Ground Sphere CubeSat Ground Station

h1. Ground Sphere Prototype Assembly Instructions v0.1 (OUTDATED)

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h2. Introduction

Version 0.2 is the second prototype, which sacrifices some of the flexibility of v0.1 in order to move toward a more polished kit version of the ground station.  The overall design is the same between v0.1 and v0.2, but the details and several components have changed. Below are the assembly instructions for v0.2.

h2. Structural Component Pre-assembly

h3. Tools

* Hacksaw or chop saw

* Sharp knife

* Drill or drill press

* Ruler or caliper

* Pen or pencil

* Optional:  Centering jig for drill press

h3. Materials

* 1ea (ANT01) ¾” sched 40 PVC coupler

* 1 ea length of ¾” PVC sched 40 pipe 3” or longer.  Makes (ANT02) coupling sections

* 1ea (ANT05) ¾” PVC sched 40 to ½” NPT male adapter

* 1ea (ANT06) ¾” PVC sched 40 end cap

* PVC cement primer (purple solvent)

* PVC pipe cement

* Optional: PVC safe spray paint in a desirable color.

h3. Safety issues

* Care must be taken when working with powertools, sharp blades, or saws. 

* When using a chop saw, drill, or drill press, eye protection should be worn. 

* PVC solvent and cement must be used in well ventilated areas.

* Spray paint must be used in a well ventilated area, and should be done in a paint booth or outdoors.

h3. Product or Outcome

All plastic components for the Ground Sphere Mk2 upper structure.

h3. Procedure

# Using a chop saw or hack saw, cut 2 sections of ¾” PVC sched 40 pipe 1¼” long.

# Using a sharp knife debur the inside and outside of the sections.  

# These become coupling sections (ANT02).

# Using the PVC cement primer (purple solvent), lightly coat the whole outside of both coupling sections.

# Without dipping the applicator back into the primer, lightly coat the inside of the ¾” PVC sched 40 to ½” NPT male adapter. (ANT05).

# Without dipping the applicator back into the primer, lightly coat the inside of the ¾” PVC sched 40 end cap (ANT06).

# Lightly coat the inside of the unthreaded side of the ¾” PVC sched 40 to ½” NPT male adapter (ANT05) with PVC cement.

# Quickly insert one of the coupling sections (ANT02) and set aside to cure.

# Lightly coat the inside sides of the ¾” PVC sched 40 end cap (ANT06) with PVC cement.

# Quickly insert the remaining coupling section (ANT02) and set aside to cure.

# As accurately as possible drill a 3/16” hole in the exact center of the side on the ¾” sched 40 PVC coupler (ANT01).  The use of a drill press and centering jig is recommended.

# Rotating the part 180 degrees, drill a 3/16” hole in the exact center of the opposite side on the ¾” sched 40 PVC coupler (ANT01). 

# Rotating the part 90 degrees, drill a 3/16” hole in the exact center of the ¾” sched 40 PVC coupler (ANT01) between the first two holes.

# Rotating the part 180 degrees, drill a 3/16” hole in the exact center of the remaining side on the ¾” sched 40 PVC coupler (ANT01). 

# The holes should be at the 12 o’clock, 3 o’clock’ 6 o’clock, and 9 o’clock positions when sighting down the ¾” sched 40 PVC coupler (ANT01). 

# If it is desirable to paint the ground station components, this is a good time to do so.

# Set the units aside for integration with the antenna body.

h2. Assembling the Phasing Loop

h3. Tools

* Needle nose pliers

* Wire cutters

* Wire strippers

* X-acto knife

* Terminal crimper

* Ruler or caliper

* Dental pick or needle

h3. Materials

* 3ea (ANT10) Insulated crimp ring terminal Red (22-18 AWG) 

* 1ea (ANT11) Insulated crimp ring terminal Blue (16-14 AWG)

* 1ea (ANT13) Antenna line, SMA female connector to pigtail

* 1ea (ANT15) Tuned length of RG62u 90ohm coaxial cable

h3. Safety issues

* Care must be taken when working with hand tools, sharp blades, or sharp points.

* Coaxial cable wires, both the center conductor and shield wire can easily pierce the skin.

* Should a shield wire pierce the skin, remove it carefully since it can break off well below the surface of the skin, requiring painful removal

h3. Product or Outcome

All radio frequency (RF) components for the Ground Sphere Mk2 upper structure.

h3. Procedure

# Cut the RG62u 90ohm cable (ANT15) to precisely 2.775”.  

## Note:  the RG62u 90ohm cable (ANT15) should already be cut to length.  

## Verify the length.

# Using the X-acto knife, strip ¾” from each end of the RG62u segment (ANT15) and retain the insulation tube.  

## Note:  If something goes wrong with the RG62u segment (ANT15), do not cut off the messed up end and retry. It is a specific length and must remain so.  

# In the event of breakage, use another segment of the correct length.

# Using the dental pick or needle, gently unbraid the shield from both ends of the RG62u segment, twisting the strands into a single strand.

## Some breakage of the shield strands is unavoidable.  

## Remove any broken strands.

# Using the X-acto knife, strip ¼” of insulation from the center conductor from both ends of the RG62u segment (ANT15).  

# With the needle nose pliers, form a hook in the end of both of the center conductors as small as possible, a 1/32” across.

# Slip a red ring terminal (ANT10) over one of the center conductors.  The hook should just fit into the hole of the ring terminal (ANT10).

# Crimp the ring terminal (ANT10) with the crimper.

# Trim the insulation tubes removed from the RG62u segment (ANT15) in step 2 into ½”.

# Slip one of the ½” insulation tubes over the shield wires twisted in step 3 on the same side as the terminal we just terminated in step 7.

# Insert a red ring terminal (ANT10) over the exposed twisted shield wire insulated with the insulation tube in step 9.  

## Allow a small amount of play in the length (the insulation tube should not be tight)

## Crimp the ring terminal with the crimper

# Cut the antenna line (ANT13) at six inches from the end of the connector and strain relief.

# Use the wire strippers at the 14ga setting and gently strip ¾” from the antenna line ( ANT13) and retain the insulation tube.

# Using the dental pick or needle, gently unbraid the shield from the stripped end of the antenna line (ANT13), twisting them into a single strand.

## Some breakage of the shield strands is unavoidable.  

## Remove any broken strands.

# Using the X-acto knife, very carefully strip ¼” of insulation from the exposed center conductor on the antenna line (ANT13).

## Note:  If something goes wrong with the antenna line (ANT13), you may cut off the messed up end and retry, beginning at step 11.

## There is enough extra to correct one mistake in this manner.

## In the event of a second mistake on the same antenna line, discard the shortened antenna line and use another beginning at step 10.

# Slide the remaining ½” insulation tube over the remaining shield wires of the RG62u (ANT15) segment twisted in step 3.

# Trim the insulation tube removed from the antenna line (ANT13) to a length of ½”

# Carefully slide the insulation tube over the shield strands of the antenna line (ANT13) twisted together in step 12.

# Insert a blue ring terminal (ANT11) over the exposed twisted shield wires on both the antenna line (ANT13) and the RG62u segment (ANT15) insulated with the insulation tubes in steps 14 and 16.  

## Allow a small amount of play in the length (the insulation tube should not be tight)

## Crimp the ring terminal with the crimper

# Insert a red ring terminal (ANT10) over both of the remaining exposed center conductors, on the antenna line (ANT13) and the RG62u segment (ANT15) and crimp the ring terminal tightly.

# Set the unit aside for integration with the ground plane and antenna body

h2. Building the Ground Plane

h3. Tools

* Scissors

* Fine point permanent marker (Sharpie)    

* Clothespins    

* Wide eyed needle    

* Ruler or tape measure    

* X-acto knife    

* Flush cutters or small diagonal cutters

* A short piece of ¾” Schedule 40 PVC pipe for a fit test.

h3. Materials

* Paper for the pattern

* 1 ea (ANT16) Conductive fabric    

* 1 ea (ANT17) Round ABS plastic needlepoint canvas 9” diameter    

* 1 ea (ANT18) 15ft length of conductive thread

h3. Safety Issues

* Care must be taken when working with hand tools, sharp blades, or sharp points.

h3. Product or Outcome

The complete ground plane assembly for the Ground Sphere Mk2.

h3. Procedure    

# Take a piece of paper and fold it in half four times on the diagonal until you have a cone.    

# Using a ruler or tape measure, measure from the folded point and mark the radius at 3¾” on the paper with a fine point permanent marker.    

# Using the scissors, cut the edge on a slight convex curve.

# Using a ruler or tape measure, measure from the folded point and mark the radius at ½” on the paper with a fine point permanent marker.

# Cut the radius on a slight concave curve.     

# Unfold the paper and lay flat.

# Verify the dimensions of the finished template.  It should be a 7 ½ inch diameter circle with a 1 inch diameter inner circle removed.

# This pattern may be reused if multiple ground planes are to be made.

# Using a ruler or tape measure, measure the plastic needlepoint canvas (ANT17) and measure across the center. Use one of the four sections that go straight across as a guide.

# Using a fine point permanent marker, mark the gap between rings that exceeds 3½” from the centerpoint of the plastic needlepoint canvas (ANT17).     

# Using a fine point permanent marker, mark the gap between rings that is ½” from the centerpoint of the plastic needlepoint canvas (ANT17).

# Using a fine point permanent marker mark the plastic all the way around the radii of the measurements and marks made in steps 11 and 12, making a 7” and 1” circle.    

# Using an X-acto knife, cut out center circle from the plastic needlepoint canvas (ANT17).  Leave the teeth of the plastic needlepoint canvas, which will be trimmed later.

# Using scissors, cut out the outer circle and trim the teeth flush from the plastic needlepoint canvas (ANT17).

# Use flush cutters or small diagonal cutters to trim the nubs from inner edge of the center 1” circle on the the plastic needlepoint canvas (ANT17) as tightly as can be accomplished with the tool. 

# DO NOT attempt to make the inner radius of the plastic needlepoint canvas (ANT17) completely smooth, as the remaining nubs hold the ground plane assembly snugly in place in the antenna coupling section (ANT02).    

# Test fit the plastic needlepoint canvas (ANT17) on a section of ¾” Schedule 40 PVC pipe.

## The plastic needlepoint canvas (ANT17) should fit, but not tightly nor deforming.

## Trim as necessary.

# Fold the paper pattern in half on one of the fold lines from step 1.

# Fold the conductive fabric (ANT16) in half at 4” from the cut edge so that the underside (less shiny side) is visible.

# Place pattern on the folded conductive fabric (ANT16) so that it is completely on the conductive fabric (ANT16) and the fold of the pattern is flush with the fold of the fabric.

# Using a fine point permanent marker trace both the inner and outer radius of the pattern on the folded fabric.     

# With the conductive fabric (ANT16) still folded, cut out conductive fabric (ANT16) on the outer circumference tracing lines from step 21.         

# Cut out center hole following the inner circumference tracing lines from step 21.         

# Test fit the conductive fabric (ANT16) on a section of ¾” Schedule 40 PVC pipe as was done with the plastic needlepoint canvas in step 17.

# Use clothespins to hold conductive fabric (ANT16) and plastic needlepoint canvas (ANT17) together at multiple points. There should be a ¼ inch overlap of conductive fabric (ANT16) on the outside edge. This overlap will shrink as the ground plane is sewn to the plastic needlepoint canvas.

# Thread the wide eye needle with a 3ft section of conductive thread.  

## Knot one end 

## Position the needle near the unknotted end of the thread.  

## Note: stitch the Ground Sphere ground plane assembly with a single strand of conductive thread (ANT18).  

## DO NOT use double strands, as this reduces the electrical conductivity and wastes thread.     

# Starting from the plastic needlepoint canvas (ANT17) side on the innermost ring, stitch down through a hole in the plastic needlepoint canvas (ANT17), drawing the conductive thread (ANT18) all the way through to the knot. 

# Move one square in either direction (clockwise or counterclockwise) and stitch through both layers drawing the conductive thread (ANT18) all the way through.

# Continue in the chosen direction, working around the ring of holes, up one square, down the next. Go all the way around one 'circle' in the plastic needlepoint canvas. 

## Note: Maintain a steady tension on the conductive thread while drawing it through the fabric.  Once the thread stops, DO NOT tighten the loop further.

## Sew slowly to prevent the conductive thread (ANT18) from knotting. 

## The conductive thread (ANT18) tangles more easily than regular and is more likely to break.  

## Keep the conductive fabric (ANT16) as smooth as possible. 

## Avoid folds or twists in the conductive fabric (ANT16) by going slowly and adjusting the clothespins frequently.

# When the circle is complete, skip a row and start the next circle outward. 

# When about 5-6” of conductive thread (ANT18) remain, work the conductive thread (ANT18) through the backs of the stitches on the plastic needlepoint canvas (ANT17) side heading back to the starting point where the knotted tail remains.

# Bring the conductive thread (ANT18) up and through the square at the beginning (where the knot is) and remove the needle from the conductive thread (ANT18) leaving the remainder as a tail. These strands will be used to electrically connect the ground plane assembly to the antenna ground.

# Should it be necessary to start a new thread during a round:

## Knot the two pieces of conductive thread (ANT18) together with a square knot and continue sewing. 

## The conductive thread (ANT18) should always be linked to a previous section, unless it ends at the original square in the central circle.

# When 5-6 full circles are done, move to the outer row at the very edge of the plastic needlepoint canvas (ANT17) with a new piece of conductive thread (ANT18), prepared as per step 26. 

# Stitch all the way around the outermost holes of the plastic needlepoint canvas (ANT17).

# Once the outer circle is complete, skip a row inward and start the next circle. 

# Continue this pattern until there are stitches in every other row from the edge to the center of the plastic needlepoint canvas (ANT17).

# Once the stitching is complete, ensure all conductive thread (ANT18) ends travel down to the center of the plastic needlepoint canvas (ANT17) forming the ground line or are tied on to previous threads which do.

# Trim off the excess conductive fabric (ANT16) from the outer edge of the ground plane.

## Taking care to not cut into the plastic needlepoint canvas(ANT17) below the conductive fabric (ANT16). 

## The surplus conductive fabric (ANT16) may be uneven or irregular.  This is normal and is due to the pull of the conductive fabric (ANT16) and the tension of the stitches.

# Set the unit aside for integration with the phasing loop and RF line assembly.

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