Wednesday, November 2, 2016

Let's build a field strength meter

A short while ago I watched a video that was floating around Facebook that detailed how to convert a cheap (freebee with coupon) Harbor Freight multi-meter into a field strength meter. Seeing as how I plan to get back into antenna building, and that I literally had ALL of the parts needed, I thought I would give it a go.

 My schematic is a bit different than the one outlined in the video. There is one capacitor that is supposed to be in series with the antenna. I simply forgot to install that, so I just removed it from the schematic altogether. Below is a picture of my crappie schematic.

I think the most complicated part of this was trying to get everything mounted and fitted into the box. The holes drilled for the antenna and switch seemed ugly to the eye but work. I had difficulty getting the switch to fit properly, so I made the hole larger with a pair of wire clippers.

 The whole circuit is wired into the meter inputs via a switch. The switch gives you the ability to turn the Signal Strength measurement ability on or off, so it can still act as a multi-meter.

  Here we can see the meter all put together and taking a reading of a small FRS radio transmission. I hope to use this in my efforts to map out antenna patterns in the future. This is a good one night project if you have all of the parts laying around.