I don't think I will need a RF amp but with this design I can simply make two of the buffers. The direct conversion RF and oscillator are the same frequency. Anyhoo,This is what I came up with.
The DBM of course.
Andy's oscillator I don't have the BC557B so I will use a PN3644.
The buffer to boost the oscillator output. The simulation shows it to be to strong which is good. It will need an attenuator.
The AF amp. Simulation show it will rattle an earbud. Another attenuator or a volume control.
So 1 transistor , 2 MOSFETs , 4 diodes . 2 transformers , and a handful of resistors and capacitors. Let the build begin.