This simply low noise preamplifier module with 2SC5551 transistor is very useful device. You can use it as high IP preamplifier for RX antennas, buffer amplifier or small driver in your own design You can simply add this device to your hardware. Gain is up to 18 dB and there is also built in variable ATT. You can easy set gain as high as you need! Amplifier has got low noise - lower than 2 dB up to 50 MHz and around 2.2 dB at 150 MHz. As well you can set right transistor bias with multi turn potentiometer. Two relays offer bypass switching if there is no power supply.

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Applications
Parameters
Schematic
PCB
Tunning and Jumper settings
Article
Product details

Applications

- Designed to be built-in your own hardware - you can download KiCAD library
- High IP, Low Noise RX preamplifier - RX antennas
- Buffer amplifier
- Driver amplifier

Parameters

- NPN transistor 2SC5551A
- Supply voltage 12 to 14 V
- BIAS current 10 to 70 mA
- Supply current up to 180 mA - include relays
- Gain up to 18 dB
- Low Noise Figure (NF) 1.2 dB (20 mA 50 MHz)
- Low Noise Figure (NF) < 2 dB (60 mA 50 MHz)
- Low Noise Figure (NF) 2.3 (20 mA 150 MHz)
- REAL IP3 34 dBm

Example of implementation to the RX Audit SDR switch

Example of implementation in your own design

Gain 10 dB 0.5 MHz to 50 MHz

Gain 15 dB 0.5 MHz to 50 MHz

Gain 18 dB 0.5 MHz to 50 MHz

Bypass 0.5 MHz to 50 MHz

Schematic

PCB

Tunning and Jumper settings

1. Current check point

- disconnect jumper JP1
- connect mA meter there (200 mA scale is fine)
- connect supply voltage to the controller (13.8V)
- switch preamp ON by front panel switch

2. Bias Current set

- turn the resistor trimmer BIAS and set bias current - it should be around 40 mA
- then connect jumper JP1 back

3. Variable ATT

- with the resistor trimmer ATT you can set amplifier gain as you need from 0 to about 18 dB
- turn the ATT (R_ATT1 201) - multi turn trimmer

Article

ℹ Read article from W7UIV.