Fusion Message Board

In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.

Subject: Magnum Insulators
Date: Apr 10, 10:58 am
Poster: Richard Hull

On Apr 10, 10:58 am, Richard Hull wrote:


I have a small supply (~4) of the large beryllia insulators like I am using on fusor IV for sale.

I any of you folks are interested you will need to contact me at my home E-mail listed above. I can supply black and white images of the insulator if desired.


The insulator is not, repeat not vacuum ready, nor is it on a standard vacuum flange. It is, however vacuum tight and properly vacuum bonded at the insulator-metal joints.

The insulator is made of normally glazed, pure beryillia (mega bucks). The insulator is fully corona limited by an integral round toroidal rim at the top connection point. The base and mount of the insulator is a 3" flange with (4) 1/4" bolt holes the flange rises slightly in a metal skirt to meet the insulator. The inuslator is about 7" long, overall.

All metal on the exterior is steel which is deeply and richly chrome plated. The top terminal appears to be a NF fine 3/8" male thread.

The internal contact is a 1/4-20 female threaded brass rod which is itself internally shielded with a beryillia extension collar, ala vacuum rated insulators, being recessed in that beryillia tube. The tube extends about 2" below the flange mount.

A really nice piece of government extravigance and a killer insulator which is certainly rated at about 40KV. (air breakover)

I believe this insulator to be a US Navy or Air Force high power longwave antenna bulkhead feed through made for severe service.

I actually adapated mine to vacuum service by hacksawing trough the lower metal skirt sheet metal and silver soldering the skirtand insulator into a 2.75" conflat flange.

I am passing them on for $50.00 postpaid in the US.