Hi,
We use the non-wonky remote. I can send you some of our old unused SAW designs if you like. I suppose you could always buy a current remote off us and copy it! You probably wouldn't be the first.
The current design uses a SAW resonator connected to the base of a colpitts oscillator. Having been so well designed(!) most of them should oscillate at about 433/434 quite naturally so the SAW just stabilises it.
We have another design which gives excellent output with excellent harmonic response but we couldn't use it for production because it required adjustment after production which costs money. You can have a look at that:
http://www.mgbelectronics.co.uk/rf/bal_loop.jpg
If you want to design your own and aren't going to use it for a professional application/dont care about harmonics use a colpitts with a SAW resonator. Instead of using an inductor for the collector load use a pcb loop (in the top half of the case) and power it with a high value 1uh+ inductor. At that point you use need to add a bypass to ground.
The resonant frequency will be the loop inductance (which is about 15 to 20nH for the straight 5 button case) combined with the parallel total capacitance of both the bypass and (series total) of the colpitts collector to ground capacitors. Get this to run at about 433mhz or whatever you want without a saw then use a saw.
