On Feb 12, 9:46*pm, "Phil Allison" wrote:
"Circuitsmith"
" Phil Allison"
"Circuitsmith"
" The 12X4 rectifier delivers a nominal output of 510VDC.
Unfortunately the rectifier filament is not on a separate
transformer winding, so the heater-cathode voltage is also 510V, far
in excess of the 100V average 400V peak max rating listed in my RCA
tube manual for the 12X4. This is one oversight in an otherwise
conservative design. "
** The heater-cathode rating for a 6X4 or 12X4 is 450 volts - long as the
heater is negative with respect to the cathode.
They are designed for circuits where there is no independent ( ie
floating)
heater supply.
http://tubedata.itchurch.org/sheets/137/6/6X4.pdf
The 100 volt figure applies only when the heater is positive wrt to the
cathode.
So the RCA and Sylvania specs disagree on this matter.
** No they do *NOT *!!!
YOU are persistently misreading the data.
The "RCA Receiving Tube Manual" *has the figure of *" -450 *" volts measured
from heater to cathode.
The positive figures are for the opposite heater-cathode polarity
http://208.190.133.201/tubes/rc25/818b.gif
It's still operating beyond the Sylvania spec.
** Only by a small percentage and clearly well able to do so.
.... * Phil
It says"PEAK value -450 max".
What part of "average value 100 max" do you not understand??
Over is over, and certainly NOT conservative in my book.
Tim Brown