who's ever designed and built a PN
generator knows how simple a task it is.
But for those who haven't, and those with
limited experience with logic design, the
task might seem a bit intimidating. This
simple 5-stage LFSR (linear feedback
shift register) design should help with
the learning curve.
circuit is an attempt to make the
simplest possible signal source for the
13 cm band without the usual grief of not
finishing up on the right frequency. It
is built on a 4.25 x 1.4 x 1/16 inch
epoxy glass board. There are just three
transistors: a FET oscillator, a BJT
frequency multiplier (times 5), and an
output-transistor frequency quintupler.
The oscillator starts with a readily
available 96MHz crystal and multiplying
this by 25 goes up to 2400MHz. The use of
filters takes the guesswork out of
finding the correct frequencies. The
circuit draws 38 mA.