VFO works with two MPF102 FEts. It should be enclosed. Many VU hams put this VFO on a Card-Bord box and wrap it with Aluminium foil. And they oparate the VFO using 6V battery and 5.1v Zener diode. I change it with 7805 three pin voltage regulator and still works okay (I mean with out any hum).
BD139 should be mounted on a large heat sink. Once everything is finish, Supply 12v to the Amp (not 24v) connect a 24v 5W bulb as the load. C4 should be tuned to the minimum brightness of the LED. Total DC current to the RF amp should be 200-300 and it should never exeed 400mA (at 12V). On its full power 28V power amp will take about 300-400mA (max 500). Use 75 ohm coax, to feed the dipole.