I ran a pair if 304tls in push pull. I think the bias was around 500 volts and the grid current was around 150ma. I drove it with a pair of 812s in push pull at about 110 watts drive. The plate supply on the 304s was around 1600 volts and the plate current was 600ma. Output power was 790 watts. The modulator was four 813s in standard AB2 PPP configuration with 2700 volts on the plates. The tank coil was shortened up and capacitance added to get the Q up for the low load Z. That was an ether heater but it used a lot of power and it was large. The 450s do require a lot of filament and drive. They can be run at lower voltages but as I did the 304s but you will need to make special coils and have a lot of capacitance to 80 mtrs. Or the efficiency will suffer. Also lower voltages generally require a little more drive. These tubes are high current capable if driven hard. And just as point of reference the efficiency of a class C plate modulated amplifier must remain the same for all plate voltages with in the modulation voltage range or the modulation will not be linear. So if the plate voltage is 2000 the efficiency must be the same from at least 1 to 4000 volts.
John Coleman WA5BXO ______________________________________________________________ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:[email protected]
