. . . Or, ‘you can have it any color you like, as long as it’s black’ - Henry Ford.
New 9cm transverter second from right
The acquisition of a second Ionica 3.4GHz PA prompted a rebuilding of the 9cm transverter. A rummage through the microwave bits box yielded a nice Anaren in-pase power-splitter and an ARRA 90-degree combiner . . . Just what was needed to combine two Ionica PAs in ‘Push-Pull’. It wasn’t until I experimented with the new layout that I realised what I had accomplished when I shoe-horned the original into such a small box! The new twin-PA design would take on the familiar double box construction with the transverter and associated electronics in the bottom box and the PAs and associated microwave parts in the upper box.
The photograph on the left shows the hardware necessary for combining the two PAs. I am indebted to Mark GM4ISM for providing the dimensions for achieving 90 degrees of shift in UT141 coax. This is achieved in the diagonal length in the picture . . . which is actually 450 degrees in length. That and the two equal lengths to the combiner were accurately cut to 1mm tolerance. The 50R load on the combiner is a 100W job. A bit of over-kill but it was going for a ‘song’ on Ebay! On a suitable heat-sink, it doesn’t even get warm.