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Old Nov 17, 2011, 10:50 PM
Gravity - It's the law
Yabba's Avatar
USA, CO, Denver
Joined Jul 2008
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Originally Posted by volto View Post
Yabba, I would be more worried about that serious camera wobble. That would drive me crazy.
Ha! I heard you. Actually I just changed the motor shaft prop adapter and checked the balance of my prop (it was spot on).

I'm thinking the adapter must have been bent at one time or another (did you notice my cowl? Hmmmmm )

I don't think it's the shaft itself, it's 5/32nd.

So I hope that it will be better tomorrow.

Howz the weather in Durango? You get any of that wind the other day?

Thanks,

Yabba
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Old Nov 18, 2011, 12:53 AM
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Originally Posted by gundamnitpete View Post
interesting templates. where did you get them? you make them? want to add them to OP? should help in constructiong this antennas.
I made them. You can get the DWG file here: http://tunerspotter.com/%5Cdropbox%5Cmisc%5C1040mhz.dwg

It's really simple to draw in AutoCAD. This is what it looks like on a regular printer(I assume you don't have a designjet):

Make sure the scale is right so you have accurate printout.


If you don't have AutoCAD or any Autodesk software get Trueview because it's free... http://usa.autodesk.com/adsk/servlet...&siteID=123112
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Old Nov 18, 2011, 12:53 AM
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USA, CO, Durango
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I get way too much wind here. Crashed my plane into a power line today because of it. (and because of my bad piloting)

I am gonna be in Denver weekend after next, after Thanksgiving, a couple of us are getting together for some FPV if you are interested.

http://www.rcgroups.com/forums/showt...431921&page=32
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Old Nov 18, 2011, 02:28 AM
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Switzerland, LU, Buchrain
Joined Aug 2006
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Originally Posted by chatch15117 View Post
Here's the Rx antenna. I need to make a stand for it. Video coming shortly(30% uploaded)
The antenna looks nice. What surprizes me a bit is that you intend to go for a cloverleaf on the reciver end. You surely CAN do this, but a skew planar wheel would be a little better. Then, for the reciver antenna I would go for a bottom feed as it's easier to place it on the reciver. Other than this, I'm sure you will be pleased with the outcome!

Markus
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Old Nov 18, 2011, 02:48 AM
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What's the difference with a 4th lobe?(pros/cons)? I made a stand for my Rx cloverleaf today and it should be a bit better at 15 inches off my car instead of resting on the roof.

I have a feeling I'll be moving to UHF on a Turnigy 9X for Christmas. If you look at 6:00 in my video on the other page there is a cessna at my altitude about 500 meters west(flies from left of screen to right)... flew right by. I'm not sure why they keep looping around the lake. The executive airport is like 3 miles south and I'm in class D airspace.
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Old Nov 18, 2011, 03:27 AM
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Originally Posted by chatch15117 View Post
What's the difference with a 4th lobe?(pros/cons)? I made a stand for my Rx cloverleaf today and it should be a bit better at 15 inches off my car instead of resting on the roof.

I have a feeling I'll be moving to UHF on a Turnigy 9X for Christmas. If you look at 6:00 in my video on the other page there is a cessna at my altitude about 500 meters west(flies from left of screen to right)... flew right by. I'm not sure why they keep looping around the lake. The executive airport is like 3 miles south and I'm in class D airspace.
http://upload.wikimedia.org/wikipedi...o_Spectrum.jpg

Most likely because you are broadcasting in an aerial navigation band (1040mhz) next to an airport!
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Old Nov 18, 2011, 03:49 AM
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Switzerland, LU, Buchrain
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Originally Posted by chatch15117 View Post
What's the difference with a 4th lobe?(pros/cons)? I made a stand for my Rx cloverleaf today and it should be a bit better at 15 inches off my car instead of resting on the roof.
Definately. Putting your side feed CL directly on the roof of your car is a bad idea. Make sure to have it high in the air. The higher the better genreally. I have mines on a tripod with a wooden stick on it resulting in a heigth of about 9 feets off the ground.

The fourth lobe (but pay attention, the lobes are of DIFFERENT size for the SPW) adds sensitivity to the antenna. In genreal, and especially for reciveing antennas you can't have enough wire in the air. The wires catch the signal, so the more wire you have, the more of a signal you can catch. Of course, the "wire" has to be shaped propperly and resonant etc but in general the equation is right. It would be a good idea to have even more lobes, but doing so would require to match/tune their lenght and positions to get the antenna propperly resonant. Others did that in the past, and one of Alex newer designs (Pentalobe) goes this way. But without measuring equipement and software to simulate such a new design, go for an SPW as there is a tutorial with propper formulas etc. The SPW is a wonderfull omni directional antenna that works very well.

Quote:
Originally Posted by chatch15117 View Post
I have a feeling I'll be moving to UHF on a Turnigy 9X for Christmas.
That's for FPV in general a good idea. UHF systems are a lot more reliable, so it's not only a question of more range, but generally better link quality. FPV menas fun with flying low between trees etc, and there a UFH system comes in handy.

Quote:
Originally Posted by chatch15117 View Post
If you look at 6:00 in my video on the other page there is a cessna at my altitude about 500 meters west(flies from left of screen to right)... flew right by. I'm not sure why they keep looping around the lake. The executive airport is like 3 miles south and I'm in class D airspace.
Maybe pete is right here. If the frequency you are on is illegal where you are you should change it.

Markus
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Old Nov 18, 2011, 08:14 AM
Engineer for Christ
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Amherst, VA
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More on what Markus said: You can't simply add lobes. I wish it were that easy. The Skew wheel is generally better than the cloverleaf as an RX antenna. However, the omni distance record is set at 7.5 miles with a cloverleaf on the RX, so the change in performance isn't that much bigger.

I do have another 5 lobe design, but the geometry is very different to get it to work correctly. It is slightly better than the skew-wheel but I find the antennas is very fickle and therefore hard to get correct unlike the cloverleaf where you can really mess up and get a good antenna.

I have released the Pentalobe sphere antenne into the TV productioin world, but not FPV just yet. Still working on a few things before it's FPV ready

-Alex
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Old Nov 18, 2011, 10:23 AM
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Could I be a pain and get your thoughts on this?

I've built a SPW for the receiver end and I've built a Cloverleaf for the TX end. Both made from 0.8mm MIG wire. The cloverleaf is currently on a long piece of RG316, I've yet to add the connector.

So, I'm thinking of mounting the cloverleaf in one of two positions as seen in the picture below.
A. On top of the horizontal stabiliser, red line shows cable route
B. On the DPCAV Vee antenna mast, blue line shows cable route
I would love some advice on where you think the best position would be. I'm not very radio-wave intelligent and some, if not most, of the technical speak on the issue baffles me. Does cable length have a significant impact on performance?

And does anyone know of a tutorial of how to add the rp-sma connector, with particular attention to the measurements of wire stripping?

Thanks
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Old Nov 18, 2011, 10:39 AM
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At high frequencies cable length matters but if you're on 900MHz you can get away with even a few feet of cable before worrying about attenuation.

I got some multipathing today. That interference caused my capture card to freak out and go all gray and lose sync(vsync?). Video is uploading and I'll post it later. I thought having my RX antenna mounted properly in the air would fix the problems but it doesn't seem like it did. It's 20-30mph winds now so I'll have to wait for saturday to fly again.
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Old Nov 18, 2011, 11:00 AM
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Switzerland, LU, Buchrain
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Quote:
Originally Posted by jonsky7 View Post
Could I be a pain and get your thoughts on this?

I've built a SPW for the receiver end and I've built a Cloverleaf for the TX end. Both made from 0.8mm MIG wire. The cloverleaf is currently on a long piece of RG316, I've yet to add the connector.

So, I'm thinking of mounting the cloverleaf in one of two positions as seen in the picture below.
A. On top of the horizontal stabiliser, red line shows cable route
B. On the DPCAV Vee antenna mast, blue line shows cable route
I would love some advice on where you think the best position would be. I'm not very radio-wave intelligent and some, if not most, of the technical speak on the issue baffles me. Does cable length have a significant impact on performance?

And does anyone know of a tutorial of how to add the rp-sma connector, with particular attention to the measurements of wire stripping?

Thanks
I would mount it on top of the rudder. Well, actually I did it this way on my Ez* with sucess. Just move the transmitter more backwards, that way the coax cable does not add damping as it can remain short. With all our FPV stuff in the plane it should not be a problem to move components in the cockpit to compensate the CG.

Markus
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Old Nov 18, 2011, 11:57 AM
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http://www.youtube.com/watch?v=wOpjOE7qYOo

Also if anyone can tell me why the video has apparent horizontal lines and jagged edges please tell me if I can fix that with OSD settings.
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Old Nov 18, 2011, 12:47 PM
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Here's the setup. I use the patch antenna base(not in use anymore) for structural support as a base for the cloverleaf. The silver rod is an old 72MHz antenna.

Maybe I'll move the antenna to the left wing. I like to fly in counter clockwise circles so that should work out nicely.





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Old Nov 19, 2011, 08:24 AM
Engineer for Christ
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Amherst, VA
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Quote:
Originally Posted by chatch15117 View Post
http://www.youtube.com/watch?v=wOpjOE7qYOo

Also if anyone can tell me why the video has apparent horizontal lines and jagged edges please tell me if I can fix that with OSD settings.
Looks like reflections off the patch panel to me. The cloverleaf has some disadvantages when it comes to ground reflections, unfortunately. This is why I designed the Pentalobe sphere. It fixes this problem.

-Alex
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Old Nov 19, 2011, 09:25 AM
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Originally Posted by IBCrazy View Post
Looks like reflections off the patch panel to me. The cloverleaf has some disadvantages when it comes to ground reflections, unfortunately. This is why I designed the Pentalobe sphere. It fixes this problem.

-Alex
Which combination of antenna types would you recommend along with the Pentalobe?

TX <-------------> RX
a) Pentalobe <-----> SPW
b) Pentalobe <-----> Helical
c) Pentalobe <-----> CP Patch
d) CL <------------> Pentalobe

Cheers,
Hartwig
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