[K3PZN-List] Again with my ignorance...

[Curt Milton]

Bill

Good question.  

Is your metal post PAINTED or otherwise treated?  if
so, this MAY be a factor.  

I suggest using your ohm-meter to see if there is
apparent DC conductive contact between your antenna
and the post.  (and try same from two different places
on the post itself).  

If there is not conductive contact, then there is the
possibility of capacitive contact (with the presence
of paint acting like a dielectric).  

The other factor that could be involved is the level
of the RF field at the point that the antenna makes
contact with the post.  If this happened to be a null
at both 144 and 440 MHz, well not much RF would get
onto the post.  

Proceed with care and interest!  

Curt
amateur with plenty of ignorance left


--- "Neeriemer, Bill (NIH/NLM/LHC) [C]"
<bneeriemer at mail.nih.gov> wrote:

> OK,  I've got a dual band j-pole made out of solid
> aluminum pieces,
> except for a couple of plastic pieces one the ends
> to protect from
> poking one's eye out.  (Actually I have 2, the other
> is Stainless
> Steel.)
> 
> I mounted it on a metal post approx 6' long.  (Steel
> I think)
> 
> The mounting brackets are metal.  (probably
> aluminum)
> 
> The system works well.  SWR = 1:1 consistently.  I
> can be heard from
> Westminster without difficulty.  I'm in Mt. Airy.
> 
> My question is:
> 
> What, if anything, prevents the entire contraption
> including the post
> from being energized when I transmit?
> 
> I'm not brave enough to touch the post to see if it
> is energized.  I
> decided to err on the side of caution and assume
> that it is.
> 
> I see no evidence of any insulators anywhere on the
> antenna or mounting
> brackets.
> 
> It would seem to me that if the post is in fact
> energized, then it would
> be impossible to factory tune it.
> 
> Can someone explain this to me?
> 
> Thanks
> 
> 73 Bill W3STG
> 
>  
> 
>
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