Anyone know about vacuum tubes?

[LonesomeLamp]

Today, my dad brought in a small box someone gave or lent him that was full of vacuum tubes. It appears that most of them are for tv applications,  but that’s irrelevant. I decided that this presented a great opportunity for me to learn about these tubes. So far, I’ve learned a little bit about them: heater, plate, grid, cathode. However, that’s about all I was able to find, other than a few circuits that other people have designed. I’m wanting to build my own crude circuit, but I can’t find the info I need to do so.

 

for example, I’m looking at the data sheet for the 6hm5/6ha5. It isn’t laid out in the most..clear way. I’ve found the heater pins and connected a 6v supply and it started glowing. The data sheet has a “plate supply voltage” and a “plate voltage,” but idk what the difference is. The data sheet also shows a negative bias voltage for the grid, but it doesn’t say what the voltage is relative to. It also lists maximum ratings and typical operating values, but no minimums.

If anyone can assist me in getting this figured out, it would be greatly appreciated.

Data sheet

 

*edit*

I think I found a good source (still reading it). It states that the voltages are relative to cathode

[Little BabyDoll Christine]

That would be like trying to buikd and use a Model T or a buggy whip. The only place of note that tubes would be used is in audio to madify or "saturate" the sound Otherwise they MAY be used in exotic circuitry or novelty items to demonstrate, like the new record players, "a fool and his money are soon parted". But if you like the novelty of old electronics, then Techmoan  Is for you. Why should I get a TRS-80 Mod I Level II because I want to relive the days of my early BASIC training when I can get an emulator that looks and does the sam

The only thing I can say is to look to see what kind of tube they are individually Tubes had an alphanumeric designation like 6L6 or AX-7. You will have to do this individdually for each tube then google up that designation. I have no idea where you would find a course in tube electronics that explain things like bias. Maybe next to one on alchemy. I was  around when tubes were in their heyday and not for nuthin' did we abandon them the first chance we had. Tube TV's, with CRT's routinely cost in excess of $500, weighed a ton and needed huge antennae to get any stations worth a ticks tiara. "Portable TV" meant you only get one hernia instead of two to move them. Would you drive around in a '55 Ford. No; if it was a restoration job, you would not want to take it out and  risk ruining $15,000 worth of work at the hands of some coked up early  twentysomething who was sexting his partner

[mick_dl]

just ask google... The 6AH5 is a VHF triode tube that was used in TV sets, maybe more "clear" specs + characteristic can be found here:

https://tubedata.jp/sheets/135/6/6HA5.pdf

I'm not shure what you wont to do with it, but the spec's show the max/usefull ratings for the mentioned purpose (VHF amp). This does't mean that they are useful for for your application. I don't think that anyone would use such a tube as VHF preamp in a tuner anymore - there are much better solutions, but maybe you can use it as an audio preamp to produce nice overtones. In this case it's a good idea to operate the tube with higher voltage and lower current in the saturation area with a very low degeneration.

And - dont't trust the "Standard" circuits you will find... I remember may first try to modify an old guitar amp - I did the calculations as I had learned it - and what I learned was to optimise the circuit for low distortion and dynamics. After setting up all the stuff it sound like shit. This was the moment where I had learned that guitar amps have there own physic and you have to throw away every thing that you learned about "standard tube circuits" before ?

Oh - and btw - tubes are still partly used for RF Applications - but then watercooled in the 50KW+ range in large radio and TV transmitter sides, but this is something complete different - also with it's own physics :-)...      

[foreverdl]

5 hours ago, LonesomeLamp said:

Today, my dad brought in a small box someone gave or lent him that was full of vacuum tubes. It appears that most of them are for tv applications,  but that’s irrelevant. I decided that this presented a great opportunity for me to learn about these tubes. So far, I’ve learned a little bit about them: heater, plate, grid, cathode. However, that’s about all I was able to find, other than a few circuits that other people have designed. I’m wanting to build my own crude circuit, but I can’t find the info I need to do so.

 

for example, I’m looking at the data sheet for the 6hm5/6ha5. It isn’t laid out in the most..clear way. I’ve found the heater pins and connected a 6v supply and it started glowing. The data sheet has a “plate supply voltage” and a “plate voltage,” but idk what the difference is. The data sheet also shows a negative bias voltage for the grid, but it doesn’t say what the voltage is relative to. It also lists maximum ratings and typical operating values, but no minimums.

If anyone can assist me in getting this figured out, it would be greatly appreciated.

Data sheet

 

*edit*

I think I found a good source (still reading it). It states that the voltages are relative to cathode

I would say look at estate sales, look for books on eBay, I still have some of my old 1970 manuals. I still have 4-5 hundred TV tubes,  A good one to look for on eBay,,,RCA Receiving tube Manual, is the name of the book.RC-30 is the part #. This book sold or $3 back when I got it. I was a TV repairman back in the late 70's, 80's. I was I guess the only one on this site, That liked them. If Someone had problems getting good reception on an old tube TV, it was more than likely the fault of the repairman . When I fixed a TV, what ever the size, a stereo, table top or Console Radio, It was better than new, because the quality of the resistors capacitors etc from the 50's 60's etc, was not good . I would rebuild the item I worked on To work like or better than new.  I tested them down to each component and if any doubt I replaced them. I would replace all of the wax capacitors just because I didn't like them. But I had a very goo teacher and we restored the old old radios back to in my opinion better than new. But you paid a lot for my work. You get what you ay for. Now there were those customers that wanted it back not repaired,,, Just make it work, I would do it, But with a much shorter and much less of a warranty. I only warranted the part I replaced on that type of customer. 

I do agree with Little Christine, about you finding any kind of class on tubes. Just look on web sites for old books and old classroom books GE put out a book in 1971, I still have it, I have seen it on eBay, Electronics Experimenters Circuit Manual it's a cool little book, to make old time projects, some tube and some solid state. It also has some of the basic text book information on circuits. If you want to build the kits for fun, these are 2 good books That I would recommend . And a note, think of the Bias kind of like a volume control, if you will. That's not going to give you everything by any chance, I do like to see a younger person that's interested in the nostalgia of the old tubes. I still have a half a dozen tube items, TV, radio etc. I don't use them anymore because of cost of electricity It friggen goes up every 3 months.

I may end up selling off some or a lot of my old tube radios etc. My hands don't work like they used to. I really wanted to retire, (Not medically) and take over a shop that was in Cambria Ca, That guy had a house full of radios, he made them completely New, and sold a radio for $8-900. And he had fun doing it. He was nice enough to let me see his home shop ,, this was I think 10 yrs ago, he's probably not alive anymore. He even had a Walton radio. That's just cool stuff.

[dressupDV]

I know alot about vauum tubes.  hit me up!

 

[foreverdl]

1 hour ago, dressupDV said:

I know alot about vauum tubes.  hit me up!

 

Hey, I didn't know you were old enough to work with tubes?, I thought just the old foggies like me and older, were alive way back then.

[dressupDV]

I am old enough! we're actually close in age

 

[LonesomeLamp]

On 10/21/2020 at 2:30 PM, dressupDV said:

I know alot about vauum tubes.  hit me up!

 

I tried yesterday but the system told me that you are unable to receive messages.

 

I’m trying to come up with a power supply capable of about 300 volts for the project. I found a transformer with multiple windings (well, I salvaged it many years ago) but I couldn’t find any information about it online. Today, I finally got around to probing it and found what appears to be the 120v mains input. I assume the other input (primary side) is for 240v. The secondary side has 3 windings. Anyway, I connected mains to the winding (through a switch) to what I assumed was for that input and took voltage measurements across all other windings, including the second one on the primary side.

 

 I did some math and concluded that if I put the 120v across the entire second winding on primary side (it has a center tap), I would get about 282v on the first primary winding. I rewired it to test that. When I turned it on, the transformer started buzzing and I immediately turned it off and noticed my bedroom light had dimmed for a brief moment (while transformer was on).

[Evelyn Dellcerro]

Take it from an old hammy and amateur radio operator, I followed in my fathers footsteps. I still have my fathers old tube amps and transmitters and use them quite often. There are many places that do still manufacture them for amplifier applications. Check some of your classic DX radio shops and classic tube transmitter shops. There are still many around.