Last semester, I designed and built the QROP Meter for my graduate school independent study project. Go to my web page at http://www.jasonhsu.com/ee.html
to learn how to build the instrument.
What makes my SWR/wattmeter different from the numerous versions available from MFJ and the numerous homebrew designs out there?
1. Works from 200mW to 100W! You get the best of both worlds! MFJ SWR/wattmeters don't work at QRP, and QRP SWR/wattmeters can't handle 100W. Tuning up at 1W instead of 100W reduces the QRM you cause by
20dB, or over 3 S units! You can also safely change the tuner's inductance taps WHILE transmitting at 1W.
2. GOOD resolution at SWR values above 3 and even above 5! This can be very handy at 160m and 80/75m.
3. 10-LED display for the SWR meter and another 10-LED display for the wattmeter: No more squinting at cross-needle meters!
4. More accuracy at low power levels: Most SWR meters understate SWR at low power levels due to the infamous diode drop loss. My design compensates for this and allows accurate SWR measurements at QRP power levels.
5. Needs NO calibration!
Let me know what you think, and feel free to contact me if you have any questions or suggestions. I intend to have this article published in QRP and homebrewing publications. If you decide to build the QROP Meter, let me know how it goes.