Big Compatability problem ADF

[Slats]

Kevin,

got a big problem - am posting on behalf of Jim Russell here in Australia (he is not much of a computer person), and myself. Jim has just received a shipment of 11 of these units and I have 2 that I ordered that are on their way here.

Ok what is the problem:
The failsafe part of the unit when operated with a Futaba radio does not work at all. That is, there is no servo control whatsoever through this unit - whether it be a fail safe loss of signal situation or the TX on and working in normal operations.

Jim so far has tested 3 units that he received of the 11 he ordered all have an identical problem. All these units work fine using JR / Hitec radios, and the problem is only with Futaba.

My concern is the same as his, given I operate ONLY on Futaba.

The leveller works fine no matter what radio is used including Futaba.
Can you please advise whether there is something that Jim and I need to do to these units to get these working.

Many thanks
John

[KevinMc]

Hi John,

That's not good at all. Which receiver(s) are you and Jim using? (138 or 168 - I've recently discovered these will cause problems.) Also, are you testing from a 5V regulated source or something else? Have faith - I'm sure I can get you sorted out.

[Subculture]

Futaba stuff uses 3.3 volt logic levels. Is the ADF compatible with that?

[toppack]

Futaba stuff uses 3.3 volt logic levels. Is the ADF compatible with that?

I copied this power level Info from Futaba website:
(May be helpful, I could Not find any other related Info)

An ABSOLUTE minimum operating voltage is very near 4.0V. Rx's typically use a 3.3V regulator which requires an additional 0.7V to power itself, resulting in the 4.0V minimum. In application, however, it is typical for performance to become severely degraded as power falls under 4.3V DC.

[KevinMc]

Futaba stuff uses 3.3 volt logic levels. Is the ADF compatible with that?

Hi Andy,
Not always, and Yes. To your question, the ADF is compatible with 3.3V logic given a 5V BEC. Unfortunately late-model Futaba receivers are putting out signals that are less than 3.3V which is the source of a recently uncovered problem.

I copied this power level Info from Futaba website:
(May be helpful, not sure how this info relates to minimum logic level output, tho)

Thanks Rick, but what you're quoting is input power where the issue at hand is likely an output signal level problem.



Hitec and JR receivers make a servo signal that's at the full voltage of the battery rail, where Futaba's servo commands are only transmitted at the internally regulated voltage level. As stated above the real problem though is that that of late their servo commands are at a lower voltage level than what they used to be - I did all my compatibility testing for the ADF using a Futaba 128DF receiver, an older model which uses full 3.3V logic levels and works just fine with the ADF. Similarly, the ADF also works without issue with the Sombra Labs SL-8 and Polks Seeker 6 receivers which also use full 3.3V logic for their servo commands. I'm still building a "compatibility list" of affected Futaba receivers but at this time I can confirm that I've seen problems with R138 and R168. (Unfortunately I don't have one of every receiver to test with.)

In the here and now I have a fix that I can apply to render ADFs compatible with newer Futaba receivers, but anyone with issues will have to contact me to have the fix applied as it's not something that's inherent to the design. A new revision of the ADF is also already in the works, but it will take time before it's available.

[toppack]

Thanks Rick, but what you're quoting is input power where the issue at hand is likely an output signal level problem.

Yes, I was hoping maybe it would help the person having the problem, if the voltage level is going below 4.3 volts at the receiver, for some reason. That level may need monitoring? (maybe futabas won't operate below that voltage, when other receivers will)
But if the problem has been seen many times before, with less than 3.3 v out, I suppose that's Not the problem.

[Slats]

Kevin,
the Futaba RX we have are the R136 and R156 FM variety.
These are 36MHz -legal for use here in Australia.

I will try and get Jim to register into the forum - seriously he is only at the point of working out e-mail.

I spoke to him this morning and as he works in a hobby shop he is going to try a few more Futaba units - like even a 29 MHz 2 channel, just to see if that works.

From what I understand Jim had 5 v going through the Rx. He has been building RC subs longer than anyone here in Australia, and actually kits out peoples subs and WTCs for them, so he is very much switched on to how it all should work.

When I get mine (hopefully very soon), I will test them with my gear.
J

[KevinMc]

Hi John,

If at all possible please also encourage Jim to try out an older model of Rx if he has one at his disposal - it won't change the compatability issues he's having with the R136/R156, but at least it will provide a baseline for identifying which combinations work and which don't.

In your opinion, is Futaba the "common" receiver to use "down under" for subs? I've actually found it pretty uncommon for folks to be using Futaba receivers in their boats, but that's just been my experience. (And that's also affected by the other choices we have here.)

If you can get Jim setup with email, please have him contact me directly and I'll do what I can to get him taken care of. As I say, chances are I know what the issue is and if so I can correct it, we'll just need to figure out how best to do it from the other side of the world. ;)

KMc

[Slats]

Kevin,
the R136 is what I would call old. Been using it with 4 and 6 channel sets for many years. The R156 is a newer unit, its a compact micro size used typcially in small park flyer aircraft, - it has 6 channels / sockets. The R136 is what I would call a traditional full size RX it has 6 channels but 7 plug sockets. So it would seem its both Older and Newer Futabas have the same problem.

The R136 actually predates any Futaba 6 or 4 channel computer radio and was supplied for both 4 and 6 channel 36 MHZ Fm units of the non computer type. It has also been supplied with both 4 and 6 channel computer FM radios since.

As far as popularity of Futaba - the sub guys in my neck of the woods use them almost exclusively. Jim lives some 1,000kms (600 miles) to my North and the use of Futaba up there might be different. You are right however, when it comes to choice, Australia tends to be the poor cousin of the RC industry - we get limited product range here even with Futaba / JR / Hitec cf the rest of the world. Part of the problem is our frequency legal for use.
You guys have the polks tracker, nautical commander, and a host of other radios that run on the seventy something bands that are not legal here, and these radios are not made in 35, 36, or 40 Mhz which is legal here.

I have also an Esky 36 Mhz 6 channel FM Rx which uses Futaba crystals and is meant to be a Futaba clone, when I get the ADFs I will try these on that RX too. I alsio have my 40Mhz Robbe Futaba F14 Navy radio and 8 channel TX which I will try to. I don't use that for subs, but some in my sub group here use it too.

Many thanks for your willingness to get to the bottom of this, and thanks to Mike too for getting this support section up.

Does the fix you suggest mean sending the units back to you, or can we do something under your instructions at this end?

Thanks
J

[Slats]

By the way,
I have been told by Hobbyco - one of the largest hobby stores in Australia that JR and Hitec will cease production of all 36 MHZ units soon so the only units coming into Australia in these brands will be the 2 channel radios on AM or multi channels 4 plus in 2.4GHZ - Futaba wil remain therefore in my country as the only supplier of FM 36 MHZ units and with enough channels to support subs. So its not only a question of whether Futaba is popular here now amongst the sub guys (and I say it is), its also that we are heading in this country to a point where all new radios bought for subs will have to be Futaba.

O how we'd love to see some more choice!

J

[toppack]

Now, I remember Why I didn't move to Ausie-Land! :D LOL

[Albion]

Now, I remember Why I didn't move to Ausie-Land! :D LOL

Yeah what with that and the cheap quality wines, great fish and chips, err great food in general, drive through bottle shops, bottle shops with huge chilled beer areas and generally laid back attitude, i could never live in a place like that :rolleyes:

[Slats]

Kevin,

I spoke to Jim tonight whom is registering for the forum and posting soon.
He tells me that where he works (hobby store) there is quite a tech savvy guy there who thinks that Hitec / JR radios use a positive pulse through their RXs but Futaba use negative pulses......I have no idea what this means or if it is the cause of the problem of Futaba incompatibility.

I'll PM you his e-mail address - but do keep me also please in the loop as I figure when mine arrive I'll have the same problem.

Also Jim mentioned on the phone that most sub guys he sails with are predominately on Futaba sets and on 36MHZ - which means same RXs as the ones I have mentioned.

Best
John

[toppack]

I know the older AM Futaba systems are 'Positive pulse'
but don't know about the FM systems.
That just means that the positive going portion of the output signal is the portion that is varied in width (time).
That Info should be on the Internet somewhere? I'll try to find it.

[toppack]

This website has a Great deal of Info about FM, but I could find Nothing about any of those systems using Negative pulse technology, for outputs of receiver.
There are 'frame-rate' differences, in the various type systems, But that should only be a Xmitter to Rx compatibility requirement, no differences in outputs of Rx to servos, leveler-circuit, etc.

http://www.aerodesign.de/peter/2000/PCM/PCM_PPM_eng.html#Anker143893

BTW- It should have been called a LFC (Leveler/failsafe circuit), a ADF is a Automatic-Direction-Finder. :D It's sort of like Mike's Snort that should have been called a LPS. :D LOL