Quote:
Originally Posted by stusnyder
I used a aluminum bodied 50 watt resistor, which is riveted to the inside of the chassis, so the chassis sorta is a heat sink....
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You could use a rectifier diode (without any filter cap) in the heater string. You just need the heater string to add up to about 83V. (2x50V) + (3x6.3V) = 69V, so you need s resistor to burn off another 14V worth (47 ohms 10 watts more than enough wattage), then the diode. Less heat. Put the diode's anode on the 120V source, and its cathode on the above resistor.
Why 83V? Power (watts) is voltage squared over resistance. The diode will half the power off AC. The heater string wants 24 watts, using a resistor will burn an extra 12 watts. The heater string looks like a 277 ohm resistor, and if we put the powerline direct on that, we'd get 51 watts, about twice what we want, so we cut that in half by using the diode. With the 47 ohm resistor, we waste only 4.2 watts vs 15 watts with an unrectified resistor.
That's a lot less heat. Only downside is you're using technology that didn't exist when the radio was made (well, maybe selenium rectifiers were around).