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Dear forum,

I have been trying to find datasheets for the Amperite time delay relays
used in older Tek scopes. They are built in 9-pin tube glass envelopes.

Looked in w140.com but maybe not long enough to find any.

No hits by simply googling the type number...

Is there someone who knows where to find specs?

Cheers

Ulf Kylenfall
SM6GXV

For instance .
Albert

Sorry - I included a graphic of the pinout on my first reply, but I guess
it was blocked.

Here's the Web site that has it - along with a link to download a PDF.



Steve Horii

On Sun, Jul 18, 2021 at 3:37 PM ulf_r_k via groups.io <ulf_r_k=
[email protected]> wrote:

Dear forum,

I have been trying to find datasheets for the Amperite time delay relays
used in older Tek scopes. They are built in 9-pin tube glass envelopes.

Looked in w140.com but maybe not long enough to find any.

No hits by simply googling the type number...

Is there someone who knows where to find specs?

Cheers

Ulf Kylenfall
SM6GXV

Ulf,

I designed these into things about fifty years ago. The Amprite type numbers generally provided the data. For example a 117NO60 would indicate a 117-volt unit with normally-open contacts that would close 60-seconds after power was applied. These thermal delay relays were often used to delay the application of plate voltage until cathodes warmed up.

Bruce, KG6OJI

Dear all,

I have received datasheets in PM's off the list and also links in this thread.

Thank you all!

Cheers

Ulf Kylenfall

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

" For instance .
Albert"

Albert; thank you; I had been thinking of this too. In industrial
controls, we would use on-shot (Time Delayed) relays too, but they are much
larger and bulkier than that tube.

I guess someone could design a tiny 555 timer and relay to replace it if
needed. An extra aggravating (LOL) step, but yaa got ta do what yaa gotta
do.

Dave

" 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

A few years ago the time delay relay in my 555 died and lacking a replacement I had to cobble up a substitute. I repurposed an old device I had made to trigger a super 8 movie camera (remember them?) for time lapse. That device was designed to work form a 9 volt battery. I started by rectifying the 6.3 volt supply for the time delay relay using a half wave voltage doubler with the input capacitor deliberately kept to a small value to allow the output voltage across the storage cap to rise slowly. When it got to a suitable level it triggered a SCR through a zener diode to discharge the output cap through the coil of a little relay to close the main scope relay. Once the scope relay pulls in the 6.3 supply is disconnected from the voltage doubler. A reverse biased diode from the storage cap to the +100 volt line removes any residual charge as soon as the scope is switched off so the time delay will function properly next time it's switched on.

There's plenty of room in the 555 power supply for small proto board with the circuit on it. All the parts were in my junque box so the whole thing cost nothing and provided a bit of fun.

In retrospect it would have been even simpler to slowly charge a cap from the raw +100 supply which is about +165 volts according to the manual, and use that to trigger the SCR..

Morris

These can still be found as NOS on eBay. I bought a 6NO45T, a couple months back for around $10, for a Tek 551 I'm restoring. Turned out I didn't really need it. The main open-air PS relay that the timer triggers was sticky and had dirty contacts.

right. I was thinking about a 555 timer chip driving a relay.
places like surplus sales of nebraska, or perhaps sphere might have the originals.
--rick chinn

I looked tonight at Nebraska Sales & Surplus. They have them. the 555 driving a relay looks more and more attractive.

I still prefer the old original stuff as long as I can obtain it as I feel great respect for those people who have designed and made it. And it's fun watching it in operation!
Anyway, the thought of having a substitude if needed is a good feeling, too!
Joe

Those Surplus Sales prices are not practical for hobbyists, especially down here in Australia. I will post the schematic of my hack later today. It has the advantage of not requiring any alteration to the scope and if you have a reasonably stocked junk box, should cost nothing.

Morris

I have uploaded the schematic of my time delay relay hack to a new folder in the files section

Is there a marking on the top or side of the glass envelope like 116NO20 where the 116 is the rated heating element Voltage, NO is Normally Open contact.
You could sub a solid state timing relay wired to a 9 pin plug.
hp

If anyone is interested I have these NOS free for the cost of shipping from Sweden::
4 ea 6NO45T (148-002 ?)
3 ea 6NO30 (148-0021 ?)
one unknown
As a lot only. Contact me off list.

/H?kan

On Tue, Aug 17, 2021 at 09:52 PM, zenith5106 wrote:

If anyone is interested I have these NOS free for the cost of shipping from
Sweden:

They have been spoken for.

/H?kan