LNA for 432 MHz
design
JH0WJF
Presenting
you another preamplifier design, made by Noriyuki
(JH0WJF). The advantages of this designs are:
cheap HEMT FET Transistor
easy to build fits in pre made tinplate housing
no expensive PCB needed good performance
You can use
either self made housing from brass or copper
sheet metal, or buy apre 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).
Alignment
Set the draincurrent of the FET to 10mA, by
adjusting the 150 ohm source
trimmer. Then tune the HQ-trimm C´s alternative
to best NF. If you do not have aNF-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.
|
.gif){kind=spacer}
