Etherwave antenna coatings - rubber, paint?

Just wondering if anyone had thoughts on coating the antenna of an Etherwave Standard with Plasti-Dip.

I'm thinking as long as the ends where they attach were kept clean it wouldn't matter but I may be missing something.

While were on the subject, what about paint and clear coat on the antenna?

(I already have the cable sleaving on them. I was just looking for another alternative)

Thanks

An easy and aesthetically pleasing way to accomplish the same thing is to purchase some clear, vinyl tubing from the hardware store. Use a little bit WD40 to slip the tube on to the loop.

Kevin - Have you done this? Were you able to remove one of the compression nuts and sleeves first?

Good catch, Jeff!

I did this with my Epro which, of course, does not have compression fittings.

Having said that, you could probably work the compression sleeve off with a pair of pliers -- or it may even just slip off -- it depends on how tightly the antenna was tightened.

That was my problem, trying to think of a way to get something over the nuts that would still be tight.

Hence the thought of Plasti-Dip.

I've never used plastic dip, so I don't know what kind of results you might get.

Another option that has been discussed here in the past is powder coating. If you are not familiar with the process, it is a heavy "paint" coating that is an electrostatically applied powder that is baked to form a durable finish.
I don't know if it is available in a clear finish, but I imagine it may be.

If the clear, vinyl tubing appeals to you, you can always carefully cut the compression sleeve with a Dremel type tool and remove it and the nut.
You can get a replacement sleeve in the plumbing section of your local hardware store. Unfortunately, I've found you can't get them individually. At our local Home Depot, they offer a package of ten sleeves or a set of two nuts and two sleeves.
You may have better luck finding an individual sleeve at a "Mom and Pop" hardware store, assuming you can still find one.

Thereminist Dave Miller brought his etherwave theremin to the 1997 theremin festival in Portland, Maine, and demonstrated a curious phenomenon that was never adequately explained.

Dave's etherwave was not housed in the regular box but had been installed in a very nice vintage radio cabinet - other than that it was a standard ehterwave. The weird thing was that he could alter the timbre of the instrument by placing a clear vinyl tube over the pitch antenna. The sound was definitely gentler and slightly more muted with the sleeve installed.

We asked Bob Moog, who was present at the event, to explain how this was possible and he said that it WASN'T POSSIBLE and that the plastic sleeve could not alter the sound of the instrument in any way.

Well, folks, possible or not, the sound was definitely different with the sleeve on. No one could ever explain it.

I have no doubt that if Bob Moog had put his mind to it, he could have come up with an explanation of this phenomenon which I mention here because anyone who is planning on adding a coating or a plastic sleeve to the pitch antenna of an etherwave theremin may find it alters the sound.

To remove the ferrule you could use a "compression sleeve puller" - take your volume loop to a local plumber or plumber's merchant and see what they say.

Alternatively, as brass expands faster than steel when heated, you might be able to slip it off easily after a blast from a propane torch.

(Note I have not tried this. Also I take no responsibility for burnt fingers.)

coalport said:

[i] Thereminist Dave Miller brought his etherwave theremin to the 1997 theremin festival in Portland, Maine, and demonstrated a curious phenomenon that was never adequately explained.

Dave's etherwave was not housed in the regular box but had been installed in a very nice vintage radio cabinet - other than that it was a standard etherwave. The weird thing was that he could alter the timbre of the instrument by placing a clear vinyl tube over the pitch antenna. The sound was definitely gentler and slightly more muted with the sleeve installed.[/i]


I view the theremin in what some consider an unorthodox perspective. As many believe the relationship between the Thereminist and pitch antenna is a capacitive effect, I have observed it to be more of a transfer of energy from the theremin to the Thereminist. It is not some capacitive feedback ground loop. The theremin needs a good earth ground to complete the physics of developing RF radiation via the antenna and ground which creates the “pitch field”.

Sliding the “plastic tubing” over the pitch antenna insulates it from direct air contact which changes the dielectric factor between the antenna rod and the air space, ever so slightly this changed the characteristics along with the “tuning” of the pitch antenna which must be viewed as more than just a wire rod.

Antenna “tuning” is what causes some theremins to sound different on opposite sides of the Null point with one side being a slightly better sound.

David Miller was fortunate that his antenna modification went in his favor; often the theremin has no mercy. ;-)

It is important to remember that the energy in the theremin pitch field is “extremely” low and this allows the theremin antenna to be extremely sensitive to minimal environmental changes. One way to observe this sensitivity is to reach toward your pitch antenna using a long wooden broom handle and observe what happens. The “wood” broom handle allows more energy to transfer away from the pitch antenna causing the pitch to rise.

My newer EWS does not have this touching the volume hoop issue. I would probably use heat shrink tubing which comes in various colors and shrinks down to less than half its original diameter. Get this at electronic supply stores.

Christopher
RS Theremin
.

[i]"by placing a clear vinyl tube over the pitch antenna. The sound was definitely gentler and slightly more muted with the sleeve installed."[/i]

There are good and quite simple reasons why the above sort of effect can occur.. On this occasion (if the account is absolutely true, and not distorted by time) Bob was wrong to say that sleeving could not make a difference - He was being an electronics engineer and not a physisist!

The capacitive coupling (E-Field sensing) principle works because the antenna acts as one plate of a capacitor, and the player acts as another (ground coupled) plate.. The capacitance is a function of area of plates, distance between plates, and DIELECTRIC/S BETWEEN THE PLATES.. There are also couplings between the antenna and other 'plates' - these include grounding on any adjacent object / circuit board, AND coupling to ACTIVE sections of any adjacent circuit board..

By placing a 'sleeve'(or any dielectric 'barrier' between antenna and player) of different dielectric to air, one can 'distort' the distribution of the E-Field - This can cause the percentage of coupling between antenna/player vs antenna/other circuits etc, to change - and this can, and often does, affect the waveform of the HF signal.

These sort of effect are most noticable if there is a discontinuity in the 'sleeve' covering the antenna.. An antenna uniformly coated with consistent thickness coating will (apart from wires connecting to the antenna, which is a whole different can of worms) have an equal distribution of field 'distortion' to both intentionally and unintentionally coupled 'plates'..

However, if one sticks some thick rubber hose-pipe on (say) the upper 90% of the pitch antenna,and leaves the lower 10% uncovered, the coupling from this lower section to internal circuit boards in the Theremin will 'increase' disproportionally to the coupling of the antenna to the player.

There are a huge number of possible 'strange' couplings which can occur in the E-Field, and most of them make little noticable difference.. But most Theremins are not designed with much attention paid to leakage of signals - In fact, often the desire to reduce 'background' capacitance (so as to optimise the playing field) means that even basic screening is reduced below a level which is normally acceptable for electronic equipment.