Range check

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The Shaw's - 21 Apr 2004 21:07 GMT

Hi all

Been doing some range testing of several receivers of different
brands.

I set up Tx with aerial down in a situation where it has no influence
from metal or body parts and about a metre above ground, and then walk
away with a model or a rig of battery/Rx/servos. All double conversion
FM Rx and standard servos

When servos are chattering I then walk back towards the Tx till they
stop chattering (Rx locks on to signal). From this point I pace out
distance to Tx.

Have found distances vary from 60 paces to 10 paces with different
brands and types.

Anyone else tried this, what results with what brands.

V

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Paul McIntosh - 21 Apr 2004 21:58 GMT

Different receiver and transmitter brands have different specs for range
checking like that. I doubt that you could adequately predict in-air
performance that way.

Most range checks are used only to indicate whether the system is operating
properly and no bad interference is present. Beyond that, all bets are off.

--
Paul McIntosh
http://www.rc-bearings.com

> Hi all
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> V

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C.O.Jones - 22 Apr 2004 00:49 GMT

It's been a few years and I don't recall the specifics. But I tested a
Futaba stock 127 Rx on FM against a Hitec/RCD Rx (model 525 I think). Both
Rx's were set on a cardboard box some 6 feet off the ground and the antennas
were extended horizontal in the same direction. The Tx was my trusty Futaba
Gold series FM. All batteries were fresh. The Hitec Rx blew away the
Futaba in range. More than twice as much range in fact. It sold me!

> Hi all
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> V

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The Natural Philosopher - 22 Apr 2004 11:16 GMT

> Hi all
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> Anyone else tried this, what results with what brands.

Similar results. I fly lots of lightweight small stuff.

Example. A futaba 6 channel rx will net me 60 paces.

A futaba parkfly barely does ten.
A jeti REX 4 is about 30 paces.

All 35 Mhz.

I have flown the futaba feather up to 300 meters no problem. Plane
becomes invisible, but still responds (I can hear the throttle)

I reckon 20-30 times range from 'antenna down' to 'antenna up' easily.

> V

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Doug McLaren - 22 Apr 2004 17:32 GMT

| I set up Tx with aerial down in a situation where it has no influence
| from metal or body parts and about a metre above ground, and then walk
[quoted text clipped - 4 lines]
| stop chattering (Rx locks on to signal). From this point I pace out
| distance to Tx.

Some PPM (also called FM) receivers detect when the signal gets
unreadable and lock the servos right there rather than letting them
chatter. And of course if you have PCM, it does the same, or it can
go into failsafe mode.

What I'm trying to say is that looking for chatter is not a reliable
way of determining range. The servos may not chatter at all, even if
you're totally out of range -- it depends on the receiver.

If you have a Futaba 9C, it has a servo tester mode where it just
cycles all servos back and forth. This would be a good mode for
testing -- if the servos stop moving, or start moving in jerks, you're
out of range. It's a nice feature -- more radios should do that.

And as another poster suggested, a range test with the antenna down is
mostly intended to find serious problems before they crash your plane
-- it's not really a good system for comparing the range of system A
vs system B.

Signature

Doug McLaren, dougmc@frenzy.com Eat right, stay fit, and die anyway.

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Model Forum / Radio Controlled / Air Models / April 2004

Range check