Dear friends,
we have been busy over the past weeks designing a TCXO breakout board for the Pluto SDR.
The purpose is mainly to support people that are afraid of soldering these tiny 1.6 x 2.0 mm sized TCXOs. With the help of this ready-made breakout board modifying a Pluto SDR should be much more accessible to the average ham.
This project was supporting the purpose to teach my 11 year old son how to use KiCAD and getting him interested in our hobby. Most of the schematic drawing and manual PCB layout was done by him with only very little support from my side. I am very pleased about the result and the learning curve of my son.
In the attached KiCAD 3D images you get an idea how the final board would look like.
It uses the famous ABRACON ASVTX-13-C-40.000-I05-T (40 MHz, 1.8v, 0.5ppm) which is very stable when mounted away from the TRX chip, next to the FPGA. This is the VCTCXO version with frequency correction pin to set the clock to EXACTLY 40 MHz via a small SMD multi-turn potentiometer soldered onto the PCB.
This TCXO model is "The Model of Choice" for most Pluto SDR users on QO-100, due to its superb performance for NB transponder use. You can find many references about this TCXO model on the web with many happy users. The only limitation so far was, that this modification was only suitable for SMD experts due to the extremly tiny size.
See the attached photos of the PCB with the drawing on how this breakout board is supposed to be inserted and connected. It is just fixed at the right place with double sided scotch tape and then wired.
We are planning to have a first batch run of professionally produced boards made in a SMD fabricating house. This means we will be able to offer this PCB ready made with all components already factory soldered as a simple kit. The board size is approximately 7x15mm with some easy to solder pads for the wire connections.
A documentation and YouTube instruction video will be provided once first batch is available. (also including an "easy method" for removing the original XO from the Pluto)
73 de Oscar DJ0MY (and Daniel - my 11 year old desginer)