Best to use a step down transformer. A transformer will give you a fixed voltage.
A resistor will drop voltage but it all depends on the load. You can replace the Candohm resistor with a modern wire wound type resistor. If you plan on increasing the resistor value to operate from 220 volts remember wattage rating also has to be increased.
When using a silicon diode in place of selenium rectifier it usually requires 47 ohms added in series to reduce voltage to original values.
Norm
:Hello, I've just bought an old T600 radio. It works correctly at 110V. What should you suggest for working at 220v? Is it preferrable having a transformer 220/110 or better the adapter Z1 containig one selenium diode and a Candohm resistor?
:I know , I can replace the selenium diode CR2 with a common silicon diode. Can I replace the Candohm resistors with common resistors?
:Thanks