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 Post subject: 450TH Transmitting Triode - A few questions.
PostPosted: Jan Mon 15, 2018 11:07 pm 
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Joined: Sep Sun 10, 2017 6:29 pm
Posts: 6
I've found this beauty for a relatively low price, the guy who sold it still has a few of them in stock :D

It was apparently made in May of 1985 by the Brazilian tube manufacturer IVAPE - Indústria de Válvulas Eletrônicas Pecunha Ltda.

- There is a number inside the tube -- W410585 -- is this a date code?

- The filament seems to be hidden inside a small cylindrical cathode - Did Eimac ever make an indirectly heated version of the 450TH?

- And last question - Does the 450 (TH and TL) use tantalum plates like other Eimac tubes do?

Here are some photos of this little monster...

https://drive.google.com/open?id=1ywNwCXImp-MEBZxm2-os8CvOS9x9OHnDbQ

https://drive.google.com/open?id=1rw4uNXmewZ9ItRIcI2J_6-GrG0n0e4vSew


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 Post subject: Re: 450TH Transmitting Triode - A few questions.
PostPosted: Jan Mon 15, 2018 11:16 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 36523
Location: Livermore, CA
Tubes have a tantalum plate which operates red in use.

https://frank.pocnet.net/sheets/088/4/450TH.pdf

Never heard of an indirectly heater version of this tube. 450TH makes a nice display tube.

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 Post subject: Re: 450TH Transmitting Triode - A few questions.
PostPosted: Jan Tue 16, 2018 2:52 pm 
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Joined: Sep Sun 10, 2017 6:29 pm
Posts: 6
Norm Leal wrote:
Tubes have a tantalum plate which operates red in use.

https://frank.pocnet.net/sheets/088/4/450TH.pdf

Never heard of an indirectly heater version of this tube. 450TH makes a nice display tube.



Thank you for the quick reply.

This tube also came in its original foam packaging, with a big "Ivape" logo on it.
Unfortunately I had to throw the foam away because it was in really bad shape.

There are no burn marks on the tube's envelope and no scratches on the aluminum base from the socket.
This makes me think it's NOS.

Very cool.


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 Post subject: Re: 450TH Transmitting Triode - A few questions.
PostPosted: Jan Tue 16, 2018 6:18 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 22310
Location: Somers, CT
Take good care of it. Hams are still using them in vintage transmitters.

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Just because it can be done doesn't mean it should be done.


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 Post subject: Re: 450TH Transmitting Triode - A few questions.
PostPosted: Jan Tue 16, 2018 7:54 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1210
Location: Orlando, FL, USA
While early versions of the Eimac tubes do have tantalum plates, later ones have plates coated with a tantalum compound. The same compound is used to coat modern graphite plates, which is why they look gray instead of black.

Jim Cross


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 Post subject: Re: 450TH Transmitting Triode - A few questions.
PostPosted: Jan Sat 27, 2018 6:56 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1407
Location: Cambridge MN USA
Heater is a spiral around a center post; the cage around it is the grid. Tube is worth its weight in gold.

Scott Todd


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