[Milsurplus] 3A5 Filament Voltage Question

[Bill Cromwell]

On 08/03/2013 09:20 PM, Al Klase wrote:
> 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
>
> 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.
>
> 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

Hi,

I'm a heathen and have been running my battery tubes on alkaline 
flashlight cells. So far no problems. I haven't bothered to measure the 
no-load terminal voltage of the 'dead' cells - sorry. If I remember to 
turn the gear off those cells last a long, long time. All of that is 
pretty much subjective but I can testify that 1.5621300671 volts will 
apparently not harm the tubes but maybe 1.5621300672 volts would make 
them explode.

I'm putting together a TX/RX set with them for portable use and I'll 
make it a point get more detailed data because I will need to know how 
many battrys to take on field trips.

73,

Bill  KU8H