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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

Those Magnificent Television Tubes

I use mostly television tubes in my amps , like PCF802 in the RIAA preamplifier , and PCC88 and EF183 in the analog stage of the CD , and PCC85 , PCL82 and RFT PL36 in my Circlotron OTL tube amplifier , and I think PL36 is very good and stable tube and performs well too .
Here is some Photos .
 

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Thats it. Can't see who made yours. Mine are ITT branded RCA's.

UH OH, the price is rising already and I only have 2. OH well The 6L6GA isn't powerful enough for my tastes anyway. I have extracted 250 watts from a pair of REAL TV tubes!

Note the pinout is the same as the 6AV5, 6AU5, 6FW5. Dissipation is downrated to 15 watts in the tiny bottle, but I haven't actually tested that limit yet.

With other overstuffed tubes (the 6AQ5) there is a fine line between the max rating and a hole in the glass. Meaning, don't red plate a 6AQ5. Rge red comes in one tiny spot.....followed shortly by a depression in the glass.....then a hole!
 
Don't worry, there is still the 12GC6 for $2 at vacuumtubes.net (12DQ6 with a different pinout)
Then there is 21HB5 at $1.

OMG! I just looked at vaccumtubes.net and they have another super sale on!!
Long list with:
$0.75 each
$0.50 per 100
$0.35 per 500

A bunch of real scuzzo tubes on it, but some interesting ones.
 
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They list the 6BD5GT for $2.

Lets see $50 gets me 100 sweep tubes. If I wire them all together how many Jiggowatts will I get......Or would I just black out a city block when I flip the switch from the heater inrush current?

I am taking about 5000 tubes to Dayton for sale......maybe I can buy a few to play with????? The wife is out of town!

I got this wicked looking power transformer with taps for 375, 545 and 800 volts rated for 735 mA. I been dreaming up some really BIG guitar amps.......

I already have a bunch of 12GC6's and several other tasty sweep tubes.
 
The tubes could be free, but a bigger tube with fewer sockets could still be cheaper.......Using 12GC6 you can make a very nice tube amp with cheap output transformer.

The 12GC6 is a good sized octal tube. The other ones I have in mind are even BIGGER!

Recall that the TV vertical output amplifier needs linear valves

The 6SN7 was one of the first vertical sweep tubes. The 6BL7 and 6BX7 evolved from the 6SN7. The dual dissimilar triode came next, followed by the triode pentode combination like the 6LU8 or 6LR8. All make good audio amps. In fact the vertical output transformer from some TV sets work good as an audio OPT. The tube / transformer doesn't care if it is driving a deflecion yoke or a speaker. Most of the transformers are small enough to have good frequency response. You need one with 4 wires asince a few are autotransformers.

The horizontal (line) output tube operates as a switched CCS and was not designed with linearity in mind, however many work quite well as audio amps.

The video output tube is usually quite linear, has excellent gain into the VHF region, and also makes a good audio amp but are limited to 10 watts of dissipation and under. Some are good audio driver tubes like the venerable 12BY7.
 
Holy Cow! Any interesting tubes left?

I had been hesitant to mention a certain number since the Chinese had been buying them from ESRC by the 1000's. I discovered this gem when it hit the $1 lists over a year ago, but at 35 cents each I bought 500. It is the 6HA6/6HB6. This guy is a 6BQ5/EL84 with an odd pinout and twice the Gm. It can bang out 20 watts per pair in P-P without breaking a sweat. They can be seen here in one of Pete's red DRIVER boards putting out 7 watts in class A P-P. That will drive the grids right out of your favorite sweep tubes! Pin compatible with a 6EJ7, they plug right into Pete's board.

In the sweep tube department I grabbed 100 25DN6's. The specs show 15 watt plates, but the tubes say otherwise. I have extracted over 100 watts from a pair at the edge of glow. The plates of the RCA's and Sylvania's that I have in hand are about the same size as the 6HJ5's plates.

Speaking of 6HJ5's......I bought enough stuff to get a nice price on 100 of them. Expect some more BigWatt amps in the future. I will wire a few 6HJ5's together and see what happens.

I also got enough 50 cent tubes to make complete kits for the next Tubelab project board. It is amp 1.3 that was created in this thread:

http://www.diyaudio.com/forums/instruments-amps/190738-hundred-buck-amp-challenge.html

The picture shows the amp as it was last November. I still haven't finished the cabinet yet though. The schematic is still going through some changes. I have added a mosfet phase inverter so that the output tubes can run in class AB and crank out about 6 watts.
 

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Did the big dumb blonde one stop to think how much 1000 tubes would weigh? NOOOOOO. The UPS man deposited two very large and heavy boxes on my front porch while I was at work today. Total weight 68 pounds.

I couldn't say no to these guys at 50 cents each! The 6922 is just for size comparison......those were not on sale. Actually they were free......I pulled them out of a junk scope.

Now I just need to find the time to light a few up.
 

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Interesting, they sure look bigger than a typical 15 Watter. Will be interesting to see what your "stress test" will produce. Might check the filament current draw just to see if the later versions still pull as much current as the 1955 datasheet specs. The 1955 date on the Sylvania datasheet would likely be using an old high temp cathode, while the later tube types got lower temp cathodes. Maybe they upgraded these later too.
 
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