Museum Hours:

Saturday 10-6

Sunday 12-5

Early Electronic Television

RACS -  Pyrex CRT Rebuilding

In March of 2008 Jerome Halphen made contact with Philippe Raedersdorff, from RACS, a French CRT rebuilder, about the possibility of rebuilding Pyrex (prewar) CRTs.


RACS explained that the problem was in the stem, which contains the metal leads to which the electron gun is attached. The stems that are available are made of lead, or low temperature, glass, which cracks when welded to the Pyrex tubing. So, a graded glass method was selected, which welds several gradations of glass tubing, each with a lower melting temperature together to the stem.


In July, 2008 RACS successfully rebuilt a British Emiscope TA-15 Pyrex CRT, and now has the capability to rebuild about any pre-1945 CRT with magnetic deflection.


We are in discussion with RACS about rebuilding 9AP4 and 12AP4 tubes. Because of the high shipping cost to and from France, we will try to accumulate as many tubes at the museum as possible from collectors around the U.S. We will then bulk ship the tubes to France for rebuilding. After rebuilding they will come back to Hilliard, and from there back to individual collectors.


Many thanks to Jerome Halphen, who spent many hours translating emails to and from RACS, and made this project possible.


When we have more information, we will post it here, and will contact all owners of sets using 9AP4s and 12AP4s.

For some time we have been trying to find a way to have pre-1945 Pyrex CRTs rebuilt. We worked with Clinton Electronics to try to accomplish this, but were unsucessful. Here is a story about RACS rebuilding of a Mazda CRM tube.

Old gun removed

Phosphor deposition

Detail of adaptation Rings Pyrex to Soft Glass

Button and stem assembly

Closeup of button and neck weld

Detail of sealed exhaust tip


Gun mounted to neck before evacuation

Quality control on rebuilt tube


Drying after renecking

Completed tube