Hi,
it looks to me that the 20V difference does not do much concerning
ionisation seeds, which seems plausible. Ambient light, however, carries
energies of about 2-5 electron volts per photon. When the intensity of
ambient light is large enough, these photons can do more together than
the 20eV acting on the gas by the higher voltage. This way, the ambient
light photons create ionisation seeds.
Once there are seeds available, the potential dofference of 20V kicks in
remarkably, of course, just as you experienced.
So it all comes down to the fact that your "bad" tubes apparently do not
have as much default seeds as the good ones, which might be due to a
smaller concentration of mercury.
Jens
I did some extensive testing today and made the conclusion that these
slow tubes need much more ambient light to ionize than other tubes.
Raising the anode voltage to 200V rather than 170/180 is not doing
much at all, I only see a dramatic improvement when I expose them to
more ambient light. Could that be related to the amount of mercury
vapor then? Is it then just a badly manufactured tube or is that due
to its age?
Michel
On Sep 5, 8:30 am, marta_kson <[email protected]> wrote:
Just a thought as the off-time before the problem reappears seems to
be very long, may the mercury in the tube be involved in some way?
That would take minutes to condense. The loss of ionization is a
microsecond process, so the explanation must be something else. The
mercury insertion is also something that could had some process
variations at the manufacture making some tubes worser than other even
in the same batch.
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