Last two weeks, having nothing to work on so interesting, and also waiting for some parts for the Minima to arrive, I built this two measurement tools for RF power.
First, this SWR meter project from Ik3OIL which I intend to use it for the 20W RF Amplifer. At the begining I wanted to put inside the amp box, something with LM3914 LED indication for power and SWR, but not to much space was available there, so I decided to make a stand alone meter for it.
Second, is this well known RF Wattmeter from OZ2CPU. It is a nice piece of equipment to have in the shack. It uses Analog Devices AD8307 input detectors, and can measure from 1nW to 1W, and up to 1kW with attenuators hooked on.
Is not finish yet, it needs to be calibrated with a good 0dBm source. Without it, it has a precision of 1dB, 0.1dB with calibration. I still have to find a decent knob for the dial encoder, two banana connectors for the DC voltmeter, and make the buffer for the frequency meter output, and also see if the serial TX is workng for a PC data logger.
But, even so, his main function, power measuring, is working! Even uncalibrated is showing a very apropiate value. I already hooked on some rigs from the shack, at 0.5W and 1W, and the measurements were realistic. Now I will try also to make myself a good home made 0dBm source, at least till I find somewhere to lend an industrial signal generator to calibrate the meter.