Let's start a useful post.

Following this discussion I'd like to propose some tips to avoid having bad surprises when flying your Jets with Spektrum...
http://www.rcuniverse.com/forum/m_7080410/tm.htm

Electrical power bus:
AR9000 and below: in my opinion it is best to use a pair of Lipo batteries of the adequate capacity and an appropriate regulator.
If you fly in hot temperatures remember to oversize the regulator if it is a linear one: the heat sink is usually the limiting factor.

AR9100: I don't like the blue plugs supplied because they tend to open easily. I have used Deans ones. I like the idea of using direct batteries without regulators.
A123 might do the job if your servos can cope with 6,5V. Otherwise I'd go to a dual regulator again. I don't like NiMh too much for Rx because of their high internal resistance and their bad habit to false peak. I use one Voltspy per pack plugged on the balance tab to check the lowest voltage inflight.

Checking the electrical power bus: It is good to do a individual servo test with an amp meter and to keep a record. it might be useful later on when your servos get old. This readout is a very good indication of the servo health. The Hanguar9 digital volt/amp meter is a perfect toll for that.

I always do a series of "torture tests" to check the complete system: under load and warm weather. A 6kg thrust model shall use 200 gr of load per control. A 8kg thrust model shall go to 400 gr. 12 kg thrustmodel, 800grs. 16 kg thrust model up to 2 kgs and so on... Once again take a record of the data. This might be extremely useful.
I use only one battery during these tests and check the drain with a Hall effect ampmeter. When in doubt I do continuous tests up to 2 hours.
An example here: http://www.rcuniverse.com/forum/m_6482230/tm.htm

Setting up the model against EMI:
Place the receiver as far as possible from any radiating source ( ECU, pump, switching regulator, light controller...). Anything closer than 10 inches will need a shielding.
Pay also attention at the servo and antenna wires. They should not be placed too close from a radiating source. Twisted servo wires arry less EMIs to the receivers than flat ones. Ferrites are good against HF noise. Might be worth the test.
If in doubt switch to PPM/PCM and use a Weatronic that is shielded by design.

RF section:
Place the antennas for the best possible diversity.
Ashlock plugs are a great tool to make easy connections of 2 servos + 1 receiver in each wing... The other ones go to the rudder and /or nose. This is just a guideline. Each model being different ( cf Flite Metal...)
If you intend to have position lights in the wings, use 2 sets of Ashlock plugs. One for the radio, one for the lights.

RF range test:
Do the test as per Spektrum manual.
The engine shall be running and all systems On ( like lights, data loggers, GPS, aso)
The Ar9000 goes as far as 60 paces without fading.
The AR9100 goes over 120 paces.
If the results show too many antenna fades, relocate this antenna.

EMI resistance test:
This one needs time because I believe that Spektrum receivers are sensitive to EMI buildup ( it might generate some king of static electricity buildup as well ).
Just run the model on ground for the entire expected flight time or even 30% more. The bind button does not need to be pushed. The engine has to be at full thrust to generate as much EMI as possible. No need to move the model in all directions because we just want to see how the system reacts against self-generated interference.
Stir the sticks constantly to detect any lockout. You can stay close to the model. No need to look at the flight log.

Guys if you have any suggestion that might improve the method, it's your turn...

Also a very good habit:

I always have a flightlog on board that I read after switching the system On. If one antenna shows ---- this means that it is inop and has to be changed ( or there is a cable problem ).
I record the Flightlog data after each flight and check the trend ( I also record max EGT in flight, max EGT during start, max pump voltage and min rx bat voltage from 2 voltspy or similar device ).
All of these data show usefull trends...

Olinco, you can probably remove the recommendation of RF filters. According to what I have read on Horizon's web site they are pretty much unneccessary for 2.4 systems.

One precaution though is to not use the PCM Y-cables as they can cause issues on 2.4.

Just place fuel pumps, etc a good distance away from the receivers on Spectrum and all will be fine. The fuel pump is by far the noisiest part of the turbine electrical system. I have nearly 200 flights on 2.4 now and about 150 of those on turbines in several different aircraft. Just keep the main receiver and remote receivers away from other components and the system works great...Gary

Yes but that recommendation is valid for the RF stage. What about EMIs ? What range of frequency is jamming the receiver chip ? I don't know, so in case of doubt...

Dual Fromeco 2600 or 5200 Li Ion packs to dual on/off switches to Dual regulators and a D-CUP...

Flawless!!!

and a D-CUP...

Flawless!!!


Like my women

Ahh FFFFFFFFFFFFF YYYYYYYYYYYYeeeeeeeeeeeeesssssssssssss

If you're worried about servo wires a better way to prevent EMI is to use shielded cables instead. The problem isn't EMI being carried to the receiver. The problem is the signal wire acting like an antenna and carrying EMI to the servo causing it to jitter and glitch. By shielding it, any stray signals are shunted to the receiver ground.

Dan

Skip the regulators, two A123's (2300 or 4600).

Hi Dan,

Do you have a source for those wire shields?

If it's not too heavy it could be very interesting...
I'm also thinking about an aluminium box custom made for the AR9000 and AR9100.

Hell, If I had to worry about all of that crap on my 10X I wouldn't have it. One should not have to go through such intensive measures just to use a radio. I'll wait until it gets better.

Hi Eddie,

I start with a 6" servo extension and cut the wire in half. I then splice in some 26-gauge, 3-conductor shielded computer data cable. I usually buy it at a local electronics store. The last time I bought some it ran me about .10-.15 / foot.

I used to wrap the receivers for EDF in aluminum foil. That really helped prevent EMI in some tight installations.

Dan

Hi Dan,
How about wrapping the servo wires with thin Aluminum foil, instead of getting shielded computer wire? I wonder if that would work and save weight?
Regards
Serj

Maybe. But, I don't think you'll get the same effect. The aluminized mylar is only one component of the shielding. The other is the bare wire. It acts as an antenna to shunt any stray EMI signals to the receiver ground.

The shielded cable isn't really that heavy. It's only about 1/4" in diameter and the wires themselves don't weigh any more than a servo extension of the same length. So, the only extra weight is in the thin aluminized mylar, the bare wire and the pvc shell.

While a lot of these recommendations are useful as a common practice, I think the use of the 2.4 was intended to minimise/eliminate most of these potential noise problems. The frequency range of the turbine pump and other noise sources in our models is lower than that of the 2.4. Having said that, it is not wise to "assume" we are 100% safe from any noise in our jets. A strong enough EMI/noise source can mask the Rx signal (multiple rx's helps thu). I think we are a bit more safe with our traditional installations in jets using the 2.4 vs the 72 mhz..

Hi Ehab.
You missed the point: EMI's will not lock the RF stage. They may lock the CPU stage.

So what's it mean when you bind the system, it works great but the light on the receiver and the satelite blinks continuosly?
K

Gentlemen, Its great to see a really USEFUL post in which we can have a meaningful discussion about this great advance in R/C technology. (Can we PLEASE keep it that way ????)

To add my 1 cent:

I have now flown the 9000 receiver in my BobCat with PST power, dual Duralite batteries, switches and regulators with not a single frame lost, antenna fades vary from just a few to a couple of hundred but control is absolutely solid.

I thought a more demanding application would be my Savex L39 with Wren 44 power because the model is so small and everything is so close together. Because of this close proximity concern, I installed one remote in the wing. Results have been perfect, again not a single frame loss and fades are less than the BobCat with the wing remote receiver consistently showing the lowest fade count. The L39 has ONE Duralite battery with a single 5.4 volt Mini Hobby regulator.

No screening or any other EMI or RF precautions have been taken, except a careful range check, and both mdels have data loggers which are checked after EVERY flight.

My new 9100 is on the bench with Dual A123 batts and no regs but I think I will use regs. and two hard switches to make sure the servos receive only about 5.6 v, well below the 6 v limit. I believe this will be safe for the Rx too as although Spektrum say the op. voltage is from 6 to 10 v the manual also suggest that brown out voltage is way down at 3.5 v and I have never seen a voltage this low on any of my aircraft (all of which fly with volt loggers on board).

For those who have new 9100s be advised that the rx lights blink after a loss of power (simulated by switching OFF and then ON for the batts.) Reconnect is instantaneous, but the blinking lights warn of the power loss, great idea.

I will flight test the 9100 soon in my BobCat XL.

Regards, David Gladwin.

Thanks for your feedback David.