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1.8 to 54 MHz Power and Return Loss Meter (10 mW ....100 W) by Paul Kiciak, N2PK

When I found the describtion of this Return Loss and Power Meter in the Internet I knew that is what I am looking for. Find the exact description on the famous webpage of Paul, N2PK. Originally designed for a MFJ antenna tuner I built this meter as a stand alone equipment. Against the description I used a piece of RG-213 for the coupler element. The AMIDON T50-3 is equal to the T50-13. Due to the bigger diameter of RG-213 I used a T63-13. With wounded wires this core matches exactly on the dismantled RG-213. Since the circuit is assembled with 2ea AD8307 the power is shown in dBm and the RL in dB. With the 50µA indicator it is not necessary to reprint the scale. In power mode it shows directly dBm's and in RL mode it corresponds to dB. Note that a high return loss means a low SWR. Therefore tuning a antenna by RL is vice versa to SWR indicators. A cross reference of SWR to RL can be found below.

Return Loss over SWR diagram RL over SWR PDF
and the RL/SWR Cross Reference PDF