[Lowfer] Loading Coils 101

Wed, 12 Feb 2003 16:55:24 -0500

Geez Peter, now you have poor Eric all tied up in loading coil knots!

Now I know why these loop antennas with only 200ft of #12 seem so easy to 
deal with - in spice of a certain amount of collateral damage from stray 
arrows! <G>

Bill

>From: "Peter Barick" <[email protected]>
>Reply-To: [email protected]
>To: <[email protected]>
>Subject: Re: [Lowfer] coil guts
>Date: Wed, 12 Feb 2003 14:18:01 -0600
>
>Hi Eric,
>
>Ah, Loading Coils: the smell freshly wound pvc coated windings, the
>nostril curl from hot solder resin, the feel of a fleshly wound form.
>Great stuff to wax over. :-/
>
>As Bill already said go with the big stuff. Sure you could use what's
>on hand but it would miss the mark I'm sure you'd like to achieve. No.
>14 solid is a good choice. Ideally it would not have pvc insulation and
>preferably enameled, though Teflon is V good--and expensive. But, gee,
>for low cost and high performance, most home stores have 500 feet spools
>for $15. My guess is you'll need 300 feet for the main coil, BUT, and
>depending on where it is placed (top mounted, more; bottom, less) and if
>a separate tuning coil is used (variometer), it will vary.
>
>So minimize the guessing and see this at Lyle's site:
>    awg-coil.zip -- Calculates wire diameters and loading coil
>properties
>
>It's intuitive to use and great to play "what if" with on coil
>dimensions. If you use it, keep in mind that a turn-to-turn dimension
>parameter is called for. For using pvc electrical wire that's touching,
>that's a 1 wire size gap due to the separating insulations between
>conductors. Though for enameled wire, "touching" is no gap. :-)
>
>Last tip. There have been many list posts on best/ideal L/W coil
>dimensions. A basic starting point is to think 2.5*D : L, that's over
>twice as fat as high. However you may be back ended into using a handy
>former, e.g., a 5-gal plastic pale or two in tandem. Further, if your
>calculations call for a larger D for the former and you've tagged the
>rather sturdy 5-gal pale, you can "expand" it! Yeah, by, say, attaching
>spacing material  axially to the pale to "Beef" it up for a larger
>diameter. Dry, varnished wood, if used in an enclosure, or say Styrofoam
>packaging strips for other installations.
>
>Oh, and Last Tip + 1. Winding 100+ turns on the pale  :-{  can be a
>challenge, esp, if you only have two hands--I reco 4 to keep sane. I did
>it myself with two, though, by making a spinning device to hold and
>allow the pale to rotate. Made it to be clamped into a big vice, had a
>temp cover for the open pale end to maintain centering about its axis,
>then just wound. And may you have fewer kinks than I've cursed at.
>
>Oops, must issue this piece of advice too. So, Tip + 2: Before you
>begin winding, prepare the form with beginning and ending terminals to
>secure those ends. Can be simple as two adjacent wire-sized holes each
>end or actual terminal lugs. You won't be sorry you did so or possibly
>risk loosing those turns. :-))
>
>GL on yer project, Eric. Hope I didn't sound tooooo pedant. Let us know
>how all works out, huh.
>
>Peter, who had part of the loading coil for the vertical rx ant. blown
>off it's perch last night in mighty stiff wind gusts. Though odd, I
>thought the 6-foot multi-turn loop was gunna go as it has a large
>plywood center plate w/ holes in it for the 5 arms. It shook but held.
>
>
>
>_______________________________________________
>From the Lowfer mailing list
>Send messages to: [email protected]
>To sub/unsub visit: http://mailman.qth.net/mailman/listinfo/lowfer

_________________________________________________________________
The new MSN 8: advanced junk mail protection and 2 months FREE*  
http://join.msn.com/?page=features/junkmail