EIA/RETMA codes

Based on what you have described to me, its Plate B+ -center tap- Plate B+

Steve

When I wrote terms I used them, appropriately. Phil introduced the term VA to the discussion. We talked at cross-purposes for a short bit, that's all.

Jon

It's been productive, not a waste at all. So, no. I'll stick around, until I don't.

Jon

The numbers were supposed to have been assigned in sequence. Gaps in later lists were due to mergers and businesses going under. Supposedly some were either reassigned, or an old name emerged, when a division was spun off.

Prior to the EIA numbers, companies were identified with a letter or two. Unfortunately, you have to join the EIA to access the full data. The lists that were published by Sams may have been limited to companies who made radio & TV parts. Old HP, Tektronix and military electronics manuals had a list of all vendors & their codes, but if 491 was a small company, you may never track them down that way.

Thanks. That's a concise explanation and it clarifies my difficulties finding the number, too. Very helpful. I'll just test it with the variac and be done with it.

Jon

Okay. I'm going to test it anyway, but I take it this is what the color code suggested. Thanks.

Jon

I'm sure that's what you like to imagine. Interesting. So why is it exactly that you feel so strong a need to warn others? Do you feel a messianic impulse?

Jon

Yes. You've said this and I'm sure that's what you like to imagine. Why is it exactly that you feel so strong a need to warn others? Do you feel a messianic impulse, some assumed role of rescuer of others? A kind of messianic arrogance? Do you imagine you have a vast views beyond the comprehension of the weak?

Jon

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Michael:

Hmm. So post-war, anyway. Boxed in between 1946 and 1957? Cripes. Did I dismantle a 1950's slide show projector? Can't be. The large aspheric lens was plastic. The other optics was glass and mounted in nice, expensive metal tubes with baffles, though.

Thanks, Jon

Aspheric lens? That sounds like part of a TV projector using a spherical mirror. Does that make any sense?

It uses lenses and projection and first surface mirrors to a ground glass view screen. I bought it from Goodwill for a couple of dollars, mostly for what I hoped to get back in lenses. My wife wanted the mirrors for making magic illusion boxes. It was worth it.

Jon

You didn't disassemble one of these, did you?

Got mine at Goodwill, and used it for what is was made for. Microfiche viewing. My Pioneer stereo had the schematic in microfiche.

What a waste of space. Those mirrors are nice, but you should never attempt to "clean" them as you will scratch them for certain.

Scott made better speakers than TVs.

No, the number of those remaining to the world hasn't changed due to my recent activities. I probably would have scavenged it (savaged it, some may say) had it been in sight, though!

Looks like a parts box to me. :)

Years ago I gave away (to a radio club in NYC) two 4'x4'x3' boxes filled with vacuum tubes I've scavenged over my first 30 years of life. These included VR-150's from a 1944 navy radar set (hmm, I wonder if I still have the Selsyns from that in some box) and everything up to one or two 4CX1000A's I'd picked up. It was a huge haul for them, I suspect. Free, including shipping. I hope they used them well.

Jon

I'll try and be careful. The only first surface mirrors I've had much experience with are ones I made for telescopes, back when. I used silver nitrate solution for that. The silver _was_ sensitive and I had to replace it periodically (once a year or so.) Luckily, that wasn't hard to do. Aluminum deposition is pretty solid, though, and forms a protective layer pretty quickly from the air's oxygen. I never made my own bell jar/vacuum system for depositing aluminum, but the mirrors I handled seemed to hold up pretty well so long as I was basically careful about it.

Jon

The ideal optical surface is one that has never been "touched" or ever needed cleaning which required other than mere liquid contact.

Well, I've no idea what they've been subjected to.

By the way, I didn't mean 'touch' as you write when I wrote 'handle'. Surfaces for telescopes need cleaning. Dust collects without a sealed environment (I never was able to afford that kind of thing.) The three volume 'bible' set on making optics (Amateur Telescope Making) recommended replacing the silvering every 6 months, something I couldn't do that often. (So did Texereau's book.) But I did try and replace the silvering once a year, or so. Aluminum surfaces were considered 'good' for about 2-3 years, which I would have appreciated while gladly accepting the slightly poorer reflection over wavelength had I been able to consider it. But one does what one can afford to do at the time.

Jon