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Old Nov 19, 2011, 11:19 AM
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Amherst, VA
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Quote:
Originally Posted by hartwig View Post
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

I haven't finished testing it yet, hence why I have nt released it. It seems to do just as well as the cloverleaf as a TX antenna. However it seems to do really well with my new Crosshair antenna.

-Alex
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Old Nov 19, 2011, 11:21 AM
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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'd recommend right on the boom of your plane and not on the mast. Generally the airplane is going to be above you so the battery will be clear of the Fresnel zone the lower the antenna is.

-Alex
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Old Nov 20, 2011, 04:25 AM
TBs are GO!....FAB....no..FPV!
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@IBCrazy
Could I bring your attention to my post #1628.
Do you have any suggestions for me? Thanks.
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Old Nov 20, 2011, 07:00 AM
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Originally Posted by Phelec View Post
I have just completed a set of CL and SPW for 1.2GHz. I have used mig wire. I have the CL out on the wing of a bixler with about 400mm of RG174 going along on the under side of the wing (CL is bottom fed) to a 800mw txr.
I measured the transmitter's current draw first with a 50 ohm dummy load. It read 228mA. With the stock whip antenna it measured 234mA. With the CL connected it measured 196mA. What does this lower amount of current draw tell me? Can anyone give some input to my readings.

Thanks in advance.
Sadly it more or less tells you nothing. If you were careful about the build of the cloverleaf, then it will work well. They are incredibly resilient to manufacturing errors.

-Alex
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Old Nov 20, 2011, 11:39 AM
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Originally Posted by IBCrazy View Post
I'd recommend right on the boom of your plane and not on the mast. Generally the airplane is going to be above you so the battery will be clear of the Fresnel zone the lower the antenna is.

-Alex
Thanks Alex, I really appreciate your input, and everyone else's for that matter, top guys the lot of you

Unfortunately Alex I was impatient and already mounted the CL on the mast for a fly yestersday, it was a lovely day.

I'm dissapointed to say that it wasn't very successful as you can see below, only 400/500 ft range, CL on Tx and SPW on Rx something obiously wrong somewhere, back to the drawing board.

FPV - CL_SPW FAIL (1 min 45 sec)


So as I was walking back from the field when I noticed one of the lobe feed lines was unstuck from the centre wire of the RG316 on the SPW. I don't think it was like that during the flight, I wasn't being very careful with it on my walk home and probably knocked it off, but it musn't have been a very good solder joint to start with.

A little more digging around led me to find that some of my SMA connectors are a little iffy. The SMA pin socket on my F-SMA adapter for the Rx is a little big, or the antenna pin isn't a tight fit in it is another way to explain it. I found that out by using the pin from a uncrimped connector to test it.

Then I thought what's the Tx socket like, and it was similar.

So I'm going to biuld another set. I was going to use the construction method in the video below, do I correctly assume that the lobe dimensions remain the same and you add a little bit of length to the wire for the centre loops and the ground legs?

Base-fed Cloverleaf build.mpg (4 min 44 sec)


Thanks again all
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Old Nov 20, 2011, 12:06 PM
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The lower legs (the soldering points) Can be any length you want. It's the total loop size that matters.

-Alex
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Old Nov 20, 2011, 12:49 PM
TBs are GO!....FAB....no..FPV!
Phelec's Avatar
Australia, NSW, Yamba
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Quote:
Originally Posted by IBCrazy View Post
Sadly it more or less tells you nothing. If you were careful about the build of the cloverleaf, then it will work well. They are incredibly resilient to manufacturing errors.

-Alex
Thank you for your reply Alex. All dimensions and angles are very good. I used a metal sheet with a hole of about 20mm with all the 120 degree lines (90 degree for the SPW) marked on it. The mig wire was held in place with magnets while soldering was done. Great thing this steel wire and magnets. Only downside is my Weller temperature soldering iron uses magnet tips to set the temperature and so the mig wire wants to jump and cling to the solding iron's tip. So I reverted to using a cheap solid copper tipped soldering iron. Thanks again Alex. Have yet to do range test. Been waiting for suitable weather.
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Old Nov 20, 2011, 06:33 PM
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http://youtu.be/11PcNas_cQo

What do you think the problem is now? Very spotty signal.... I have the antenna on the elevator. It's very far away from electronics(all my servo jitters went away).
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Old Nov 20, 2011, 06:39 PM
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Honestly it looks like null reflections. You are flying between a 40 and 60 degree horizon thus exposing the nulls of the antenna. Reflections come in fairly strong while the main signal comes in weak. Try going for some lower altitude and longer distance. Your signal should clean up considerably.

-Alex
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Old Nov 20, 2011, 06:42 PM
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Thanks I'll try that. After I range test this 2.4GHz system lol.

So you say about 50 is a reasonable maximum angle for LOS? I could easily change that "MIN" to "MAX" and have that be sin(50)*LOS.

2nd edit: I'll do sin(45) and see how it goes.
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Old Nov 20, 2011, 07:46 PM
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Quote:
Originally Posted by IBCrazy View Post
Honestly it looks like null reflections. You are flying between a 40 and 60 degree horizon thus exposing the nulls of the antenna. Reflections come in fairly strong while the main signal comes in weak. Try going for some lower altitude and longer distance. Your signal should clean up considerably.

-Alex
I have noticed a null directly overhead. That's about it...

I rarely make it there anymore, and when I do; The helical is usually tracking the plane, so I rarely see the null...
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Old Nov 21, 2011, 02:00 AM
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Quote:
Originally Posted by chatch15117 View Post
http://youtu.be/11PcNas_cQo

What do you think the problem is now? Very spotty signal.... I have the antenna on the elevator. It's very far away from electronics(all my servo jitters went away).
Were you flying on a windy day?
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Old Nov 21, 2011, 02:06 AM
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I got a question that has nothing to do with a CP antenna, pls. forgive me if this is out of place.

People at my club told me that in order to get maximum GPS signal, the antenna has to be installed on an aluminum foil, is that confirmed?
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Old Nov 21, 2011, 02:19 AM
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Were you flying on a windy day?
yes but I have a gyro so it makes it easier. Wind was 15mph with 20mph gusts.
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Old Nov 21, 2011, 02:28 AM
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Quote:
Originally Posted by chatch15117 View Post
yes but I have a gyro so it makes it easier. Wind was 15mph with 20mph gusts.
What kind of gyro do you use, personally I have the Range Video OSD that also serves as an autopilot, I always activate the Fly by Wire function that helps keeping the wings level.
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