UPDATE: The 50 to 300 Ohm BALUNs have been installed and tested ready for the event. All the antennas that we are planing to make available for use have been disconnected from the switch and wired to a BALUN. These BALUNs work pretty well. Here is the test setup.... There are 2 x 50:300 ohm BALUNs in series to give 50:50 ohms. The Codan 8525A is the test source. Starting temp plus a few mins, = 27.4C VSWR is pretty good! Around 70W in, and 65W out. This is via the 2 BALUNs in series. 32.2C after 20 mins carrier. (Note the "IRWIN" brand tune button operator It was easier than holding a finger on the button! Construction info is here... https://ra.sadarc.org/#!/baluns An addition not shown in the construction article is the Earth connection that each BALUN now has to make sure all the antennas are safely tied down for static protection. My legs are sore from being on the ladder for long periods of time!