Topic: MPX TX Range

Hello,

Can anyone tell me what the realistic and/or theoretical range of a 35MHZ Multiplex Evo 9 TX is please? I know it is condition dependent, but I have never seen a figure offered, it only ever says that it will be out of sight before it is out of range. Whist this may well be true, I still need a base figure for my next project.

Can anyone help?

Cheers,

Craig.

Hi Craig.

We don't give range figures for radio sets because it is very difficult to quantify.

It is effected by any number of factors, as you say, such as temperature and humidity, receiver type and design, even installation.  And as this is impossible to consistently reproduce, therefore no figures are obtained or recommended.   So any manufacturer would be foolish to quote definitive figures as this would lay them open to all sorts of claims.   Also, airborne range is greater than any ground test carried out.

However, it is regularly acknowledged that the Multiplex IPD receiver system has arguably the best range of any 35MHz system available at present as it will filter out any spurious signals and 'listen' better to the transmitter at extremes of its operating envelope.

Any figures people can give you will give you a good ides, but they will rarely have actually been measured.  But I have been told by several well known MPX users that they have got quite eye-watering ranges with their systems! 'Spotting' a 7m+ glider is quite usual with MPX gear.  Maybe some of them will reply with their personal experiences?

Sorry I can't be of much more help though!   

Regards

Gordon.
 

Hi Craig

When I began using Multiplex gear almost 20 years ago, one of the first things I noticed was the vastly superior range over other equipment then in use when carrying out a ground range test. It's not at all unusual to get 200+ metres with a fully collapsed Tx antenna. Multiplex themselves recommend a minimum of 80 metres when carrying out this test.

My feelings are that it would be fair to assume the extreme range would also be greater than most other equipment too. The interference rejection also appears excellent. 

Hi Craig

When I began using Multiplex gear, almost 20 years ago, one of the first things I noticed was the vastly superior range over other equipment then in use when carrying out a ground range test. It's not at all unusual to get 200+ metres with a fully collapsed Tx antenna. Multiplex themselves recommend a minimum of 80 metres when carrying out this test.

My feelings are that it would be fair to assume the extreme range would also be greater than most other equipment too. The interference rejection also appears excellent. 

All I can say is I can get 50M + with a totally collapsed aerial and 20M + with no aerial at all on my 3030 using either MPX IPD or Hitec Rx.
I do not test at any greater distance as it is pointless, I do this purely as a confidence check. I have owned my 3030 for six plus years and aesthectics not withstanding it is the best piece of kit I have owned in 40 years of RC modelling.

I've just had a look in my notes at some range tests I did using my Evo 9 with a Synth rf module onboard, and a Schulze alpha 435 receiver last year.  I did the tests on my local beach, and the setup was on a simple stand, with a battery pack, rx and servo.  The servo had a nice bright orange flag on it, so I could see it clearly at a distance. It was setup approximately 1.2 metres off the beach, and the rx aerial was dangling straight down.  Weather conditions were overcast, but warm.  I was testing out various aerial setups, mainly to see the effect of using a Becker aerial instaed of the stock Evo one.  I used a GPS receiver to verify distances.

With the stock Evo aerial collapsed completely, the range was approximately 150 metres, and didn't change appreciably with the oreintation of the tx.

With the Stock Evo aerial extended fully, the ground range was approximately 1400 metres with the aerial pointing straight up. When the aerial was moved away from the vertical, the range decreased, and was worse with the aerial pointing directly at the receiver (~1090 metres)

With the Becker aerial adpater installed, but no Becker aerial, the range was approximately 130 metres.  The was no appreciable change with different TX oreintations.

With the Becker aerial installed, and fully extended, the range was approximatley 1270 metres with the aerial pointing skywards.  The range reduced to 960 metres with the tx aerial pointed at the rx.

That was about it, and it was enough for me to decide the Becker aerial was good enough for all but the most extreme range requirements.  I actually had to use a pair of binoculars to see the 6" square flag attached to the servo with the aerial extended tests.  Oh and by the way, I decided the range limit was the point at which control was lost completely.  There was a period of slightly jerky operation leading up to the complete loss of signal, but interestingly, this only happened for around 5 metres on the aerial down tests, and around 25 metres on the aerial up tests.

Any use to you?

Cheers
Andy

Thanks everyone, you have all been a big help! 

Wow 1.4km is impressive, any thoughts what this might translate to as an airborne distance assuming I have line of sight?

Have a look at this video, it should explain my curiosity!

http://www.aeropix.ch/videos/OSDTestTriangle2Public_hi.wmv

Cheers,

Craig.

The only measurement I have for airborne range, is taken from my Ram2 pressure altimeter that I installed in my Prangster to test it.  I took that up to an indicated 700 metres, with no control issues at all.  The only problem I had, was keeping my eyes on the plane!

Personally, I would use the ground based range test as a safe airborne limit.  Anything more than that is a bonus really!

Cheers
Andy

Oooo 700m without a camera is brave, it must have been a tiny little spec.

Wise words indeed. Thanks Andy!

Cheers,

Craig.

The only measurement I have for airborne range, is taken from my Ram2 pressure altimeter that I installed in my Prangster to test it.  I took that up to an indicated 700 metres, with no control issues at all.  The only problem I had, was keeping my eyes on the plane!

Personally, I would use the ground based range test as a safe airborne limit.  Anything more than that is a bonus really!

Cheers
Andy

It was!  At one point I remember blinking because my eyes were watering.  It took me a good 10-15 seconds to find the plane in the sky again, and that was only because I chopped the throttle, and held in full aileron/elevator/rudder.  The movement and changing shape must have made it a bit easier to pick out agains the sky.

I decided to fly a bit lower after that!

Cheers
Andy

 :laugh: A bit lower... Half that height is still really high. I'm glad it came back in one piece!

Cheers,

Craig.

I decided to fly a bit lower after that!

A few years ago I was flying my 6 metre Ventus 2c at a well known aerotow event. I found one of the few thermals that came through that day and stuck with it as long as I could. It was remarkable flight on two counts. I nearly made 2 hours flight time (1:51) and the range the model was down wind of the field. I got my ear chewed off because someone coming through the local village had spotted my model thermalling above. This was forbidden territory so I headed up wind and landed, a decision I was about to take anyway, since if I had have blinked I would never have aquired the model again visually. When we looked on the map, it was around 2 miles from the launch point! This was a 4000 Tx and an IPD 12 Rx combination.
Just as remarkable was the range check I did with my Eurosport. I taxied away from me with the engine running on the pan at Elvington, until my helper flagged me to stop as I had reached the fence. I had one segment of aerial extended. This was about 2/3 of the length of the pan, which is .6 of a mile long, so around .4 of a mile. This model used and IPD 12 Synth Rx and the same Tx.
Regarsd,

John

Spot on John.

That's why we pay a little more for Multiplex gear!