A few days ago, I built myself a simple 30 W dummy load out of Caddock power resistors. As I mentioned in the previous post, I was doubtful about the readings that I was getting from my LP-100 (not that I doubted the LP-100 itself, just my calibration of it). Tonight was my first night back to work after a long break, and I finally got a chance to put the dummy load on a calibrated VNA to verify its performance.
The instrument that I used was an Agilent N5230A. A very nice instrument, but one minor drawback is that its lower frequency limit is 10 MHz. Not to worry, as I suspect that if it does well from 10 to 30 MHz, that the lower bands are probably good enough for my home lab.
Sure enough, it turns out that the performance of the dummy load is great and that my LP-100 calibration is off. The return loss is excellent all the way up to the 2 meter band. There’s not much else to say since the plots speak for themselves. If you need a dummy load, you could definitely do worse than to pick up a couple of these resistors on your next Digi-Key order and slap one of these together in a few minutes. Caddock also makes 100 W resistors, which will probably be on my next order for goodies.