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[TowerTalk] tower & antenna project questions

Subject: [TowerTalk] tower & antenna project questions
Reply-to: "Tower and HF antenna construction topics." <>
Date: Thu, 11 Mar 2010 21:43:42 +0000 (UTC)
List-post: <">>

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. 



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