September 1935 QST
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
QST, published December 1915 - present (visit ARRL
for info). All copyrights hereby acknowledged.
metal-encased vacuum tubes came on the electronics scene in the
1930s, they were billed as the innovation that was going to radically change the
radio world. The built-in Faraday shield properties of the tubes did in fact stop
the effects of cross-coupling between adjacent tubes and permit more densely packed
circuits, but they also caused some other problems as well. Capacitance between
tube elements and the shield caused electron flow control issues and affected operational
frequency. Packing tubes closer together also meant the rat's nest of resistors,
capacitors, inductors, and wires on the underside of the chassis that were installed
in a point-to-point manner rather than neatly on printed circuit boards (which largely
did not exist at the time) were closer together and therefore created new problems
due to proximity. Still, metal tubes served a very useful purpose when employed
wisely and continued in use along with unshielded tubes right up until transistors
and PCBs dominated the electronics market.
General Electric Radio Advertisement
Hark Ye, 'Phone Men!
The New All-Metal Tube
The new tubes - "sealed in steel" - invented and perfected by General Electric
engineers - have many improved electrical characteristics. Here are a few of the
1. More effective shielding allows higher I.F. gain with stability.
2. Higher I.F. gain means - greater signal on diode, less harmonic
distortion on high modulation - less audio gain required, quieter operation.
The New General Electric Radio with All Metal Tubes
Mail Coupon for Details
General Electric Company,
1 Bridgeport, Conn.
Attention: Sales Promotion Section R-159:
Please send me complete details regarding General Electric Radios with the All-metal
The 1936 General Electric Radio with new all-metal tubes brings to amateur operators
the latest advancement in radio science and engineering. Its fidelity and crisp
clear-cut reproduction is far in advance of the field.
Model A-82 ... An all-purpose receiver, scientifically designed for the many
exacting demands of modern amateur stations. The following out-standing features
will appeal to all hams.
• Air Trimmers - provide better calibration stability • Sliding-rule Tuning Scale
- easy to read as a ruler • Improved A.V.C. due to higher I.F. gain .• 5 Watts undistorted
output delivered to 10 in. high-quality dynamic speaker. • Frequency coverage 140-410
and 540-19,500 KC in 4 bands .• CW oscillator may be added.
Merchandise Department, General Electric Company, Bridgeport, Connecticut
Posted August 18, 2022
(updated from original post on 5/18/2016)