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eimac 152TL and 304TL

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facelvega

facelvega

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Joined 2009
#1
Hi all,

I have a question for the Eimac tubes experts. I won auctions for 304TL tubes on e-Bay and received some of them with defective filaments. I mean one of the two filaments of the tubes is open and i was wondering if one could consider such half heated 304TL as a 152TL tube 😕

Thanks for your information.

Regards,
Facelvega
 
#3
facelvega said:
Hi all,

I have a question for the Eimac tubes experts. I won auctions for 304TL tubes on e-Bay and received some of them with defective filaments. I mean one of the two filaments of the tubes is open and i was wondering if one could consider such half heated 304TL as a 152TL tube 😕

Thanks for your information.

Regards,
Facelvega
Click to expand...

I never succeeded in running 304TL with half filament. Bad news is that most probably the other half will die shortly (well ... it happened to me twice).
 
#4
facelvega said:
Hi all,

I have a question for the Eimac tubes experts. I won auctions for 304TL tubes on e-Bay and received some of them with defective filaments. I mean one of the two filaments of the tubes is open and i was wondering if one could consider such half heated 304TL as a 152TL tube 😕
Click to expand...
Yes you can.

The 304TL has a fun background story. During the early part of WW-II, the US military needed a tube suitable as a pulse modulator for one of their radar systems (naval, I think...). Eitel & McCulloug, later Eimac, was tasked with developing a prototype (at all cost and preferably yesterday). They already had a triode design, which seemed appropriate, and it was sent in for evalution. It was called the 75TL. Unfortunately it wasn't powerful enough, so E&M put two 75TLs in one bottle and called it a 152TL.

Still not quite big enough, they doubled it again to a 304TL. And the man was pleased. 😀

Gluca said:
I never succeeded in running 304TL with half filament. Bad news is that most probably the other half will die shortly (well ... it happened to me twice).
Click to expand...

Have never tried that, but wondering what heating arrangement you used? If you use 10V filament power, then you will overload the surviving half of the series/parallel filaments in short order for sure.

If only one filament is broken, then running half the tube at 5V should work, unless having the first filament break might mean the remaining 3 has been overloaded somehow.
 
#5
Hi guys,

Thanks a lot for your feedback 😉

Sure i could return the items to the e-bay sellers and try to get money back but i thought i could have some fun running the 304TL as 152TL...

I will let you informed soon after i try :xfingers:

Facelvega
 
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