Of course, amateurs have for years used pentodes and tetrodes, including 807's and 1625's, as triodes in grounded grid linear service. I have never seen the resistor used. They simply ground all the grids and feed rf to the cathodes.
With 1625's and 807's, a modification is required, to bring the beam forming plates out to a separate pin so that it can be grounded along with the grids. This is possible on some brands of tubes. In others, the bf plates are internally connected to the cathode, rerdering them impossible to modify. Without the modification, they are unsatisfactory as g-g amplifiers because the bf plates produce undesirable coupling between the input and output.
-k4kyv
