Over the weekend I have designed a couple of PCBs for use with the rtl dongle to improve my reception of weak signals and possibly be able to receive GPS and other signals in the L band.
Both hardware projects were inspired by Adam’s 9A4QV LNA4ALL.
The first piece of kit is a MiniCircuits PSA4-5043+ based low noise amplifier. The board is very simple and only has the essentials you would expect from an LNA.
The LNA board has an LM317 on board regulator which allows to run the LNA either off of 3V or 5V. Optionally BAV99 diodes can be fitted to protect the input from ESD, although with the possible drawback of intermodulation products and distortion being introduced into the signal when strong signals (think FM broadcast or POCSAG pagers) are present at the input to the LNA.
To keep the powering scheme for the LNA flexible I have added some jumpers allowing the following configurations:
- unregulated or regulated DC input via 2.1mm jack directly at the LNA
- unregulated or regulated DC input through the coax connection via an external bias tee
While I was at it I designed the external bias tee as well. Both boards have the same size and the connectors in the same locations which allows me to use two more PCBs as a front and back panel for both devices.
The PCBs are designed to fit into an extruded aluminium case (Fischer Elektronik AKG 33 24 50).
These are both of the panels. I actually messed up when ordering one of them so one is red instead of black how I wanted it.
The project files can be found here.
I might post this on hackaday.io as well so make sure to check out my projects there!