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By Jim Cross

I recently got several NIB examples of some of those odd Gold Seal cylindrical metal-shielded tubes, including a type "M 6D6," which I had not heard of. The box and the accompanying paper have the "M" prefix, but the "M" is not printed on the tubes. As I am sure you know, these tubes are most properly referred to as "MG" types, even though the suffix had not been invented when these tubes came out.

Gold Seal Types 24A, 26, 35, and 6D6

Anyway, the M 6D6 included a paper listing the different available types. It also proclaimed the advantages of these Gold Seal brand tubes. Here is the list of available Gold Seal metal shielded tubes followed by the quoted advantages.

"Available metal shielded tubes (the list includes the space between the "M" and the number): M 01A, M 24A, M 26, M 27, M 35, M 42, M 43, M 45, M 47, M 57, M 58, M 71A, M 77, M 78, M 80, M 2A5, M 6C6, M 6D6, and M 25Z5." Here is the text of the rest of the paper:


"The new metal-shielded radio tube offers many advantageous features not found in the straight glass types. These new tubes will replace with decided im-provement, the following types of glass tubes [listed above]. They have standard 4, 5, and 6 prong bases and are interchangeable with the regular types".

"The metal covering functions as a perfect electrostatic and magnetic shield adding greatly to the radio's selectivity and volume. This reduces to a great extent noises in certain types of receivers. These tubes are of course, nonmicrophonic. Mechanical vibration of the receiver has no effect on their performance. The internal elements are protected by the metal-shield and breakage is minimized".

"Due to the construction metal-shielded tubes are more uniform in quality and performance".

"Another desirable feature is that of space saving. This is of interest to the home constructor and service man as the trend today is for compactness in radio receiver construction".



This article was published in the April 2002 issue of "Tube Collector", the magazine of the Tube Collectors Association, Volume 4, Number 2, page 13. For information on the association and membership go to

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