Shaping new antennae for my Theremax

Posted: 3/13/2006 4:53:57 PM

From: TX, USA

Joined: 1/29/2006

Hey all,

I'm well into the soldering of my Paia Theremax and want to start looking at antennae. Someone said that the theremax is much easier to work with when the stock antenna is replaced with chome-plated rod. So, how do I go about doing this? I've seen the video in Projects on how to achieve the shape of the (edit: *volume*) antenna, but how do I do the actual bending? Do I need any special tools?

Posted: 3/13/2006 9:40:44 PM
Jeff S

From: N.E. Ohio

Joined: 2/14/2005

Congratulations on completeing your Theremax.
I don't have any direct experience with this, but I would believe a larger diameter pitch antenna would be better than the heavy wire antenna sold with the Theremax kit. While chrome plating is definitely desirable, I doubt that it has any appreciable effect.

I'm curious why you think you need to bend the pitch antenna? The vast majority that I've seen are all straight. It would be impractical to bend a large diameter rod to resemble the Theremax design. More often, the pitch antenna would be mounted with a 90 degree compression fitting.

For reference, the pitch antenna for both the RCA and Etherwave Pro theremins is 17 1/2" long. The RCA pitch antenna is made from 7/16" tube that is capped at both ends. The Etherwave Pro pitch antenna 3/8" diameter, and "seems" to be solid.

As I've mentioned a week or so ago, the details of how to reproduce the antennas and mountings for the RCA theremin will be made available VERY soon. However, to produce one it would be necessary to solicit the services of a qualified machinist. If you're using the Theremax cabinet, the sloped top would make mounting it a challenge.
Posted: 3/14/2006 10:23:56 PM

From: Kansas City, Mo.

Joined: 8/23/2005

Jeff is correct, you don't want to bend your pitch antenna. I just used a chrome-plated pipe (used for plumbing) that fits into a compression joint (thus removable). The compression joint connects to a 90-degree standard plumbing fitting. You should be able to find this stuff at your local hardware store.

To bend the volume antenna, you would need to fill the pipe with sand then bend it around a form (some folks have used the main drain pipe in their basement as the "form"). I have not personally done this... however, you must fill the pipe with sand or else the pipe will kink when you try to bend it.

Of course, you would remove the sand before use :)
Posted: 3/14/2006 11:08:51 PM

Joined: 2/21/2005

I used solid 1/4-inch brass rod for my Theremax antennae. 15 inches were used for the pitch wand, and about 24 inches were bent into the volume loop. I used the steel support pole in my basement as a form. It was a bit of an effort, but well worth the trouble. The volume response is very much improved, and more importantly my instrument now looks like a real instrument and not a science-fair oddity.
Posted: 3/15/2006 1:07:40 PM

From: TX, USA

Joined: 1/29/2006

*Ahem* Pitch antenna = volume antenna. Yes, please do excuse my noobishness. I've edited the post.

Thanks for the replies, everyone! The main thing I'm confused about is [i]how[/i] the bending of the antenna is done-- how stiff is this piping? I assume if people are doing this in their basements I won't need any heavy-duty tools...?

Posted: 3/15/2006 3:48:34 PM

Joined: 10/8/2005

If your using chrome plated brass plumbing tubing get a piece several inches longer than what you want the antenna to be so you can bend the center part of the tubing and then cut off the ends. This gives you some leverage for the bending. When you fill the pipe with sand put a little in and tap the end of the tubing on something solid to compact the sand and repeat until it is full. You want the sand in there tight. Lay the tubing against something like drain pipe with approximately the diameter of the bend you want, probably in your basement, and use your hands to bend the tubing to as close to the shape as you can. Final, small adjustments of the bends can be done by hand to get the exact radii and shape that you want. You may have to loosen the sand with a wire little by little to get it out and finally wash it clean. You may have a "practice" bend but the tubing is cheap and it may take a try or two to satisfy you.
Posted: 3/16/2006 3:13:53 PM

From: TX, USA

Joined: 1/29/2006

Thanks Dayfan! That's exactly what I needed to know.

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