In order to have the SWR/Power meter to be more accurate, you may want to run the
calibrations below. Default values are often good enough to start with but the mcHF can
be fairly accurate if calibrated properly.
Calibrate Zero Power Offset
Preparation: You have to make the resistor-change modification to the SWR hardware
circuitry. If you haven't done so, the mcHF will show a message in the boot screen.
1.
You should have done at least the PA BIAS calibration.
2.
Connect dummy load. Better safe than sorry.
3.
In Configuration Menu set "Pwr. Display mW" to "ON"
4.
Set Input to DIG, with no USB cable connected
5.
Set mode to USB or LSB
6.
Key the transmitter by pressing PTT
7.
Adjust in Configuration menu the setting "Pwr. Det. Null" so that the displayed
mW power values are flickering between 0 and 2 max. Do not go lower than
necessary to achieve that.
8.
In Configuration menu disable "Pwr. Display mW". It will be disabled on next boot
in any case.
Calibrate Power Coupling
You will need a good power meter or oscilloscope in order to measure the true power
emitted by the mcHF.
1.
You should have done at least the PA BIAS calibration.
2.
Connect dummy load which can handle at least 5W.
3.
Set TX power to 5W.
4.
In Configuration menu enable "Pwr. Display mW".
5.
Set mode to USB or LSB
6.
Select lowest band you want to transmit in (80m).
7.
Go to the PA Calibration menu to the "80m Coupling Adj." setting.
8.
Press Tune. Align as closely as possible the displayed mW value for forward
power and measured power by changing the setting.
9.
Repeat this for 40m (60m), 20m (30m), 15m (10m, 12m, 17m). Bands in
parentheses are using the same coupling factor.
