Apollo Coil

[Silver Dollar]

I won an old Apollo Coil on Ebay for only $14! I figured a coil housing was worth that.
This is what I received;


It had a lower clevis and coil cover!


I took off the cover then had to cut the housing apart. Lucky the cover could be
used as a lower housing;


It looks like an Omega coil;


I ripped the coil out:


And ended up with a nice housing for my next project;

[Silver Dollar]

I was going to make an Omega but I've been testing some PI coils and wanted to try
a basket using the right size Litz. I got some 176/46 Litz off Ebay and cut out a form
off of a fiberglass tray to fit inside the apollo;


I made some room for the wires;


Then cut out the ring and made the slots;


Now to wind it up!

[6666]

As you wind the coil it would be good if you could take photos of the winding process for others to see, thanks.

[Silver Dollar]

Well here's some pictures!
Form with general idea


All the way around once


Here's the trick. After 5 times around you end up in the same slot again. You then
go to the other side of the form and go over one slot (see straight segment at bottom of pic)
This takes you to the other side where you go around 5 times again. Then repeat;


After one time on each side you end up with this pattern;


Here is after twice on each side. Notice the 4 wires in each slot;


Another View;


Finished coil. I left 40" on each end to run up the stick. Final inductance 330 uh. Not bad I was aiming for 300...


Seems a shame to make it heavy by putting it in the Apollo housing but it might need some shielding as I'm not too
sure about the self shielding on it...

[6666]

Thanks SD, good work.

[Silver Dollar]

Well I may have ruined this one. I tested it after winding and got 800 ohms and 4.88 us to damp out.
Then I decided the windings may flop around and give false readings so I epoxied them down;


Then I figured that using just the top of the coil housing would make it lighter. So I filled the outer
ring with fiberglass resin;


Well it came out heavy and slow! New readings give 350 - 450 ohms and 8.88 us. Maybe they'll change
after the resin cures a bit? Maybe I can add the magic MUR460 diode to speed it up again?

Not sure about that one. A bit of a waste of some perfectly good Litz wire!

Well I got an idea and decided to wind a twisted pair center tapped coil. I had dismissed the idea due
to the possible super high capacitance between the windings. But I have a huge spool of teflon coated
AWG 24 twisted pair so I gave it a go. I found a lazy susan type flower pot base and used the ring from
it and used hot melt glue to secure the windings and got this;


It measured out at 2.5 ohms and 270 uh and damped at 550 ohms and 4.4us not too bad! You would drive
one half at 80 uh and receive with both windings deferentially. Which I have to work out a circuit for...