Hi Jim,
That tube employs a DIRECTLY heated filament.
Two good reasons for low voltage in this case:
High voltage operation would require thin elements that would be
mechanically fragile.
Current distribution would be way whack with the potential differences in a
high voltage setup and induce lots of hum.
73 & Good morning,
Marv WC6W
http://qsl.net/wc6w/
--------------------------------------------
On Tue, 4/22/14, Jim Garland <4cx250b@miamioh.edu> wrote:
Subject: [Amps] Filament Voltage Question
To: amps@contesting.com
Date: Tuesday, April 22, 2014, 8:19 AM
I was reading the data sheet this
morning on the 4CX3500A and noticed the
filament requirements are 5V@90Amps. It occurred to me
that I've never
understood why so many tubes with indirectly heated cathodes
have such
low-voltage - high current filaments. Since the only thing
the filament is
used for is to heat the cathode, then why not design it to
run at, e.g.,
115V@4A? That sure would be a lot easier to implement. I'm
sure there's a
reason, howevrr, and would appreciate somebody informing of
it!
73,
Jim W8ZR
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|