137.5 MHz NOAA/APT Filter/Preamp
Uputronics filtered preamps for improved reception on 137.5Mhz.
This is a cost effective SAW based unit which give excellent performance gains.
All Uputronics preamps are compatible with most USB SDR Dongles such as the Airspy. You can power them from either bias tee (This item is 100% compatible with the Airspy bias-tee) or a simple USB minicable (Purchased separately). Bias tee/USB voltage is 5V max.
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. 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. 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, which does increase the overall noise figure of the unit to 0.75dB. Connectors are SMA female both sides.