>> Get the Harger ground bar.
>
>Big waste of money.
>
>73, Jim K9YC
Agreed. The topic here is "back of the desk grounding", and in that
location a massive copper busbar is a big waste of money. Worse still,
it may indicate a dangerous lack of understanding.
The place for massive copper conductors is <outside> of the building and
at the common entrance point. These conductors need to be large enough
to handle huge lightning-induced surges and divert them away from the
shack. Once again: the aim is to keep large surge currents <out> of the
shack entirely, or at least to reduce them to some low residual level.
By the time those residual surges reach the back of the desk, there
should be no further need for massive copper conductors. The bonding
strip along the back of the desk is there for a different purpose: to
provide a low-impedance "local ground" reference for all the equipment
lined up along the desk. The aim is to provide a low impedance at all
frequencies from DC through 50/60Hz up to RF, and when you run the
numbers the main requirement is for low inductance, which is best
achieved by a wide flat strip conductor or a large-diameter pipe. Aim
for the low inductance, and you will almost always find that the
conductor cross-section is large enough for 50/60Hz safety and hum
suppression as well.
One more time: the main purpose of the strip along the back of the desk
is to ensure that all the equipment metalwork is closely connected
<together> at all frequencies from DC to RF. The best term for this is
"BONDING".
(Thoughtful authors try to avoid calling it "grounding" or "earthing"
because a connection to the Mother Planet is not the main aim. You
should connect the bonding strip to a mains safety ground as well, but
that was not your main reason for having the bonding strip.)
73 from Ian GM3SEK
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|