I’ve ordered this QRP antenna tuning unit to use with my ZachTek WSPR Desktop Transmitter. The idea is to set up a dedicated WSPR antenna and ensure matching on various bands. The ATU can handle up to 5 Watts, making it ideal for the 200 mW output of the WSPR transmitter. Once the unit arrives, I’ll run some tests and update this page.
The circuit diagram:
The transmitter can withstand infinite SWR. This good news if you are band-hopping or if your antenna isn’t properly matched. However, the radiated power could be down to single digit milliwatts due to reflected power. Hopefully, the QRP ATU will solve this problem.
There’s an LED on the ATU to indicate SWR but I’m pretty sure that 200mW will not be enough to show reflected power. If that’s the case, I’ll use my Icom 7300 on low power to set up the ATU.