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Topband: 8 element antenna - Amplifier placement

To: "Gary@ka1j.com" <Gary@ka1j.com>, "topband@contesting.com" <topband@contesting.com>
Subject: Topband: 8 element antenna - Amplifier placement
From: Lee STRAHAN <k7tjr@msn.com>
Date: Mon, 19 Sep 2016 18:33:54 +0000
List-post: <topband@contesting.com">mailto:topband@contesting.com>
 Hello Gary,
   Spray painting the elements is no problem. As far as mounting the amps to 
the elements I would not recommend that. It likely could compromise 
performance. It would be much better if you could take a steel post like a 
piece of rebar and provide a second place for the amps to mount  with just the 
wires reaching the element and ground. If you have to lengthen the leads to the 
amp do not lengthen the ground lead any more than absolutely necessary. 
Lengthening the element wires will have to be done exactly the same length and 
dressed as closely the same way as possible on each element/amp.
  Lee  K7TJR


Subject: Topband: 8 element antenna - Amplifier placement

I'm so close to being done with putting this together. I have all 8 antennas 
made @ 23' each the tip section is .5" and the base is .850" I'm using a 3/4" 
fiberglass rod as an insulator 

doctorgary.net/Hi-Z-8-Pro-1.jpg
doctorgary.net/Hi-Z-8-Pro-2.jpg

I am having a conundrum with the placement of the enclosure for the preamp 
mounted at each antenna and need some advice. The problem is I am at sea level 
and the antennas will be mounted in a location that will possibly get a storm 
surge during a Hurricane, it ruined my remote coax switch during Sandy from 
this very reason. The preamp does have a silicone gasket but if the amp gets 
submerged in salt water, I'm sure it will get past the terminals and ruin the 
amp. I have no alternate choice, this is the location where I have to put the 
array.

Seeing the photo of the end cap on the PVC tubing with the zip tie holding the 
amp in place (to protect from rain & Snow), gave me an idea for the solution; 
At the top of the PVC tube, make two opposing holes, run a loose loop of thin 
wire through and twist together. Run the coax up & over the wire to hold the 
amp elevated inside the tube, all the way to the top. Use a rubber cap with 
radiator clamp to secure the top and make it truly airtight. Now if the tide 
water from a storm surge encroaches, there will be a pocket of air inside and 
will be unable to push high enough to reach the amplifier. I tried this with a 
Mason jar and the water did not get very high in the upside down jar.

doctorgary.net/Hi-Z-8-Pro-3.jpg 

So here's the dilemma: As a further hedge against water damage assuming there 
are strong winds making waves (they would not be breakers, just waves in the 
marsh) at this time, I'd like to raise the placement of the amplifier so it 
would be another foot higher than standard placement which is on the base below 
the insulator. This would require me to clamp the PVC on the antenna instead of 
the base. Can anyone see how this might be a problem with operation?

Also, I'd like to spray camo paint on the elements so they don't stand out. 
When the leaves come down, I'd prefer the neighbors not see the elements, 
they're nosy enough as it is. I think I remember reading a layer of paint on 
the element shouldn't cause a problem, is this correct?

Thanks & 73,

Gary
KA1J



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