Amateur Radio Station grounding

Amateur Radio Station grounding

What’s the problem

Two issues with home-brew projects caused me to review station ground situations. The Sutton Transceiver was showing strange mismatch symptoms when transmitting through a z-match but not when into a dummy load or resonant antenna, and the 6m Transverter and Linear project indicates there is some RF leakage around the ferrites on the leads. Both are indicative of poor RF-hygiene and whilst improving ground is not necessarily the fix for either or both problems, it improves the level of RF-hygiene in the shack. My friend, Maurice G3MMK, has decades of relevant experience from TV broadcast transmission and came with lots of test gear to help me to check grounds and feeders. This is where everything has got to…

Shack Earthing

Outside I now have six earth spikes, copper pipes hammered into the ground, underneath the run of my 80/160m inverted-L. The spikes were already connected using 10mm sq multi-core copper cable which was attached to some galvanised conduit which the feeders run through. Rather than relying on the galvanised conduit to get ground to the equipment, I bypassed this with further heavy gauge multi-core copper through to the operating desk.

Equipment Ground Bus

At the back of the equipment I’ve installed a ‘ground bus’, a piece of 22mm copper pipe. The equipment is all grounded radially, using standard mains earth clamps attached to this bus. In addition, unused leads and metal work has been removed from the operating area; excess lead lengths have been bunched rather than coiled and ferrite is on almost all leads. See pictures below…

Looking down onto Earth bus running along the back of the equipment

Radial Earths clamped to Bus Radial Earths clamped to Bus Bus clamped to Earth spikes and Water pipes

Bond everything together!

I next bonded the ground bus, running behind the equipment, to the outside earth spikes, the galvanised conduit carrying the feeders, the water, gas, central heating and mains earths in the house. In addition, we checked the earth clamps installed on water, gas, central heating pipes etc. In all cases, we removed the clamp and cleaned the pipe properly before replacing it. Typically these clamps had been installed by plumbers for electrical health and safety protection. RF current is far more picky than electrical mains currents, it has reactance as well as resistance to impede the RF of course. So it was critical to improve the state of all these earth bonds.

Assume RF is water that can flows through a pipe or cable in a particular direction. The last thing you want to create are RF loops in your low-resistance path to ground. Loops might not be in phase thus creating high reactance points! The system I have implemented is shown below with earth clamp bonds highlighted…

M0EZP Shack Ground schematic

Last updated: 9th April 2007