAN has made improvements but I have not looked into the new versions as I never had any issues with the first generation.