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 Post subject: 24 and 45 tubes in schematic different than datasheet
PostPosted: Nov Wed 29, 2017 7:16 am 
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Joined: Aug Fri 28, 2015 3:22 pm
Posts: 150
Hi all,

A bit of a newbie with the details of how tubes work, pardon the ignorance in advance.

I'm working on a radio, and figure a huge help in knowing what's what would be to know the tube pinout. Problem is, the schematic shows the tubes a lot differently than I'm used to with my 1940s models. I think I have this figured out, could someone confirm or correct me?

24:

Image

Based on this pinout:

Image

And the 45:

Image

Based on this pinout:

Image

I figure the filament is pretty obvious, and the 24s have 2 grids (one in a pin, one as a cap), and the 45 has no cathode. With those differences in mind, I took an educated guess at which symbol is for plate, grid(s), and to a lesser extent, cathode (since it doesn't exist on the 45, should be easy)

While I'm posting, I also thought I'd ask... it doesn't really matter which plate goes where on the rectifier (80), correct?


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 Post subject: Re: 24 and 45 tubes in schematic different than datasheet
PostPosted: Nov Wed 29, 2017 7:26 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 31406
Location: Maryland 20709, USA
On the schematic, the squiggly vertical line to the left is the grid.
It goes to the cap on the tube.

The plate on the schematic is the small rectangle with the line going to the coil to the right.

When in doubt, look at what other components are connected to which pin.

Signal flow in a schematic is usually from left to right.
So the grid circuit will be on the left, and the plate circuit will be on the right.

You have the plate and grid reversed on both the 24 and the 45.

- Leigh

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http://www.AtwaterKent.info
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 Post subject: Re: 24 and 45 tubes in schematic different than datasheet
PostPosted: Nov Wed 29, 2017 7:33 am 
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Joined: Aug Fri 28, 2015 3:22 pm
Posts: 150
Ok, I think I'm good on the 45 - just reverse plate and grid, easy.

But on the 24, there are two grids. If the squiggle is the cap, which is the other grid on pin #3?


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 Post subject: Re: 24 and 45 tubes in schematic different than datasheet
PostPosted: Nov Wed 29, 2017 7:43 am 
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Location: Maryland 20709, USA
spongebue wrote:
But on the 24, there are two grids. If the squiggle is the cap, which is the other grid on pin #3?
The "squiggle" is the signal grid, often called grid #1.

The screen grid, grid #2, is the U-shaped element that contains the plate rectangle.

Inside the tube, the screen grid is closer to the plate than the signal grid.

- Leigh

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73 de Leigh W3NLB
http://www.AtwaterKent.info
Click "Grebe Stuff" for Synchrophase info


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 Post subject: Re: 24 and 45 tubes in schematic different than datasheet
PostPosted: Nov Wed 29, 2017 7:53 am 
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Joined: Aug Fri 28, 2015 3:22 pm
Posts: 150
Gotcha. So... something like this?

Image


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 Post subject: Re: 24 and 45 tubes in schematic different than datasheet
PostPosted: Nov Wed 29, 2017 8:08 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Maryland 20709, USA
spongebue wrote:
Gotcha. So... something like this?
Correct.

- Leigh

_________________
73 de Leigh W3NLB
http://www.AtwaterKent.info
Click "Grebe Stuff" for Synchrophase info


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 Post subject: Re: 24 and 45 tubes in schematic different than datasheet
PostPosted: Nov Wed 29, 2017 8:14 am 
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Joined: Aug Fri 28, 2015 3:22 pm
Posts: 150
Awesome, thank you!


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