CT-100 Dropping Power Resistor

[Electronic M]

Originally Posted by Penthode

What power rating resistors did you use? Does the chassis upright holding the seleniums get noticeably warm?

I don't remember, and I'm not sure if my mouser order history goes back that far. I think I rounded up (from my power calculations)to the nearest standard wattage and one of the parts was 50W.
I wanted to go double the wattage, but I think sticker shock on the parts I did buy and worse sticker shock on the 2X wattage stopped me (the 2X wattage may not have been available for one of the parts).

The chassis upright (especially where the resistors are) gets about as hot as a running tube (not something you want to touch). I didn't own a thermometer back then so no measurements were taken. I figure as long as the resistor is rated for higher wattage than it sees, then it should be fine. The chassis riser being hot shouldn't be a problem either...It's metal so it won't melt at those temps, and it would probably get that hot if it was next to a power tube anyway... there's really only wires, 2 diodes, 2 fuses and an octal socket on the riser so if you dress the wires to not touch the chassis there's really nothing that the heat can harm... Especially given the back is a very open metal mesh that lets the heat out well.
With how many tube heaters alone are in this set the ballast isn't that big of a heat producer in the grander scheme of things, and the original ballast put out the same amount of heat.