Re: Looking for data on 9-pin Vacuum time delay relays used in old Tek-scopes


David Kuhn
 

" If you were building a replacement for one of these delay relays
(hypothetically speaking, maybe for a 533A), would it be enough to have a
timer that cut a relay in after a fixed time? Is that really all that the
delay relay is doing?"

If its filaments are in the heater chain, something would need to be done
to replace the filament of the time tube. Also, if it is in the heater
chain in a serial fashion (I don't think they are, eh? I have to study the
schematics again), that is a safety factor if one tube's filaments open,
that power does not get applied.

I am probably overthinking it. a 555 and a S202SE2 SS Relay would probably
suffice.

Dave

On Sun, Jul 18, 2021 at 11:06 PM Jeff Dutky <jeff.dutky@gmail.com> wrote:

Bruce,

If you were building a replacement for one of these delay relays
(hypothetically speaking, maybe for a 533A), would it be enough to have a
timer that cut a relay in after a fixed time? Is that really all that the
delay relay is doing?

Might there be another way to determine when the heaters are at
temperature, like by monitoring the current through the heaters, or even by
directly sensing the temperature of the tubes themselves?

Just curious (though I am in the process of refurbing a 533A, and this may
be useful information when I get to the point of applying power to the
instrument)

-- Jeff Dutky





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