Station Earthing

[VK5PJ]

A sometimes forgotten part of a ham’s shack is the earthing system, I must admit I had only made half hearted attempts at a good station earth in the past.  Which is odd as my previous work life had a large component of making sure all gear was properly earthed.  I am not sure if it was the cost of heavy copper cable and copper bar stock that put me off the scent but I just always seemed to find a reason not to do it.

About 18 months ago I had a light globe moment, why try and use all these fancy earth bars when I had some left-over copper GAS pipe (19mm O/D) in the shed.  A scheme was hatched to use commonly available parts from a hardware store to make a shack earthing system that could be flexible to use and not break the bank.

My operating area is in an L shaped desk so I bought a 19 mm copper elbow to combine with my scrap 19mm pipe, some heavy duty solder and borrowed a small gas torch as my old BIRKO soldering iron was not up to the task, plus a handful of copper saddles to fit the 19mm pipe but not in the traditional way.

Now the method I settled on to attach each bit of the radio gear was to us the copper saddles soldered along each leg of my L shape of pipe as the connection points for flying leads to each piece of radio gear, with the pipe mounted on the back of the desk and earth leads passing through existing holes to the gear.  I firstly measured, cut and soldered my two pieces of 19mm copper tube into the 90 deg bend so I could take it to the shack and mark on it where I needed the connection points to be.  Some areas of the shack had lots of gear grouped close together so multiple copper saddles (attached in the opposite direction to what you would to secure the pipe to the desk) were needed in those spots.

Looking back at it I should have used a pop rivet through each saddle to help locate it on the pipe as soldering of the multiple copper saddles in some areas became tricky when I could not control the heat from the gas flame.  This resulted in a number of oddly angled saddles as they slipped around the pipe when the heat was on.  Note to self, do not do it like that again.
Clean up each saddle and the locations on the pipe where they are to go, then I tinned each of the inside surface of the saddles and then tinned each location on the pipe where the saddles went,  This was a bit messy but effective.  As I mentioned earlier a pop rivet through the U of the saddle and the pipe probably would have been a good way to keep each saddle in the right spot when the heat was applied.

At the end of the copper pipe nearest to my wall (exit point), I flattened the copper pipe using my vice and hammer to create a TAB that I could drill an 8mm hole to attach my cable out to the copper coated earth spike (bought from bunnings) just outside the shack wall.
For the flying lead used between the rear of the radio gear and the earth system, the cable chosen was from the RS components catalogue as it has a high stand count in the cable (84 strands of 0.3mm) to ensure the cable is super flexible with a cross section of 6mm squared , which was one of my main criteria for the cable.  In retrospect this is where I blew my budget as I could have settled on a lower spec cable but once again my previous work experiences drove this choice for flexibility, size and colour.  Our old Quality Assurance person at Jindalee would have been happy with my cable choice for once.

The cable from the end of the copper pipe to the earthing rod was a bit of a fluke, I was given a short length of left over cable from a commercial transmitter’s earth connection install and had hidden it away for a one day project, this proved to be ideal for the purpose BUT on the flip side I could have used multiple runs of the more common household earth cable in a bundle, there is nothing that says it has to be ONE cable.  For the main connecting LUG to the earth rod, I visited my local car parts people and bought a heavy duty crimp lug to fit the cable I had.  If you chose the multi cable bundle then you could use a similar cable lug or many smaller crimp lugs, there is no strict best way here, it is all about getting a low resistance connection.  You must remember this earth is not there to carry high current, just to provide a low impedance path between the radio gear and provide a common earth point for the shack equipment.


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