Differential amplifier and balun/power inserter board, RJ45 to BNC to interface 4 pair cable to coax. 100 ohms to 50 ohms.
This amplifier is designed to be used with a 1 meter loop antenna. It works well from DC to 30MHz. It uses 12 to 14vdc power. The transistors have been matched for performance in each stage to obtain a good differential effect, reducing common mode noise. This combination provides a shielded RJ45 on the balun board to ground the FPA cable shield at the receiver, but the RJ45 is not grounding the shield at the LNA. This is usually the best configuration to reduce common mode currents in the system. The antenna input is diode limited to 0.7v and has VHF/UHF filtering to help protect the amplifier from very strong signals and static noise.
This Differential LNA is providing signals to a websdr using a 1 meter loop antenna like the one advertised elsewhere on this site. You can listen to the websdr to evaluate the amplifier @ http://ka7u.no-ip.org:8075
These boards are custom made by K7RHB and KA7U. You can ask about having specific things concerning these amplifiers and we may be able to adjust the circuits to your needs.
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