(a bit OT) Tube radios

Your question is ambigous. Do you want to make a radio that can receive either the AM or FM broadcast bands (e.g. with a switch to select between them) or a set that receive one or the other? If the latter, I stongly recomend you build it as 2 separate receivers up to the detector stage followed by a common audio amplifier. Most commercial sets were not made this way, (in order to save valves) but the performance does suffer. A typical trick used was to have a pair of IF transformers one resonated at the AM IF requency (465kHz or so), the other at the FM IF frequency (10.7MHz) and connect them in series (remmeber a parallel tuned circuit is a high impedance at resonance, off resonance it is a low impedance so it has little effect)/. Doing it with vavles that are still made is going to be hard, since the vlaves currently made are mostly audio types. If you will allow 'valves that aare still trivial to find in large quatities' it becomes a lot easier. Try to get a set of the 'Impoverished Radio Experimenter' books. One of them covers making a superhet receiver, including home-made air-cored IF transformers -- the transformers for such sets are a lot harder to find new rhan valves. These books mostly cover the amateur short wave bands, but the principles are much the same for AM broadcast receivers. There was a circuit in the Radiophile magazine a few years back for an AM broadcast-band receiver using TV valves, mostly EF80s IIRC. The input stage was a cascode amplifier using a PCC84 I think. Odd, and the valves are still very common. Making a valve FM tuner from scratch is hard due to the high frequecines invloved (every bit of wire matters!). Mullard published a design of one in an early version of their hi-fi amplifier book, but left it out of later versions since it was so difficult to get working correctly. You will need a good, stable, RF signal generator to have any chance of success, I think. -tony