The tests yesterday went well enough that I was comfortable getting on the air. So far the GaN FET is holding strong! I think the tweaks to the circuits improved efficiency (around 90% PAE I think) and removed the risk of a 200 amp current surge as it turned off. The Class F portion of…

The surface mount parts are on! I still need to do all the through hole parts, and then test the darn thing… more updates later today. Update 1: Through hole parts are on, mechanicals look good. Need to add heat pipes from the FETs still, but the fan is nice and quiet (which was the…

As expected, the antenna did not perform as modeled on my balcony. I think my F/B ratio is not great, but I seem to have a strong beam towards CA / NM / AZ. Once I mount it above the railing, I should be able to turn it , but I’m guessing South will always…

I took some measurements of my balcony, and modified my EZNEC file, adding some straight sections at the end. The goal is to make it easy to disassemble and tune, so I bought 4 cheap telescoping sections (max length 74 cm) from Amazon (4 pack for $12). EZNEC says the reflector should only be 4…

Years ago, (probably the late ’90s) I played with EZNEC and haven’t really used it much… until today. I was trying to find information on reduced size yagis using meander techniques. There really wasn’t much out there, so I tried my own. Ignore the W8JK name – I guess I forgot to update the comments…

The idea is to design a clean switch-mode power supply that can envelope-track (class H) a SSB or digital narrow-band signal, and use it to drive a Class F ultra-low-loss amplifier with some extra harmonic filtering. Simulations look pretty good, except for how sensitive it is to reactive loads. Targeting 20 meters, 1 kW, >85%…