Back in 2016, Skywave (Al) spent a good deal of time working on an amplifier circuit for use as an RF probe which used a 2N4416 at the front and two additional transistors, which was flat to about 100Mhz (an evolution of a Marconi design).
See post #22 here
http://www.vintage-radio.net/forum/s...977#post896977. That might be worth looking at, and would certainly work well at 30Mhz.
Having spent some time looking at pre-amps for using with DFM's, quite a few incorporate a chip operating as a Schmidt trigger, so the DMF is fed with a square wave, which is said to be useful.
B