Icom IC7300 output power. Does the percentage match?

Hi all,

as you can see in the Merlin Station page, I own an Icom IC7300 and it is my main HF transceiver.

Sometimes I need to make some tests with no power at the output, and of course the transceiver has the possibility to control the output power level as a percentage. Suprisingly in one of that tests I received an answer from an radio operator! So when 0% is set, there is any output power! But how much? And 5% may not QRP?

Some months ago I made a 200W (low duty cycle) dummy load in which I am able to measure the coaxial core so it was time of made use of it. I connected the dummy load to the Icom output and measured with the oscilloscope the output waveform, using CW modulation.

Finally I extracted the following table, which represents the figure at the right side:

  Reference Voltage (Vp) Power (W)  


Measured Output Power for each Configured Output Power

0 % 8.2 0.6724
5 % 17.2 2.96
10 % 28.8 8.3
20 % 38 14.44
30 % 47.6 22.66
40 % 56 31.36
50 % 65.5 42.9
60 % 70.5 49.7
70 % 79 62.41
80 % 85 72.25
90 % 90 81
100 % 96 92.16

Not that bad at all! Highly linear as it should be. Two observations are to be done: The first is that 100% does not measure 100W, but 92.16W that are not too bad taking into account that there was a cable + switch + cable + transition + microstrip (+ probe + scope) + load. The second one is what we told at the beggining, 0% giving output power??

May be easy to set a conditional sentence in the firmware to do not create any signal on the output DAC when 0% is configured, right?

Some photos of the measurements ;)