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LNA for 70cm band

LNA for 70cm band

LNA for 70cm band

LNA consists of the matching transforming circuit, E-PHEMT SAV-541+, low noise integral voltage 5V type LP2992 regulator, 3rd order band-pass filter, biasing transistor circuit and power supply circuit by feeder reduction.

PCB sizes are 60×32 mm, it manufactured with 1mm thickness FR4 substrate material, plated vias and mask. MPL inductances of the filter are based on the pieces of the microstrip lines. BW (-3dB) < 40 MHz. Blocking bandwidth attenuation is -80 dB at 144 MHz. PCB layout is shown at Fig. 1

LNA 70cm SAV-541 PCB

Fig. 1 LNA-70cm-SAV-541 PCB

The housing of the LNA is manufactured from aluminum plate D16 by milling on CNC machine. There are different options of the housing for the N-type socket and SMA socket connectors. Power supply is designed through the feeder or capacitor that mounted on the surface of the housing. Power supply voltage is 8 – 13 V.

Measurements results are shown below:

Amplitude-frequency response of the LNA 70cm SAV-541+, BW = 36 MHz

Fig. 2 Amplitude-frequency response of the LNA-70cm-SAV-541+, BW = 36 MHz

NF measurements results

Fig. 3 NF measurements results

Compared with the LNA based on chip SPF5122z, the designed LNA is inferior in dynamic range, but much better by noise figure. The designed LNA is recommended for EME tests and everyday work in the air in the absence of strong interference.

Technical specifications of the LNA-70cm-SAV-541+

  • Model: LNA-70cm-SAV-541+
  • Active element: SAV-541+
  • Gain: 18 dB
  • Noise Figure: < 0.3 dB
  • Output IP3: 33 dBm
  • BW(-3 dB): < 40 MHz
  • DC voltage: 8 – 13.8 V
  • DC current: 40 mA
  • Impedance: 50 ohms
  • RF connectors: N-female или SMA-female
  • Dimensions: 110 mm x 43 mm x 20 mm (with connectors)
  • Weight: 0.15 kg

Package includes

  • 1 x LNA-70cm-SAV-541+