On Mon, 17 Oct 2011 02:51:21 -0500, Jeffrey Angus
wrote:

On 10/16/2011 11:11 PM, Jeff Liebermann wrote:
Ok, that's not going to work. Most of the impedance is coming from
the DC resistance of the wire. Decreasing the gauge decreases this
resistance, but also decreases the number of turns that will fit on a
the spool to a maximum OD of 1.5". This isn't working. I give up for
tonite.

Well as long as your bitching at me for leaving something out....

I always find something to complain about. It's part of my standard
usenet protocol. Nothing personal.

The original coil is being fed through a bridge rectifier (mentioned
elsewhere in the thread). So the AC impedance is less of an issue.

Bad news. 60Hz is still AC. The AC current, is determined by the AC
impedance also known as Z. Fortunately, most of it comes from the
resistance of the wires, making the coil specs easier to guess.

Using the proline scripting, I came up with 80 mH using #28 AWG wire,
1988 turns and 1.54" outside diameter with 42.63 ohms.

You cheated by going over the OD by 0.04". Assuming you can pack the
windings in as tight as the original, that shouldn't be a problem. I'm
not all that confident you can do it. Use a mandrel and a slow
turning lathe.

I come up with 11192 ampere turns. I've got some wiggle room to
increase the bobbin size a bit. So rest well good sir, we are at
a point that is "close enough" to wind up a prototype and see if
works properly.

It will probably work. I just hate to say that as I'm sure you'll
blame me when it explodes and sprays coil bobbin parts all over the
shop. It might help to immolate an old solenoid on the barbeque as a
burnt offering to the god of electric power for a favorable outcome.

If it does, then it gets potted in Epoxy to match the original
physical dimensions and we call it a success.

Right. Hide the evidence. Be sure to embalm the windings in yellow
Kapton (Polyimide) high temp tape before potting. I learned that the
hard way after trying to pot some radios. The epoxy shrinks as it
hardens, which likes to tear wires away from their attachment points.
The tape provides an easy air space for the epoxy to shrink.





--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558