Re: Regulation for Filament Voltage on 833A Tubes

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <Tesla729-at-cs-dot-com>

In a message dated 5/21/03 4:22:20 PM Pacific Daylight Time, 
tesla-at-pupman-dot-com writes:
>OH NO!
>
>If i were you, i would do what i did ;)  I opened up the filament
>transformer that i had and removed enough secondary turns to get my voltage
>at 10.2V when my house voltage is 130v (sometimes my house is up to 140V!!!
>and sometimes at 120v, its goofy around here).  But at 120V from a variac,
>my transformer makes exactly 10.00V.


Hi Steve, Captain,

First of all, I think Captain has already determined that the no-load
voltage output of a transformer is always going to be a little higher
than the rated loaded output. It's just like when the water pressure
(which is equivalent to the voltage pressure of electricity) of your
shower head drops when someone flushes the toilet! If the water
lines are physically larger then they can carry more water flow just
like a larger thicker conductor can carry more current.

In regards to Steve's unstable line mains voltages, this may also be
due in part to the above mentioned phenomena. I had noticed at the
house that I had lived in before my last move that the measured
line voltage would often drop when a heavy current appliance was
turned on. The cables between the pole and my house were only
like # 6 and the main fuse for my 50 year old house was a mere
60 amps. At my hew house (built last year) the wires from the
pad mount 50 kVA transformer across the street that lead to my
200 amp breaker box are like #00. I don't notice near as much
variation in the measured line voltage here at the new house.
Firing my big x-ray tranny powered Jacob's ladder at the old
house would cause all of the lights in the house to flicker but
I do not have that problem here at the new house :^)

David Rieben