[ARC5] ART-13 Power Output

[Chris Bowne]

Was wondering what the consensus is re typical RF power output of an ART-13 when powering a nominal 50
Ohm non-reactive load, especially when using a DY-17A dyno power supply. Mine has consistently shown a nominal 175 watts when fully loaded on a variety of watt meters including two different HM-102 Heath units.  None are probably high accuracy (I have a Bird combined 500w dummy load/wattmeter but the wattmeter does not work). I use a nominal 500 pf  variable cap across the transmitter output and when loaded up to the top of the plate meter green band on CW to and indicated 125 mA, I will see about 3.4 units indicated an the RF output meter function indication.  I suspect the RF  current indication is not calibrated in true RF amps because I squared R of 3.4 A into 50 ohms works out to 537 watts!  OTOH if the plate current is true mA plate input power works out to about 137 watts for 125 mA and a nominal plate voltage of 1100v from the DY-17 (I know that the current meter also includes  the screen current also but I am neglecting it for an ROM  calc).  137 watts input seems in the ball park for the rated nominal 100 watts out, implies a plate efficiency of about 73 percentage, a little on the high side but not by much.  So my guess is that my actual RF output is probably closer to 100 watts than 175.  Anyone done any measurements
with an accurate wattmeter?


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