This months tube is another crazy specimen from the collection of Josef from Vienna : The VT-127A
The VT-127A is a directly heated transmitting triode with thoriated tungsten filament. Designed as VHF pulse oscillator. Josef uses it as output tube and operates it similar to a 211.
The tube has a weird bulb shape. The four rods protruding from the sides through the glass are the plate and grid connections. The two on the top connect to the plate and the two in the middle to the grid. The two pairs of connectors are in parallel. Filament voltage is applied through two rods coming out at the bottom of the bulb.
The first tube is made by EIMAC.
The filament runs at 5V and needs a whopping 10A current. Maximum ratings and typical operating conditions for continuous use are the same as those of the EIMAC 100TL.
Some close up photos of the tube:
Next we have a Gammatron VT127A:
Some photos with the filament lit up.
The tube in operation in an amplifier built by Josef:
Quite a beast of a tube! Thanks to Josef for providing the samples for this post.