This page covers how to setup a Hermes-Lite 2.0 and get it on the air! If you don't yet have a Hermes-Lite 2.0, please see the Releases wiki page. See the main Hermes-Lite Web Page for links to the latest schematics, BOM and production files. This page focuses on the fully assembled Hermes-Lite 2.0 Build8 units and later. For those building their own Hermes-Lite 2.0, please refer to the Hermes-Lite 2.0 Getting Started Kit page and the HL2 Build Completion video.

Power Supply and Connector

The Hermes-Lite 2.0 requires a 11 to 16 VDC power supply capable of supplying at least 2.0A. Although 11 to 16 VDC is supported, it is best to stay in the 12 to 13.8 VDC range. The supply input is protected against polarity inversion.

A 2.1mm center pin 5.5mm outer diameter barrel connector is expected to supply power to the Hermes-Lite 2.0; the positive terminal must be on the inside connection and the negative (ground) on the outer shell. If you don't have this connector, a inexpensive source of cable with the correct barrel connector is your local thrift store.

A low noise linear power supply should be used for best results, although many quality switching power supplies can be just as good. One way to test a power supply for noise is to measure the noise floor with no antenna using Quisk at maximum LNA gain of +48dB. A better power supply should result in a lower noise floor.

LEDs

There are several LEDs which provide information about the Ethernet link and board status. From left to right, when viewing the front of the Hermes-Lite 2, there are:

Ethernet Connector CN3

1. Green LED flashes when there is link activity. It is not necessarily activity to or from the Hermes-Lite 2, just activity on the link.
2. Amber LED lights solid when a link is established. It is the same solid color for both 100Mbs and 1000Mbs links.

Onboard LEDs D2, D3, D4, D5

These LEDs operate in two modes. When software has connected to a HL2 and enabled run, the HL2 is in run mode and is transferring data with the host PC. When in run mode, the HL2 LEDs indicate basic operation information. When no software has connected to the HL2 or the HL2 is first powered up, then the HL2 is in idle mode. When in idle mode, the HL2 LEDs indicate various status.

Run Mode

1. Run Mode or Idle Mode Network Subsystem

• Off. See the Idle Mode section below.
• On indicates that software has established a connection with the HL2 and set the HL2 to run mode.
• Flashing. See the Idle Mode section below.

2. Transmit

• Off indicates the HL2 is not transmitting.
• On indicates the HL2 is transmitting.

3. ADC Good Level

• Off indicates the HL2 ADC is seeing less than 75% of the available range.
• On indicates the HL2 ADC is seeing more than 75% of the available range. Adjust the LNA to see this LED on or flashing occasionally.

4. ADC Clip

• Off indicates the HL2 ADC is not seeing maximum values.
• On indicates the HL2 ADC is seeing maximum values. Adjust the LNA to to see this LED rarely flash. Occasional flashes, 1-5 very short flashes per second, are okay.

Idle Mode

1. Run Mode or Idle Mode Network Subsystem

• Off indicates a problem with the network subsystem such as no clock.
• On. See Run Mode section above.
• Flashing indicates the network subsystem is up and receiving the 25MHz ethernet phy clock.

2. IP Assignment

• Off indicates IP assignment failure.
• On indicates IP assignment via DHCP was successful.
• Flashing indicates IP assignment via APIPA or fixed IP was successful. If DHCP was unsuccessful, APIPA assignment will be made after 15 seconds from HL2 power on.

3. Link speed

• Off indicates no link or communication failure between the FPGA and U4 KSZ9031.
• On indicates 1000Mbs link established.
• Flashing indicates 100Mbs link established.

4. Radio Subsystem

• Off indicates a problem with the radio subsystem such as no clock from the AD9866 or U6 (VersaClock5 IC) was not programmed successfully.
• On indicates radio subsystem clock is up and operating at the correct frequency.

A summary of the LEDs meaning is in the picture below:

Software

For basic operation, the Hermes-Lite 2.0 is compatible with all software supporting the openHPSDR protocol 1; a specific configuration may be needed to enable the PA output and use the companion filter board. Please refer to the following chapters for detailed instructions.

Quisk and SparkSDR have additional support for the Hermes-Lite, such as setting the PA bias, and are recommended.

Quisk Setup

Please see the HL2 Quisk Setup video.

PowerSDR

Please see the HL2 PowerSDR Setup video.

RX Only Test and Use

As an initial test, you can connect your Hermes-Lite 2.0 directly to a long wire antenna and check out receive. Use the 6th pin from the end on the companion card connector for the long wire antenna. A picture without the male header is shown below.

Enclosure

For proper heat dissipation during full power transmit, you must use the recommended enclosure or other means of PA heat sinking. In all cases, do not operate the Hermes-Lite 2.0 if the onboard temperature sensor registers 60 degrees Celsius or higher.

The recommended and tested enclosure for the Hermes-Lite 2 is brand SZOMK model number AK-C-C12. A raw finish (no powder coating) is recommended for best thermal dissipation. These enclosures are available from AliExpress, Ebay and Amazon. Equivalent enclosures can be found by searching for "55*105*150 aluminum" or "55*106*150 aluminum" on Google. Different permutations of 55*105*150 and substituting x for * will lead to more hits. Note that some makers specify this enclosure at 106mm width and others at 105mm width. Some sources are:

• Amazon raw aluminum
• Ebay unknown finish, MOQ 10
• Ebay raw aluminum, MOQ 1
• AliExpress

Hardware

There is one hole in the PCB near the PA is to provide some mechanical pressure between the PCB and the enclosure slot to improve thermal dissipation. This is a 3.3mm diameter for standard fit of M3 size hardware. Other similar hardware, including M2.5, M2 or imperial, may be used.

A countersunk M3 screw is recommended to provide the mechanical pressure for thermal dissipation. This requires drilling a countersunk hole in your enclosure, but can be done in a way that keeps the bottom of the enclosure flat and smooth. To determine the correct position for this hole, you can slide in and position your Hermes-Lite 2.0 and then use a center punch through the PCB hole to mark on the enclosure where to drill the hole. Finally, apply some thermal grease on the bottom edge of the PCB near the PA that contacts with the enclosure to further improve thermal dissipation.

If you fully enclose the Hermes-Lite 2.0, you may need to add a small fan to provide proper ventilation. There are various plans for 3D printer end caps on github. One preferred way top operate a Hermes-Lite is to just use half of the recommended enclosure for thermal dissipation and no end caps. This allows easy access and viewing of the Hermes-Lite as well as decent airflow. This is what is pictured above.

The AD9866 may run hot in some builds of the Hermes-Lite 2.0 or at some locations. There are small heat sinks such as this or this which may be used to help cool the AD9866. The size of the AD9866 is 9mm by 9mm, so care must be taken to not short pins if any heat sink that size or larger is used. There are heat sink kits, intended for the Raspberry Pi, which can be repurposed for the Hermes-Lite 2.0. The larger heat sink can be used on the FPGA, and the smaller heat sink can be used on the AD9866.

There are other 4 mounting holes on near each corner which are for optional mounting in custom enclosures; these holes also have a 3.3mm diameter. Only M3 (or smaller) screws with smaller heads, such as cheesehead, should be used here as there is limited clearance.

Gateware Update

The assembled Hermes-Lite 2.0 comes with the latest gateware preinstalled. When the Hermes-Lite 2.0 gateware is updated, you may want to flash your unit with the latest version as described in the Updating Gateware page.

Calibration

The Hermes-Lite must have the proper bias current set for the PA. This is done at the factory. If you wish to reset this, please use Quisk, SparkSDR or this simple standalone program. Please see the HL2 Quisk PA Bias video for more details.

The forward and reverse power sense uses a default profile. For best accuracy, calibrate the power meter against a known reference with repeated readings. In Quisk this is under Config->Your Radio->Hardware->Power meter calibration. A similar calibration table can be made and/or used in Spark SDR.