RF Charts

Determine loss of an RF feeder cable. Short circuit the end and measure SWR and then read off according to chart.

Wire gauge versus current. Note that you can make RF fuses with thin wire ! Lots of old (and very expensive) big name RF spectrum analysers and VNA's used this method. I have also used simple 1.25v  35ma "pea lamps" as input protection on pre-amps and stuff just in case I transmit into them.  A practical example of this is when I built a PA0RDT mini whip antenna that used a J310 FET driving a 2N3904 for my FT817 receiving system on the LW/MW AM broadcast bands. I deliberately tested it by transmitting 5 watts up the spout. It worked flawlessly. Another example is the GW3DIX / G4WMX Null Steerer. 

Vertical angle of radiation versus hop lengths on HF radio.Upper trace,purple is Km, lower trace is miles.

S Meter Calibration Values.

S Points - PD into 50 ohms - dBm into 50 ohms

S0 - 0.1uV -127dBm

S1 -  0.2uV -121dBm

S2 - 0.4uV -115dBm

S3 - 0.8uV -109dBm

S4 - 1.58uV -103dBm

S5 - 3.16uV -97dBm

S6 - 6.3uV -91dBm

S7 - 12.6uV -85dBm

S8 - 25uV -79dBm

S9 - 50uV -73dBm

[6db per S Unit]

SWR and Power Loss

(Ignore the range column,not relevent)

Alternative Chart for SWR  and Return Loss

Note the descending order !