What did you have in mind to stop the slinky from collapsing on itself? When you get your spacing and then stand it up in the PVC it's going to collapse on itself - stretching the top and piling on the bottom of itself.
Are you thinking from the tap point down won't matter and just let it hang?
Hams use the slinky in horizontal orientation on a piece of PVC or other non-conductive material. If a PVC section with an OD that was close to the ID of Slinky was used you could get close to a self supporting coil in the horizontal.
That turns site is here:
http://www7.brinkster.com/yvesroy/10ft-antenna.asp
Experimental broadcasting for a better tomorrow!
That's the site, thanks!
I've seen most of those before, the trick there is the antenna is in one sense directional. Off the sides instead of omni directional. I saw one that was kind of promising and will read the page more tonight.
My girlfriend suggested checking a floral shop for a foam rod they use in layouts, she's almost sure there's one that's the same diameter that we could spiral the slinky around to maintain the spacing (smart girl!). Now the question is: Is that foam (green Styrofoam) RF reactive or otherwise negative?
If that green foam is made right, it should degrade rather quickly in sunlight... but you never know.
Understood, but it would be inside the pvc base.
I was dragged to a craft store during the Holiday season and while I was fighting it with every fiber of my being I realize now that there was a wide variety of white styrofoam shapes available there.
The name of this spousal torture chamber was "Michaels" and I have only recently recovered from that experience 🙂
Here is a Google commerce (Froogle) search return showing what are called "styrofoam rods"
Experimental broadcasting for a better tomorrow!
2 3/4" in diameter
One has 87 turns, the other has 86. So it may take more than one slinky per loading coil...?
The Slinky is made from flat stock and has much more surface area against the adacent windings so it may produce more reactance. Maybe enough by using one and just let it stretch out on its own..?
Is what I'm going to start with.
Since I don't have any fancy instruments my testing will be fairly subjective.
I have all the parts now but one so I'll start assembly tonight.
What did you have in mind to stop the slinky from collapsing on itself? When you get your spacing and then stand it up in the PVC it's going to collapse on itself - stretching the top and piling on the bottom of itself.
Are you thinking from the tap point down won't matter and just let it hang?
I had envisioned connecting the top winding to the radiator and connecting the xmtr to the bottom winding. With all of the coils "compressed" at the bottom, This should somewhat short them out. While stretching the Slinky, The coils would then raise and become part of the reactance scene. I'm not thinking of "tapping" the Slinky anywhere. Just the fact of stretching it out will change the reactance. The bottom part will remain somewhat inactive untill its stretched out..
I've also noticed that the amount of windings in the Slinky is just a few short of what is suggested at 1.62 Mhz. Hmmm...
OK, lemme see what I can come up with that way. No taps, just stretch the slinky.
Resistance does change minimally while stretching it.
Resistance (DC) shouldn't really change while stretching it, but inductance and maybe capacitance should change.
I stand corrected... It does nominally change when I hold the leads while stretching. Clamped leads don't change.
Greg_E is right. The D.C. resistance of the whole coil isn't going to be much. Not enough to be concerned about..
Some good news if anyone hasn't tried it yet. Solder will stick to it! This makes for a great connection..
If you look at the original SStran coil design, Only the lower portion is used in the adjustment via the taps. The upper portion is to create the inductance/reactance necessary in the circuit..
What if..
..We stretched the Slinky out as far as gravity will allow and gave the windings a light coat of clear varnish or something to insulate the windings from each other. Now the top 1/2 to 3/4 of the Slinky could be bunched tightly togather on a form of some sort or tied with tie wraps. This should produce plenty of inductance/reactance without the windings shorting togather. This leaves the lower "Free" portion for adjustment.. Without taps! The area involved would be less than 2 ft. in length..
Again, It's a thought.. Comments?
Sounds better. The heaviest part of the coil at the top does sound better as long as the retaining mechanism doesn't give way.
I've been sitting here playing with the slinky and zip ties tonight...
What about using the coating you can buy in the pint container for rubberizing tool handles?