If you increase the value of R8 to 82k you should be able to power it directly from a lead acid battery. If you decide to use a battery use a 100mA fuse or at lease put a 10Ω resistor in series with the whole circuit.
If it's run from a 12V supply the LM2931A 5.0 can be replaced with a cheap LM7805 or LM78L05 regulator.
So you don't have to change Q3, just change R8, add fuse and power from that wall adapter with the 7812 and the capacitors shown in the circuit in my previous post?
why not 6V battery? even the bias of last transistor can be shifted to regulated voltage, leaving collector only to unregulated. Value of R8 can be re-calculated for the same collector current.
Its some cheap homemade transformer supply, I used it to build ignition coil drivers. but those thing gives you horrible headache, from the sound or the ozone.
2N3866 is a specialized VHF power amplifier. I think it will boost your signals with just a 10R emitter resistor in the above circuit. Add a proper heat sink.
**broken link removed**
I made one kind of that and tested and put it inside my junkbox . I must say it emits ultra strong radiation that severely overloads cheap receivers nearby.