RE: Hi-Tech servos?
 

I have regularly gotten well over 3000 foot MPX range on full antenna length ground tests with a turbine running, in ground effect when I could not even see the plane (shooting through the Earth, tangentially). Same test with ye old 9Z was half that. I would not trust a jet to anything BUT MPX, nowadays!

RE: Hi-Tech servos?
 

Jim, i'm not so familiar with multiplex designation, i beliebe one was a 3030 and the others were somewhere in the 4000.

Woketman, 3000ft with extended antenna (should be around 1 km) is nothing unusual for JR or futaba....on my sabre i did a test in which i ran up the turbine, left the plane with a friend and drove off in the car. Easily made 1,5km without loss of control in all aspects of the plane. Didn't go further because i could not make out the plane as anything more than a darkly shaded dot.

Well, everyone is going to use what he deems right... :)

RE: Hi-Tech servos?
 

Ah, that could explain it. I'm pretty sure the model that the guys here are referring to is the Royal Evo. Perhaps it has a different RF output design?

...jim

RE: Hi-Tech servos?
 

I use futaba (FC-28), and in all my jets, i get at least, with aerial down 100 Meters! (around 330 feet )
in my Harpoon, i walked until the receiver was in fail safe, it was almost 165 meters !!

if i'm under 50 meters, i don't even think to fly..

RE: Hi-Tech servos?
 

No Jim, my extreme range was with the 4000. I have a Royal Evo, but have only done antenna ground range checks with it (but it actually beat the 4000 in that, hard to believe!).

Miniflyer, in the testing that I mentioned, it was not straight line of sight. It was at Lumberton MS airport. The runway is slightly curved (the ends are lower than the center) so I can not even see the area where the plane is when I get to the far end (we use the cheap GMS radios to talk). The Futaba I tested was very much so less than the MPX. I have done a lot of local field ground testing with other JRs & Futabas. The MPX always blows them away. And now it appears (from the limited testing that I have done) that the Royal Evo may indeed beat the Profi.

RE: Hi-Tech servos?
 

I stand corrected. But still cool!

It was yours, and a couple of others, rational and well presented descriptions of the MPX systems that convinced me to "make the switch" this winter. Only problem is that I've already sold my previous rig, but the new rig is back ordered! Good news is that they expect it by the end of March. Plenty of time to get ready for the flying season.

Regards,
...jim

RE: Hi-Tech servos?
 

About a week ago did a routine range check with JR3810 aerial extended on my R&D Hotspot. On the tarmac with ECU, autopilot/GPS, RF modem (200mW 2,4GHz) and Radar Altimeter (1W 4.3 GHz) all functioning got 1000m plus by driving down a runway. According to GPS we routinely fly directly away from us at up to 800metres in the air. This is far to even see a jet, believe me. Never a glitch. It of course helps to be on 35Mhz as opposed to 72 MHz. About 10 years ago I got the first of the MC3030 MPX systems. Sold it a month later. Maybe they have improved since.
I have studied both MPX and JR RF technology in detail. JR is better by miles. BTW aerial removed or retracted range checks means nothing when compared between brands.

Not my 2 cents opineon. Spent a lot of time and money figuring it out for military purposes at the time. For my money a brand that need not had to improve their basic technology in 10 years is what I want.
Now if only JR can make a sensible user interface and get rid of the terrible slop in them digital servos and get rid of the temp drift I would call it perfect. Hell, I will write the damn software for them for free if they fix the servos. Please.....please...
Andre

RE: Hi-Tech servos?
 

Hi Andre,

In what ways is it better? I have no agenda I am just curious what you saw and what criteria you use, given your stringent RF requirements.

Also, how directional is your onboard telemetry system? Do you use a high gain antenna on the ground station?

Regards,

RE: Hi-Tech servos?
 

Hi Matt,
I had all the circuit diagrams for JR and MPX available to me. Simply looking at the front end, oscilator circuitry and mixer coupled with ultra quality ceramic IF filters it is an obviously well thought through design and very similar to high end VHF aircraft coms in design and component quality. MPX on the other end used the test circuit from the Siemens catalog for cheap cordless phones. In particular the SO40 and SO41 Rf amp/mixer and i/f amp. for the dual conversion type they simply added another if chip with consumer grade filters. The TX power was far down on the JR but what caused many a problem was the TX module at the back which had connector pins on a single sided PCB with narrow tracks. They would lift and start to tear after a few cycles of insersions. It needed to be epoxy pcb through plated and not bakelite. The JR had good power filtering from the servo side and the RF section regulated very well as a result at 3.3V. The operating voltage for the siemens chipset was minimum 5V.....

I have no agenda as I am not a dealer for JR. I was for a (very)short period a MPX dealer. I must stress however this was 10 years ago. I have noticed that JR has also started using ic i/f solutions of the type motorola pioneered for cordless phones. The front end remains as before for the most part. JR got away with a very narrow band signal yet good detector performance by ofsetting the RX xtal by slightly less than 455kHz. This put the frequency shift on the steep slope of the filter response resulting in large signal detection capability. Poor design for voice but perfect for data. They called it "single side shift" (not to be confused with single side band).
My modem is a standard Aerocom OEM module and I use the standard old 3dB omni duck type. My base station is about 2 metres up but we do get dropouts in steep turns far out. 2.4GHz is great but the directional nature is problematic. Look at the 900MHz types for better range under our conditions. I believe you can use up to 1 watt in the USA.
These units seem to be very reliable and clean. The mini RF connectors are a bit flimsy though.
Andre

RE: Hi-Tech servos?
 

Miniflyer,
I am very, very surprised! If I don't get 135 metres with one segment of arial with my 4000 I think there is something wrong and I don't fly. I used to own both Futaba and JR. I don't anymore. After 18 years I have never had a single Multiplex component fail. I have flown a large model at 2 miles range. Try that with your JR but make sure you have a bin liner with you.;)
John.

RE: Hi-Tech servos?
 

Woketman,
Absolutely!

Regards,

John.

RE: Hi-Tech servos?
 

We have never had a Multiplex failure at my club and that includes me flying a jet and a club member who is one of our national team members at his umpteenth world scale championships, he has used Multiplex for decades and refuses to put any other brand in his world championship models.

On the other hand, I can tell you time after time after time I have had Hitec servos fail on me, even when just being tested on the bench. In fact, every batch of Hitec servos I have ever had has had at least one failure in it. The worst servo is the 225 which is fit only for landfill, I have even had one shred its gears all by itself when being bench tested. I had one plane destroyed when the Hitec rudder servo tried to turn through 180 degrees on only its second flight. The highest failure rate I had was when I was persuaded against my better judgement to buy 4 Hitec digitals, 3 of the 4 failed on bench testing within one minute of being taken out of their boxes. I am happy to use any equipment from Multiplex or Futaba or JR, I use mostly JR servos, but I wouldn't fit Hitec servos to a child's toy car.

H

RE: Hi-Tech servos?
 

Why doesn't someone just test these things... Can't be that hard..
All I read on here is speculation...

Tell you what... At FL Jets.. you get all the people who think there radio range is the bomb
and put them on the runway at the same time... (not running)... At least 4 of each
kind of Radio... JR.. Futaba... MPX.. And just start walking...

Everyone will be there and will all there stuff... We are forced to stop flying long
before dark...

I will put my old 8 channel up there but I think I will loose to a MPX...

Could be very informative.. Tell you what.. I will keep track of everything..
Just put the plane out there, have some one watch it and we will all walk down the runway together...
Can't get any more real world than that..

Eddie Weeks
(winner don't get jack)

RE: Hi-Tech servos?
 

:D

RE: Hi-Tech servos?
 

Sure he does................with the longest walk back, he should have the biggest thirst for the beer that evening!