Have a Supreme Model 562 Audolyzer that I am trying to bring back to life and I see on the schematic what is called a "Bias Cell", which I took to be a battery, but turned out to be a small acorn shape item that looks to be made from two differnt metals. Can anyone explain what the bias cell is and what does it do? I suspect it acts like a zener diode but not sure.

Thanks,

David S

Hi David

A bias cell is a battery to make grid #1 of a tube slightly negative. A bias cell was often used in battery equipment to save current. A tube with a more negative grid draws less current.

AC operated equipment sometimes have bias cells. In most cases a radio can be operated by shorting the bias cell but don't leave it open. Open a tube grid will not have a return path to ground.

Chuck has information about bias cells on his site.

http://www.philcorepairbench.com/biascell.htm

If you want to keep the bias cell in the circuit a watch or calculator battery will work.

Norm

:Have a Supreme Model 562 Audolyzer that I am trying to bring back to life and I see on the schematic what is called a "Bias Cell", which I took to be a battery, but turned out to be a small acorn shape item that looks to be made from two differnt metals. Can anyone explain what the bias cell is and what does it do? I suspect it acts like a zener diode but not sure.
:
:Thanks,
:
:David S

Norm,

Went to the website you identifed and down loaded the information on Bias cells and was able to re-work the cell per the information. After reworking the cell, the voltage measured around 1.2 volts on my VTVM so I put it back into the Audolyzer and turned it on (ramping up the ac voltage with a varable ac supply) and to my surpise, it worked, picking up the am broadcast bands. Now I look into replacing the capacitors and cleaning up the cabinet and chassis.

Thanks for the link and input,

David S

:Hi David
:
: A bias cell is a battery to make grid #1 of a tube slightly negative. A bias cell was often used in battery equipment to save current. A tube with a more negative grid draws less current.
:
: AC operated equipment sometimes have bias cells. In most cases a radio can be operated by shorting the bias cell but don't leave it open. Open a tube grid will not have a return path to ground.
:
: Chuck has information about bias cells on his site.
:
:http://www.philcorepairbench.com/biascell.htm
:
: If you want to keep the bias cell in the circuit a watch or calculator battery will work.
:
:Norm
:
:
:
::Have a Supreme Model 562 Audolyzer that I am trying to bring back to life and I see on the schematic what is called a "Bias Cell", which I took to be a battery, but turned out to be a small acorn shape item that looks to be made from two differnt metals. Can anyone explain what the bias cell is and what does it do? I suspect it acts like a zener diode but not sure.
::
::Thanks,
::
::David S