Presenting you another preamplifier design, made by Noriyuki (JH0WJF). The advantages of this designs are:
You can use either self made housing from brass or copper sheet metal, or buy a pre made tinplate housing. The dimension is 111 x 55 x 30 mm. The cavity is made by 100x6 mm copper or brass pipe (for better performance [0.01db ??] you can put some silver on it).
Set the draincurrent of the FET to 10mA, by adjusting the 150 ohm source trimmer. Then tune the HQ-trimm Cīs alternative to best NF. If you do not have a NF-meter, take the signal of a weak beacon and tune for best signal-to-noise (I did so and got 0.6 dB, measured later).
You may use GaasFet MGF1302 with not so good NF performance. Therefor the two 1N4148 must be left out.