On 7/2/11 9:55 AM, Roger D Johnson wrote:
> On 7/2/2011 11:45 AM, Mark Robinson wrote:
>> I would crimp and solder the ring terminals. I would also apply some
>> Penetrox between the ring terminal and the SS hardware. I imagine that if a
>> lightning strike occurred that the radial wires are more likely to be
>> vaporized.
Not unless your radials are AWG 40...
Lightning has high currents, but it's short duration. A single AWG 10
would probably not melt with lightning, so a bunch of AWG20 or 24
certainly isn't (AWG10 = 10 times the cross sectional area of AWG20,
3.16 times the surface area)
The radial field isn't really meant to deal with lightning as it
>> is an rf return. Maybe a ground rod and a spark gap would protect a
>> vertical. I am not sure how to deal with static on the verticals
>>
>> I am building their 40m four square right now too, so I will be interested
>> in people replies.
>>
>>
>> Mark N1UK
>>
>>
>>
> I disagree strongly! Lightning IS mainly RF and a good radial field is one of
> the better
> ways of dealing with it. Generally speaking, a good RF ground is a good
> lightning
> ground. A good 60 Hz safety ground is generally a poor lightning ground.
Lightning might be 1 MHz RF, but the design goals for a lightning ground
and an RF ground are very different.
For an RF ground, you want low resistance, but you're not so worried
about inductance (because you can tune out the inductance, but you don't
want loss), so things like strap (which has low RF resistance) are nice.
For a lightning ground, the voltage rise due to inductance so dominates
over the AC resistance, the concern is more about short wires than the
shape of the wire, and bonding to make sure everything moves together,
and mechanical strength so that the EM forces from the transient don't
break the wire.
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|