[ARC5] VR Tubes

[Mike Morrow]

Ian wrote:

> The Amperex data sheet for the 0B2 says:
>  Anode breakdown voltage with illumination of 50-500 foot candles: 127 volts max
>  Anode breakdown in complete darkness: 210 volts max

Yet, for an example of a set with which many of us are familiar, the OB2 found in the
  (1)  CN-690*/GRC-109
  (2)  PP-2684*/GRC-109
  (3)  PP-2685*/GRC-109
power supply units is in total darkness with absolutely no source of light intrusion.

So likewise similar tubes used within the AN/GRC-3 series of tactical FM sets, and the
AN/GRC-9 HF set.  Even the VT-139/VR-150/0D3 found in the modulator units of the ATA,
SCR-274-N, and AN/ARC-5 see little filament shine from other tubes in the unit cover.

I suspect that in such applications it is sufficient that tube firing at a higher
value than the regulation voltage is OK as long as the regulation voltage is quickly
stabilized.

Mike / KK5F