Tagged: LNA4ALL

New Inline Low Noise Amplifier Design for the RTL-SDR and RTL-SDR Power Injector Modification

Recently a reader named Fabio wrote in to let us know about his new Low Noise Amplifier (LNA) design for the RTL-SDR. Fabio writes that his design is similar to the LNA4ALL, but is small enough to fit inline with an antenna. An LNA can help improve reception especially if you have long runs of coax cable between the antenna and RTL-SDR.

Fabio’s design requires that the LNA be powered inline with a bias-tee power injector circuit which can be easily built from an inductor and capacitor. But instead of building an external bias-tee he modified the RTL-SDR dongle itself to provide the required 5V output power from the USB bus. He writes that with this modification the RTL-SDR could also be used to power an active antenna.

Fabio has also released his circuit designs on his GitHub page for free.

Inline LNA for the RTL-SDR
Inline LNA for the RTL-SDR
RTL-SDR Bias-T Modification
RTL-SDR Bias-T Modification

LNA4HF Now for Sale Plus Review

Back in November last year we posted about the possibility of an “LNA4HF” low noise amplifier (LNA) for the HF bands being made available for sale. The LNA4HF is now available for purchase.

The LNA4HF is a low noise amplifier with built in low pass filter that runs on a 6-12 V power supply and covers a frequency range of 150khz to 30MHz, with a 18-20 dB gain and 1-2 dB noise figure. It costs 20 Euros. The low pass filter can also be disabled with a small board modification which will allow the amplifier to be useful at up to 2 GHz.

LNA4HF
LNA4HF
LNA4HF Block Diagram
LNA4HF Block Diagram

Akos from the SDR for Mariners blog has reviewed the LNA4HF on his latest post. His results show that the low pass filter significantly reduces broadcast FM interference and that the amplifier also increases signal strength by around 20 dB as advertised.

LNA4HF Comparison
SDR for Mariners LNA4HF Comparison

LNA4HF: Interest Check

Adam, the manufacturer of the LNA4ALL low noise amplifier designed for use with the RTL-SDR, and similar software radios is putting out an interest check for an LNA4HF product. The LNA4HF will be a low noise amplifier with low pass filter designed to work with an existing RTL-SDR upconverter. It will amplify signals between 2 Mhz – 30 Mhz by 16.5dB.

Adam will make a batch once there is interest for at least 50.

lna4hf
LNA4HF
LNA4HF block diagram
LNA4HF block diagram

LNA4All Low Noise Amplifier Review

Over on the SDR for Mariners blog, author Akos has reviewed the LNA4All low noise amplifier. The LNA4All is a 25 euro amplifier designed to improve the performance of the RTL-SDR.

His results show that the LNA works very well. Akos tested the LNA4ALL on multiple frequencies and applications including commercial radio, airband, NOAA weather satellites, AIS and ADSB. As an example of the improvement, his ADSB reception was improved from 83km to 94km. In his review Akos also shows how to provide power to the LNA, and puts the LNA through some simple stress tests.

LNA4ALL Airband Performance