The Hermes-Lite Project

The Hermes-Lite project aims to design and market a software defined radio transceiver that directly samples the antenna with an analog to digital converter, is completely controlled by Ethernet, and costs about USD 200. It is contained on a single 10x10 cm PCB. The standard enclosure is 10x15 cm and the extra space is meant for filters, transverters and other add-on boards. The Version 2 hardware includes a 5 watt push pull MOSFET amp as well as a 40 mW low power output. Since the FPGA and the digital up/down conversion is on-board, a sound card is not used for radio samples, and is only used for the microphone and for playing radio sound.

Filter Board by James Ahlstrom, N2ADR

The Hermes-Lite 2 is ready to use at 40 mW output or at 5 watts output as an exciter for a subsequent RF amplifier. But to use the 5 watt amp as a complete QRP rig, it needs transmit low pass filters. I designed a 5x10 cm filter board that clips to the main board and fits into the standard enclosure. It has transmit low pass filters for 160 to 10 meters, and a 3 MHz high pass filter for receive. The filter board is automatically controlled by the Hermes-Lite main board. The filter is currently being tested, so is not yet available. The schematic of the filter board is available.

Here is a photo of the filter board. The 2x20 pin header has opposite pins connected together with the small PCB shown. The 2x20 header then plugs into two 1x20 pin headers on the Hermes-Lite and filter boards to connect them together.

filter board

This photo shows the filter board and Hermes-Lite installed in the standard enclosure.

filter board

March 2018. More to come...........