Futaba FG Gold Series Thread - RC Groups
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Oct 09, 2012, 11:12 AM
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Futaba FG Gold Series Thread

Hello fellow modelers, I'd like to start a discussion thread devoted to upgrading these classics to 2.4 ghz. It would appear that firm information on modding these radios is sketchy at best (or the Iluminati wants to keep all the FGs for themselves ), So it would seem like a good place to share your experiences with installing internal or external 2.4ghz modules. Perhaps if the interest is high enough it might inspire some of the off-shore companies to introduce new modules or replacement boards to keep the radio case going for years to come.

And yes, I know there's tons of newer radios out there with more capabilities. There is something magical about the FG series. First off, it's a robust metal cased radio. Perhaps the finest mass produced combination of plastic and metal ever made. It has a feel that when you hold one can't be duplicated with the current bells and whistles plastic radios. When you held an FG, you were holding a real man's ( or women's) radio transmitter!

Secondly, it's nostalgia. The radios were a part of the best era in the US, perhaps the world. I had my best times flying R/C in the 80's and 90's with the FG. It's someones first radio or has been passed on from departed dads.

Lastly, they are durable. The only weakness is the plastic side flanges where the screws secure the metal face. Those were breaking frequently, and there's money to be made in the after market world replacing these.

In short, it's a great radio with a lot life left in it. So let's see how we can keep them going.

First, I'd like to share what I've learned in the last few days, established facts about extending the life of the FG:

- The radios can be upgraded once you determine where the PPM signal is coming from either off the module pins or the trainer cord connection. There are two models of FG/K, FGs can be upgraded to 2.4 ghz regardless of whether it's AM or FM

- External modules made by FrSky and Corona will work, but you need to fill in the gap left by the smaller module meant for later model Futaba radios. This is done with foam, but some enterprising soul should consider making a new adapter to replace the old module socket to be snapped into place, allowing it to fit properly.

I believe there is a place in this world for the FG. We have new cars, but we always admire the classics and want one. It's the same for these radio cases if not the internal bits, which could be removed and replaced with modern boards. And when it comes down to it, you hate throwing out good equipment when you see potential for a good restore. The batteries are still around from aftermarket companies and the new LiPos can be made to work in them as well.

Finally, there's alot of us who fly who really don't need or want the fancy stuff these computer radios offer. There are probably a lot of us who don't even use all the features they have. So let's talk about how you keep your FG going here on RC Groups.
Last edited by RWalker; May 22, 2013 at 01:44 AM.
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Oct 09, 2012, 11:20 AM
Veni Vidi Volavi
Brian Allen's Avatar
Simply great radios. I have probably 12 or 15 that I have ollected over the years. Was my first really good radio when I got back into the hobby in a big way in the mid 80's after 10 or so years of being on the periphery. Would be neat to convert a few to 2.4 for C's and G's.

Brian Allen

Veni Vidi Volavi

I came I saw I flew
Oct 09, 2012, 12:43 PM
Andy2No's Avatar
Are those the ones that had the 10 pin modules? If so, do you know the pinout?

Oct 09, 2012, 01:07 PM
Registered User
Just had a talk with Tony of Radio South. He says that the FGs, regardless of markings on the case (AM or FM) can be 2.4'd. When the RF module comes out, it still has a PPM circuit to the trainer receptacle and the board. From this you can tap in and install an internal module. He installs an XPS 2.4 module for $200.00 and that includes the new receiver. That's the high end of the market, but we're going to explore the DIY route.
Oct 09, 2012, 01:10 PM
Registered User
Originally Posted by Andy2No
Are those the ones that had the 10 pin modules? If so, do you know the pinout?

No Andy, FG s had 5 pins and did not use the TD series at all.
Oct 10, 2012, 05:25 PM
Andy2No's Avatar
Okay. Thanks, RWalker.
Oct 10, 2012, 05:58 PM
Registered User
Harri Pihl's Avatar
The older gold boxes had the servo center set to around 1.3 ms while current standard is around 1.5 ms. However, adjusting is possible with the pots on the pcb, just connect one of the receiver servo connectors to the osciloscope and adjust.

Edit: I think it's possible even with AM version.
Oct 10, 2012, 08:42 PM
Veni Vidi Volavi
Brian Allen's Avatar
The AM gold case radios had the servo centers at 1.3ms while the FM versions use the standard 1.5 ms centering. At least this is what Pete Waters at Kraft Midwest told me years ago.

Brian Allen

Veni Vidi Volavi

I came I saw I flew
Oct 10, 2012, 09:45 PM
Thermals, Tom
RyanNX211's Avatar
Doesn't matter if it's AM or FM.
Radio South can turn it into an XPS 2.4. He's done that with some
Kraft radios I've been using while I determine why I'm having so many
issues with Spektrum
Oct 11, 2012, 03:00 AM
Andy2No's Avatar
Originally Posted by RWalker
we're going to explore the DIY route.
FWIW, I've connected a FrSky 2.4GHz Futaba compatible plug in module to a Futaba 6XHS (Field Force 6) which doesn't have a module socket. At the time, the hack modules weren't available, but those might be a better option now. The only real issue I've had is with the push fit connectors, so a soldered in solution would be preferable.

Here's where I drew my inspiration:

Using Frsky modules in other transmitters (as a 'hack module)

That whole thread is worth a read, but the first post more or less covers it, except it was later revealed that the centre pin isn't unconnected; I think it's connected to ground, IIRC. It seems that's an optional signal to tell the transmitter the module is functioning correctly - optional in the sense that you can just ground it, but probably can't just leave it disconnected.

Here's a synopsis of the 5 pin Futaba pinout, according to the slightly mysterious Terry Keeley:

"Found this pinout for the Futaba FP-TP tx module that's in the 3PJ, 7U, 8U, 9C & 9Z:

looking at the back of the transmitter, antenna pointing away from you:

left side
#1 PPM
#2 switched battery positive
#3 RF good (pulled low through a transister when signal is present at the final amp)
#4 ground
#5 RF out
right side

- That corresponds to the pinout that's been agreed for the 5 pin FrSky Futaba compatible plug in module, so plugging one of those in (and packing with foam, as RWalker suggested) should work fine.

The fifth pin is RF Out on the original RF module, but isn't connected on the FrSky module - the 2.4GHz signal comes out of its own antenna, mounted on the back of the module.

I guess you could use the shell of an original module to make an adaptor, and fill in with scrap EPS and a few dabs of white gorilla glue (which expands nicely to fill the gaps). You'd need to grease that part of the case with something temporarily, to make sure the gorilla glue didn't stick the module in permanently. I've used vaseline to do similar things but some people say it's bad for the plastic. I don't suppose it does much harm if you clean if off afterwards.
Last edited by Andy2No; Oct 11, 2012 at 03:15 AM.
Oct 11, 2012, 10:43 AM
Registered User
I've got a FrSky module coming from Aloft Hobbies in the days ahead. Scoping out the test FG I've got here, I note there are a bunch of wires connected around the base of the antenna mount with nuts tying them into the case. I intend to mount the new antenna here, so does anyone know if removing these connections to clear out the old antenna will affect the mod? There's also a braid of wires coming from the board to that area. Andy, I read the postings you provided. A darn shame I can't see the photos at the moment, but that FG post looks like what I'm looking for.
Last edited by RWalker; Oct 11, 2012 at 11:01 AM.
Oct 11, 2012, 05:25 PM
Registered User
Well, somebody did it earlier this year! Here's an FG AM radio fitted with a FrSky DIY module: I would LOVE to talk this guy! These pics came from a blog called Shropsireflying. I've contacted the blog owner for details.
Last edited by RWalker; Oct 11, 2012 at 06:07 PM.
Oct 12, 2012, 03:33 AM
Andy2No's Avatar
Do you have a link to the blog?

Instead of using a plug in module, he may have used a hack module, inside the case of the original module. They're a bit too big to fit in a more modern 5 pin module, but should fit in the bigger, older modules. If not, cut a hole in one side and let it occupy some space inside the case, I guess.

The connectors that are used on some Arduino shield boards are a good fit to the pins, and there are right angled versions, e.g. ones made by Truconnect. I used one to repair one of my FrSky modules that had a bad connector.

One of this range of connectors is suitable, and you can cut them down, though there are some 5 pin ones:


I expect those are sold internationally.

The hack module looks like this


They're normally installed by soldering, but you could use one of those connectors to push fit onto the module pins instead. They're better quality than the ones that FrSky uses in it's push fit modules.

The main advantage of the hack module is tidiness. The antenna is separate so you mount it where you want it, and all you need is a small cut out somewhere (e.g. in the back of an old module) for the LED and button. If it's inside an old module case, you'll need a cut out to run the antenna through into the main case too. The coax for the antenna has a screw on connector where it attaches to the antenna. A hole big enough to fit your little finger (pinky) through is enough to route the cable, and you need something like a 1/4" hole to mount it, where the antenna goes.

There's a telemetry version of the hack module too, which has a mode switch. Apparently that switch goes wrong after a while, so I prefer the simpler version. FrSky design and electronics good. FrSky connectors and switches bad The alternative would be to just solder it in whichever mode you use. If you're buying all new gear, that shouldn't be a problem.

There are only three connections to make to a FrSky plug in or hack module, so it's quite simple. You just need ground, switched power and PPM. Once you know where to connect those three things, the rest is just mechanics.
Oct 12, 2012, 09:49 AM
Registered User
Here's the link showing the pinout from the module pins. Courtesy of Ioan Whittman, Shropshire Flying Club, UK.


A link also to his text:

This one makes use of the old module as a case for the FrSky module. Makes sense to me. I'll play around with placing it elsewhere in the case later.
Last edited by RWalker; Oct 20, 2012 at 11:31 PM.
Oct 12, 2012, 10:46 AM
Thermals, Tom
RyanNX211's Avatar
Love those manual trims!

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