The QCX+ 25MHz TCXO module option provides frequency accuracy and stability to your QCX+
This is a tiny, ready-assembled PCB measuring 14.8 x 10.5mm, containing two capacitors and a Temperature Controlled Crystal Oscillator (TCXO).
Installation in the QCX+ is very simple. It replaces the 27MHz crystal and 0.1uF capacitor C2. The TCXO module has a cut-out so that it fits over the Si5351A chip on the main QCX+ board. Three pads (Ground, VDD and Out) on the TCXO module are connected to the main QCX+ PCB by soldering off-cut wires through the corresponding pairs of holes.
The TCXO module was tested from 4.5C to 65.5C. The graph above shows the corresponding output frequency change, in parts-per-million (ppm). Basically from 4 to 65C it was within +/- 0.25 ppm.