I found this Gammatron 24-G (VT-204) tube at work, along with several siblings and a lot of other valves. I thought this one looked particularly nice because its construction so clearly shows that it’s a triode.
This valve (vacuum tube) type was introduced in 1945 and was intended for transmitters of up to about 30-40W (some sources say 25W) at up to about 60MHz, although it was characterised up to 200MHz. That was quite high frequency engineering for the time (although radar systems operating into the GHz ranges were developed during the War, general-purpose power devices for VHF were still relatively few and far between).
Overall, this device is about 95mm tall, excluding the pins, and 35mm diameter. It weighs 1¼ ounces, and yet its shipping weight was quoted as 1¼ pounds – sixteen times as much! (1oz = 28⅓g; 1lb = 160z; 1¼lb = 20oz = 567g). That’s a lot of packaging material.
The British National Valve Museum has a page on this device, and even a scan of its datasheet. It’s interesting to note that the datasheet shows a slightly different construction, with the grid pin taken down through the base rather than out of the side of the envelope as shown here. My guess is that this allowed higher frequency operation by reducing cathode-grid capacitance.
It’s notable in that the “Type 24 Gammatron” (as its datasheet formally calls it) has its internal electrodes made from tantalum and is evacuated to hard vacuum without using a ’getter’ to get the last few atoms of gas out. In use, the tantalum cone was normally expected to run cherry-red hot!
This is one of the first moderately serious photos I’ve taken with my shiny new Nikon D850 camera.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.
Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7:30pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.
Join us every Wednesday night at 8pm ET for Ask an Engineer!
Maker Business — Will it scale? Culture at Google, it seems, will not.
Wearables — Playtime reference
Electronics — Can’t afford a current probe?
Biohacking — Vitamin-C + Gelatin for Accelerated Recovery
Python for Microcontrollers — MP3 decoding, CircuitPython snakes its way to Fomu, NXP, and more! #Python #Adafruit #CircuitPython #PythonHardware @circuitpython @micropython @ThePSF @Adafruit
Adafruit IoT Monthly — Machine Learning 101, PWNing the ESP32, and more!
Microsoft MakeCode — Lenticular Art Display with Crickit
Sorry, the comment form is closed at this time.