[928GTS]

I've had some work with subminiature tubes such as the CK series of tubes produced by Raytheon and I wonder if 2 or 4 of those could have enough amplification. In order to power those you'd need either 22.5 or 45V which can be supplied from specialty batteries that are available at a store called BatteryMart. If you google the name you'll find it,they're rather small batteries but they'll power those subminis for quite some time. The batteries aren't horrendously cheap at perhaps 3-5$ a unit but you'd probably only need 1 of those and a 1.5V AA battery to power the filaments.

If someone makes one and its not insanely expensive I'd be sure to save my pennies for it.

 

[sacd lover]

Quote:

Originally Posted by 928GTS /img/forum/go_quote.gif I've had some work with subminiature tubes such as the CK series of tubes produced by Raytheon and I wonder if 2 or 4 of those could have enough amplification. In order to power those you'd need either 22.5 or 45V which can be supplied from specialty batteries that are available at a store called BatteryMart. If you google the name you'll find it,they're rather small batteries but they'll power those subminis for quite some time. The batteries aren't horrendously cheap at perhaps 3-5$ a unit but you'd probably only need 1 of those and a 1.5V AA battery to power the filaments. If someone makes one and its not insanely expensive I'd be sure to save my pennies for it.

Smart man .... subminatures.

When the tube industry was in the last days they made one last attempt to compete with solid state. The result was a number of extremely small, low voltage, low power consumption, low noise, non-microphonic tubes with .... get this .... up to 100,000 hour lifespans. These tubes were called subminatures or"pencil tubes". Several of these tubes can run off batteries as 928GTS stated and many of these tubes do not even use tube sockets. You solder the tubes to a board just like with a solid state device.

Listening three hours a day, 365 days a year .... these tubes would last 90 years!

http://home.netcom.com/~wa2ise/radios/penciltubes.html

 

[928GTS]

Quote:

Originally Posted by sacd lover /img/forum/go_quote.gif Smart man .... subminatures. When the tube industry was in the last days they made one last attempt to compete with solid state. The result was a number of extremely small, low voltage, low power consumption, low noise, non-microphonic tubes with .... get this .... up to 100,000 hour lifespans. these tubes were called subminatures or"pencil tubes". Several of these tubes can run off batteries as 928GTS stated and many of these tubes do not even use tube sockets. You solder the tubes to a board just like with a solid state device. Listening three hours a day, 365 days a year .... these tubes would last 90 years! http://home.netcom.com/~wa2ise/radios/penciltubes.html

I do a lot of work with radios and I've been building a subminature tube powered AM radio that fits in a pocket and I've been using plans scanned from a hobby magazine from the 1950's and they did indeed have sockets available for these tubes but it seems like the supplies of such sockets have dried up as I can't find these buggers anywhere. What I think might be a viable solution is to find a really small contact strip that uses those screw down connectors where you stick the wire in and you turn the screw on top to secure the conductor down tight onto the wire of the tube. So all you'd need to do to replace tubes would be to unscrew each connector,slide out the old tube,trim the new tube's leads to an appropriate size and then install it. The only problem would be to find a contact strip like this in a small enough size..

 

[jamato8]

Quote:

Originally Posted by 928GTS /img/forum/go_quote.gif I do a lot of work with radios and I've been building a subminature tube powered AM radio that fits in a pocket and I've been using plans scanned from a hobby magazine from the 1950's and they did indeed have sockets available for these tubes but it seems like the supplies of such sockets have dried up as I can't find these buggers anywhere. What I think might be a viable solution is to find a really small contact strip that uses those screw down connectors where you stick the wire in and you turn the screw on top to secure the conductor down tight onto the wire of the tube. So all you'd need to do to replace tubes would be to unscrew each connector,slide out the old tube,trim the new tube's leads to an appropriate size and then install it. The only problem would be to find a contact strip like this in a small enough size..

The tube is small enough that you can use a socket like is used for a chip on a board. I have seen this done and it enables you to remove the tube with no screws and no soldering. There were different manufactures of the tubes so you have to be able to tube roll. :^)

 

[phergus_25]

http://search.ebay.com/search/search...&fsop=1&fsoo=1

 

[sacd lover]

Quote:

Originally Posted by 928GTS /img/forum/go_quote.gif I do a lot of work with radios and I've been building a subminature tube powered AM radio that fits in a pocket and I've been using plans scanned from a hobby magazine from the 1950's and they did indeed have sockets available for these tubes but it seems like the supplies of such sockets have dried up as I can't find these buggers anywhere. What I think might be a viable solution is to find a really small contact strip that uses those screw down connectors where you stick the wire in and you turn the screw on top to secure the conductor down tight onto the wire of the tube. So all you'd need to do to replace tubes would be to unscrew each connector,slide out the old tube,trim the new tube's leads to an appropriate size and then install it. The only problem would be to find a contact strip like this in a small enough size..

You are correct, there were tube sockets for these "pencil tubes". But, as you stated, you cant find any. With 100,000 hour lifespans you wont need to change tubes anyway. In a portable I tend to think I would want such a tube secured directly to the board for the best reliability. I also doubt a manufacturer is going to go to exteme lenghts to make the tubes removeable when they virtually last forever. Moreover, I doubt a tube in such an amp would be exposed as this would definitely compromise portability .... the main purpose of such an amp.

 

[928GTS]

Quote:

Originally Posted by sacd lover /img/forum/go_quote.gif You are correct, there were tube sockets for these "pencil tubes". But, as you stated, you cant find any. With 100,000 hour lifespans you wont need to change tubes anyway. In a portable I tend to think I would want such a tube secured directly to the board for the best reliability. I also doubt a manufacturer is going to go to exteme lenghts to make the tubes removeable when they virtually last forever. Moreover, I doubt a tube in such an amp would be exposed as this would definitely compromise portability .... the main purpose of such an amp.

Yeah the only thing that you can really do to kill them is mix up the filament and plate battery connectors(just label them well)or by installing the wrong battery(i.e too much voltage)but with the latter they can generally take a fair amount of abuse before they go.

 

[phergus_25]

I think that if we get a schematic up then this would be pretty awosme. Now would one of these tubes be used as power tube and an identical as voice or what?
-greg

 

[sacd lover]

Quote:

Originally Posted by phergus_25 /img/forum/go_quote.gif I think that if we get a schematic up then this would be pretty awosme. Now would one of these tubes be used as power tube and an identical as voice or what? -greg

There are so many different types of these you could do the circuit in a number of ways. So given I haven't researched these much .... I dont know .... yet.

 

[phergus_25]

Quote:

Originally Posted by sacd lover /img/forum/go_quote.gif There are so many different types of these you could do the circuit in a number of ways. So .... given I haven't researched these much I dont know .... yet.

O great tube archeologist.. get to work.

Ps- I made the list!

 

[sacd lover]

Quote:

Originally Posted by phergus_25 /img/forum/go_quote.gif Ps- I made the list!

Yes indeed.

 

[jamato8]

The 6111 and 6112 (dual triodes) have a filament draw of 300ma's at 6.3 volts. They are equivalent or close to a 12AU7, 6SN7 (around 20) and a 5751 (70) in gain. One 6111 with a buffered output would be interesting.

 

[Sovkiller]

Have you ever think if one of those amps for any reason hit the floor while jogging or running in the park???...

 

[928GTS]

Quote:

Originally Posted by Sovkiller /img/forum/go_quote.gif Have you ever think if one of those amps for any reason hit the floor while jogging or running in the park???...

As I said before I think it'd be more plausible if these were portable in the sense that you could carry them in a pocket/bookbag/something small and then listen to it when you're in a slightly more stationary position.

 

[jamato8]

Quote:

Originally Posted by Sovkiller /img/forum/go_quote.gif Have you ever think if one of those amps for any reason hit the floor while jogging or running in the park???...

Have you looked at the specs? They could probably take it more than some solid-state devices. The G force they are tested at, vibration and impact are way above most anything normal on earth.