Are tube plate dissipation's peak or rms?

OK, fair enough. But as John L noted elswhere, the problem is that the glass melts.

Cheers! Rich

Yup, I spent all of my disposable income on Fair Radio Sales, at least until I discovered girls.

I used to buy 4FP7 CRTs, from airborne radar indicators, when I was a kid. Just for fun, I emailed them a couple of years ago, and they still had some! WWII surplus! I bought a couple, just for old times' sake.

ftp://jjlarkin.lmi.net/4FP7.jpg

They're cool. The P7 glows in the dark for a while after you turn out the lights.

Fair used to sell an entire under-wing radar pod for $70.

John

My first scope was built using a 3BP1. Same sort of vintage, but 3" tube with medium green phosphor. One or two valves for the timebase and another for the vertical amp. Triggering, what triggering ?. Also built another later using a 1cp1 tube, but that was more for the challenge of miniaturisation, rather than anything really usefull.

Real junk shops are a dying breed in the uk. J Birkett in Lincoln still has quite collection of almost WW2 stuff, though he will probably retire soon. I would guess that there are dealers in the US with warehouses full of the stuff, but when did you last see a BC45x command set in the flesh ?. You could buy those less dynamotors for a few shillings each in the 50's. Beautifully made, light weight radios with invar tuning capacitor plates and tiny spring loaded glass balls for stator insulation and support...

Regards,

Chris

It's the difference between the pure academic and engineering path. Both are needed, but what you learn in school is a tiny fraction of what a few years experience in the real world teaches you. You do need the theory later on, but arguably only a small subset of what you were taught. Without the practical experience of knowing what works, the only thing you can do is design conservatively.

The guy had respect for your ability and you probably both learned a lot from each other...

Regards,

Chris

Mail order, or did you ever visit the store? It was a couple hour drive from my house, and I used to go about once a year.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

Mail order, from New Orleans.

When I moved to San Francisco, 1979-ish, there was an electronics surplus place on Market Street, a couple of blocks from here. And there ware scads of them down towards Silicon Valley, and Mike Quinn in an old Quonset hut on the Oakland airport grounds. Electronics Etcetera in Berkeley. Our Saturday Morning ritual was to hit the Foothill Electronic Flea Market about dawn, then circle the bay and hit the surplus houses. Once I found a bin full of tunnnel diodes, 10 cents each, at Haltek. And a guy at Foothill had a couple thousand SRDs for sale, 50 cents each if you haggled. Old HP guys would die and their kids would empty the garage and sell it all off at Foothill.

The .com real-estate crunch killed off most of the surplus stores, and ebay killed the Foothill Flea Market.

John

Here in the US the little local places are dying out, but the big ones that can do mail-order (like Fair Radio) seem to be chugging along.

I don't know if the same thing will happen there, but I suspect that someone who has some cheap land for storage space, and enough savvy to do internet sales, should do OK.

Maybe not UK, but maybe one of the poorer EU countries? Dunno where that'd be -- Ireland? Spain? (I'm going to piss someone off by mentioning the wrong place, I know it). Is there some corner of GB where the Men are Men and the sheep are Very Afraid? It just takes an enterprising fellow with an interest, and a willingness to sell what everyone else things of as 'junk'.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

Have seen the FR site and they do international, fwir. So much interesting stuff to play with, or even use for projects. I guess you never lose the bug once bitten. The endless curiosity of finding out what's in the box and what makes it work :-).

In gods own county of Yorkshire, to be exact and the next line is: "and the women are glad of it". Yorkshireman myself, if that wasn't obvious, but have never owned a long pair of wellies, honest :-)...

Regards,

Chris

Well, its successor is still active at De Anza College, on the same schedule. It's almost certainly not what it once was, but there's still Interesting Surplus Junk showing up there.

--
Dave Platt                                    AE6EO
Friends of Jade Warrior home page:  http://www.radagast.org/jade-warrior
  I do _not_ wish to receive unsolicited commercial email, and I will
     boycott any company which has the gall to send me such ads!

I built my first TV set in 1946, using a 12" P7 radar CRT. There was a rumor that the P7 phosphor would lose its long retention times if you left it out in the full sunlight for a while. (It didn't work...my first TV reception was a rodeo in Madison Square Garden. The picture showed the cowboy still on the horse after he had been bucked off!)

I was lucky not to have killed myself. The CRT HV power was from a 60 cycle high voltage transformer.

--
Virg Wall

My first scope used an RCA 913, which was a metal shell like a 6L6 but with a 1" glass screen with a P1 phosphor at the end.

I worked in New York City right after WWII. There was a place known as "radio row" right where the twin towers were built. It had all sorts of electronic surplus.

--
Virg Wall, K6EVE

I haven't been to the "new" one, as getting up a 5AM has lost its charm. But Foothill was fading as all the good gear was moving to ebay.

John

A blue filter would fix that. You'd have a fast, blue cowboy.

John

"John Larkin" "Phil Allison"

** No more real than any other "getting the design right" design issue.

..... Phil

For tubes, there often exists both ICAS (Intermittent Commercial and Amateur Service) and CCS (Continuous Commercial Service) specifications.

In TV sweep tubes and e.g. SSB two way radios the duty cycle is quite low and average values quite a lot lower. The large thermal inertia of the tube electrodes will allow quite high peak dissipation values. Especially for sweep tubes, there are also separate peak ratings for cathode current and peak anode voltage, usually several times larger than the steady state values.

** For a *very specific set* of other conditions you completely fail to mention. ** You made no point at all.

It was all bollocks.

** Did you bother to read anything I wrote ??

All of it went right over you pointy head - didn't it.

** You are so far off with the fairies it is laughable.

Piss off.

.... Phil

Try aiming a 5 meter C-band antenna while watching a monitor with a P7 phosphor. You're two birds away before the image fades. :)

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

My dad made our first tv sometime in the early 50's, using a 5" vcr97 (similar size to 5bp1) with green screen and perspex oil filled magnifier in front of the tube. The tube came from some sort of wwII indicator and I think the chassis would have been used as well, as it had the tube support and loads of valve holders. It was a trf design, one channel, and rows of red ef50 valves on the chassis. He was pretty good at radio, but probably took ideas from the radio / tv mags of the time as well, which were full of designs fo home built radio and tv. The psu was on a separate chassis, with vertically mounted selenium stick hv rectifiers, with no covers or any kind of safety precautions. The chassis had a single toggle switch and everyone had strict instructions to touch nothing but the switch when turning it on or off :-). The health and safety people would have fit these days, but was eventually passed to one of our grandparents, who used it for several years without incident.

A much more innocent world, less meddling by our so called "public servants" and better for it, imnsho...

Regards,

Chris

My second TV was a much more ambitious endeavor:

In 1949, I was working for Bell Labs in New York City. The RCA 930 was just coming on the market, but cost >$400.

I found a pre-punched chassis, complete IF coil sets, the tuner (VHF only), and the power transformer available at "radio row" dealers. Small parts were available free at Bell. They had a policy that time lost by engineers shopping for resistors, capacitors and the like would exceed the cost of making them "freebies" from the electronic stock room.

This left only the tubes, (valves), of which there were 29, and the 10" round picture tube to be bought. It took a lot of soldering to put it all together!

The set was quite good for the times. It had a separate IF channel at

4.5MHz for the sound. About the only thing I added was gated AGC so the picture would not flicker every time an airplane flew overhead.

--
Virg Wall