[TowerTalk] tower & antenna project questions

Fri Mar 12 00:21:48 PST 2010

Wrong... Google UFER ground or "concrete encased grounding electrodes".

73 de Perry - K4PWO

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Jan Wise
Sent: Thursday, March 11, 2010 4:22 PM
To: 'Tower and HF antenna construction topics.'
Subject: Re: [TowerTalk] tower & antenna project questions

I am not sure, but I think if you look at the Hand Book It will state that
you do not want the tower or anything else to be grounded that goes through
concrete. The reason being that a hit from lightning 
Will cause the concrete to explode. If I am wrong someone please let me know
!

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of ke2d at comcast.net
Sent: Thursday, March 11, 2010 3:44 PM
To: towertalk at contesting.com
Subject: [TowerTalk] tower & antenna project questions

Good afternoon.   Finally, the 3rd sunny day in the 50s here in NJ, and time
to start the antenna work!  Hopefully we'll be pouring concrete in another
week or two for the new tower. Nothing like having a new tower delivered
with 24" of snow on the ground!  Now,...... 

I am looking to purchase a few 6m/2m/440 yagis to stack above my HF
antennas.  In my last installation, I used Cushcraft antennas - 13B2 for
144, 719B for 440, and A506S for 6m.   The VHF/UHF will be vertically
polarized, as I work more FM simplex than SSB.   6M, however, will be
horizontal for SSB DX.   This time I am now looking at the M2 stuff, namely
a 2M12 for 144, a 440-18 for 440, and a 6M7 for 6m.   

Does anyone have any recommendations of one over the other (Cushcraft vs.
M2), or  recommend any other manufacturers for VHF and UHF yagis?  

Also, I plan to stack a Hy-Gain 7-3 along with a TH-11DX.   I was thinking
of placing the 40m beam above the TH11, as the TH11 has the higher
windloading.   Anyone have any comments on which should be on top (am I
correct in placing the heavier antenna lower?), and also how much distance I
should allow between the TH11 and 7-3 40m antenna so as to minimize any
potential interaction? 

In addition, I need to run grey conduit under ground from the base of the
tower to where the cables will enter my home.  I need to run 9 coax cables,
and a rotor control line. 10 cables total.  Each run will be approx. 210ft.
100ft up the tower, then 50ft from the tower to the house, then 50ft along
the basement and up into the shack, then 10ft or so for movement in the
shack.   Due to the long runs, I was planning on going to LMR600 type cable
to cut down on the losses, especially at  50MHz and above.   I am thinking
of going with LMR600 right up to the antennas, making sure to oversize the
rotor loop.  I successfully used solid center LMR400 for 10 years, so I
might gamble this time again.  The loss figures for LMR400 keep pushing me
that direction! Any idea what size conduit I will need if I opt to run 9
runs of LMR600 size cable and one rotor cable?  I was able to easily get 10
LMR400 size cables in either 2 or 2.5" conduit (can't recall, as the last
tower/qth was 10yrs 
 ago).  I stopped at HD and looked at 3" conduit, but damn, that stuff just
looks too darn big, especially when it will be going into the side of my
home. I was planning on entering just above the concrete foundation, where
there is an approx. 8" sill between the concrete and where the first floor
rests. Same as the utilities do.    

One other thing - my plan was to run the conduit from the house out to the
base of the tower, sink a few 4x4s into the ground near the tower base, then
mount some sort of grey weatherproof enclosure on them. Have the conduit
from the house go directly into the bottom of the box, then have another
elbow come out the bottom, allowing the coax cables to make a drip loop
before they head up the tower.  Inside, I was planning to install a copper
plate to which I would affix 10 or so Polyphasor arrestors, and the rotor
control surge arrestor.  Then bond the plate and tower to common ground rods
near the tower.  Can anyone recommend a suitable enclosure that will
comfortably fit 10 or so surge arrestors, plus some room to spare. I took a
quick look at the DX Eng website, but their stuff only accomodates two or
three devices. 

I also need to install an electrical outlet near the base for the tower
motor. So I will be running a 3/4" conduit as well, from the main panel out
to the tower base.  Any objection to dropping the electrical conduit in the
same trench as the coax conduit? 

Finally, as far as grounding goes - is there any advantage to installing
three 8ft ground rods at the bottom of the tower foundation hole BEFORE I
pour the concrete, and run the ground wires up thru the concrete base, to be
attached to the tower once it is erect? Or just stick to three ground rods
into the dirt around the base of the tower foundation after it is done? 

Thanks for your insight and knowledge.  I've been learning a lot just
reading the postings of the last month or two in preparation for this
project. 

Eric 

K2WD
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