Post 9g6l37Z2jjjpAVF3pY by ab3xu@mastodon.radio
 (DIR) More posts by ab3xu@mastodon.radio
 (DIR) Post #9g6l37BIA2jtyq85oG by rev_mook@lsngl.us
       2019-02-22T00:28:11Z
       
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       Giant variable capacitor. Useful for getting the impedance of long circular shaped wires down to 50ohms above 3Mhz. #cq
       
 (DIR) Post #9g6l37Z2jjjpAVF3pY by ab3xu@mastodon.radio
       2019-02-22T02:29:34Z
       
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       @rev_mookThat's a nice looking cap, dare I say magloop? Can't quite tell from the pic is at a butterfly?
       
 (DIR) Post #9g6l37zz7ZHyW3qZpA by rev_mook@lsngl.us
       2019-02-22T03:24:13Z
       
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       @ab3xu Not quite a mag loop, but it is connected to a loop. Yep! Butterfly capacitor. A set of stator plates rotate through an air gap to vary the capacitance. This one is 10-70pF-ish.  I've used it quite a bit indoors on 30M, sometimes 20M.
       
 (DIR) Post #9g6l38LFqUIpa1nYye by ab3xu@mastodon.radio
       2019-02-22T05:03:18Z
       
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       @rev_mookWhat's the circumference of the loop if its not considered a magloop?Here's my cap used in a magloop. It measures about 20pF - 134pF. Underneath is the stepper motor controller by the arduino board that connects through bluetooth to an app on my phone.
       
 (DIR) Post #9g6l38hwU8S0iOPgLA by rev_mook@lsngl.us
       2019-02-22T06:50:27Z
       
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       @ab3xu That's a nice setup.  Mine is just a 4 meter wire connected across the capacitor.  I always thought the 'mag' part of loop antennas required a small coupling loop inside a larger radiating loop?
       
 (DIR) Post #9g6l38ybUBmJY4CzJI by ab3xu@mastodon.radio
       2019-02-22T22:27:36Z
       
       1 likes, 0 repeats
       
       @rev_mook thanks!  Yeah, you can see the smaller primary loop at the top. Here's a close up of it. It's fed on the bottom by the coax.It's hard to tell but it's not a simple loop going from center to shield, though that is one way to do it. In the 2nd pic I have mine circled.