Remembrances of vacuum tube days

[mr__ed]

As a young teenager, I developed a love for electronics which became a lifelong love affair. In those days vacuum tubes were the norm and solid state devices such as transistors weren't in usage then. I built many projects using vacuum tubes as a hobbyist during my teen years, such as ham radio equipment, stereo amplifiers and tuners and various pieces of test equipment, all employing vacuum tubes. I obtained some of the early transistors' back then and tried to experiment with them, but quit trying to learn how they worked since I was so involved with tubes. Of course, my position changed in time. Many products we use today wouldn't be possible or feasible without the advent of solid state devices.

I also remember my first portable radio, which employed miniature vacuum tubes. I recall 2 batteries were necessary, a size D "A" battery, which supplied power to the tube filaments. and a much larger "B" battery, around 70 to 90 volts, which supplied power for the tube plates. The radio performed pretty well, AM & FM, as I recall. I also remember when most drug stores had do-it-yourself tube checkers available for the public. They're real dinosaurs now and nonexistent!

The older I get (now 76) the more I look back to the good ol' days of my youth! 🙂

[Gdetrailer]

mr. ed wrote:

BobsYourUncle wrote:

mr. ed wrote:


Tubes that aren't being used are impervious to extreme cold (or heat for that matter). I'm not sure about electrolytic capacitors, though. Perhaps the electrolyte substance inside could freeze at minus 30, but I can't say for sure. In time, through use, electrolytic capacitors can eventually dry out and need replacing. That jukebox sounds like it could be a valuable item. Too bad you can't store it in a warmer indoor location, but I don't think it really matters. Of course, there are mechanical devices inside (i.e., turntable motor, which shouldn't be affected, either). Any lubricating oil used on moving parts may thicken up somewhat, but return to normal when warmer temps arrive.

Thanks for that.
Didn't think the tubes would be affected, but I did wonder about the big caps.
It is a valuable item, and I was paying big bucks for heated inside storage. I was fed up with 151 bucks a month for heated storage, had to bring it home. I live in a very small townhouse and there is no room inside for it.

Since that Wurlitzer is dated from 1955, it's possible the electrolytic caps may be due for replacement anyway. But I would wait until you run it again. If the sound is good, without noticeable hum, you're probably good to go.

If it is valuable to you and it hasn't been played for some time I would recommend erroring on the side of caution when powering up.

You cannot physically view the electrical "condition" of those canned electrolytics, nor can you do that with the old wound paper and wax caps. Many times they will look perfectly fine but with age and sitting around they can become leaky or burnout/explode.

Something from the 1950s if it is all original caps would be better to fully recap with new ones before you have any decide to let go in some fashion.. The cans when they blow can blow hot tar everywhere making for one heck of a difficult mess to clean up. Tar filled cans may not like extreme temps swings and over time the tar will harden and crack allowing moisture to be drawn in..

The caps issue is one of the reasons I sold off my 1950s HK Award series A50 Stereo amps.. Hated to be the one cleaning that chassis and replacing the cans with new cans was not in the cards as they were out of production for years which meant digging tar out of the cans to put modern caps inside..

If it was inside a TV, I wouldn't have hesitated clipping the old caps out but the HKs were open chassis so you could see the cans on top of the chassis.. My friend if there is space often clips off the connections on the can then solders in modern caps in circuit on the underside, works if you have the space underside, if you don't have space, digging tar out is what you will be doing.

I would suggest powering up on your porch before sitting it on your carpet or hardwood floor..

Have a friend who buys/sells/trades antique radios, recapping is high on his list to do right after seeing if the tubes light up..

Some antique radio folks also suggest using a auto transformer to slowly power up the chassis in stages to reform the electrolytic caps slowly.

OP might wish to consult a local person who buys/sells/trades antique radios (Local HAM clubs might be a good source to find someone to help) to find out their take on it, they might just suggest trying it first or they may suggest recapping first..

[mr__ed]

BobsYourUncle wrote:

mr. ed wrote:


Tubes that aren't being used are impervious to extreme cold (or heat for that matter). I'm not sure about electrolytic capacitors, though. Perhaps the electrolyte substance inside could freeze at minus 30, but I can't say for sure. In time, through use, electrolytic capacitors can eventually dry out and need replacing. That jukebox sounds like it could be a valuable item. Too bad you can't store it in a warmer indoor location, but I don't think it really matters. Of course, there are mechanical devices inside (i.e., turntable motor, which shouldn't be affected, either). Any lubricating oil used on moving parts may thicken up somewhat, but return to normal when warmer temps arrive.

Thanks for that.
Didn't think the tubes would be affected, but I did wonder about the big caps.
It is a valuable item, and I was paying big bucks for heated inside storage. I was fed up with 151 bucks a month for heated storage, had to bring it home. I live in a very small townhouse and there is no room inside for it.

Since that Wurlitzer is dated from 1955, it's possible the electrolytic caps may be due for replacement anyway. But I would wait until you run it again. If the sound is good, without noticeable hum, you're probably good to go.

[BobsYourUncle]

mr. ed wrote:


Tubes that aren't being used are impervious to extreme cold (or heat for that matter). I'm not sure about electrolytic capacitors, though. Perhaps the electrolyte substance inside could freeze at minus 30, but I can't say for sure. In time, through use, electrolytic capacitors can eventually dry out and need replacing. That jukebox sounds like it could be a valuable item. Too bad you can't store it in a warmer indoor location, but I don't think it really matters. Of course, there are mechanical devices inside (i.e., turntable motor, which shouldn't be affected, either). Any lubricating oil used on moving parts may thicken up somewhat, but return to normal when warmer temps arrive.

Thanks for that.
Didn't think the tubes would be affected, but I did wonder about the big caps.
It is a valuable item, and I was paying big bucks for heated inside storage. I was fed up with 151 bucks a month for heated storage, had to bring it home. I live in a very small townhouse and there is no room inside for it.

[mr__ed]

BobsYourUncle wrote:
Since we are all reminiscing about our tube equipment days, I have a question to ask of a bunch of you who know way more than I do:

A few pages back I posted a picture of my 55 Wurlitzer jukebox. It has always been kept in a climate controlled storage location. I have only just recently, 2 weeks ago, brought it into the unheated garage at home for storage.

Alberta winters can be harsh and this jukebox will see minus 30 temperatures. I don't think it will hurt the tubes as long as I don't bump or jar them, but part of me wonders about it. There is nothing in them that will be harmed by freezing I don't think....

Tubes that aren't being used are impervious to extreme cold (or heat for that matter). I'm not sure about electrolytic capacitors, though. Perhaps the electrolyte substance inside could freeze at minus 30, but I can't say for sure. In time, through use, electrolytic capacitors can eventually dry out and need replacing. That jukebox sounds like it could be a valuable item. Too bad you can't store it in a warmer indoor location, but I don't think it really matters. Of course, there are mechanical devices inside (i.e., turntable motor, which shouldn't be affected, either). Any lubricating oil used on moving parts may thicken up somewhat, but return to normal when warmer temps arrive.

[BobsYourUncle]

Since we are all reminiscing about our tube equipment days, I have a question to ask of a bunch of you who know way more than I do:

A few pages back I posted a picture of my 55 Wurlitzer jukebox. It has always been kept in a climate controlled storage location. I have only just recently, 2 weeks ago, brought it into the unheated garage at home for storage.

Alberta winters can be harsh and this jukebox will see minus 30 temperatures. I don't think it will hurt the tubes as long as I don't bump or jar them, but part of me wonders about it. There is nothing in them that will be harmed by freezing I don't think....

[magicbus]

Learjet wrote:
I'm old enough to remember using one of these as a kid.

Old tube tester

And then we got our Motorola Quasar TV. Solid state “with a drawer you can pull out to replace parts”. Well, I was just a kid but the parts weren’t replaceable but the color TV was pretty cool.

Dave

[Learjet]

I'm old enough to remember using one of these as a kid.

Old tube tester

[mr__ed]

LScamper wrote:
The first checks done at low voltage about 10 kV. Don't remember what state things are in for the picturs (some 25 years ago). You can see two shorting hooks (JESUS sticks as someone called them in previous post) sitting on top of the amplifier. I'm sure there was hard shorts on all storage caps. When higher voltage the sides had covers on and the cables on the outside. As an aside these tubes were seasoned at 50kV plate votage for the 2.5 gigawatt amplifier string.

OK, now it makes sense. 50kv plate voltage? machines I worked on never went that high, maybe 20kv max, still enough to ruin your day if contacted!

[LScamper]

The first checks done at low voltage about 10 kV. Don't remember what state things are in for the picturs (some 25 years ago). You can see two shorting hooks (JESUS sticks as someone called them in previous post) sitting on top of the amplifier. I'm sure there was hard shorts on all storage caps. When higher voltage the sides had covers on and the cables on the outside. As an aside these tubes were seasoned at 50kV plate votage for the 2.5 gigawatt amplifier string.

[mr__ed]

LScamper wrote:
In the mid 90s helped with the design of a 200 megawatt two channel amplifier. It used 12 ML8618 water cooled magnetically beamed triodes.

Some of one bank of tubes.


Click For Full-Size Image.

Amplifier testing area.


Click For Full-Size Image.

At one time while working on Scyllac we had an amplifier chain of 100 ML8618 tubes for a total output power of 2.5 Gigawatt. filament power was 32 kilowatt.

Those wires are dangling mighty close to the tubes. They should have been routed more carefully, IMO.

[mr__ed]

MrWizard wrote:
Da*!#

Don't touch the wrong place, that's not a shock
That would be instant charcoal for any warm body that came into contact with it

Phase one create insane amount of power
Phase two attempt to channel it to the target point
Phase three interpret test results

Be sure to wet fingers first before testing for any stored voltage! :B

[mr__ed]

LScamper wrote:
In the mid 90s helped with the design of a 200 megawatt two channel amplifier. It used 12 ML8618 water cooled magnetically beamed triodes.

Some of one bank of tubes.


Click For Full-Size Image.

Amplifier testing area.


Click For Full-Size Image.

At one time while working on Scyllac we had an amplifier chain of 100 ML8618 tubes for a total output power of 2.5 Gigawatt. filament power was 32 kilowatt.

WOW, that’s some gnarly equipment! Get near 2.5 gigawatts of RF and you may start cooking your insides, unless the energy was well contained. I know from servicing dielectric sealers, even being too close to the output of even a 10kw machine coul cause your feet to heat up uncomfortably. I could hold a fluorescent lamp in my hand and amazed the machine operators when it lit up brightly when the machine fired. They thought it was some kind of magic. :E

[Thunder_Mountai]

Been watching this thread, but haven't had a chance to reply. We got our first TV in 1952 or '53 when I was three or four years old. My dad had a WWII friend who kept stuff flying and fighting. He transitioned to the new technology. I started watching him work on our televisions. One of the first things he did was look to see if the vacuum tubes were glowing.

When I was about ten or eleven our TV quit working. I took the back off the TV and looked around. I saw a tube that wasn't glowing. I pulled the tube and convinced my mother to take me to 7/11 which had one of those tube testers. Sure enough it was bad. The clerk pulled a replacement from the cabinet underneath.

When my dad got home from work the TV was working. He said to mother you called me at work and told me the TV wasn't working. Mother told him the story. After that thay gave me lots of things to fix.

I transitioned into computers in 1968... The rest is history. I still fix stuff that should be pitched.

[MrWizard]

Da*!#

Don't touch the wrong place, that's not a shock
That would be instant charcoal for any warm body that came into contact with it

Phase one create insane amount of power
Phase two attempt to channel it to the target point
Phase three interpret test results