“Standard Brand“, “Rad-Tel“, “Atomic“, “Cosmic” — what kind of brands are these? I found an interesting tube-related article in the Dec-1955-Jan-1956 issue of NATIONAL RADIO-TV NEWS. The article exposed a supply-chain problem during the 1950s where unscrupulous vendors would buy “pull-outs” (duds or near-end-of-life tubes) from repair shops, then manipulate the tubes in a manner …
©2011 Bob Putnak. I am frequently asked how to test voltage regulator (VR) tubes, which are sometimes called “glow regulator” or “glow discharge” tubes. Few tube testers test VR tubes, and most models that claim to test VR tubes do a worthless job at this task. They use AC voltages instead of DC the AC …
Here is something that you will not see everyday, an NOS NIB NEW Globe-style Arcturus blue-glass 071A audio output tube. Type 071A is also known as 71-A, 71A, 171A, 271A, 371A. This tube has the star-logo on the top of the glass bulb with 071A inside the star logo. Engraved base reads “ARCTURUS – No. …
This is one of many examples where tube testing requires experience to properly evaluate any tube. In this situation, using a tube tester would yield a completely wrong answer. These tubes were factory marked as E283CC, but are actually 12AX7A tubes. Hence, if you tested them in your tube tester using E283CC settings, you would …
I am frequently asked to explain what all of the “letters and numbers” mean in a vacuum tube number. In the early days of radio, tube numbers were haphazardly assigned to new tube types. As more vacuum tube types were developed, it became more difficult for technicians to recognize any fundamental characteristics about a tube. …
