开云体育

Hello Dave,

If those gas filled tubes were high voltage indicators, as Walter thinks,
they would not indicate for very long. There are no serial resistors to
limit current, once 'indication' takes place, current would go sky high and
burn them up. I do not think that gas is neon, either. Neon is fine for
indicators, but does not seem capable to support high current density. The
indicator that Walter read about in manual is hung across two caps in
voltage doubler.

Although Tektronix was known to run some caps at the knife edge of voltage
ratings, this setup would be a real stretch. The 'high voltage warning
indicators' were called 230V and caps after rectifier were rated 200V.

I would guess that spark gaps that you are talking about are part of the
caps, so they do not show in schematic, I could not find them. A name
'Capacitor with Sparker' seems to be what cap manufacturers used for them
(another case of foggy memory). The caps which I saw were discs with an
elongation opposite from leads and a radial cut of various width, probably
depending on rating. My guess is that disc cap was leaded with continuos
wire, making a short across the cap. Then, cap was dipped in coating and a
saw cat made desired spark gap width. I have not seen one of those in a long
time.

I am quite sure that sparkers were to protect scope from outside world. I do
not think that to this day there is a requirement to protect line from load.
Someone in this group is in power business, maybe he can tell us if 500 hp
motor would require protection of the line.

Just in case, we should keep quite about that requirement for protecting
line from small loads. If European Union hears about it they might add it to
EC requirements; those boys have been on a regulation binge forever.

Regards
Miroslav Pokorni