If you examine the data sheets for most general purpose transistors, it will be discovered that their current gain, fT, input capacitance, output capacitance and Miller capacitance are very similar. Why is it necessary to alter the circuit? I might even be able to do a simple swap-out of the transistors and give that a shot (for the heck of it), but I'm thinking I'd be much better off using LTSpice and design the thing properly. Unfortunately, I don't have a 2N2907 in my junkbox, but I do have a LOT of 2N3904 and 2N3906 transistors, so I'm trying to alter the circuit to accommodate these devices. Guess I'll have to go read the tutorials again! God - how I hate being old and forgetful! LOL. I have most of it already input into LTSpice, but it's been so long since I've used the program that I've forgotten how to setup the AC voltage source and frequency. The PTO provides 400-500 KHz of bandwidth, and I'm hoping that, properly designed, I can keep the diode turned on enough to actually hear stuff decently. What I'm trying to do is see how well I can make a minimal-parts-count receiver play.

I'm also thinking about adding an RF amplifier to the front end, just to see how she plays. I do have schottky diodes to roll my own passive, doubly-balanced mixer, though I'd like to experiment a bit to see how well I can get the diode detector/mixer to work. It's also important to point out that I'm trying to use a 1N34A diode as a mixer. Well, this is kind of a somewhat unique application, so, first and foremost, let me provide a link to a schematic: If it is a matter of voltage, and not dBm power, just use a broadband transformer wound on a ferrite core.

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