I'm familiar with using LEDs as RF indicators with a diode as rectifier and a capacitor to filter. On thinking of fitting LEDs for forward and reflected current to my little QRP (5W) ATU I found at least 2 circuits that used the RF direct so gave it a try.

It doesn't work as hoped and the LEDs are dim, becoming progressively dimmer as frequency increases. I have used LEDs on ac mains with a suitable series resistor but, without a diode rectifier, their lifespan is much reduced.

Anyone looked at this direct coupling idea?