Looking at the schematic for a Howard 400
I see a "1 volt bias cell" on the grid of the 6f5 that feeds one of the 6v6 output tubes.
(schematic notes indicate the 6F5 is a bass boost stage regulated by the bass control)
http://www.nostalgiaair.org/PagesByModel/270/M0009270.pdf

Is this really a battery? if so couldn't the voltage be derived someway from the powersupply?.. why would a battery be required?

Yes sir that is what it is. There is also another one on the 6Q7. You could try to derive the volatge by adding a resistor at the center tap for the rectifier to ground and add an additional filter cap. You would have to play around a bit to find the correct value and you may have to change the radio's filter arrangement some what. How about putting a battery holder on the outside of the chasis where you can get at it easily.

D. Witt

:Looking at the schematic for a Howard 400
:I see a "1 volt bias cell" on the grid of the 6f5 that feeds one of the 6v6 output tubes.
:(schematic notes indicate the 6F5 is a bass boost stage regulated by the bass control)
:http://www.nostalgiaair.org/PagesByModel/270/M0009270.pdf
:
:Is this really a battery? if so couldn't the voltage be derived someway from the powersupply?.. why would a battery be required?

Hi Peter

You could replace the bias cell with a calculator or watch battery. It can also be eliminated.

Later radios used zero bias on 6F5 & 6Q7 tubes. Short across the bias cell but do not leave it open. Later circuits increased grid bias resistors to 4.7 or 10 meg. You won't notice any difference in radio operation. Check later schematics.

Norm

:Yes sir that is what it is. There is also another one on the 6Q7. You could try to derive the volatge by adding a resistor at the center tap for the rectifier to ground and add an additional filter cap. You would have to play around a bit to find the correct value and you may have to change the radio's filter arrangement some what. How about putting a battery holder on the outside of the chasis where you can get at it easily.
:
:D. Witt
:
:
::Looking at the schematic for a Howard 400
::I see a "1 volt bias cell" on the grid of the 6f5 that feeds one of the 6v6 output tubes.
::(schematic notes indicate the 6F5 is a bass boost stage regulated by the bass control)
::http://www.nostalgiaair.org/PagesByModel/270/M0009270.pdf
::
::Is this really a battery? if so couldn't the voltage be derived someway from the powersupply?.. why would a battery be required?