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Lots of QRP rigs are to small to use a standard µAmmeter for SWR. But any kind of rig will offer at least the place for a 3mm or 5mm LED at the frontpanel. For this rigs DL2AVH contstructed an SWR meter based on a red/green mixed colour diode. The two signals Vf(forward) and Vb (backward) are processed by SMD-Transistor arrays. The red LED is feed by the Vf and the green LED is feed by the difference Vf-Vb. This technic results in a broad colour spectrum between red and green depending on the SWR which give a pretty good analog feeling during tuning operation.

The edge points are:
SWR 1 = green
SWR 3 = yellow
SWR >10 = red

Between this we get a big number of mixed colours. To tune an Antenna, you have have to trimm of the red colour. Between 10 mW and 10 Watt you get very similar coulors. Only the brightness of the LED is below 1 Watt a little bit lower, but still bright enough to allow smooth tuning. We did not find any frequency dependency between 1,8 MHz and 50 MHz

 

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