[Elecraft] KAT2: Power Calibration Problem

[Don Wilhelm]

Steve,

Set the menu ATU parameter to CAL P when adjusting R1 for the power 
reading.  CAL S is the setting used to align the SWR (use a dummy load 
which will provide a known SWR such as a 25 ohm or 100 ohm load which 
give a 2.0 SWR).

Also, be certain that your RF Probe is a type that provides RMS 
readings.  Some (those with the diode connected in series with the meter 
probe) will indicate peak voltage.  At 5 watts, 15.8 volts is the 
correct voltage for an RMS reading probe across a 50 ohm load, but if 
your probe indicates peak voltage, you must adjust for 22.36 volts minus 
the diode voltage drop.  If you are looking at an oscilloscope, you will 
see a peak to peak voltage and that should be 44.72 volts for 5 watts.

Consider how you checked your dummy load?  If you checked it with an 
ohmmeter, that is the value at DC, but the value at any given frequency 
may be different - check it with an antenna analyzer to be certain.

73,
Don W3FPR

list1 wrote:
> Hi all,
> I decided to realign my ole trusty KAT2.
>
> Adjusting the bridge null seemed to go OK.  However, when I adjust the power knob to give 15.8 Volts (5 Watts) at my precision dummy load (50.3 Ohms), turning R1 clockwise to the maximum position only shows 4.4 Watts on the CAL S readout.
>
> Any suggestions?
>
>