[Milsurplus] 3A5 Filament Voltage Question

[J. Forster]

> Hi John,
>
> I fail to see that 1.4 is defined as the maximum filament voltage,
> rather 1.4 is the voltage at which the typical characteristics are
> measured.
> See: RCA HB3 page here:
> http://www.mif.pg.gda.pl/homepages/frank/sheets/049/3/3A5.pdf

Oops. My transistor education is showing. The first thing on a data sheet
is usually absolute max.

> I've always assumed that 1.4 is the nominal filament voltage, and that
> 1.5 or maybe even 1.6 is not a reliability problem.  I also assume that
> you should get reasonable performance down to about 1 volts, the so
> called "end point" where the battery has delivered 80+ percent of it's
> available energy.

OK. If so, I'll try about 1.2. I just want to see the operating frequency
and a couple of other things.

> Here's another situation where I'd really like to see the original RCA
> applications notes that must have existed in one form or another. when
> these tubes were introduced to the market.
>
> Regards,
> Al

They must be archived somewhere.

Best,

-John

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