Search RFCafe.com                           
      More Than 17,000 Unique Pages
Please support me by ADVERTISING!
Serving a Pleasant Blend of Yesterday, Today, and Tomorrow™ Please Support My Advertisers!
   Formulas & Data
Electronics | RF
Mathematics
Mechanics | Physics
     AI-Generated
     Technical Data
Pioneers | Society
Companies | Parts
Principles | Assns


 About | Sitemap
Homepage Archive
        Resources
Articles, Forums Calculators, Radar
Magazines, Museum
Radio Service Data
Software, Videos
     Entertainment
Crosswords, Humor Cogitations, Podcast
Quotes, Quizzes
   Parts & Services
1000s of Listings
 Vintage Magazines
Electronics World
Popular Electronics
Radio & TV News
QST | Pop Science
Popular Mechanics
Radio-Craft
Radio-Electronics
Short Wave Craft
Electronics | OFA
Saturday Eve Post

Software: RF Cascade Workbook
RF Stencils Visio | RF Symbols Visio
RF Symbols Office | Cafe Press
Espresso Engineering Workbook

Aegis Power  |  Alliance Test
Centric RF  |  Empower RF
ISOTEC  |  Reactel  |  RFCT
San Fran Circuits



Amplifier Solutions Corporation (ASC) - RF Cafe

RF Cascade Workbook 2018 by RF Cafe

Please Support RF Cafe by purchasing my  ridiculously low-priced products, all of which I created.

RF Cascade Workbook for Excel

RF & Electronics Symbols for Visio

RF & Electronics Symbols for Office

RF & Electronics Stencils for Visio

RF Workbench

T-Shirts, Mugs, Cups, Ball Caps, Mouse Pads

These Are Available for Free

Espresso Engineering Workbook™

Smith Chart™ for Excel

TotalTemp Technologies (Thermal Platforms) - RF Cafe

Glass-"Metal" Tube Shield
October 1935 Radio-Craft

October 1935 Radio-Craft

October 1935 Radio Craft Cover - RF Cafe[Table of Contents]

Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Craft, published 1929 - 1953. All copyrights are hereby acknowledged.

While working on vacuum tube based USAF air traffic control radar and radio systems, and having seen many tube television and radio sets I never recall seeing one of these form-fitting metal shields like this one appearing in a 1935 issue of Radio-Craft magazine. All the ones I've seen are simple cylinders that slide over the tube and either twist into a receiving rim slot like a bayonet type lock or they have spring metal fingers that grab the glass envelope. One kind of scary feature of this shield is that there is a tab with a hole in it to go around a grounded pin on the tube, requiring that the installer pay close attention to how it goes on. Putting it on the wrong pin could cause serious problems like shorting out part of the circuit if the shield also happens to contact a nearby ground, or it could inadvertently broadcast (or pick up) a signal, or likely put a hazardous voltage on the shield. As you might guess, utilizing a metal shield around a tube for anything other than a low frequency application like an audio amplifier or poser supply requires circuit design that takes into account the capacitive effects of the large, usually grounded, metal plates.

Glass-"Metal" Tube Shield

Glass-"Metal" Tube Shield, October 1935 Radio-Craft - RF Cafe

Glass-"metal" tube shield.

Glass-"metal" vacuum tube shields - RF Cafe

Amazingly, I happened to find a photo of what looks to be this snap-on tube shield.

Fitting tightly around the glass, these shields are designed for use with the new glass-"metal" tubes, making them interchangeable with the metal tubes in sets designed for the latter. The shield is in four parts, the two main shell pieces being held in place by the top and bottom pieces, which snap into place. The bottom piece has a tab which springs over the ground pin on the tube, and thus grounds the shield as in the metal tubes.

 

 

Posted July 28, 2022
(updated from original post on 11/3/2015)

TotalTemp Technologies (Thermal Platforms) - RF Cafe
Noisecom

Rigol DHO1000 Oscilloscope - RF Cafe

KR Electronics (RF Filters) - RF Cafe