[sdiy] Tubes in Synths [ was : Harry's Nightmare! ]

[Ingo Debus]

John L Marshall wrote:
> 
> A mild radioactive additives are added to reduce the dark effect; firing
> voltage becomes high and erratic.
> 
> I am using neon lamps in some of my synthesizer modules. The power supply
> for the neon lamps uses six *zero* tubes; 0A3 and 0D3. I love the glow the
> tubes give off.

In the amplifier built into my Leslie 251 there's a 0C3. Is this a
similar tube? It's smaller than the 6550 but of similar shape. It glows
bright violet, and it flickers a bit after the amp is powered up. Is
there a radioactive additive in this tube too (gulp)?

Ingo