[TenTec] RE: Power Supply & Equip. grounding

["Rob Atkinson, K5UJ" <k5uj@hotmail.com>]

Right.  If the bonding between shack rf and service gnd. has to be long 
(long defined as long enough to be a 1/4 w. at highest frequency you operate 
on) it should be outside and below grade far enough to be in contact with 
moist earth at all times.  Moist means not only damp but thawed in winter 
because ground resistance goes way up when frozen.  Ideally you should get a 
ditch witch and carve a trench below the freeze line and lay copper strap 
that's cadwelded between your two ground electrodes (service and rf).  This 
is beyond what most hams are willing to do, including me, so dig around your 
rods, clamp the strap, and get it down a foot or so with a pick and it 
should be okay most of the time.  Use 1.5" copper strap, available in rolls 
from AES among others.  A wire running along the basement wall inside for 
several feet (> 6') from rf ground to service will just radiate rf at some 
frequency and you don't want that.  This little detail of station 
construction is left out when books etc. advise bonding rf and service 
grounds.  This is probably because the books are written by professionals 
who are writing about, and for, professional installations.  A 
professional/commercial installation usually involves the construction of a 
building designed for one thing:  communications, not some guy's house.  
When you can build a commo vault from the ground up, you can place the gear 
and the service entrance right next to each other so the ground links are 
about two feet long.
(you can also bring in a backhoe and dig a trench all the way around outside 
and a lot of other things most of us can't do with our houses.)

My service entrance is in the darkest, coldest, dingiest part of my 
basement.  That's not where I want my shack.  Running an outside below grade 
bond is what I have to do.

Rob Atkinson
K5UJ

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