CloudSkipper

I wasn't suggesting that right angles as such are a big deal.

First off I was thinking along the lines of RX swapping at the field. And the rather short wire leading up to the antenna is rather thin coaxial cable. You probably know that coaxial cable generally can get compromised from bending. So add to that that you need to secure the antennas at the right angles so they don't shake lose... it envolves some handling that could over time end up in damage to the coaxial (and the cables are short with not much play). I have no experience with 2.4 Ghz, but I know about coaxial cable and this coaxial is also quite thin.

Apparently the worst that could happen is that the antennas shake loose and come near each other or other electronics or metal within the fuse.

I'm sure people probably swap them around all the time, though I don't think I would do that too often knowing how sensitive those stubby antennas are to signal loss given the right conditions (again just based on what I read in the Futaba manual, not experience).

So was just pointing out an additional factor that I noticed that seemed interesting to me. Maybe someone can comment on how durable the coaxial cable appears to be.

The Futaba manuals by the way are here: http://2.4gigahertz.com/downloads/downloads.html

Cheers

pilotpete2

Hi Paul,
The Futaba FASST receivers as well as Spektrum/JR receivers all have standard servo/power pin connections, though Futabas are truly universal in that they have the little notch in the case for the tab on Futaba servo leads. The only exception is the new Futaba 6 channel micro park flyer receiver has those little JST servo connectors that the micro/indoor flyers use, I got the impression from the Futaba team at the WRAM show, that a slightly larger park flyer version with standard plugs is coming.
Pete

DadsToysBG

My Feedback: (35)

That's not not quite true on Futaba. They are the only one that uses the tab on the servo plug. Everybody else uses the same plug type. This allows you to use three out out four servo types with JR. And with a little snip and sand paper use four. Dennis

pilotpete2

Sorry, I wasn't clear. Futaba receivers and most Hitecs are "universal", as they will accept all plugs without modification.
JR, Hitec and new Airtronics have plugs that are referred to as universal, but if you are talking female connectors and want them to be universal, then Futaba females are universal. as they will accept all male plugs without modification
Pete

Paul Cataldo

My Feedback: (10)

Ok guys,
Well what is up with those Spektrum? or JR? "AR9100" Rx's??? I saw a pic of one that had two funky looking "heavy duty" leads coming off of it, which almost looked like some heavy duty plugs were used too? Not sure what these two leads were??
It sounds like you guys are saying that the 2.4ghz Rx's are pretty much just like the old 72mhz Rx's, in physical characteristics (with the exception that the 2.4 Rx's are smaller and lighter, correct?)
Thanks guys.

pilotpete2

Paul,
I think you were seeing the connections between the main receiver and the satellite receiver(s).
Spektrum uses at least one satellite receiver for antenna diversity, Futaba does it a bit differently.
Pete

Ken6PPC

You are probably referring to the heavy duty "EC3" battery connections on the AR9100. (Blue plugs in the picture...)

The EC3 is Horizon's answer to Deans Ultra plugs. I like Dean's better, but that is just me.

http://www.horizonhobby.com/ProdInfo...AR9100-450.jpg

khodges

My Feedback: (1)

The way I understand that, the Spektrum system receives one of its two frequencies on the main Rx, and the second frequency on the satellite Rx. Spektrum recommends mounting them 6 inches apart and at right angles to each other so each Rx gets a different "picture" of the signal, ensuring there is at least one solid RF link.

The FAAST only has the one Rx, and the antennae are each longer than the Spektrum's; putting them at 90 degrees to each other also gives the Rx a different "picture" of the signal.

I've heard and read about "glitches" from 2.4, but it seems to be better explained by calling it a voltage induced lockout; it seems that the 2.4 Rx, Spektrum's at least, has a higher low voltage threshold than the FM Rx's did. If your battery isn't at full charge, and/or you're using high draw servos, they can pull the system voltage below the Rx's cutoff threshold. The Rx goes into failsafe and everything stops working until the voltage can rise above the cutoff. Even a fully charged battery will do this, depending on whether it's a NiCd, or NiMH, and it's age and capacity. My Decathlon had a fully charged (read 5.4V immediately before takeoff with a loaded meter), but had two digital and two high torque servos, and just doing a loop with a half roll dropped the voltage below the cutoff, and I had no elevator or anything else coming out of the loop. EVERYTHING worked perfectly immediately after the crash.

I was talking with a friend who was having a binding problem with his Spektrum Rx, so he sent it back, and had a conversation with the guys at Horizon service who told him that the cutoff voltage on the Rx is 3.5V, and all it took was an instantaneous spike below that to shut things down. They had replaced the "firmware" in his Rx, said it was to change the "reboot" time from 5 seconds to 2 seconds. They are also supplying 6V batteries now in their Tx/Rx/servo sets. Personally, I think if you're using anything bigger than minimally standard servos to go with 6V on any 2.4 system just to give a wide margin of safety.

Paul Cataldo

My Feedback: (10)

Hey khodges,
I don't see how this situation of the low voltage dropout causing the Rx to go into failsafe could EVER be a problem for Giant Scale guys? I mean, we ALL use Lithium Ion or A123 batteries mostly, and NO ONE uses ANYTHING under 6V.
Does this mean we are SAFE from this 2.4 failsafe Rx lockout issue, OR are we also at risk???
I'm currently deciding whether or not I should swap over to 2.4, and I am having a hard time doing so, when I hear things like this.
On the other hand, I LOVE the idea of NOT being able to be shot down by another dummy who pulls up to the flying field, and accidentally turns his radio on, and shoots my plane down because he flies on the same 72mhz frequency as me.
Hell, it makes me wonder WHAT should I do? Go with 72mhz or 2.4ghz?????


Someone a while back told me that 2.4ghz is OLD technology, and has been used in cordless phones for years.
This makes me wonder if 2.4ghz really is as SECURE as everyone says it is? I mean, I think back on ALL those times that I have been talking on a cordless phone, and overheard my neighbors voice and full conversation over the phone, when somehow the lines crossed, and I could hear every word of my neighbors conversation...???? How's that for 2.4 security?? Is there something I am missing here, or is there some logical explanation which will prove these past cordless phone call experiences are no real risk when it comes to 2.4 R/C use????


BTW,
Hey Ken6PPC,
You are correct, and thanks for the link! Those are the connections I was talking about. I did NOT know that someone in the R/C industry FINALLY WOKE THE LAZY ASS UP and started giving up better connectors on at least SOMETHING!
Now, IF they would only start producing RECEIVERS which would take some type of HIGHER quality connector than those standard JR POS's...
I mean, Giant Scale guys should have SOME type of option, which would allow ZERO USE of those standard JR connectors we've all grown to hate! I am referring to the plug-ins to the RECEIVER mostly. Oh how I would love one day, for my Receiver to be able to accept something like maybe a 3 prong deans maybe. I realize that IF a 10ch Rx were to accept Deans ULTRA plugs, it would be HUGE, but maybe something like the smaller Deans 3 prong plugs maybe???

CloudSkipper

It's not just cordless phones... also "secure" wireless networking and home TV distribution transmitters are in the same frequency range. If someone is determined and skilled enough, they could crack a very secure network and mess things up, but that's a different matter.

Like a cordless phone your receiver may "hear" the chatter of other TX's, but it will ignore all TX's that do not have the hopefully unique ID of your own TX. ID uniqueness has apparently not been a problem other than with a limited supply of Futaba TX's as you already know.

I have wireless networking, 2.4 Ghz cordless phone and a wireless TV distributer. I haven't noticed that the wireless networking would suffer, but the TV reception gets messed up when the wireless networking is turned on. The phone seems to never pick up any interference. Your R/C RX will be more like the wireless networking... By design it should be able to disregard rogue 2.4 Ghz signals.

I have read about problems with flying in between a microwave directional beam for example causing the 2.4 Ghz connection to be lost though. I guess the problem there is that the directional beam disrupts the 2.4Ghz signal completely. Don't bring your microwave with you to the field When I turn on my microwave, my 2.4 Ghz TV reception gets completely screwed up (I only warm up coffee during commercials).

Paul Cataldo

My Feedback: (10)

Good to know these things Cloudskipper.
Well I wonder what is the range of a microwave unit from a house nearby? Not very far I suppose. I wonder how long it's going to take to have some illegal immigrant show up at a jobsite nearby our flying field with a microwave to nuke his burritos for lunch?? Sheesh...

pilotpete2

Paul,
If that microwave is leaking radiation that bad, he'll probably nuke more than his burritos [X(]
Pete

CloudSkipper

The range of scattered microwaves from a microwave oven is be pretty short and it is significantly disrupted by physical barriers like walls. Occasionally, I get intermittent very slight interference on my TV and coincidentally right around dinner time So I guess that sometimes the air quality allows for small amounts of microwaves to reach my TV receiver from the neighbors (or maybe someone has a door or window open).

As for the directional beams, I would imagine that at any RC field they will be well aware of any communications towers and whether a microwave beam crosses the field.

One possible rogue type of microwave beam that could occur is if a news van is broadcasting from a location nearby and that beam crosses your field. They also use microwave beams (you've probably seen those towers that telescope up from the roof of the van).

Someone with a 2.4 Ghz TX could try placing a running microwave in between himself and his RX... see what happens.