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Another great site...Charles MacDonald's Electronic tube page
I came across this while trying to learn a bit about TV Damper Diodes - And it looks like a good list of what "NOT TO SEEK OUT/PURCHASE/COLLECT FOR FUTURE USE/ETC WHILE ON EBAY OR OTHERWISE"
ARE THERE ANY REALLY USELESS TUBES?
While some would say that usefulness is in the eye of the beholder, the tubes that were created to act as shunt regulators in tube type colour TV sets have got to be the least useful of all tubes. (outside of retoring an old Colour TV of course.) These are high power triodes, that act as a variable load on the high-voltage section of a TV set. Failure would result in excessive high-voltage, and many were recalled because they were a prolific source of X-rays. Long before the end of the tube era, Colour TV designers switched to other regulator circuts. Because they were intended to work at a very high voltage, they are not useful at normal voltages. I am amazed the number of times that I see someone listing one of these on a auction site as a rare high-power triode audio tube. Some typical numbers:
6BK4 6BD4 6BU4 6EF4
6LC6 6BK4 6EH4 6EJ4
6EL4 6EN4 6LH6 6LJ6
6MA6 6EA4I guess this list isn't really all that extensive. In any event, I think it's good to know...
In other words, if there really are USELESS Tubes, why hang onto them (unless you're gonna get into rebuilding TV sets and stuff)?
- Brian
Follow Ups:
I do have lot of "useless" tubes. At least I have no use for them. Anyone interested I'll send 'em a list.- SJ
thanks for the offer. you can get me through the Asylum. Perhaps a trade can be arranged, include 'wants' if possible.
regards,
Douglas
Brian,I suppose I'm learning from the responses that everyone with more than a few tubes ends up with odd ones. I've never found a guide that lists tubes by the equipment that use it- someone bored with actuarial tables might consder creating such a list as their contribution to mankind.
But, to show my solidarity with those with piles of beautiful NOS tubes that they can't discover a use for:
1- 12 BE6 Zenith NOS
1- 35W4 GE NOS
2- 5879 RCA NOS
1- OC3 RCA
1- 6953 RCA
1- 1B3GT Sylvania
1- 19T8 Sylvania
1- Amperex 7AU7-NOS
2- Amperex/Mullard 0G3-USEDAnd the infamous:23- 6AL5's
2- GE JAN- NOS
20- Rogers/Mullard, Sylvania, GE, RCA, etc-NOS
1- Telefunken- EAA91- NOSI also bought some tubes on the chance I might use them somday- and these are of course almost as useless:
EF86: 7
5- Valvo NOS
1- Lorenz- USED
1- Siemens- USEDThe EF86s were in case I used an EF86 based board to upgrade my ST70, but that eventuality is unlikely. Still, I have the tubes!
Line Array Nut mentioned having a "shoebox full" of 6AL5s. I do too and have no excuse. I bought my pile of 23 based simply on someone telling me that I needed these no longer produced tubes for my Scott 330D tuner. As the tuner was packed away, I just jumped in and got a good selection. And here I bought for $25 a big pile of these including NOS Mullards and a Telefunken premium version! I have more Mullard 6AL5s than any other Mullard type. Sad really- why couldn't those be 10M 12AX7s?
But take heart! I think the 6AL5 is really used in at least one Scott tuner!
I think some of the odd tubes in the top list were typically TV tubes. and I see that an OC3 is some kind of regulator tube worth up to $4, but the 6953 is an unknown in the tube database I use!
http://tdsl.duncanamps.com/tubesearch.php
I think it was Chris Garrett who wisely uses otherwise useless tubes as Christmas tree ornaments.
Anyone need a 6AL5?
Cheers,
Bambi B
You can sell these on Audiogon or ebay.
> > Anyone need a 6AL5? < <You might need 'em. :~)) Scratch build a Foreplay style preamp with a hybrid bridge rectifier in the B+ supply. The 6AL5 is suitable for that application.
BTW, the 6AL5 is CLASSIC as a ratio detector in FM tuners.
Eli D.
I found this link a few months back, or one very similar to it. It is not chock full o' info, but a decent guide nonetheless. However, it appears to be missing some tube types mentioned in these threads.Last year, I bought a box full of tubes at an antique store for $5. It had 5 GE 8950's that are used for ham radios inside. Two were unused, 3 used, and I made a mighty healthy profit off of them. But I am stuck with a bunch of tubes with TV applications, and unsure if I will ever find a home for them. Time will tell, I guess...
Just must say, don't hit the 6AL5 as we had approx. 5000pcs in stock and we sold the entire lot to some nutter.Nicolas
I always thought a quad of 6BK4s could make a neat direct coupled PP electrostatic tweeter amp.
Brian, it's interesting question that you pose here. It's interesting to me at least since I just came in possession of some 6BK4 tubes when I won an ebay auction for a tube caddy. I have a quad of these. If anyone wants them, they can have 'em for the postage. Some times I see them listed on ebay but no one ever places a bid on them.There has to be some sort of cool tube fun that we can figure out to do with these otherwise good for nothing tubes. The ones that I have are NOS.
Ron
Well, there was a time, not so long ago when a few dealers were paying $15 each for NOS 6BK4C/6EL4A tubes. That's far better than worthless IMO. Never did find out what the demand was for them, but it is over for the time being...
regards,
Douglas
Douglas -Apparently they were being used in some xray lithography/IC manufacturing equipment.
nice to know how they wee being used. Always nice to see some dirt cheap, useless-for-audio tube get nutsy priced when I have access to stocks of them...
thanks Gary.
Douglas
I'm convinced, theres a gremlin that tosses a few 1B3's and 6AL5's into every box of tubes just before I look inside.I'm starting to wonder if 1B3's would make a good fuse...
- Gary
nothing to see here, move along :-)
or a square foot of the tubes would make a cool looking PS rectifier section. Maybe for a low voltage, high current thing, a low power 6C41C PP amp with about a hundred 6AL5's on each phase.BTW, heard a triode strapped 6AK5 used as a gain stage and thought it pretty nice. The little pentodes are probably good as multigrids too.
regards,
Douglas
Hello Douglas,a nice little valve - used triode-strapped or as pentode. I like it.
It was used in some German studio gear as well, f. i. in the V72a...
Best regards,
---mb---
======
815. I have mint pairs from 1947 and no one wants them at all.
.
Ya mean like this one?How much ya want?
How many have you got?
I think I've seen `em used somewhere - and they're so darned cool!!
Another futuristic robot tube from the RCA 800-Series;-)
RBP,Please contact me offline about those 815's - that is, if you were up
for some sort of trade or wanted to sell 'em or whatever...
I wouldn't mind having some of those in my (evergrowing) collection of Tubes [and now - Capacitors, Transformers, Resistors, Chokes, Regulators, etc.]:-D I love this stuff!!!
Thanks!
- Brian
I have some of those too if anyone wants any. yes, very cool looking. Sort of like 2 x 6L6 in same bottle, I think. (?) Gary K. knows more about that...-Ed
Hey Ed (and RBP?),Please contact me offline if you wanna make some sort of deal. I'm into DIY, so this tube seems like it could be a lot of fun - for something... I suppose anything/circuit that would use a pair of 6L6 type (variant) tubes? I can be pretty determined to make a tube work if there's any hope for audio! I can't wait to get those 829B's running:-D
Thanks!
- Brian
Being somewhat simular to a 12AX7, I wounder what that tube would be like with all four plates & the two grids tied together? Wild guitar amp tube?
Do you know about the 7X7?It's a loctal Twin Diode Triode... The Triode Section seems to spec out similarly to a 12AX7!! Have you seen these before? I got a pair thrown in with a bunch of 7N7 Loctals. They're kind of neat;-D
Right?
- Brian
http://www.mif.pg.gda.pl/homepages/frank/sheets/049/7/7X7.pdf
Personal opinion 6SN7 as a driver
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