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Old Dec 06, 2012, 11:46 AM
renatoa is online now
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That ground wire is the counterpoise of an Inverted Vee.
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Old Dec 06, 2012, 11:53 AM
BriGuy82 is offline
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Quote:
Originally Posted by pmackenzie View Post
We called them Rabbit ears, not bunny ears, so I didn't make the connection

Bunny Ears make me think of a certain magazine run by an old geezer
Lmao.. Yes I meant rabbit ears. Same thing I suppose! Back to my question, ok so keep the ends clear of any obstacle. How about leads with power to them? Will it effect my RS? Can I mount these antenna ends inside of a carbon rod on the fuselage?
Old Dec 06, 2012, 11:55 AM
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Quote:
Originally Posted by RENATOA View Post
That ground wire is the counterpoise of an Inverted Vee.
That's what I figured, but I also don't think it would work as expected because its length is much longer than the wavelength. I think it should also be perpendicular to the active element, not some sort of 3D loop.

The BODA is sort of an example of a 2.4 Ghz counterpoise.
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Old Dec 06, 2012, 11:56 AM
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Quote:
Originally Posted by BriGuy82 View Post
Lmao.. Yes I meant rabbit ears. Same thing I suppose! Back to my question, ok so keep the ends clear of any obstacle. How about leads with power to them? Will it effect my RS? Can I mount these antenna ends inside of a carbon rod on the fuselage?

The active end can't be inside carbon or anything else conductive.
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Old Dec 06, 2012, 01:34 PM
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Question guys: I have the DHT-U module that I'm using with my Hitec A9. I was considering going with the DHT-DIY for a cleaner install, but I'm not clear on what the switch does. Does it allow me to switch to between the Frsky and Hitec modules or does it simply turn on/off the frsky module? It would be nice to be able to switch between the two so I can still fly my overpriced Hitec rx's.
Old Dec 06, 2012, 03:13 PM
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It switches the frsky module's mode between telemetry mode (for the D-series receivers), one-way mode (for the old V-series receivers), and firmware upgrade mode.

If you want to switch between modules you'll have to wire that up yourself.
Old Dec 06, 2012, 03:26 PM
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Originally Posted by Kilrah View Post
It switches the frsky module's mode between telemetry mode (for the D-series receivers), one-way mode (for the old V-series receivers), and firmware upgrade mode.

If you want to switch between modules you'll have to wire that up yourself.
ok, ya I was thinking I could just wire that myself anyways, but that clears up the 3 switch positions (didn't get what the fw position was for), thanks
Old Dec 06, 2012, 04:08 PM
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Can I mount these antenna ends inside of a carbon rod on the fuselage?
no. If your going to mount the antenna ends in anything, it has to be non-conductive.

Also, experience with 2.4g systems, try not to bend the coax too sharply.. gentle curves are best.
Old Dec 06, 2012, 04:22 PM
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I got about 60% or more reduction in range mounting my antennas inside a plastic tube even though I had the exposed ends completely sticking out of the tubes. This happened on two different multicopters. The plastic tube was a control rod housing used in model planes, fairly thick plastic but still.
Old Dec 06, 2012, 05:04 PM
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I've read somewhere that if we put a piece of the plastic tube in a microwave oven and it gets hot, we should not run the antennas inside because the tube absorbes the RF..
Don't know whether this test is valid or not, but it makes sense to me..
Last edited by jhsa; Dec 06, 2012 at 10:47 PM.
Old Dec 06, 2012, 05:09 PM
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Originally Posted by u2builder View Post
I got about 60% or more reduction in range mounting my antennas inside a plastic tube even though I had the exposed ends completely sticking out of the tubes. This happened on two different multicopters. The plastic tube was a control rod housing used in model planes, fairly thick plastic but still.
This is contrary to everything I have been taught!
Old Dec 06, 2012, 06:25 PM
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Some plastic tubes have graphite or metal in them.. You have been warned. use the microwave test (with a cup of water in the microwave.)
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Old Dec 06, 2012, 07:36 PM
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This is contrary to everything I have been taught!
It sure surprised me. I put the antennas in the tubes thinking I was making an improvement, took off, went about 200 feet and the machine went into failsafe. I put it on a stand and did the Frsky green blinking button range check. It lost range in less than 10m. I removed the tubes and got about 40m.

I had put the same tubes on my Hex at the same time. I got the same reduction in range on that machine.

In both cases the uncovered part of the antennas were sticking out of the tubes.

These two tests were done with no other changes whatsoever. I was totally shocked.

The tubes were red plastic Gold N Rod tubes. I just put them in the Microware for a minute and the temperature went to about 140F. I put some clear plastic Dubro throttle tube in at the same time. It went to about 95F.

I have put 72 mHz antennas in tubes many times and passed a range check.
Old Dec 06, 2012, 07:59 PM
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any plastic tube that gets hot in a microwave will absorb RF.

..however, you can use this to your advantage..

If you need to run your antenna cable past a motor or esc, then the tube can act as a shield.

even a thin coat of vaseline on a telescopic antenna at 27, 40 or 72Mhz will affect range.

makes me wonder about the heatskrink that flysky puts on its Rx antennas...
Old Dec 06, 2012, 08:03 PM
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throw new IOPilotException();
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Dang... I usually use the snakes rods from gliders to help guide the antenna wires.


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