Anyone ave any old/dead/spare valves?

Hey guys - long shot I know, but does anyone have any old/dead/spare vacuum tubes they'd be willing to part with?

I have two projects on the go for an exhibition next year - one is a series of 1:5 scale drawings of vacuum tubes, and the other is a set of collectors cabinets that I'm filling with old-school electronics. I've been lucky enough to find an amp repair guy who's willing to let me crash around in his workshop a bit in January to draw some of his, but would like more variety (and of course need actual tubes to put in the collectors cabinet).

Am obviously happy to pay for tubes and postage.

Do tell more about the set of collectors cabinets... public display? museum ? behind glass ?

I possibly could get you a seriously large ceramic power tubes if the destination is appropriate. The huge 15kW sort near 15cm across and weighing in at about 5kg formerly used in broadcasting. Sadly they do contain the carcinogen Beryllium Oxide hence the caution on the appropriateness of the destination. Definitely a rare tube to have for a display ...

Might have a few other larger tubes lying around but would need to go hunting in my shed first.

Hey Marcel,

The cabinets will be on public display (not always behind glass), moving venues frequently, and stored at my place between times - so Berillium Oxide is probably out, unfortunately. They sound amazing though - do you happen to have photos?

Do a Google image search on "3cx15000h3"

FYI, The metal parts are inert but the white surfaces are the BO loaded parts. Okay to occasionally inadvertently touch but not to rub or cause dust. (Think of and treat as a very serious Asbestos)

Oh, they're cool! (Though they sound terrible to work with)

Sounds like a cool project. I enjoy seeing your art stuff come up on Insta and FB.

Not to bad actually... put on a set of gloves, a leather apron and protective glasses or a face mask and after letting it cool down you're good to go. It's typically quite easy to remove and install these larger tubes without ever touching the ceramic parts. just need to be a little cautious and situation aware and be very wary of their weight. A tube change can take anywhere from 30mins to 2hrs depending on biasing and tuning requirements of the transmitting equipment it's fitted to. Plate voltages depend on the gear it's in but usually start at somewhere above 5kV with typical near 10kV, though I have seen as high as 25kV in one transmitter variant, all of which is plenty enough to kill on first touch and all of which usually scares the hell out of most run of the mill electricians.... and everything is just a tad bigger and different and more 'heavy duty' than to a Marshal or Fender tube guitar amp

The 3CX part denotes that it's a Ceramic triode and the 15000 means it's a 15kW plate dissipation tube and the remaining letters denote the wiring/connections arrangement. In this instance the leads (when fitted) are as thick as starter cables on a car which is fair enough considering they are carrying near 200A continuous of filament current. The vanes around the top are for cooling with forced air flow often measured by the dozen in cubic feet or litres per second. Some tubes only last 6 months whereas others can last tens of years so consistency is not their strong point, but they do survive lightning particularly well (better than solid state) and look quite spectacular when operating with the white ceramic parts emitting a Pink through Orange to Yellow glow....

And yes, they are quite expensive when new though they can be rebuilt/refurbished for somewhere near half new price. Refurbishing was popular in the day as quite often the refurbished units would out perform and out last new units....go figure...

In Australia when these were popular amongst commercial radio broadcasting stations their typical 24/7 output power would only have been a measly continuous 5kW of radio waves. A few exceptions like our ABC and the military may have them spitting out 10 or 20kW. I have seen rare examples where 50kW of radio 24/7 is the norm for this size tube. Back in the day these and similar though different variants such as the 4CX variants (Tetrode) tubes of many different power ratings would commonly find themselves in AM or FM or even TV station broadcasting use. There were also military and aviation applications for specific variants.

These days for maintenance reasons nearly everyone uses only solid state gear so old large tubes like these are becoming quite scarce. In practicality the only ones to use tubes in 2018 are guitarists and microwave ovens... (Yep, the humble Magnetron in a microwave oven is in fact a [ceramic] vacuum tube..!)

Those voltages scare the bejeezus out of me Marcel, but I love that those kinds of electronics exist, even if it means I can only admire from afar!

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Originally Posted by Sonic Mountain

Sounds like a cool project. I enjoy seeing your art stuff come up on Insta and FB.

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Thanks Sonic! I'm meant to be having this year off from exhibiting so I can finish our kitchen reno and a writing project I've been working on, but somehow I keep ending up with new projects almost by accident (this one started because I visited a guy repairing amps and he invited me to hang out in his workshop...)

Might have some lying around. ?any type in particular?

Quote:

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Originally Posted by Marcel

These days for maintenance reasons nearly everyone uses only solid state gear so old large tubes like these are becoming quite scarce. In practicality the only ones to use tubes in 2018 are guitarists and microwave ovens... (Yep, the humble Magnetron in a microwave oven is in fact a [ceramic] vacuum tube..!)

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Don't forget the Boat Anchor enthusiasts among the amateur radio ranks...

I think I've got a couple of old 6550s and ECC83s laying about: any good?

We also have an old weather radar bottle here, but that's my wifes', and as she used to use that particular radar, I'm pretty sure you won't get that one!! :-D