SQUARE SDR

That it is possible to create a modern SDR with small dimensions proves SQUARE SDR. Its construction includes a PCB with dimensions of 100 x 100 mm, on which a receiver, transmitter, final stage, filters are integrated together HPFaLPF.

René OK1XTG came up with the idea to combine the existing SDR transmitter project Hermes-Lite 2 (HL2) with HPF and LPF filters for amateur radio bands from 160 to 10 m - N2ADR

Basic specifications of SQUARE SDR

• Power supply voltage 11 - 15 VDC
• Frequency range RX 100 kHz - 30 MHz / TX 1.8 - 30 MHz (amateur bands 160 - 10 m)
• Integrated HPF and LPF filters (N2ADR)
• RF output power max. 5 W
• power consumption during reception without the fan on approx. 3.6 W
• transmit power (CW 5 W) without the fan on approx. 18 W
• 12-bit ADC/DAC
• Gigabit Ethernet
• External frequency reference I/O
• LED relay indication on the board
• SWR meter (PSV)
• Internal fan 80 x 80 mm. From version PCB 05 with independent control, which is not in conflict with PWM Band Volts
• Integrated serial interface TTL 3V3 voltage including pull-up resistors on data lines. Connection of Hardrock-50 (DB-9 ACC connector on the rear panel)
• Integrated SMA connector (RX) for connecting the 'Pure Signal' probe
• Protection and indication of incorrect power supply voltage (undervoltage) or incorrect connection (reverse polarity)
• Full compatibility with SW, GW and functionality with Hermes-Lite 2
• 4-layer PCB, dimension 100 x 100 mm
• single-sided SMD assembly
• overall external dimensions in the box 126 (w) x 46 (h) x 110 (d) mm
• Approximately 490 g

Mechanical construction

Foundation of the mechanical construction is an aluminum profile with dimensions of 120 x 40 x 98 mm and a wall thickness of 4 mm. Holes for mounting side panels, PCBs, and fan are machine-drilled into the body. On the front side of the aluminum profile, there are plastic parts into which the side panels are inserted. Side panels are implemented as PCBs with quality printing. On the inner side of the side panels PCB, copper is left, which is electrically connected by four screws in the corners to the aluminum profile. All of this ensures sufficientshielding for the operating frequencies of the SDR itself. The entire construction also provides sufficient cooling for continuous operation.

Alternative power connector

An alternative for permanent installation in demanding climatic conditions was developed to mount the PCB with a more robust connector for the power supply voltage (P2). The connector type used is PTR STLZ1550/2G-3.81-H-GREEN with a counterpart PTR AKZ1550/2-3.81-GREEN.

Putting SQUERE SDR into operation

For maximum and optimal utilization of SQUARE SDR hardware, perfect knowledge and setting of the operator program (console) controlling SQUARE SDR is required. If it is not set and operated correctly, some parts of the device may not work correctly or at all. SQUARE SDR is compatible with all software supporting the openHPSDR 1 protocol. Thetis is currently probably the most sophisticated.

In the operator program (console), SQUARE SDR is selected and connected as 'HERMES LITE', 'Hermes-Lite'. Therefore, all published settings for HL2 can be used.

This SQUARE SDR design was not created to make a cheap clone of Hermes-Lite 2, but to improve, simplify, and overall streamline the design for single-purpose use. It is not a kit. The original concept of Hermes-Lite 2 was brilliantly designed by Steven KF7O and I admire it for that.

To order SQUARE SDR, visit https://www.wideservis.cz/square-SDR/