As mentioned in my 437 Mhz antenna project, thanks goes to Chris G4YCA for his website details on how this works, complete with instructions.

Heres how I made mine!

The material I used was 25mm x 1mm Aluminium box section and 12.7mm copper water pipe. I chose to use BNC connectors on my 437Mhz yagi, however on my VHF yagi I plan to use N connectors.

I first measured and cut the copper pipe to a ¼ wavelength of the frequency I wanted including 10mm extra either end. I marked the ¼ wavelength on the pipe and drilled two holes. One hole was straight through on one end and the other was only drilled through one side.

Copper pipe:-

Make sure the hole size fits the terminals of whatever connectors you choose. Now prepare the box section, make sure it’s a little longer to fit the connectors and allow some room for what ever method you use to waterproof the ends. I used two part epoxy putty. Before your final assembly, fire up the soldering iron and tin all the points inside the copper pipe.

Copper pipe in box section:-

Next mount one of your antenna feed connectors to the box section, then slide in the copper pipe. Align the hole you drilled straight through to fit into the terminal of the connector, (you can hold this in place with hobby putty if you like). Now fit the other antenna feed connector again aligning the connector terminal to the whole. (If you used something to hold the copper pipe in place you can now remove it. Lastly fit the final connector and align to the single hole. Make sure it looks all even before you solder the copper pipe to the connectors.

Lastly waterproof the ends of the box section and the connectors where they meet the box. Time for testing

Formula

Again thanks to Chris G4YCA for the info
Use this formula to work out what sizes of material you can use to obtain the closest match. This would depend as in my case what was available.

138Log10{1.08D/d} Where “D” = Inner dimension of the box section & “d” = diameter of the tube.

 

Nick Soter
Call: VK4ZXX
Location: Brisbane

VK4ZXX Ham Radio Splitter for Yagi's

 

 

 

 

 

 

 

 

 

 

 

Web Links

 

 

 

 

 

 

 

 

 

Project Links

Project Comments

Google Community

 

 

 

 

 

© vk4zxx 2013