flyerdave

My Feedback: (212)

Yes ,I'm still operating with 72mhz. Futaba 9CAP super with 149DP receiver. I have NEVER in 8 years had a glitch,or failure of any kind with this radio, but yesterday I was trying to adjust my Zenoah GT-80 engine with my 33% sukhoi on the bench. Everything was working great and I had been working with it on the bench for about 30 minutes when all of a sudden, the engine went to half throttle, the flying surfaces went to different positions and the radio communication was gone. I couldn't get any response from any control imput. I had not changed anything on the radio, no switch was moved, I was not in a programming mode, I have no clue why, but the connection between the Tx & Rx just seemed to die.

I manually switched the engine ign. off,checked the batteries,and after they checked out fine,I pulled out the 149DP receiver with a ch.17 dual conv. crystal and removed the ch. 17 module from the back of the Tx.. I went to the shop, got one of my 149DP receivers with ch.48, a matching crystal and hooked it all up, turned everything on and it worked perfect.

In all my years of flying and 8 years with this particullar radio, I have never had something like this happen, I know that if I had been flying at the time, My sukhoi would have been history, not to mention someone could have been hurt.

I could just toss the Rx. and crystal along with the Tx. module, but that will leave a lot of questions unanswered.With this never ever happening before, you can understand how puzzled I am.

I know many of you guys will say that I should just go ahead and bite the 2.4 bullet, but I'm not financially ready to get the Futaba 10C, much less the 6 additional rx.'s that I would need to buy.

Any ideas on what this could have been? Thanks

JIMF14D

You have never had anything electric or electronic fail in your life? Wow

BarracudaHockey

My Feedback: (11)

I'd guess you have a bad reciever, specifically the ceramic crystal filter.

Silent-AV8R

And I am guessing in that 8 years the radio was never once sent in for service or otherwise looked at.

The GT-80 is not known as the smoothest running engine in the world and I agree with BH, you likely shook the crystal too much.

flyerdave

My Feedback: (212)

All I was saying was that I had never had this type of communication failure with a radio in my 31 years of flying. I am really trying to find out if it possibly wasen't the radio's fault, maybe it was something I did/didn't do.

Texastbird

Maybe the battery switch is failing from the vibration. Turning it off and back on again would mask the problem. I had one that would intermittantly do this. Otherwise I agree with the other guys about the crystal being loose or failing. They are one of the most fragile components in a receiver.

Zor

It is quite possible that "once when the moon is blue" there was a strong signal on the channel originating from an unknow source blocking your receiver.

Just a possibility.

Zor
.

Silent-AV8R

As BH noted above, you likely lost the RX crystal. When you swapped crystals all was well. Ths is a fairly well known situation, especially with gas engines. Vibration is not the friend of a crystal. This is another area where 2.4 shines. since it is not crystal based it is much less prone to vibration induced issues.

flyerdave

My Feedback: (212)

Thanks for the help, I will definitely change the way the Rx is mounted. It currently has velcro on it and on the power expander and as it is now, there is no padding or foam to isolate it from the vibration. I see alot of guys with just the velcro and no padding, but maybe because most are using 2.4 systems, that is not as much of an issue. Thanks again

BarracudaHockey

My Feedback: (11)

There's no crystals in a 2.4 system but they should still be given some care when mounting.

Note I said "ceramic crystal filter", there were some vibraton related issues with that reciever a while back where the filter went bad, it would range check but throw some vibration and get it a little ways away and it would go crazy.

Personally I'd send the receiver in to get tuned/checked.

Gremlin Castle

My Feedback: (14)

Barracuda Hockey is most likely right about the ceramic filter in the receiver going bad. I had a variation of this happen to me where it flew fine and went dead while firing up for the next flight. R-149s had this as a known problem but Futaba sort of stonewalled the issue. At the time I scrapped 4 R149s and went back to the older R129DP series. After that I went on their 2.4 Fasst stuff with no problems to date. I still fly the old R129s in a bunch of stuff but am converting more planes to 2.4 simply for fly in convienience.

ddaveb

I have had a fault on two of thoese Rx's causeing them to be completely dead it's a small choke that looks in appearance to a resistor that goes open circuit the choke feeds the 5v from one board to the other I can't be more specific because I no longer have any of those RX's as I only fly 2.4ghz now but the fault is easy to check with a voltmeter as the 5v will be missing completely from one board ,a new choke I think it was a 10uh is only a few pence. Dave

A.T.

All receivers, even 2.4GHz must be wrapped in a Flight Preserver or at very least impact resistant latex rubber such as packaged by DuBro Latex Foam Pad in 1/4" & 1/2".(never use foam or bubble wrap plastic).
This to protect delicate crystals and ceramic filters as well prevent wires and or SMT item solder joints breaking from vibration.

Crystals also fail through corrosion of the case and/or legs.
Check all switch contacts and wiring in the TX for any sign of corrosion, especially if Tx has been used for slope soaring in misty conditions or cliff top over water.Given age of receiver, a hermeticity failure is also quite likely, refer pictures:
Crystals - Why Transmitter & Receiver Crystals Fail Without Warning (or being dropped) ]

For further information, refer to sub section
"Crystals, Oscillators & Piezo" at
Alan's Hobby, Model & RC FAQ Web Links

Alan T.

Silent-AV8R

2.4 receivers are all asolid state surface mount IC technology which is very robust and vibration resistant. There are no crystals or other fragile ceramic components as with the 72 MHz equipment. It is still a good idea to use some sort of vibration isolation, but fully wrapping the RX is not really required. In fact, at one point Futaba expressly instructed you NOT to wrap the receiver.

I install my RX with a bit of foam under it and call it a day. I am also fond a a gel pad product that was marketed under the label "Zeal gel pad". It was green and works great. I use it in my helis!

fizzwater2

My Feedback: (61)

Yes, indeed there is at least one crystal in a 2.4GHz receiver. The processor and RF generation have to get a stable clock signal from somewhere.. they just aren't the large cyrstals you're used to in 72MHz receivers.

Silent-AV8R

If so, then I stand corrected. I will stand by the statement that 2.4 equipment is far more robust WRT vibration than the older crystal based 72/35/40/50 MHz stuff was.

fizzwater2

My Feedback: (61)

Very true - much more tolerant of vibration! Perhaps not completely immune, but better for sure. I don't want to go back to the old days of through-hole leaded parts, leads bent so they stand up so you can cram more of them in the same space, etc. Vibration induced failures used to be much more common.

A.T.

Correct - This was onlyduring the period that Futaba 2.4Ghz RX were experiencing major failures from overheating, widely reported..
. 6014 receiver is having issues with overheating and going into lockout seems that when the receiver case reachs 137 degrees F it goes to failsafe
futaba has released info to not wrap the receiver with anytype of foam or padding and to only mount the 6014 on its side with velcro so the bottom of its case is exposed for cooling and also cover your bird with a white towel when parked in the sun the issue only occurs when the plane is parked in the sunlight and the interior is heated by the sun the issue does not occur in flight due to air movement "
. futaba-fasst-receiver-overheating
and many more examples of Futaba RXoverheating
. There are no modifications to the R6014FS receivers that will expand the maximum operating temperature of their components. It will remain at 60 degrees C. We've heard of receivers overheating only when they were in aircraft that had the receivers mounted below a canopy in direct sunlight where the modelers were operating in high-temperature environments...mostly in the desert Southwest. Large-scale airplanes with exhaust canisters running through the fuselage with no heat shield between the canisters and the interior of the model were also contributing factors. Bill Baxter, Manager Hobby Services/Futaba Service/North America
. "The temperatur range of ALL Futaba receivers is limited to +60 C - 35 Mhz (I suspect 72 Mhz also) and 2.4 Ghz alike, with +55 C as a conservative limit recommended. I got this information from a call to Robbe, the German Futaba distributor.
. Bax then posted http://www.rcuniverse.com/forum/m_7606959/tm.htm
"Using less foam lets them operate cooler" -why should those particular RXbe any different from Futaba 29<72 Mhz RX and other brand 2.4Ghz RX with regard to overheating? (- no longer mentioned with later models)

Quote:

ORIGINAL: Silent-AV8R If so, then I stand corrected. I will stand by the statement that 2.4 equipment is far more robust WRT vibration than the older crystal based 72/35/40/50 MHz stuff was.

Granted that later model of all receivers are more robust than the ones often years ago, but receivers remain delicate items.
Anti vibration / shockprotection is essential in GPModels, to stop vibration damage in any form of RX, and also helps retain leads.
e.g.SMT components breaking free from boards, wires breaking and more as explained in several articleson my web page.

Alan T.

Silent-AV8R

Of course "wrapping" the entire receiver is not necessary to isolate it from vibration. As I said, I use foam under the RX to isolate from vibration. The attached photo below shows a 90-size heli. You can clearly see the green gel padding (Zeal) under all the electronic components. You can also see that none of them are completely wrapped. I did confirm that the FASST receivers do in fact have a surface mounted clock crystal. But it is smaller and more robust than the earlier version.

So the bottom line is that vibration isolation is still required, despite the 2.4 equipment being more robust. However, there is no requirement to completely encapsulate anything in foam to do this.

Zor

All readers,

I do not endorse the method defined in post #13.

The reason is that a receiver should have free air circulation on enough of its surfaces to remain cool.

There are ways of mechanically isolating the receiver from vibration without a near complete wrapping.

Suggest using rubberized foam on just enough receiver surface to hold the receiver and wrap the foam with #10 sewing thread wrapped around the foam ( about 3 turns not too tight ) then provide some support using your imagination such that free air movemnt is available.

I also do not like the "crazy glue" ( see the picture in post #13 ) from leaking all through and gluing the receiver to the foam material.

Zor

BuschBarber

My Feedback: (2)

For my 2.4Ghz aircraft, I put Velcro on the bottom of Rx and attach it to the mount point on the aircraft. I then put a Velcro strap around the Rx.

Prior to using 2.4 Rx's, I used 72Mhz for over 30 years. We Always wrapped them in Foam Rubber, except for the ends. We never had any heat problems.

The 2.4 Rx's are more resistant to vibration and I do not know anyone I have flown with who wraps them in foam or anything other than Velcro or rubber bands on a foam pad.

Zor

Red inserts in text by Zor

Rubber bands (elastics) holding the receiver against a 1/2 inch thick rubber foam (not glued to the receiver) is one of the best method. Of course tie points must be provided in the fuselage structure to attach the rubber bands with enough tension to hold the receiver.

Just some thinking worth considering.

It would be useful to see some of your installations in pictures.

Zor

BuschBarber

My Feedback: (2)

I mount my Fuel Tanks, Air Tanks, Batteries, and Receivers using a Velcro adhered to the bottom of the item an another pad adhered to the mount point in the aircraft, with the adhesive that comes on the back of the Velcro, and a Velcro Strap with no adhesive. The Velcro pad keeps the item from moving and the Velcro strap keeps it from detaching from the Velcro pad. For very light items, such as a JR/Spektrum Satellite Rx, I use just the Velcro Pad that is adhered to the mount point in the aircraft and the bottom surface of the Satellite Rx. This also helps to reduce any vibration.

When I have pictures I will post them.

The 72Mhz receivers were all wrapped in Sig Foam Rubber and rubber bands were used to attach the Rx to Cup Hooks screwed in to a plywood or hardwood mount point.

Zor

Thanks BuschBarber,

am sure that many are anxious to see your pictures.
A picture is worth a thousand words.

Attached a typical installation in a very narrow and shallow fuselage of a sailplane.
It was a challenge to figure out this one.

The antenna center line is vertical in the fuselage. The satellite receiver antenna is closer to the fuselage nose and is horizontal at 90 degrees from theantenna on the main receiver.

I did not have much choice in this very restricted space.

Zor