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Old Mar 25, 2011, 10:07 PM
Engineer for Christ
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Amherst, VA
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Originally Posted by QiW View Post
great .. thanks again
the type/thickness of wire used should not be an issue right ? as long a it holds up against the wind and does not deform so easily
Yes, any wire will do. I use steel wire for a mig welder. Old Man Mike prefers memory wire. Copper wire is a bit soft, so go with steel.

-Alex
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Old Mar 29, 2011, 03:40 AM
Pat K
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Originally Posted by IBCrazy View Post
Yes, any wire will do. I use steel wire for a mig welder. Old Man Mike prefers memory wire. Copper wire is a bit soft, so go with steel.

-Alex
Hi Alex,
do you mean that the wire gauge has no effect on the antenna performance? Is it just a matter of mechanical strenght? I am presently preparing a couple of antennas for the 5,8GHz Tx/Rx that came in yesterday. I have plenty of enamelled copper wire of awg#28 (diam 0,32mm). Will it work at 5,8GHz?
Just as a matter of test, I made one antenna with 12 petals (all at 45deg from ground and 60 deg appart from each others). It was much easier to make than I was expecting. What I do is to CA glue all petals on a small piece of paper before soldering (materialising the ground "plane" with angular positions). I think I can easily do much more but I have no clue whether this would bring performance. What is your opinion?
What would be the best number of petals for Tx and Rx antenna?
Pat
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Old Mar 29, 2011, 07:21 AM
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I mean that wire thickness has very little effect on antenna performance. However I am finding that the number of lobes the antenna has will change it's SWR. Thus last night I changed the equation and numbers slightly to fit the empirical values I was getting in my frequency sweeps.

Typically, I prefer a 3 lobe for the TX and 4 lobe for the RX. I am working on a few multi lobe units now, but they will require tuning stubs to resonate properly.

-Alex
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Old Apr 02, 2011, 11:28 AM
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Wow! So many jokes, so little time!
Building a batch of these liked to have killed me about 3 hours ago. No really! Had talked to IBC about welding the antennas together. Mainly because I see some being made & as a welder I just kinda cringe. No one else seems to have gtaw'd any. Tigging them sure makes it stronger and way easier to join to the cable electrode. Tho the cheap PTFE coax I had laying around really doesn't like it much.

So having some 3/32" ER70S2, 1/16" ER316 & some 14ga Romex (Oxidized copper house wiring) laying around I started a few. :P

Then my ears started ringing.
And my ear went numb.
Uh oh..... I think all welders know what that means. > : (
Yup sure enough. 120cuft tank of argon was showing 22psi. Had 1800-1900psi in it when I started working 45-60min before. Filled up the garage with Argon & I just never heard it leaking. And that's WITH the garage door open 1 stop. (small gas lens on the torch will run OK at extremely low flow rates.) Gas line split inside the machine.
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Old Apr 06, 2011, 10:43 AM
Pen
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United States, AL, Huntsville
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Originally Posted by Toysrme View Post

...

Then my ears started ringing.
And my ear went numb.
Uh oh..... I think all welders know what that means. > : (
Yup sure enough. 120cuft tank of argon was showing 22psi. Had 1800-1900psi in it when I started working 45-60min before. Filled up the garage with Argon & I just never heard it leaking. ...
Yikes, glad you are alright neighbor!
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Old Apr 06, 2011, 12:45 PM
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Rx/Tx

Hello,

Just wonder, if spw antenna does not work well with LawMate, what would be the best choice of tx and rx for, let us say, 2.4 and 1.3 GHz?

Thanks
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Old Apr 06, 2011, 03:10 PM
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Hello,

Just wonder, if spw antenna does not work well with LawMate.....Thanks
That is just another one of those internet rumors that somehow got started. The SPW antenna works excellent with the Lawmate.

OMM
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Old Apr 06, 2011, 03:27 PM
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Originally Posted by Old Man Mike View Post
That is just another one of those internet rumors that somehow got started. The SPW antenna works excellent with the Lawmate.

OMM
It was started on the first post of this thread
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Old Apr 06, 2011, 03:43 PM
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Originally Posted by aSa2 View Post
It was started on the first post of this thread
I have three SPW antennas and six Lawmate receivers. I also have the test equipment to accurately measure performance. There is no problem. The first page needs to be corrected.

OMM
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Old Apr 07, 2011, 06:10 AM
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Thanks, that answers my question
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Old Apr 07, 2011, 05:28 PM
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Originally Posted by Old Man Mike View Post
That is just another one of those internet rumors that somehow got started. The SPW antenna works excellent with the Lawmate.

OMM
It doesn't work at all with my 1.2GHz Lawmate RX's. Maybe you have a different revision than I do?

I get good RSSI and signal strength reading, but the frame rate drops to 3 frames per second. I have 3 Lawmates and all get the same results.

-Alex
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Old Apr 07, 2011, 06:02 PM
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Originally Posted by IBCrazy View Post
It doesn't work at all with my 1.2GHz Lawmate RX's. Maybe you have a different revision than I do?

I get good RSSI and signal strength reading, but the frame rate drops to 3 frames per second. I have 3 Lawmates and all get the same results.

-Alex
Frame Rate? That is not an RF/antenna issue. It sounds like you have a problem with the video levels. In fact, a very good RF signal can show up a problem with incorrect video levels because of video sync/saturation issues. Do you have a video generator to make sure the sync and video levels are correct? Here is what I use:

http://www.elexp.com/tst_pg68.htm

You also need a scope with special video sync to adjust it correctly.

With the lawmates you can only adjust levels on the TX side. Even without the correct video test equipment, you could mark the current position and try adjusting the TX levels to a point where it will work. Monitor the video white/yellow levels to make sure you are not into saturation.

OMM
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Old Apr 07, 2011, 10:41 PM
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That makes some sense, but why would it work fine with a helical antenna? I can place the TX right in front of the helical and get no problems. I fly with a cloverleaf and go 400 feet out and it's still flashing screen at about 3 frames per second. With the cloverleaf, I get no signal at all. This happens with all three of my Lawmate RX's.

I can check the sync on my oscilloscope. I'll see what I am getting there.

-Alex
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Old Apr 08, 2011, 01:04 AM
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Originally Posted by IBCrazy View Post
That makes some sense, but why would it work fine with a helical antenna? I can place the TX right in front of the helical and get no problems. I fly with a cloverleaf and go 400 feet out and it's still flashing screen at about 3 frames per second. With the cloverleaf, I get no signal at all. This happens with all three of my Lawmate RX's.

I can check the sync on my oscilloscope. I'll see what I am getting there.

-Alex
First step might be to connect the output of the Lawmate to a monitor and not a digitizer for the PC. You probably have a TV which has a direct video input. You should then be able to tell what the analog signal is really doing instead of depending on digitizers that often do a poor job with anything other than a direct camera input.

OMM
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Old Apr 08, 2011, 08:50 AM
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Well, it's not a sync I don't think. Total loss of signal (static) at 600 feet away. I will try connecting it to an old TV.

I'm not the only one who has this problem either. Many have reported the SPW does not work with airwave 5.8GHz modules. That's why I avoid all the confusion of "it doesn't work" and post the issue.

-Alex
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