The four boards in the board stack are shown here:

You will need these tools:

• Safety glasses (to protect eyes while soldering or trimming leads)
• Soldering iron and solder (I use lead-free solder, but leaded solder is easier to work with)
• Small Philips screwdriver
• Small flathead screwdriver
• Needle nose pliers (to bend leads and hold parts)
• Side cutters (to trim leads)
• Drill and drill bits, sandpaper or emery cloth (if you are making the dipole or monopole antenna)

Useful to have:

• Liquid flux to solder SMA connector

Video

Here is a video of the antenna install and board stack:

Checklist

The BOM has a sheet "By Steps" which lists the parts needed for each step in order. http://cubesatsim.org/bom If you have a Google account, you can make a copy of this spreadsheet ("File" then "Make a Copy") and check off each part as you install it.

8.1 Antenna Install

Before we build the board stack, we need to install our antenna. You can build a SMA antenna (left), a tape measure dipole (center), or a tape measure monopole (right) as shown here:

The images in this section show the Main V1 board, but the instructions still apply generally to attaching antennas to the v1.3 STEM Payload board. However, for the V2, there will be two SMA antennas.

SMA Antenna

To connect antennas using SMA connectors, you just need to solder two SMA connectors onto the top and bottom of the STEM Payload board.

This part takes a lot of heat, so make sure your iron is set to high heat. You might also want to apply liquid flux to the pins to help solder it.

Which gives this:

You will connect SMA coax cable and a rubber duck antenna to each SMA connector when you put the frame together. Note that there are two lengths of SMA coax cable that will work, but the shorter (90mm) is more convenient.

Tape Measure Dipole Antenna

Alternatively, you can make a tape measure dipole or monopole (vertical) using these parts:

• 1/4" Tape measure (3/8" and larger ones work too)

• Two metal screws, nylon will not make electrical contact

• Two nuts, nylon or metal since it is just a spacer

Extend all the tape out of the measure before cutting or the remaining tape will retract inside and you will need to break open the case. Be careful of sharp edges, and put electrical tape over the cut edges immediately.

For the dipole antenna, you will need two 1/4 wavelength lengths of tape measure, each with a hole drilled in it. Drilling the hole can be tricky, so drill the hole first, then cut the tape to length. Also, using a punch or small screwdriver to dent the tape in the middle can help prevent the drill from moving around. Also, start with the smallest drill bit you have, ending up with a 3/32" drill bit. It doesn't matter if the hole is slightly off center. Using sand paper or emery cloth, remove the paint from the tape around the hole on the bottom (no numbers) side of the tape measure. Cut to length after you have successfully made the holes, approximately 6.5 inches:

Screw the nut onto the screw, the put the screw through the hole in one of the tape lengths. The screw will cut threads into the center hole of the antenna connector as shown. It can be easier to start the screw in the hole without the tape measure at first to begin cutting the threads.

The two tape measure antennas will go through the gap between the solar panels in the frame.

Tape Measure Monopole Antenna

To build the monopole, you need to cut two lengths of tape measure to the same length as the dipole, approximately 6.5 inches long. You need to bend the tape measure next to the hole to a right angle, but don't fold it as it will break off

Screw the screw into the board so the monopole antenna goes vertical. There will be a slot in the top frame piece for the tape measure antennas to stick out.

8.2 Stacking the Boards

In order to stack the boards, we will need a set of 2.5mm brass or nylon spacers and two GPIO stacking headers.

Standoffs are described by the thread size (M2.5 in this case), length of the standoff (6, 10, and 15mm), and length of the standoff threads if any (+6mm). Also M2.5 screws and nuts are used. Here are the standoff pieces needed for the three board stack along with their names in their correct order and orientation:

In total, you will need 8x M2.5 screws, 2x M2.5 nuts, 2x 6+6mm, 8x 10+6mm, 8x 15+6mm, 2x 10mm, 2x 15mm which can be found in a standoff kit such as this one: https://www.amazon.com/gp/product/B075K3QBMX/

You will also need two stacking GPIO headers to give extra spacing between the boards. They are identical to the ones soldered onto the Battery and STEM Payload boards.

Start with the Battery board. Make four sets of a 10+6mm and a 15+6mm for on top of the Battery board. Under the board, you will need two 10mm and two nuts:

The 10mm go on the holes next to the GPIO header (+X side) while the nuts go on the holes furthest from the GPIO header (-X side):

Here's how the Battery board looks from the bottom:

Next, plug the Raspberry Pi into the GPIO header on the bottom of the Battery board:

Here's how it looks from the side facing the GPIO header (+X side):

Next, you will need two 6+6mm and two 10mm. The 6+6mm go into the Pi Zero while the 10mm go into the Battery Board as shown:

Here's how it looks from the bottom:

The stack of the Battery board and the Pi Zero should sit level when placed on a flat surface:

Install a stacking GPIO header, as shown in the photo above. Here's how it looks from the top:

Next, insert the STEM Payload board on top. With the extra stacking GPIO header, the pins will make good contact.

Install another four sets of 10+6mm and 15+6mm standoffs on top of the STEM Payload board:

Install another stacking GPIO header, as shown in the previous photo. Here's how it looks from the top:

Next, install the Solar board on top of the stack:

Secure the board with four screws. Here's how it looks from the top:

The board stack is now complete. Here's how it looks from three sides:

You can test the CubeSatSim by removing the RBF pin. Unless the batteries are fully depleted (NiMH batteries normally come charged up), the green light on the Pi will flicker and the CubeSatSim will boot up and start running.

The green LED on the Main Board will be lit up after booting is complete and the software is running. The blue LED on the Main Board will be lit up when the CubeSatSim is transmitting. The red LED on the Main Board will be lit up when the battery is being charged by either the micro USB power supply.

The pushbutton on the Main Board can be used to reboot or shutdown the CubeSatSim. Pressing and releasing the pushbutton will cause the green LED to turn off and the Pi to reboot. Pressing and holding the pushbutton until the green LED flashes three times slowly then releasing will shutdown the Pi. Once it has shutdown, it is safe to plug the RBF pin back in. Pressing the pushbutton with the RBF pin inserted will not turn on the Pi.

8.3 Installing the Board Stack into the Frame

The Board Stack is now ready to go into the Frame.

Video

Here is a video of the frame assembly:

The 1U frame of the CubeSatSim has solar panels on each face, which are labeled by the Cartesian axes X, Y, and Z. For the sides that face in the direction of the axes (see https://en.wikipedia.org/wiki/Cartesian_coordinate_system#/media/File:Coord_system_CA_0.svg), they are labeled +X, +Y, and +Z. For the sides that face in the opposite direction, they are labeled -X, -Y, and -Z. The CubeSat Design Specification (CDS) standard also has drawings showing the X, Y, and Z sides of a 1U CubeSat https://www.cubesat.org/cds-announcement. Here is a figure from that document:

On the CubeSatSim, the +Z side is the top of the CubeSatSim, the +X side has the pushbutton, micro USB connector, and the LEDs. The -X side has the Camera. The STEM Payload printed circuit board has the axes labeled on it as well.

In the Step 6. Solar Panels and Frame you soldered the JST connectors to the solar panels, did a test fit of the frame parts, and mounted the solar panels on the top (+Z), bottom (-Z), and sides (+X and -X).

To build the frame, we will now attach the board stack to the bottom frame, then attach the two sides, then the top.

Four screws mount the bottom of the board stack to the frame bottom. In this photo, the LEDs and other connectors are facing to the left. The Pi Camera ribbon cable is routed as shown here:

Here's how it looks from the +X side, the side with the LEDs and connectors.

The Pi Camera should face outward on the -X side opposite the LEDs and switches as shown here:

The solar panel JST connectors plug into the Solar board on the top of the stack. Start by plugging in the -Z solar panel connector from the bottom.

(Not shown)

If you are using the SMA antennas, screw the SMA coax cables into the STEM Payload board:

(Not shown)

The first frame side to be mounted is the -X side which has the Pi Camera mount. We will mount the Camera using two nylon screws and two nylon nuts. You will have to drill out the two holes in the frame to mount the Camera

Here's how the Camera looks from inside the frame when it is mounted. The holes in the Pi Camera are slightly small for the plastic screws so you will need to apply pressure as you screw them in. The nuts aren't really needed but they can be used to secure the Camera:

Carefully stand up the frame, being careful not to stress the Pi Camera ribbon cable and snap into position on the bottom frame. Here's how it looks from the outside:

Secure the -X frame with two nylon screws and two nuts to the - Z bottom frame.

Here is how it looks from the the -X side:

Here is how it looks from the top. Plug in the -X solar panel cable.

The next frame side to be mounted is the +X side. We will use the frame without the camera mount and two nylon screws and two nylon nuts.

On this side with the LEDs and button, screw the SMA coax cable into the SMA connector on the STEM Payload board.

If you are using the tape measure dipole antenna, the tape measure will come out in the gap between the solar panels.

This photo shows the SMA coax cables which were attached earlier:

Next, we will connect the top frame +Z, but we won't secure it with screws until all the solar panels have been plugged in:

If you are using the SMA antennas, remove the nuts from the coax and insert the coax through the frame, then put the nut on the other side to secure the coax.

Then, carefully bend the coax so that you can put the top frame in place

The two SMA antennas can now be screwed on:

Now we will attach the -Y solar panels:

Start by plugging the JST cables in:

Then attach them to the frame:

Now do the same thing for the +Y solar panels. First connect the JST connectors to the board:

Then attach them:

Now you can secure the top frame using four plastic screws and four nuts

(Not shown)

Here's how it looks:

Your CubeSatSim is complete and ready for Step 9. Final Testing