[TowerTalk] 75/80 vertical

[jimlux]

Richards wrote:
> okay tower talk fans -- I am new at this, but considering a similar project.
> 
> 1.	Rather than run a a second, separate wire all the way  parallel to 
> the tower, which would, I believe, if I learned my electrical theory 
> correctly, have a different resistance than the tower itself, more or 
> less, I don't know -- but still it seems that some knowledge of parallel 
> circuits and parallel resisters should be applied before you do that. 
> It seems to me the current will go the line of least resistance. 
> Either the Tower or the wire would be more or less redundant or ignored.

The current will divide according to the resistances, or more properly, 
the inverse of the resistance.  If the tower is 1 ohm, and the copper 
wire 1/10th ohm, then 10 times as much current will flow in the wire as 
in the tower.

That is, it's not an all or nothing proposition with "electricity 
following (only) the path of least resistance"...




> 
> 2.	I would think, therefore, based on the above, it would be better to 
> use short stainless steel jumpers to bridge the tower section linkages. 
>   That would make sure the connection is complete, and make sure that 
> power, itself, is doing the conducting.


One might want to ask what the conductivity you're seeking is for?  For 
lightning protection? Small gaps make no difference, nor does 
galvanization. the lightning current will flow.

RF currents using the vertical radiator? You also have to consider 
inductance, and the single wire will have a more inductance than a foot 
diameter tower.



> 
> 3.	Could one use his multimeter to check for continuity and good 
> conductivity before messing with any of this?  I won a multimeter at the 
> Dayton Hamvention last year, and I'm still learning how to use it, but 
> it seems like one of those could test for good conductivity.


Yes one could.  the trick is getting the leads to the two ends of the tower!

> 
> 
> =============   Richards - K8JHR ===============
> 
> 
> 
> donovanf at starpower.net wrote:
>> Gregg,
>>
>> I recommend not using bare copper wire alongside your tower.  Copper will cause galvanizing to fail not only at the connection points, 
> 
>> I'm sure dozens of Towertalkians use Rohn tubular-leg towers as vertical radiators, and I've never seen a problem reported here.
>>
> 
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