[HAM] DC filtering to the heater filament voltage of the AO28

[Kon Zissis]

Hi Keith.
Thank you for clarifying this.
If I remember correctly , the RCA Receiving Tube manual specifications
say that the maximum plate voltage for valves such as the 12AX7 is
around 300 or 350 volts whilst the 12AX7 valve in the AO28 receives 145
volts which is approximately half of the maximum ratings and the other
valves receive voltages ranging from 25 volts ( V6 6C4 ), 130 volts (
6AU6 ), 200 volts ( 6C4 ) and 290 volts ( 12BH7 ) so therefore in this
regard it makes sense that apart from the 12BH7 which runs hotter, the
rest of the valves are running lazily , almost in a "starved plate"
mode. 
All the best.
Kon
 
 
Keith H Clark wrote: 
    The comment about tubes running lazily in a Hammond is true. Just
because the filament voltage is 6.3 does not mean they are used hard. It
has
to do more with the applied plate and cathode voltage and their
potential to
each other that determines their conductivity and dissipation than
filament
voltage. Check typical tube manual voltages against Hammond applied
voltages,you will find Hammond pretty conservative,except for their
later
offerings ie 7591's in H's and E's. Keith