Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Old June 2nd 19, 04:57 PM posted to sci.electronics.repair
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Default Another old-timer tube/valve question


Gentlemen,

What are the typical average/maximum operating temperatures of a full
wave rectifying tube/valve? Is it normal for them to become too hot to
touch after only a minute or two?
I'm talking specifically about the 5Y3GT in this context.




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Old June 2nd 19, 05:56 PM posted to sci.electronics.repair
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Default Another old-timer tube/valve question

On Sun, 2 Jun 2019 15:57:22 -0000 (UTC), Cursitor Doom
wrote:


Gentlemen,

What are the typical average/maximum operating temperatures of a full
wave rectifying tube/valve? Is it normal for them to become too hot to
touch after only a minute or two?
I'm talking specifically about the 5Y3GT in this context.


Vacuum Tubes (Valves) work by heating the cathode to "boil off"
electrons. The 5Y3 has a 5v filament that draws 2 Amps. So that's 10
watts even without any current flowing in the plate circuit. So, yes,
I would expect it to get hot quickly.
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Old June 2nd 19, 06:12 PM posted to sci.electronics.repair
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Default Another old-timer tube/valve question

Thanks, guys. They'd juxtaposed it with a VR150 which quickly reached a
similar temperature due to its proximity. I just thought that was a
rotten layout, but clearly it's not a concern in that case.



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Old June 2nd 19, 06:21 PM posted to sci.electronics.repair
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Default Another old-timer tube/valve question

In article ,
Cursitor Doom wrote:

Gentlemen,

What are the typical average/maximum operating temperatures of a full
wave rectifying tube/valve? Is it normal for them to become too hot to
touch after only a minute or two?
I'm talking specifically about the 5Y3GT in this context.


Voltage drop times current, filament (cathode) to plate, plus voltage
times current across filament. Never measured temperature, but energy
has to go somewhere. Gets hot, radiates.

Fred
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Old June 2nd 19, 06:25 PM posted to sci.electronics.repair
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Default Another old-timer tube/valve question

In article ,
Cursitor Doom wrote:

Thanks, guys. They'd juxtaposed it with a VR150 which quickly reached a
similar temperature due to its proximity. I just thought that was a
rotten layout, but clearly it's not a concern in that case.


Its not proximity. Voltage times current. Gets hot.

Fred


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Old June 2nd 19, 08:29 PM posted to sci.electronics.repair
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Default Another old-timer tube/valve question

On Sun, 02 Jun 2019 12:56:58 -0400, Pat
wrote:

On Sun, 2 Jun 2019 15:57:22 -0000 (UTC), Cursitor Doom
wrote:
What are the typical average/maximum operating temperatures of a full
wave rectifying tube/valve? Is it normal for them to become too hot to
touch after only a minute or two?
I'm talking specifically about the 5Y3GT in this context.


Vacuum Tubes (Valves) work by heating the cathode to "boil off"
electrons. The 5Y3 has a 5v filament that draws 2 Amps. So that's 10
watts even without any current flowing in the plate circuit. So, yes,
I would expect it to get hot quickly.


Ah yes, but you can get far more efficient Sovtek 5Y3GT tubes
(thermionic valves):
https://shop.ehx.com/item/5y3gt/tubes-vacuum-sovtek/
which features a filament that draws only 2mA +/- 0.2mA 5V or 10
milliwatts.

I like the description on the data sheet:
https://shop.ehx.com/catalog/addimages/5y3gt-sovtek.pdf
MINIATURE DOUBLE ANODE KENOTRON IN GLASS DESIGN
WITH OXIDE-COATED INDIRECTLY HEATED CATHODE INTENDED
FOR RECTIFICATION OF COMMERCIAL-FREQUENCY ALTERNATING
CURRENT.
That explains why one gets frequent commercials on TV sets that use
Sovtek 5Y3GT kenotrons.


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Old June 2nd 19, 10:40 PM posted to sci.electronics.repair
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Default Another old-timer tube/valve question

On 02.06.19 17:57, Cursitor Doom wrote:

Gentlemen,

What are the typical average/maximum operating temperatures of a full
wave rectifying tube/valve? Is it normal for them to become too hot to
touch after only a minute or two?
I'm talking specifically about the 5Y3GT in this context.




Draw a lot of current and you get a lot of heat.

Dont want the heat?
lower the current, or use bigger components and cooling.
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Old June 2nd 19, 10:48 PM posted to sci.electronics.repair
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Default Another old-timer tube/valve question

On Sun, 02 Jun 2019 13:21:58 -0400, Fred McKenzie wrote:

Voltage drop times current, filament (cathode) to plate, plus voltage
times current across filament. Never measured temperature, but energy
has to go somewhere. Gets hot, radiates.


Er, yes. That wasn't quite what I meant, but never mind. My fault for not
being clear enough having re-read it.




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Old June 3rd 19, 12:54 AM posted to sci.electronics.repair
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Default Another old-timer tube/valve question

On Sun, 02 Jun 2019 23:40:29 +0200, Sjouke Burry wrote:

Draw a lot of current and you get a lot of heat.

Dont want the heat?
lower the current, or use bigger components and cooling.


Thank you, Captain Obvious.
I can't see what was so misleading about the wording in my original
question that's causing some folks to misinterpret it.
Anyway, the first two respondents told me all I wanted to know so many
thanks to them and their excellent comprehension skills.




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