[TowerTalk] Cadwelding vs Silver Solder for Ground Radial Systems

[Jim Lux]

At 03:21 AM 7/9/2006, Dr M J DiGirolamo wrote:
>Dear TT Colleagues,
>
>    There has been so much discussion here about dealing with lightning
>protection and grounding systems that I can't remember whether I read 
>about the
>following topic or not.
>
>    I'm planning a ground radial system for each tower leg (yes, a peripheral
>ground system and single point ground, etc too) and have decided to use a 
>heavy
>braided tinned copper cable as the radial for each of these legs.  I have just
>about ruled out copper ribbon for various reasons.  Ground rods will be 6' 
>or 8'
>deep set on 12' or 16' centers.
>
>     Question is: Cadwelding is VERY EXPENSIVE when used to attach the 
> radials to
>the ground rods!   Can anyone comment on whether there will be sufficient
>bonding and heat protection if a heavy silver solder bond is made in place of
>the cadweld.  I realize that cadwelding forms a molecular bond but it's 
>just so
>darn expensive.


A couple observations...

The ground resistance from a buried wire 16 ft long is probably comparable 
to a pair of 8 foot rods connected above ground by a 16 ft wire.  Why not 
just trench or slit and bury the wire?  No connections to worry about, no 
rods to buy, etc.

Cadweld oneshots from Tessco are only $6-7 each.  I imagine that the cost 
of the ground rod is comparable..[Tessco shows a Harger 8'x5/8 rod is $17 
(list)].  Ultimately, you're looking at a cost/benefit tradeoff (better 
ground = lower risk of damage from transients).. Assuming you've got 3 legs 
on your tower, and a couple ground rods on each, you're looking at $60 or 
so for the CadWelds.. that's not a huge number compared to the several 
kilobucks you've got into the tower/antenna/radio....