[Boatanchors] Power Triodes

[Barrie Smith]

Re:  6C21

These tubes are (according to an Eimac bulletin written by William Orr) are 
a somewhat more rugged version of the 450TH.

The spec sheet calls for 8.3 volts on the filament.

That voltage is for pulse-service only.  For amateur RF service the filament 
voltage is the same as the 450TH:  7.5 volts.

I used a pair of these tubes in push-pull on 160 several years ago.  Made a 
heap-of-smoke.

73, Barrie, W7ALW