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    Rick D
    Forum Participant

    I have rebuilt a Northern Electric Model 1331A radio , I replaced all caps except the mica caps and repaired the volume control , the set seems to be working fine now , only thing is this set has a 1.25 volt Bias Cell , I attached the info and schematic, on page 7 and number 162 you can see the Bias Cell , this radio has sat for years so I would think the cell is dead , should I just leave the Bias Cell alone or should I put a jumper across it , I have never worked on a set with a Bias Cell before ,would be very thankful for any input , thanks for your time all the very best Rick


    CVRS Member

    I removed the bias cell from a Universal Radio Z/13A105-E and 3d printed a holder for a coin cell. The thread can be found here
    I did add distilled water to the bias cell and it came up to 1.5V, but didn’t last.

    Brad Winder
    CVRS Member

    You can find small watch batteries that will fit in the holders. I find most holders need the positive and negative wires reversed due to the build of the modern cells. The battery is important because it allows for a negative bias on the tube it serves. Without it, the tube may work but not well.

    There are also small circuits you can add to the radio to replace the bias cell; it does require modifications to the set though.

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