The primestar article made me look at low cost alternatives.
The 10 euro satellite dish came with a LNB size adaptor such that 22mm copper water pipe could be used.
Bill of materials
120mm RG402 rigid coax
70 mm copper tube 22mm outside diameter
hexnut 3/8?valve; ?/span>nut inside diameter 8mm
N-type chassis female
The feeder is built starting from the N-connnector side;
Grind away the N-connector pin to remove the solder half-cut, until the pin is round.
Drill a 4mm whole in the center of the nut.
Countersink the nut until the edge is 45 degrees, this makes the nut fit nicely on the chassis connector.
Strip the RG402 rigid coax leaving 2mm centerpin, and 2mm dielectric free.
Solder the coax center to the N-connector pin, do not use solder abundantly. A resin marker (flux pen www.kester.com) may help the fluxing process.
Clean the joints that need soldering , remove oxides using 400 grade waterproof sandpaper.
Place the assembly standing on a fire proof tile. Then solder the nut onto the ?/span>chassis part. I used a small propane torch intended ?/span>for jewelry repair. Be careful not to overheat the assembly; ?/span>as soon as the solder flows remove the heat. Solder the RG402 rigid coax onto the nut in the same process. Use solder scarcely.
Now solder the 22mm copper tube on the N-chassis connector.
From here on use the drawings and dimensions of the biquad feed by Trevor Marshall
Solder the 22mm tube on the PCB . solder the RG402 on the PCB on the other side
Here you can see the ring adapter supplied with the dish.
The base plate has a slot to fit the LNB mounting stick. This slot is constructed by drilling a 20mm diameter whole centered centrally 14mm off the edge. Grind, file or saw the opening to fit the rod. The wings are constructed using 2 pieces PCB 44 x 30 mm. The other wing is according to the original design.
Then the RG402 is cut to length (15mm from the base) to fit the biquad.
The biquad wire is soldered on one side to coax outer metal, the other side is connected to the center.
Other biquad designs have more detailed drawings.
The final dish with feed looks like this