old tubes, what to do?

[Duo]

Lol, I wouldn't worry too much about running out of tubes just yet.

I have radios with original tubes from the 30's and 40's and they still work just fine. My grundig console with el84 outputs has all of its original european tubes in it and I never turn it off. It sits there generating heat all year round (5 years now?) and hasn't changed noticeably. Sure it does get turned off once in a while, but mostly it stays on.

It is, however, very useful to have a collection of tubes. If you have room and a safe place for them, keep lots if you like them. I do this because I restore and use old radios and military equipment. Or basically anything that has tubes. It's really nice to be able to bring an old radio home and have the tubes for it right in my shelf.

[djQUAN]

from what I recall, heater failure is because of turning the unit on and off? thermal stress..........?

[Duo]

Yes, heaters fail because of thermal stress, also other connections inside the tube. The emitting surface of the cathode gets weak from current flow. Thus why cathodic emission is key in how well a tube works. Actually, it is how a tube works

[Mr. Triatic]

yep, save all tubes you can, you'll never know when you can use 'em!! i think i have approx. 300-350 tubes in stock, mostly military but all of them are surely useful sometime 8-)

[djQUAN]

350? I'd never know where I'd use all those if I ever had them. my dad wants a tube amp but I don't have any output transformers or sources for them so I went with the next best thing. the tube preamp.

basically, I've been into solid state all my life so this is something new to me. but I've had experience with high voltage.

I don't know where to get some tube sockets over here (gonna start looking for that) but I think it's fine to solder the tubes on the PCB? I'm going to use 12AU7, 9 pin miniature. I'm still gonna look for the sockets though.

[Duo]

Lol, 350 isn't that big of a collection really. I know people with thousands. Mine is ranging maybe 500ish?

[GlassAudio]

Try this link: http://www.tubesandmore.com
I am sure you will find what you need.

[djQUAN]

I can't find tube sockets over here so I soldered them to tha board.

one question though, the circuit needed 220uF 350V caps so I went looking for them. the local store had only 450V 220uF caps which cost Php80 (local currency, ~US$1.5)each and are too big for my PCB, then I looked around and saw 120uF 330V caps, bought these instead as they were Php60 for a pack of 5. they were supposed to be for photoflash applications. paralleled two so now I have 240uF 330V caps. these were for the PSU.

as far as I know, I see no problems with these?

[rcavictim]

Photoflash capacitors give you very high energy density by reducing internal insulation. They will not last if subjected to heat or ripple current (another way of saying heat).

It is always wise to obtain the parts first before committing to a PCB layout or chassis layout. Of course such is not possible when ordering a pre-made blank circuit board.

The French have a saying....bon chance.

[djQUAN]

heat is a possible problem since the caps are mounted about an inch away from the tubes. (I could move that if that's really a very big trouble) but ripple would never be a problem since the caps are the last stage in a CRCRC filter.