Two ?plate RF chokes in series ?were used in the homebrew 4-1000A amplifier that I designed and built in the early 80's and is still in reliable service at my 4X4NJ station. At the time, I didn't have convenient access to any references that detailed the construction of a suitable single plate choke. And I felt that even given the lacking information, it would have been unlikely that I would be able to find the proper coil form for the choke. ?The need for a second choke arose because of the undesirable frequency of the series resonance of the first choke. Instead of cut-and-try attempts to get a single choke to work properly, it was much simpler just to add a second choke in series with the first choke.? Since the total impedance is the sum of the impedances of both chokes, and the second choke series resonant frequency was far away from the resonant frequency of the first choke, the problem was solved.? An additional advantage was the overall increased impedance of the two choke combination on most frequencies. The obvious potential disadvantage was the increased space for two chokes, but this was not a problem (in this project) with plenty of space for a second choke.

73, Riki Kline K7NJ/4X4NJ