Octal Voltage Regulators

OC3 / VR105
OC3, VR105, VT200
Nominal voltage: 105 V
Current range: 5 mA to 40 mA (2 V regulation).
Strike voltage: 115 V (average), 133 V max.
Cathode is wired to pin 2, Anode to pin 5.
A jumper is provided between pins 3 and 7. This is intended to be used for disconnecting the power in the event that the tube is unplugged. It does not connect to the tube

RCA datasheet .

Photo left
© Andy Cowley,
M1EBV, 2008

Photograph left shows the tube operating at 30 mA DC. Running voltage is 107 V for this particular tube. The outer cylinder is the cathode, and the glow discharge is mostly associated with its inner surface. The anode is in the centre.

Right: Bulk gas discharge obtained by placing the tube in a strong RF electric field. The fill gas appears to be pure argon.

The setup for obtaining the bulk discharge is shown below. The field source is a coil self-resonating at about 25 MHz. The tube cathode (outer electrode) is grounded to increase the field gradient and enhance the glow. See coil resonance experiments for more information.

VR105 rough service
Ruggedised VR105
This tube has a special protective base (probably intended for rough service). Inside the bulb, it is practically identical to the OC3 shown above.

(The centre spigot of the octal base of this example has broken off)

Photo left
© Andy Cowley,
M1EBV, 2008



Discharge Tubes

Coil Resonance Experiments

© D. W. Knight 2013, © Andy Cowley 2008