The front panel interface is
Each press of the button steps through a cycle of five transmit display modes. (Mode can be changed on receive or on transmit):
The 'reflected/10' mode is a 10 x more sensitive setting for fine tuning with low reflected power levels.
The same pushbutton is also used to receive calibration information from the PC based Calswr program.
see Calswr - send to Picswr
The LED display modes illuminate a LED when its power or SWR level is reached.
For example:
My Picswr LED calibration specifies 2 watts per LED
- thus the range of the 12-LED display is 0 to 24 watts.
The analogue meter is programmed in the status PIC to have serial data of 0 to 54 displaying S0 to S9.
The calibration on transmit speaks in terms of dB over S0 because numerically this is what is sent to the status PIC.
My Picswr analogue meter calibration specifies 0.4w per 'dB over S0'
Thus the S9 position on the analogue meter will correspond to 0.4 x 6 x 9 = 21.6w. ( 6dBs per S point x 9 S points).
Above S9 the G6AK calibration is more compressed ... but this is dealt with by making a calibrated scale for the meter.
The SWR calibration is fixed at 0.25 units per LED, ie:
LED 1: SWR = 1.0 | LED 5: SWR=2.0 | LED 9: SWR=3.0
See also PEP indication? and Calswr - send to Picswr