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Author Topic: Capacitance Hat Homebrew Trick  (Read 1053 times)
N3MG
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Posts: 27




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« on: May 09, 2002, 02:20:35 PM »

Here's a cool idea for a homebrew capacitance hat for your screwdriver or bugcatcher antenna I came up with.  Who knows, it may have already been posted in a Hints and Kinks somewhere.

Depending on the diameter of your whip (stinger), pick up a 3/16" or 1/4" metal tubing compression fitting.  You'll find them in the plumbing section of your hardware store and they typically are made of brass.

The 1/4" size has a 1/2" nut on either end that collapses the (2) metal ring inserts thereby locking the compression fitting on your whip at any location you like.  This is a great advantage as you can experiment with the hat's distance from the coil (the futher up the whip the better) verses the wind load.

The next trick is to find a disk of metal, such as a small stainless steel mixing bowl, lid to a large can of coffee, old paint can lid, collander, wire straining basket, etc.  You just need to make a hole in the center of the disc such that it fits over the outer threaded portion of the compression fitting.  You might need to add a washer or two in there as well to take up space as you tighten the nut.

For about $2.50 I made one of these capacitance hats and it works quite well.  I may try the center wire support off of an old lamp shade as well to minimize the wind resistance.

I'll try to post a picture to cyberspace when I get a chance.

73 and safe mobiling!
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K0BG
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Posts: 9862


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« Reply #1 on: May 13, 2002, 09:50:35 AM »

Your idea about using an old lamp shade isn't new, but as far as I know, it has never been in Hints and Kinks. Many years ago, there was an article in Ham Radio mag where some ham used the core part (call it the spider at the top where the finial attaches the shade to the banjo hoop) and placed some copper tubing around the outer ring. He used a similar method of attaching it as you suggested, but as I recall, it was a packing nut assembly from a power cord. So, you see, there really isn't anything "new" under the sun.
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N3MG
Member

Posts: 27




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« Reply #2 on: May 26, 2002, 02:28:40 AM »

I finally completed my mobile webpage.  Lots of cool stuff, especially if you own a Toyota Tundra.

Check out the capacitance hats on my Tarheel Screwdriver.

http://www.fastq.com/~louvu/N3MGMobile.htm

73-

Mark
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