[Hallicrafters] 0A2 question

[wb8jkr at juno.com]

  I remember about 30 years ago, I replaced the 5U4
LV rectifier tube in my HT-37 with a homemade
SS replacement consisting of  4-1KV 2.5 amp diodes
(HEP-170) and a series 10 watt 200 ohm resistor. This
combination should have been the equivalent of the 5U4
tube however, I remember when I turned the transmitter
on the 0A2 would flash over for a very brief amount of time.
 I stopped using the solid state replacement and went back to
the 5U4, never trying it again.
 My question is, does anyone know if the 0A2 has a certain
finite amount of time it requires to ionize, and until the
gas in the tube actually ionizes maybe the voltage input to the
regulator soars too high and caused the flash over? 
 I'm thinking of trying the same thing again, but thought maybe
because of the above problem it would be wiser to use a
string of three 50 volt 5 watt zeners in place of the 0A2, thinking
the zeners would conduct faster than the 0A2.

 Any thoughts?

73,  Mark  WB8JKR