A-P_Solenoid

This tube was designed by Henry K Huppert. He was an x-ray technician and later was employed by Moorhead Laboratories, where he worked on this tube and the 2 in 1 tube. He applied for a patent on the solenoid tube on 19^th January 1923. Patent no 1564070 was granted to him on December 1^st, 1925. No record exists that he assigned his invention to Moorhead Laboratories, but retained ownership of it. Many experimental tubes were made before a commercially successful tube made and several of these were submitted to Moorhead for approval. At least one tube had a copper coil control. The coil was a control element with the wire coil outside the plate.

History of the tube is covered extensively in the article "Henry K Huppert and his tubes" etc, by Eric P Wenaas, which is in the Antique Wireless Association's Review, volume 30, 2917, pages 173-222.

A-P_Solenoid: Fin Stewart Fin Stewart
	Just Qvigstad	A-P_Solenoid: Fin Stewart collection Fin Stewart Mas ...

Colección personal de