14rp4 substitute

[dieseljeep]

Originally Posted by timmy

The 14atp4 I wanted to use in place of the 14rp4 and I'm not sure what your saying with the resistor. Are you saying to put in the 17ax4 and 17dq6 in place of the 12dq6 and 12ax4 and then this raises the heater voltage and use a 50 ohm 2 watt resistor between the heater. I'm probably way off here thinking the 17, volt tubes would take more .im missing something on how to get more voltage for the crt . If the physical size is the same as the 14rp4 I could just use a separate heater transformer for the 14atp4 , that should work.

My last entry just cited the tubes that would be in a set that used a 14ATP4 crt. My calculations still show the resistor to be 42 ohm, 3 watt resistor across the 14AT heater.
I just mentioned a 50 ohm, as it's a more common value and will shunt 7.5 volts, kind of a happy medium.
Current in a series circuit is constant and the slight increase will balance out.