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Radiation is a bugaboo for many folks. Think of it this way, a little bitty birthday candle emits photons. It will scarcely light a room, leaving the edges dark. You can burn yourself, but don't

I have a lot of interesting property tags on stuff, from all over. Naval Underwater Systems Center (doesn't exist anymore, absorbed into something else), LANL, Sandia, Boeing, IBM, Bendix Kansas City

A thoriated tungsten cathode will glow bright yellow. It gives an incandescent light bulb a run for its money. Nobody wants that in a radio tube. So, barium and strontium ceramics are used to get

Anyone got a link for this mod? Schematic?

Well... I tried it, and made things worse (risetime ~ 3 ns, fall ~ 5 ns)! After some tweaking of pullup R and a shunt capacitor on the resistor to the PNP base, the waveform at the trimpot/TD has

Just acquired a working 7M13 but the C and H buttons are broken. The 10-way button assembly doesn't have a Tek part number in the manual, it is just listed as an assembly. Is there any source for it?

My interest in vintage Tek gear comes from my first two scopes, which belonged to my father: a 475 from his time working as a service engineer for Varian MAT, and a 2213 that he bought when he went

I'm pretty sure that at least for non-high voltage transformers, Tek used a black polyurethane varnish for impregnation. I recall long ago, I picked up a couple of expired gallon cans at the Country

Steve, you may be thinking of beryllium alloyed with magnesium. Many structural and precision mechanical parts were made with Be in the old days, for light weight and strength. Be particles can be

Glyptol was a General Electric product. It was used extensively for motor and transformer windings, and did it's job very well. Otis Elevator used it for general painting of car frames, machine

Unbroken, the vacuum tubes with thoriated cathodes would not be a problem. The government made things worse by having them smashed. But the government also sold off Bomarc Missile surplus years ago

Chuck is absolutely right. The amount of thorium in a cathode is vanishingly small — it is used to lower the work function at the surface of the tungsten, and is typically present in concentrations

So, I am a new member and maybe this topic been discussed before.... I recently was trying to use a 1A1 plugin in my 1956 type 531... Have some issues with it.... Reason for joining. While I was

Q784 and Q794 form an emitter coupled differential amplifier. Put a signal in on the base of Q784 and you should see a signal on the collector of Q784 and the inverted signal on Q794. It looks as if

How about adding a PNP switching transistor... emitter to +5, base driven from the TTL output, and collector to the trimpot/TD? That way the +5 supply stays negative-ground, and the TD continues to

Thanks, I fiddled with this a bit more today. Seems like even channel 1 has a little issue but not as much as 2 that I didn't notice earlier. This definitely needs a full going through.... I had

There is more radioactive thorium in a coleman gas lantern mantle than is in a transmitter cathode. Typically, the thorium in a cathode is alloyed in the tungsten filament to make it emit electrons

G.E. is no longer into it... and Glyptol is now a brand (for at least a couple decades)... and like a famous de-oxidising snake oil (not really for snakes: either the plumbing kind... or the reptile

I guess that depends on what you call "work well". You just won't see (part of) the triggering edge but otherwise, the image is fine. Apart from it possibly being a nice exercise, I don't see the

The fastest sweep the 7603 is "specified for" is 5ns/div which is obtainable with a 7B53A set the highest sweep (.05us/div) with the x10 multiplier engaged. I'm amazed you find the 7B85 or 7B87 work