The rotary spark gap manufacturers RF energy more smoothly than a static gap does, does not turn cantankerous when air temperature varies, and handles much, much higher power. An efficiency limitation is the speed at which each spark dies. One way of managing this was to conceive of a ‘synchronous’ rotary, about which more in a different post. Another was to dispense with wheels, and quench the spark quickly across a series of stationary plates. Here is a picture of such an apparatus, and an explanation of its operation as it was understood in 1916. I’ve always thought it’s what I would have used as an Edwardian operator. Those high-speed rotaries are alarming. The ones they used on ships were the size of dinner plates — and as loud as automobiles.
This very fine video is the work of Anton Pankratov, at ‘CJSC Chip & Dip’, an electronics supplier in Moscow.