Cost To Date

Tubes, TubeDepot, $23.75
Tube, VacuumTubes, $10.00
Filter Caps, Digikey, $2.05
Filter Caps, Digikey, $3.15
Paper Caps, Digikey, $24.28
Knobs, Bias Pot, IF Xformer Play Things of the Past, $31.35
Speaker Connector, NAPA, $2.96
Transistor, Quest Components, $32.50
Weld Nuts, McMaster-Carr, $2.00
TOTAL $132.04

Tuesday, December 3, 2013


 I temorarily added a filter capacitor to reduce hum from my battery charger. Those higher wattage resistors are replacing a trimmer potentiometer.

Here is the old trimmer potentiometer that adjust the output transistor bias current. It is dead. Looked on Digikey, apparently this type is no longer being made. I can just pick and choose fixed resistors to get the bias correct or find another potentiometer that would work. This is a 125 Ohm potentiometer.

Control shaft detail

Found a pot at Newark for $11.14. Not exact fit but a better part and it will do the job well:

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