HOW THEY DO IT.


Piezoelectricity is the property of quartz that we utilise in our receiver and transmitter crystals. So what is it? Put simply: it is an electric voltage produced by certain crystals and by a number of ceramic materials when they are subjected to pressure. What’s more, the piezoelectric effect works both ways: stress a piece of quartz and you get an electrical output from it that is proportional to the stress it undergoes. That is to say, when the quartz has an electric field applied to it, the crystal becomes deformed or strained by an amount proportional to the applied field; the sense of the strain depends on the direction of the field. Incorporate a crystal in an oscillator circuit (in our Tx and Rx) and it will make the circuit run very accurately at the required frequency.

Each slice of crystal has a natural resonant frequency it likes to oscillate at depending on the ‘cut’ of the crystal. The frequency of the crystal is controlled by the thickness of the quartz slice plus the added metal electrodes. Most crystals are made from one of three different cuts of quartz according the frequency required . AT-cut (1MHz to 300MHz), BT-cut (2MHz to 38MHz fundamental) and the X-cut (24kHz to 50kHZ