[Today’s run: Schafers Chapel 5 miles]
Now that I have a really cool power meter, I need a device that will let me measure larger quantities.
The power meter I built goes way down to somewhere around -70 dbm. That is a very small signal. And it goes up to around +10 dbm. That’s a range of about 100 picowatts to 10 milliwatts. It is a big range but heavy toward the little-bitty end of the scale.
So what an intrepid guy does is do a google search for a “tap”. In this case I found a great web page for a -40 db tap. Which means that it taps off a very small portion of the real signal and sends that small portion to the meter. The rest continues on to the dummy load or the antenna or wherever it is going. The small portion is 1/10,000th of the power of the total signal. That will let me then measure from -30 dbm to +50 dbm (100 watts).
He uses a short length of copper pipe and puts the parts inside with two pipe-end plugs and a bnc connector on each end.
When you get into building radio things sometimes the shape of the thing has significance in how it works. I don’t know how much that is true in this case, but having the cylindrical shape probably does help it work better. And it is completely enclosed in copper pipe. That is good.
Unfortunately, Lowes doesn’t carry that kind of end plug. So I have some more shopping to do to find that.
Add it to the project list!