12AX7

EL-34
6L6
6550

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I love sanding.

Unless some really good solid-state replacement has been (or is) developed, TWTs (Traveling Wave Tube RF amplifiers) may power satellites and space probes for a long time to come. Speaking of tubes in another way:

There is a tradition that is rather analogous to building model ships in bottles--building solar-powered radios inside tubes! The circuits can be quite simple, one-transistor variants of crystal radio circuits, using a 1N34 diode or equivalent instead of a galena crystal & cat's whisker (the Radio Shack 150-in-1 Electronic Project Set manual has several good schematics for such radios), with a solar cell being used instead of a 3 volt battery power supply. The tube is mounted vertically on a wooden or plastic base, with an earphone jack (a crystal earphone is used) affixed to the base. The glass envelopes of many different tubes can be used; one particularly popular one is the 6LQ6. The radio can be turned off by laying a hat over the tube. :-)

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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
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NAR #54895 SR