Hi Eric -
Sounds like a real firat class installation. Just wondering if / why you may
have ruled out relays for antenna selection and maybe just a pimary and a
backup for coax cables. For the price you might run a 7/8" or 1 1/4"
hardline and an LMR for backup, or even two hardlines, perhaps allowing
multi / single contest operation, assuming you'll have 80 and 160 wires hung
off the tower. I would guess that the "6 pack" type relays wouldn't pass
muster at 144 and 440,but should be ok up thru at least 10 and maybe 6. I'm
sure there are good VHF/UHF relays that would handle whatever power level
you plan on using on 2 and 70cm.
And, I would ageee with not running the ground wires through the concrete. I
would guess that the coefficient of expansion of concrete is pretty low and
the heat caused by a direct strike melting the copper wires would be rather
catastrophic for the concrete.
73's and Good Luck.
Gene / W2LU
----- Original Message -----
Sent: Thursday, March 11, 2010 4:43 PM
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
> 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
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