This is a cost effective SAW based unit which give excellent performance gains.

All our preamps are compatible with most USB SDR Dongles such as the RTL USB, Airspy, Fun Cube. You can power them from either bias tee (This item is 100% compatible with the Airspy bias-tee) or a simple USB minicable (Not Supplied). A regulator is fitted as standard which means the bias-tee voltage input range is 5V to 26V. USB input is 5V.

This unit is a small filter and preamp designed to go between a software defined radio receiver and an antenna. Using a SAW bandpass filter and a low noise amplifier (LNA), it stops out of band intermodulation while providing additional gain for increased sensitivity. The LNA is before the SAW filter. This particular model is tuned for use with 137.5MHz. To block strong commercial FM signals a high pass filter is installed before the LNA.

The LNA used is a MiniCircuits PSA4-5043+ which provides at least 21dB of gain @ 137.5MHz. To stop out of band intermodulation an 137.5MHz SAW bandpass filter, which has a 7.6MHz bandwidth is also present. The insertion loss of this filter is approximately 1.4dB.  Connectors are SMA female both sides.

Since March 2020 we have fitted improved SMA female connectors for antenna input and radio output to address the issue of the SMA barrels coming away. Also the Bias Tee regulator kit is now fitted as standard

See related items for a suitable USB Type A to Mini B Cable to power the unit.

Documentation

137.5MHz Filtered Preamp Datasheet
CE Certificate of Conformity
UKCA Certificate of Conformity