Is it possible/practical to replace a defecive ballast resistor tube with modern components? Or should I just get an original. If so, where can I get a K42B?

: Is it possible/practical to replace a defecive ballast resistor tube with modern components? Or should I just get an original. If so, where can I get a K42B?

Hi Chris

Your ballast restistor should be no more than a metal tube with a wire wound resistance element inside. If you have a defective one bend back the 4 tabs at the bottom and pull out the element. Replace it with a wire wound resistor.

The 42 means it has a 42 volt drop and your radio should use 25 & 6 volt tubes which draw .3 amps current. 42/.3 = 140 ohms 42X.3 = 12.6 watts You will need a wire wound resistor around 140 ohms with a rating greater than 12.6 watts.

Norm

: : Is it possible/practical to replace a defecive ballast resistor tube with modern components? Or should I just get an original. If so, where can I get a K42B?

: Hi Chris

: Your ballast restistor should be no more than a metal tube with a wire wound resistance element inside. If you have a defective one bend back the 4 tabs at the bottom and pull out the element. Replace it with a wire wound resistor.

: The 42 means it has a 42 volt drop and your radio should use 25 & 6 volt tubes which draw .3 amps current. 42/.3 = 140 ohms 42X.3 = 12.6 watts You will need a wire wound resistor around 140 ohms with a rating greater than 12.6 watts.

: Norm

Hi Norm

Terrific! I had opened up the tube and found that the wire was indeed broken. Thanks