A correspondent wrote to me about Ameritron AL811H tube selection. The article contained a table of performance figures derived from RF Power Amplifier Tube Performance Computer calibrated for measured supply voltages and power output in the various modes.
Above is the table, Table 1 `from the article.
I mentioned in my response that you would get a very good estimate using Calculate initial load line of valve RF amplifier.
Let’s try that on the SSB and AM cases.
SSB
Above, the SSB case reconciles quite well.
AM
AM at modulation crest or PEP
This models the PA at 100% modulated AM input.
Above is the AM initial load line estimate, configured for peak envelope power, ie at a modulation crest.
This reconciles reasonably well.
AM carrier
To model the same scenario, carrier only, we must halve the peak anode voltage Vak and make quarter the output power.
Above is the AM carrier only initial load line estimate.
This reconciles reasonably well.