[TowerTalk] Station Grounding

[Roger (K8RI) on TT]

There are some essentials in the previous thread, some buried, some 
touched on, and some missed and it's unlikely I'll catch them all.

These are my thoughts from a practical approach.

Ideally all the equipment is connected to a Single Point Ground (SPF) 
through equal length grounds without creating ground loops.

It is almost impossible for most stations to do this in practice, but we 
can come close.

A starting point is a low resistance common grounding plate where all 
conductors enter the shack.  Right away we run into problems because 
even if the electrical, telephone, and internet enter close to each 
other, they typically do not enter at the same point. There is surge 
protection available that will handle these at a common point. This 
reduces pulses coming in on these lines and puts them very close to the 
same potential.

All my coax has the shield, grounded to both the top and bottom of the 
tower. My ground system consists of a network of over 600 feet os bare 
#2 wire, CadWelded(TM) to 32 or 33 8' ground rods.

Now the problem is all of these reach the station via different length 
paths while the coax and control cables usually enter from the opposite 
side of the house.

So, lets just put a big grounding plate where the coax and control 
cables enter the shack. It takes little to route the network, telephone 
and internet to this plate as well.  The AC to the outlets in the shack 
could also be routed this way with protection mounted on the plate.  
Now, all the lines to the rigs and computers in the shack have a common 
ground. Polyphasers, and lines all have their protection grounded to 
this plate

Typically, the interconnecting cables between station components are in 
the neighborhood of 18" unless they are custom cut. I find that they are 
about the same length as the ground leads to a common point. More on 
this in a bit.

We've now reduced the conducted voltages that come in on one or more 
lines to what we/I hope is a manageable level, but there are still 
induced voltages.  Here the question is one of the grounds and equipment 
interconnects.  Near as I can tell, IF the grounds and interconnects are 
the same lengths AND the follow similar paths they do not form loops. 
They are cut by the same force lines at the same time and should have 
about the same voltage at the same polarity,  Hence the interconnects 
and the grounds should should not create a problem. Routing differences 
such as short interconnects and longer grounds to a point can create 
loops which is not good.  Differences in lengths and routing  they can 
create loops or parallel circuits. I do plan on installing a ground bar 
behind the desk, but more for neatness and ease of use rather than 
lightning protection.

Lightning is of a power that we seldom have to deal with.  My station 
has taken many direct strikes to the antennas with some damage "up 
there", but none to the equipment since the grounding system was 
finished.  I've stated before that it has taken 17 visually verified 
direct hits to the tower and antennas. So it's likely there have been 
more. I do know there have been many, very powerful nearby strikes

In addition to the regular problems, I run SO2R with 2 stations 
connected to the same antennas and ground systems, but in different 
buildings fed with different electrical services.

My goal is to minimize any spikes getting to the equipment so by the 
time  we get to the rigs, the magnitude is something that can be handled 
with good practice. Lightning is unpredictable and there is little we 
can do if hit with one of those "super strikes".

The rigs (except amps)are/will be on a 3000 watt UPS, voltage regulated, 
sine wave generator/line conditioner as soon as I replace the outlet.  
(kinda pricey) I don't know if one of these could be set to regulate for 
the 110 on the valuable antiques.

Jim, if you read this, I'd like to hear your thoughts on this 
installation/approach.

73,

Roger (K8RI)