Measuring the QRPp’s Isn’t Easy

Posted on Tuesday, February 9th, 2016 at 9:32 am in
SWR Detectors

SWR Detectors

Interesting how a development in one area of this hobby can force a sudden change of direction to explore some new areas. I’ve been happily experimenting with my Hans Summers Ultimate 3S kit when I realised that I could band-hop and get a picture of propagation conditions updated every 30 minutes or so. Cool idea.

But band-hopping requires a multiband antenna. Alternatively a tuner or something to adjust the U3S (which has quite a robust albeit low power output) to the piece of wet string hanging out the window. Even then, one may never know exactly how well you are getting out, and therefore whether your propagation forecast is accurate.

Thus the sudden change in direction: I want to measure exactly how much RF is going down the cable to the antenna. This should be easy, right? A quick search on Google brings up dozens of very good kits and circuits, and I dive headlong into the challenge. That was a few weeks ago already. And I learnt a painful lesson: There are not a lot of options available for the QRPp operator.

Let me be honest, many of the circuits and kits I saw were designed for the American market where they must handle kilowatts with a minimum scale of 100 watts. But when you start talking in the milliwatt region there is a big void. I spent hours and hours winding toroids, soldering up detector boards, wasting tons of paper taking meticulous readings, all in the 5 watts plus region. But I couldn’t get things to work in the 150mW and less region where the Ultimate 3S is working.

So here is the challenge: Does anybody have a working circuit or plan for a QRPp SWR / Power meter? Drop me an email and I can share some of the ideas I have already tried, but I’m desperate for some new ideas.

73s de Leon ZR6LU from Johannesburg 0825735580