VK5QI has designed a legendary low noise preamplifier for HAB tracking. M0UPU has improved it and sells them in his HAB Supplies shop for a very reasonable price. However here in the US balloon tracking mainly happens on APRS in the 2 m band. Unfortunately there are just a very few SAW filters available at this frequency and of course they have a completely different footprint. Therefore it was necessary to design a new PCB in order to build one for the 2 m range. The result of this 2 m version can be seen in the pictures below. As usual I gave it a name that’s typical for Texas: “Mosquito”. I was stitched several times through the design phase an I thought it was an appropriate name considering the almost inaudible high pitch tone a mosquito makes while in the descent phase before landing.
The SAW filter TriQuint Semiconductor 856929 is available from Mouser and I ordered twenty PSA4-5043+ amplifiers directly from Mini-Circuits. The ferrite beads were replaced with TDK MPZ2012S102A (Mouser).
I’ve pushed the Eagle files to my GitHub: https://github.com/tkrahn/mosquito
The Mosquito1 amplifier seems to perform great with a RTL-SDR but I haven’t made any serious measurements yet.