What to do with Tubes?

[cubemike99]

So I was driving today and noticed that lying by the side of the road was an old TV that someone had thrown out. Knowing that TV's contain a plethora of salvageable goodies like HV diodes, a flyback, and numerous passives, I promptly claimed it as my own. Back at home, I realized that this is no modern throwaway set, but a beautiful Zenith manufactured decades ago when tubes were in their heyday. I managed to pluck 13 of them out of the TV and am now left wondering what could be done with them. I was initially planning to rip the sockets out of the TV and rig up a nice glowing display of them, but maybe they could be actually useful in some electronics? Do any of the following numbers ring any bells?

6EA8
3HA5
4BZ6
10GN8
8BA11
13Z10
10GK6
21HB5
17BE3
6GH8A
2BU2

Thank for the help.

[jh15]

Those are what is called a series string set.  The first number is the filament voltage, and they add up to the mains voltage plus sometimes a ballast resistor. I never thought about the tube voltages on a 220v Limey voltage though.

Usually the odd filament voltahe tubes, and tv-only tubes of the past are not too desirable. The 6gh8, is a very popular tube in all products, but I always joked they had about a 30 hour life, Kept a lot of repairmen (especially RCA) in business during the tube color days.

The 5u4 was the brakes and mufflers cash cow in the 50's.

[SeanB]

Keep those doorknob capacitors as well. There is a steel can inside with a valve buried in either oil or tar, the HT rectifier.

[Radio Tech]

In the 80's I took old TV's amd made audio amplifiers out of them. Mostly built on top a flat top chassis but the sound quality was to die for. I miss those days,

[vk3yedotcom]

I'd suggest try some low HT tube stuff - eg audio preamps, oscillators, regenerative receivers, novelty noise makers etc.

It varies but I've had success with a 12AU7 with 12v DC on both the filament and as HT.

You can use solid state component ratings and integrate it with low voltage gear as well easier. 

And no risk of shocks!

[cubemike99]

TV-only string series? Sound almost like the custom ASICs you find in a lot of stuff today  .

And keep the caps? I'm not sure I'll even take the thing apart. I've half a mind to frame the point to point work of art. I did find a rectifier tube, but it wasn't in oil nor tar; rather, it was just in a socket near the flyback with a lead connected to the nipple it has on its top.

Thanks for the great advice!

[cubemike99]

And a simple question: do the heater and plate have to share a common ground? Thanks

[c4757p]

And a simple question: do the heater and plate have to share a common ground? Thanks

Technically no, but you have to respect V_KH-max (cathode-heater maximum voltage).

[c4757p]

TV-only string series? Sound almost like the custom ASICs you find in a lot of stuff today  .

Yep. It's been going on for a long time. Thankfully, unlike ASICs, these are usually simple enough to be perverted to your intended purpose, even if it's not as easy as with a GP triode like 12AX/U7.

[free_electron]

find tubes of different length
suspend on rubberbands.
get two xylophone sticks..

tubes sound soooo good ( especially when hit by a hammer )

[N2IXK]

The 6EA8 or 6GH8 (a pentode and a triode in one envelope) would be good front end tubes for a basic audio amp. The pentode makes a good input voltage amplifier stage, with the triode used as a phase inverter/driver.  See the Dynaco Stereo 70 or MK3 schematics (all over the web) for typical implementations using the 7199 tube. Both types are dirt common, and cheap, unlike the 7199. I believe Heathkit used the 6EA8 in some of their amps, and the 6GH8 is used on many of the Dynaco upgrade boards.

The 2BU2 is the HV rectifier. A simple diode. Pretty useless these days.  Same for the 17BE3 damper tube.

The 21HB5 was the horizontal output tube. A chunky little beam power tube without the usual plate cap found on TV sweep tubes. Other than the oddball heater voltage, a perfectly usable tube for audio or RF power amp applications. Could also be used as a series pass regulator for a power supply.  6HB5 is the same tube, with a more useful 6.3V filament.

The 3HA5 was likely the RF amp tube from the tuner. A low power, high frequency triode.

The 13Z10 was the audio tube.  It contains a small beam power amplifier (audio output amp) and a somewhat less useful "gated beam FM discriminator" (Zenith loved these things), which was used as the FM sound detector stage.

10GK6 is a moderate power pentode, probably the video driver for the CRT or the vertical sweep amp.

10GN8 is a general purpose triode/pentode.

4BZ6 is a general purpose pentode, probably used as an IF amplifier.

8BA11 is a triode, as well as a weird dual-plate pentode. Probably used for the vertical oscillator and sync stages. Fairly useless.

[Excavatoree]

The 2BU2 is the HV rectifier. A simple diode. Pretty useless these days. 

Apply slightly more than the 2V nominal filament voltage, and if give a nice incandescent glow.  (albeit briefly)  Not a bad thing to do with a useless tube.

[ftransform]

x ray

[N2IXK]

The 2BU2 is a late-era tube, specifically designed to reduce X-ray emissions. It incorporates a heavily leaded glass envelope and other features towards this end.

If you want to play around with a homebrew X-ray source (and I wouldn't recommend it), you want one of the early HV rectifier or shunt regulator tubes from before the X-ray emission problem was fully understood.  Some folks actually do play around with this stuff:

http://www.belljar.net/xray.htm

[commongrounder]

I remember, as a kid, the TV repairman coming to our house and working on our TV with the back open and the HV rectifier tube unshielded!  He thrilled us kids by drawing big arcs off the anode cap with his screwdriver.  That poor guy must have gotten quite a cumulative dose of radiation over his career.