Posted: 9/12/2013 12:57:45 AM EDT
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Hi, i am building a magnetic loop and have purchased a nice air variable cap for it. 25-310pF, 3.3kV. I have everything i need but the cap didnt come with instructions so wiring the cap is the on thing holding me back from building the mag loop.
http://i.imgur.com/epHBeMq.png That is an image of the end with some arrows, i am wondering if i connect my outer loop to the red arrows of the black arrows? Or something different entirely? If i use the posts where the black arrows point, do i just unscrew the nut? I dont want to ruin this thing as it wasnt cheap. Thanks! |
You may want to take a look at the AlexLoop website. There are several DIY videos and articles with pretty detailed pics of all sorts of magnetic loop antenna projects. Maybe find some tips there. 
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That might work for your situation, but keep in mind there are different styles of vac. Some have multiple taps so you can run in series or parallel.
There are some cool videos on YouTube about this subject. Post pics and reports when your done with your antenna |
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Quoted:
You may want to take a look at the AlexLoop website. There are several DIY videos and articles with pretty detailed pics of all sorts of magnetic loop antenna projects. Maybe find some tips there. I love my AlexLoop, perfect for use in my 4th floor apt on Oahu. I've made PSK-31 contacts on it from Russia to Central America. I've been heard on WSPR all the way to Europe. Mag loops seem to be a good way to go if you are limited on space. |
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That might work for your situation, but keep in mind there are different styles of vac. Some have multiple taps so you can run in series or parallel. There are some cool videos on YouTube about this subject. Post pics and reports when your done with your antenna This is what i am up to so far: http://i.imgur.com/61qjONn.jpg |
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Also, you can easily verify that you have the right connection points with an ohmmeter or continuity tester. There will be no DC current flow between the terminals, one terminal will have zero ohms (or nearly zero) to the fixed plates and the other terminal will have zero ohms to the rotating plates. |
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Do you have a link to the plans? Sorry, I dont have actual plans, I am building it based on this calculator though: http://www.66pacific.com/calculators/small_tx_loop_calc.aspx This can give you the info you need to build it for the frequencies you want to cover (along with giving you an idea what kind of capacitor you need) The gentleman that buit this loop is helping me with the details: http://gridtoys.com/glen/loop/loop3.html |
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OP....what is the power rating of your loop? Will it take 100 watts or more? Hi, with my 3.3 kilovolt capacitor I should be able to safely do 75-90 watts. It may be able to handle 100 watts but it will be pushing it a little above the rating of my capacitor. |
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Quoted:
Also, you can easily verify that you have the right connection points with an ohmmeter or continuity tester. There will be no DC current flow between the terminals, one terminal will have zero ohms (or nearly zero) to the fixed plates and the other terminal will have zero ohms to the rotating plates. Thank you, I am going to do this with my multi meter before hooking it up to be sure. Thanks again. |
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Hi, with my 3.3 kilovolt capacitor I should be able to safely do 75-90 watts. It may be able to handle 100 watts but it will be pushing it a little above the rating of my capacitor. Quoted:
Quoted:
OP....what is the power rating of your loop? Will it take 100 watts or more? Hi, with my 3.3 kilovolt capacitor I should be able to safely do 75-90 watts. It may be able to handle 100 watts but it will be pushing it a little above the rating of my capacitor. I thought about building a magnetic loop using a vacuum variable capacitor, but I never could find one that I could afford. 
Thanks for the info. |
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I thought about building a magnetic loop using a vacuum variable capacitor, but I never could find one that I could afford.
Thanks for the info. Quoted:
Quoted:
Quoted:
OP....what is the power rating of your loop? Will it take 100 watts or more? Hi, with my 3.3 kilovolt capacitor I should be able to safely do 75-90 watts. It may be able to handle 100 watts but it will be pushing it a little above the rating of my capacitor. I thought about building a magnetic loop using a vacuum variable capacitor, but I never could find one that I could afford.
Thanks for the info. Yep, exactly. I wanted to use a vacuum cap but like you said, they are EXPENSIVE! That is why i went with air vairable. Much cheaper. The vacuum ones do perform better t hough. |
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Hi, with my 3.3 kilovolt capacitor I should be able to safely do 75-90 watts. It may be able to handle 100 watts but it will be pushing it a little above the rating of my capacitor. How close will you be to your loop when transmitting? My loop tuner sits within arm's reach, so it's strictly QRP for me. |
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I finished the loop and it works great! At first the performance was poor but I hung it from the ceiling and it made the world of difference. During the recent SSB CQ contest I worked Germany, Ireland, Columbia, Brazil, the Caribbean, France, Italy, Morocco and many more all on 20m. Due to it's size it works best on 20m.
Here is a picture of the finished antenna http://i.imgur.com/eIJG4X7.png Next i am working on a motor to connect to the cap so i can adjust it from my desk. |
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