Procure Parts

Partially Assembled Kits

Currently, the easiest way to obtain a Hermes-Lite is to buy one of the partially assembled kits. These kits are only made available when there is enough interest. Check and post to the google groups to inquire about partially assembled kit availability or for builders to help build your Hermes-Lite. Here is the BOM for the kit.

The partially assembled kits have the most difficult to solder on surface mount components presoldered. You must complete the kit which requires soldering of 0805 size SMT components and winding your baluns. Please read over the instructions starting from C19 and C20 and on before ordering a kit to make sure you feel comfortable with the assembly requirements.

Below is a picture of what comes in a partially assembled kit. All parts except the BeMicro, Computer and WaveShare ethernet card (if needed) are included.

DIY

The Hermes-Lite is completely open hardware and open source. All the information you need to make a Hermes-Lite is available on this github site. Beware that there are some fine pitched SMT components that can be difficult for a hobbyist to solder.

If you already have some parts, perhaps samples from Analog Devices and SamTec, and would like help with assembly, see this post from Duane Brantley. He does this type of assembly regularly and is willing to help out. You can contact him at dbrantley @@ gmail.com. (Replace @@ with one @.)

BeMicro CV, SDK or CV A9

The Hermes-Lite requires an Altera FPGA BeMicro CV, BeMicro SDK or BeMicro CV A9 card for digital signal processing and ethernet interface. These cards are heavily subsidized by Altera and Arrow and are currently the most cost effective solution. They can be purchased directly from Arrow and found sometimes on ebay.

Unlike the BeMicro SDK and the BeMicro CV A9, the BeMicro CV does not have a built-in ethernet interface. Compared to the SDK, the BeMicro CV is less expensive, utilizes a newer Cyclone part and has additional IO. To use a BeMicro CV with the Hermes-Lite, you must also purchase a Waveshare DP83848 Ethernet Board. These are available directly from the manufacturer or on amazon or ebay. If you need this board quickly, check where it will be shipped from. To connect the ethernet interface to the BeMicro CV, you will need a WaveShare2BeMicroCV swizzle board. This board is included in the partially assembled kit. The CV A9 is more expensive and more powerful than the CV, allowing a larger number of receivers.

Note that there are other members in the BeMicro family. Currently, the CV, SDK and CV A9 are tested to work with the Hermes-Lite. The MAX10 does not have enough programmable resources.

Printed Circuit Boards

When in stock, you can purchase printed circuit board sets from Tindie. These sets are lead free. The smallest board uses a HASL finish and the two larger boards are ENIG finish.

Printed circuit board sets are also available from OshPark. You will at least need a Hermes-Lite board v1.21 and a basic frontend v1.0. If you will be using a WaveShare ethernet interface, then you will need a WaveShare2BeMicroCV swizzle board.

The Hermes-Lite was designed with the open source KiCad EDA Software. Schematics and PCB layout files are shared on github. Gerber files are also hosted on github and may be submitted directly to iTead Studio, Hackvana or Elecrow for manufacturing.

The Hermes-Lite has a modular design. Various RF frontends are possible. To get you started with your own frontend, take a look at the template or basic frontend designs again on github.

Discrete Components

All the necessary discrete components to build a Hermes-Lite are listed in the Hermes-Lite BOM file. Most parts are available from a single supplier, Digi-Key. An alternative supplier is Mouser. International builders may consider LittleDiode. A good resource to find stock of some components is FindChips.

The SamTec MEC6-140-02-L-D-RA1 connector that connects the BeMicro to the Hermes-Lite is often the hardest part to obtain. You can request a sample or purchase this part directly from SamTec. Search for "MEC6-140-02-L-D-RA1" on the SamTec site.

Sometimes you can receive a sample of the AD9866 directly from Analog Devices. Click on the "Sample & Buy" button found on this page.

The discrete components required for the basic frontend are listed in this basic frontend BOM. A good source for the binocular cores is Kits and Parts.

The single discrete component required for the WaveShare2BeMicroCV swizzle board is listd in this BOM. Two commonly available single-row 6-pin Arduino headers will also work.

Tools

You will need a good soldering iron with a fine tip to build the Hermes-Lite. Hot air is also useful. The "852D+ SMD soldering rework station" sold on ebay or amazon is recommended.

A toolset for surface mount rework or jewlery with fine tweezers is helpful. Search for "SMD SMT tools" on ebay to see what is available.

Flux and desoldering braid is very valuable.

Many hobbyist use modified toaster ovens to do reflow surface mount assembly. If you google "toaster oven" and "surface mount" you will find a wealth of information. It is possible but not required to assemble your Hermes-Lite this way. The challenge is to get the right amount of solder paste on the fine pitched pads. A laser cut stencil can help. Early experiences with thin inexpensive stencils showed that these stencils were too thin for the fine pitch of the AD9866 or BeMicro connector.

Hermes-Lite Assembly

Partially Assembled Parts

The BeMicro connector, PCIe connector, AD9866 and Oscillator are presoldered on to the Hermes-Lite in the partially assembled kit. You must solder these on if you are are building the entire Hermes-Lite. Unfortunately, these two connectors and AD9866 can be extremely difficult to solder. It can be done by hand, but most of the time is spent making sure you have solid solder joints and no shorts. I do not have much good advice to share here and hope that we will gather best known practices as more people build a Hermes-Lite. There are many examples of people soldering surface mount components on youtube. It is helpful to watch some of these before starting. Below is a collection of tips.

1. Copious amounts of flux makes it easier to solder. As you can see in later pictures, the AD9866 is covered in flux.
2. Dragging a ball of melted solder with a fine tipped soldering iron or a hoof tip across the pins can work. This is called drag soldering. Search google or YouTube for examples.
3. Hot air can be used to reheat a section of pins and clean things up.
4. Desoldering braid is useful when you have shorts or to remove excess solder from SMT components.
5. A jewler's loupe can help you spot shorts.
6. Solder will wick up the BeMicro connector pins so look for shorts farther away than just the pads.
7. Beware of thermal shock. Don't heat or cool the AD9866 too quickly. Take a look at reflow temperature profiles online to see what is recommended.
8. For the AD9866, try to keep the surface as flat as possible. Do not tin one pad and then solder on as the AD9866 might not be flat. Position the AD9866 and then solder a few pins to tack it in place before dragging a side.
9. Hot air can be too forceful and blow the AD9866 out of position. A pointer weight can be constructed to hold the chip to the board during reflow with a hot air hand tool.
10. The large hole on the back and seen in the picture below is very helpful to solder the AD9866's thermal pad. It can take a bit of time for a soldering iron to heat this pad up. When doing so, make sure you do not get the AD9866 too hot or hot too quickly as the actual silicon chip inside the package is about at this location.
11. If you are not starting from the partially assembled kit, it may be easier to solder on the PCIe connector last as then the board will lie flat during assembly.
12. Cleaning flux residue from the assembled board is recommended even if you have used a "no-clean" flux. An easy way to do this is to use a soft bristled toothbrush and anhydrous isopropanol (99% isopropyl alcohol). You can usually find this at a pharmacy, but it is hard to find in some states. The fuel antifreeze product "Iso-Heet" is available at most auto parts stores and is the same thing. Regular Heet is methanol and will also work. Alternate with an alcohol scrub and water rinses until the board is clean. Give the board a final rinse with distilled water or alcohol and dry thoroughly before applying power.

In the picture below, note the orientation of the AD9866 and oscillator. The AD9866 is oriented so that the printing is rightside up as seen below. Pin 1 of the AD9866 should be in the upper left corner and is marked with an asterisk. The oscillator is oriented so that pin 1, marked with a dot, is in the upper right corner, with writing upside down as seen in the picture.

Note the solder connection to the AD9866 thermal pad.

C19 and C20

These two capacitors are 10 uF filter capacitors on the main 3.3V power in. As shown in the picture below, they are the larger 1206 size, black and in a clear strip. There is one extra included in the kit.

One way to solder two pin surface mount components is to first tin one pad with solder, then use tweezers to slide the component in while reheating the solder. After that you can solder the other side and revisit the first pin to make sure it is nicely soldered. In the picture below, note the two tinned pads and tweezers.

The picture below shows C19 and C20 solderd in place. These are polarized capacitors. Note the orientation with the bar at the bottom.

C25

At the top of the last picture, you see C25. This is also a 10 uF capacitor but is not polarized. One extra is provided in the kit. These are also the larger 1206 size, but tan and in a clear strip. The picture below shows C25 soldered in place.

R1

You may have noticed that resistor R1 is already soldered. The wiki assembly order is slightly different from the original picture order. This is a 1.6K resistor in the smaller 0805 package. Two are included in the kit. They are in white paper tape with a red stripe. The picture below shows where R1 is soldered in place.

J5 and J8

At the top of the last picture, you can see two copper wire jumpers. These can be used for J5 and J8 or standard 0.1 inch jumpers will fit. J5 connects PWREN# to ground which signals the BeMicro SDK to disable the USB and take power from the Hermes-Lite. It has no effect on the BeMicro CV or CV A9. J8 connects the Hermes-Lite 5V to the BeMicro 5V. This is the typical configuration if you would like to supply the FPGA board thru the Hermes-Lite.

J4 or J3 and J6

At the top of the last picture, you can see the size 0805 0 Ohm resistors used for jumpers. They are in white paper tape with a yellow stripe. At this point, you must decide whether your Hermes-Lite will connect to a BeMicro CV, SDK or CV A9. These jumpers route clocks to different dedicated clock pins on the CV, SDK and CV A9. Unfortunately, they do not share all dedicated clock pins.

• for a BeMicro CV, only J4 must be soldered as shown below.

• for a BeMicro SDK, jumpers J3 and J6 but not J4 must be installed. The example board is built for a BeMicro CV, but the locations for J3 and J6 are identified in the picture below.

• for a BeMicro CV A9, only J3 must be installed.

v1.2 Builders

If you are building a v1.2 Hermes-Lite, there is no J6 for the BeMicro SDK. Instead, you must run a wire from the pad of R4 around the board to TP1 as seen in the two pictures below.

C5,C6,C7,C8,C12,C13,C14,C21,C26,C27,C30

The strip of 1 uF size 0805 capacitors in the longer clear tape is seen at the top of pictures in the previous section. These are primarily used as decoupling capacitors for the AD9866. The picture below shows where these 11 capacitors should be placed on the bottom side of the Hermes-Lite. Note that the large hole to solder the thermal pad removed the silkscreen for C5 and C8. These are labeled in red on the photo.

C17 and C18

These are also 1 uF capacitors as in the last step but placed on the top side of the Hermes-Lite as seen below.

C15,C16,C23,C24,C31,C32

These are 0.1 uF decoupling capacitors as seen at the top of the last picture. They are in the longest white tape strip with no color marking. The placement on the top side of the Hermes-Lite is shown below.

C1,C2,C3,C4,C9,C10,C11,C22,C28,C29,C34,C35,C36

These are also 0.1 uF capacitors as in the last step. There placement on the bottom side of the Hermes-Lite is shown below. The silkscreen for C9 and C11 is missing but labeled in red in the photo.

FB5,FB6,FB7,FB8

At the top of the last picture ferrite beads are shown in white tape with a black stripe. These are used for noise suppression. The picture below shows where four of these beads are placed on the bottom side of the Hermes-Lite.

FB1,FB2,FB3,FB4

Before soldering the last four ferrite beads on the top side, there are a few simple tests to make. With an ohmmeter, make certain that there are no shorts between the top pad of FB1, FB2, FB3 and FB4 to GND. The top pad is the pad nearest to the silkscreen lettering. Any of the three through holes near the GND on the silkscreen may be used as GND. Next, make sure there is no short between any two of the top pads of FB1, FB2, FB3 and FB4. This checks that all power supplies are indeed separate and not shorted to ground. If you do find a short, use the schematic and the still supposedly isolated power supplies to help find the short.

The picture belows shows the top pads and placement of FB1, FB2, FB3 and FB4.

Power Supply

To power the Hermes-Lite, you must supply 3.3V. If you are powering the BeMicro from the Hermes-Lite, you must also supply 5V. Future power amplifiers will use the 12V. Here are three common ways to power your Hermes-Lite.

Power Hermes-Lite from BeMicro CV or BeMicro CV A9

The BeMicro CV and CV A9 have a 5V barrel connector and onboard switching regulator for 3.3V. This can be used to power both the BeMicro and Hermes-Lite as the BeMicro CV and CV A9 are designed to power peripherals via the GPIO expansion headers. (Unfortunately, the BeMicro SDK does not supply enough current to power itself and the Hermes-Lite.) To power the Hermes-Lite from the BeMicro CV or CV A9, add J7 as shown below.

Power BeMicro from Hermes-Lite

The Hermes-Lite has through holes for GND, 3.3V, 5V and 12V as seen in the previous picture. You can directly solder wires to these holes. Anderson powerpole connectors or a cut SATA power Y splitter can be used to connect to various power supplies.

The Hermes-Lite v1.21 supports an edge-mounted 6x2 0.1 inch spaced standard header. You can add a male or female connector for power with this. All connections on the bottom side are GND, and the two pads per voltage can be visually traced on the top side. See this project for an example.

When powering the BeMicro from the Hermes-Lite, J8 must be shorted as described in the build process so that the Hermes-Lite 5V is connected to the BeMicro's 5V. Do not short J7 which connects the two 3.3V supplies if powering from the Hermes-Lite. The Hermes-Lite will have its own 3.3V and the BeMicro will generate 3.3V from its onboard switching regulator.

Power Hermes-Lite and BeMicro Separately

Remove J8 and J7 if you want to power the Hermes-Lite and BeMicro separately. If you are using a BeMicro SDK, also remove J5.

Unpopulated

The following components should be left unpopulated in a standard Hermes-Lite build but are included in the kit if needed for later modifications.

• R2 and R3 are termination resistors for the AD9866's balanced RX and TX respectively. 200 Ohm resistors are supplied with the kit.
• J1 and J2 are 0805 0 Ohm jumpers to experiment with a higher power but linearly degraded TX mode of the AD9866. See the AD9866 datasheet for details.
• R4 and R5 are termination resistors for the AD9866's digital clocks. 47 Ohm resistors are supplied with the kit.
• J3 and J6 or J4 select clocking for the BeMicro CV, SDK or CV A9. Either J3 and J6 (BeMicro SDK) or J4 (BeMicro CV) or J3 (BeMicro CV A9) should be shorted but never all.
• C33 and U2 are an extra serial EEPROM to support IP address storage. This is included as a backup in case the IP can not be stored on the main BeMicro EEPROM. Currently the firmware does not support C33 and U2. They are included with the kit.

Basic Frontend Assembly

The basic frontend BOM lists the required components for the basic frontend. These components are included with the kit.

T2 and T1

The binocular core baluns on the basic frontend are wound exactly as those found in the softrock kits. Please see here, here and here for more help.

As the basic frontend schematic indicates, T2 is wound on a BN-61-2402. Use ~6 inches of the included enamel wire for the 4 turn unifilar winding and 2X8 inches for the 6 turn bifilar winding. The 6 turn bifilar winding results in 12 total windings. Scrape or melt some enamel off the wire ends to identify the unifilar pair and the two bifilar pairs. Below is T2 with the 3 pairs identified, a pair on the left, a pair in the middle and a pair on the right.

For both T1 and T2, the unifilar pair is nearest the BNC connector as shown below. The two bifilar pairs follow in any order. When installing the balun on the PCB, there should be no crossing of wires from one side to another. All the wires on one side feed through holes on one side of the footprint. If one of the bifilar pairs is reversed, it can result in no power transferred as canceling occurs.

The enamel wire included in the kit (32 AWG) has insulation that will melt when soldered. Solder the wires before they are trimmed. Once soldered, flex the wire back and forth until it breaks at the solder joint. Reheat the solder joint and apply abrasion to the wire with the tip of the soldering iron. Check with an Ohmmeter that each pair is a short.

T1 is also wound on a BN-61-2402. Use ~10 inches of the included enamel wire for the 6 turn unifilar winding and 2X6 inches for the 4 turn bifilar winding.

J1 and J2

If desired, the shields for the TX or RX connector can be isolated from the system ground by leaving J1 and J2 open. The default is to short J1 and J2 as seen below.

D1

In the last picture, note the short piece of black tape with a single TVS diode. This is easy to lose so you may have to look carefully in your package to find it. D1 is soldered at the location shown below without regard to orientation.

FB1

In the last picture, the white tape with black stripe identifies the ferrite beads, also used in the Hermes-Lite. FB1 is soldered in place as seen below.

R1

In the previous picture, 0 Ohm jumpers are identified in white paper tape with a yellow stripe. Install R1 as shown below. This resistor is provided to limit the current used by the TX if desired.

C1,C2,C3,C4

The previous picture identifies 0.1 uF capacitors in white paper tape with no stripe. Install four capacitors as seen below.

P1 and P2

Solder P1 and P2 to the frontend board as shown below. It can take some time for the soldering iron to heat the shell so that solder flows. The shell can get quite hot.

Unpopulated

The following are unpopulated on a standard basic frontend build.

• CN2 is a breakout connector for power and 8 digital signals from the Hermes-Lite.
• CN3 is the alternate low power TX output. This should have better linearity than the default TX output.
• CN4 and CN5 are extra connections to analog ground.

The basic frontend includes prototyping area including places for standard edge mounted 0.1 inch dual-row headers on two sides.

WaveShare2BeMicroCV Swizzle Board Assembly

The BOM and schematic for the WaveShare2BeMicroCV swizzle board are found here.

The WaveShare ethernet board and CN1 (included in kit) are soldered to the swizzle board as shown in the following two pictures.

Final Modular Assembly

The VCIO jumper in this picture is for 2.5V. The CV manual is incorrect and has the 2.5V and 3.3V settings reversed for J11. Please use a volt meter and measure that 3.3V is being connected by J11.

CW Key Connection

To reduce latency, the Hermes-Lite has a CW key input pin on connector CN3. When grounded, this pin will cause the Hermes-Lite to transmit without need of any processing by the PC. The Hermes-Lite will shape the transmission (3 ms rise to and fall from full power) and engage the transmitter at the selected frequency. There is also a CW key output provided to drive a LED or external sidetone generator.

Shown below is a possible wiring for a CW key connection. Pin 1 is ground, pin 3 is the CW input pin. Note that a pull-up resistor of 6K-10K to 3.3V may be required on this input. The FPGA is set to have a weak pull-up which may be sufficient. VCC is 3.3V on the Hermes-Lite and all connections must work with 3.3V. When the CW key is pressed, pin 3 should be connected to pin 1.

You may also choose to put the pull-up resistor on your key or keyer. If you need 3.3V, note that pins 9, 10 and 12 of CN3 are S1, S2 and S3 respectively. S1, S2 and S3 are through-hole pads that you can configure to powerk ground or other signals via jumpers.

Pin 5 is a CW key output indicator. It is high (3.3V) when the key is pressed and can be used to drive a LED or external sidetone generator.

Hermes ADC78H90CIMT Support

The Hermes includes an ADC78H90CIMT 8-input general purpose A/D converter for various measurements. For experimentation, the Hermes-Lite incudes the SPI interface to connect to this A/D converter externally on connector CN3. Shown below are the required four connections. Please refer to the Hermes schematic for more details.

Debug

No Heartbeat

No heartbeat LED flashing when the Hermes-Lite is connected to your BeMicro and the firmware is installed indicates that the Hermes-Lite is not supplying a clock to the BeMicro. (When no Hermes-Lite is present, the BeMicro SDK and CV switch onto a synthetic clock, see [here] (https://github.com/softerhardware/Hermes-Lite/wiki/Software#test-mode) for the BeMicro CV A9.) Use an oscilloscope or even a voltmeter to check that there is a clock at pin 3 of X1 and the common pad for J3 and J4. A DC voltage of ~1.6V on a voltmeter indicates a reasonable clock. If you do not see a clock, check the soldering of the AD9866 and X1.

No DHCP

If DHCP fails and no static IP is assigned, the Hermes-Lite will default to "IPIPA" and use the address {8'd169, 8'd254, This_MAC[15:0]}.