[N2HTT] New Wire

[N2HTT via rec.radio.amateur.moderated Admin]

73, de N2HTT

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New Wire

Posted: 31 Oct 2015 10:25 PM PDT
http://n2htt.net/2015/11/01/new-wire/


Almost exactly three years ago, super storm Sandy made landfall in our
neighborhood, with devastating results. While we did not suffer much damage
compared to many others, we were without power for fourteen days (a record
for us) and a tree struck the front of our house, doing serious damage.
Among other things, my antenna system was completely erased.
Sandy 10/29/2012

It wasnt a big commercial antenna or tower or anything like that. I have
always used simple wire antennas, supported in various ways. At the time of
the storm, I had a mast attached to the second story of our house,
supporting the apex of a doublet hung in a sloper configuration, and fed
with 450 ohm window line. Pretty effective, and very cheap.

The mast was composed of those four foot fiberglass mast sections you can
find on eBay. I think I had six or seven sections of the stuff hooked
together, which starting from the second story of the house gave me about
35 40 feet at the apex. The mast was attached with brackets to the
clapboard side wall of a dormer extension.

These mast pieces were never intended to be used to construct a tall mast.
My understanding is that their intended purpose is to be used, one or two
pieces together, to support camoflage netting. You know, when they hide
airplanes under a lot of fake foliage. And I can attest to the fact that
they dont work very well for tall masts. I once tried to make a 40 foot
mast out of the stuff, and attempting to get it vertical was a complete
failure rather like trying to stand a stack of cooked ziti on end. Al
dente, of course.

Anyway, in the aftermath of Sandy I had nothing left but a pile of mast
pieces and some tangled wire. In the days that followed, I scavenged the
still usable bits, and put up a shorter version of the same arrangement,
minus one piece I think. This second incarnation was liberally reinforced
with Gorilla tape, and was splinted with four pieces bamboo around one
particularly dodgy joint. (We had a lot of cut bamboo on the property, but
that is another story for some other time.) The slightly crooked, splinted,
shorter mast proudly adorned our house for about two years. You can guess
that we dont live with an HOA. My wife. God bless her, is very tolerant and
allowed me to continue to persue my radio interests with this abomination
attached to the house, but I must admit that even I would occasionally look
up and mutter got to do something about that antenna Oddly enough, when I
looked for some pictures of the splinted version I couldnt find any. I
guess we didnt think it was that photogenic.

In any event, last winter, which was very severe, finaly brought the matter
to a head. After a particularly bad storm later in the season, the top of
the thing snapped off. Ironically, it was the join above the bamboo splints
that failed. I took it down again removed another section, and refreshed
the duct tape. It was abundantly clear at that point something had to be
done.
Sad remains of old mast

Over the summer, I started shopping for a new mast. No point in waiting,
get it done while the weather is good. I dithered about comparing lots of
different masts on the internet. It didnt need to be very tall, since it
would be attached to the house, but I wanted something very sturdy; a
telescoping mast would be fine, but it couldnt be one of those lightweight
portable jobs. No kite poles for me, it had to have some gravitas.

I finally settled on an MFJ-1904HD mast, which is apparently designed to
hold five element 80 meter monobanders and the like. I found a pretty good
deal on the mast, (including free shipping, which surprised me. I was
afraid of the shipping on somehing like this.)

The mast arrived surprising quickly. Next step: wire. I have always bought
my wire from The Wireman, and I highly recommend them. I decided to replace
what I had up with all new materials, so I bought sufficient wire and
window line to redo the whole thing. After I placed the order, I realized I
hadnt ordered quite enough wire, and called them. They adjusted the order
without any fuss. Is is a delightful business to deal with.

With wire and mast on board, I waited for a weekend when we would be home
based to do the work. On the first such weekend, I climbed to the sunroom
roof, only to discover that the brackets on the existing mast were woefully
too small for my new, robust mast. Back to the internet, to find bigger
brackets. This proved tough in the end I found only one bracket, made by
Rohn, which could handle the diameter of my new, robust mast. I ordered
them. They were backordered. We were out of town for a few weekends.

Finally, today, the new antenna went up.

The weather was glorious, a perfect October day. And my younger son was
available to help with the roof work, a major plus.
Installation crew hard at work

I tried to plan out all the steps of the job: things had to be done in the
correct order since I intended to use the mounting hardware and antenna
center insulator from the old doublet in the new antenna. Here was the
breakdown:

lower the ends of the old antenna
remove the center of the old antenna from the old mast
take down the old mast. This was the most nerve wracking part.
remove the old brackets
caulk the mounting holes
assemble the new antenna, which included
measure two halves of the wire doublet
assemble the center insulator with wire and window line
drill the new mast for mounting the new antenna
measure and install the new brackets
install the new mast, collapsed
mount the antenna on the new mast
extend the new mast
attach the ends of the new antenna to the support ropes at either end
raise the new antenna


As simple as that.
Carfully organized tools and materials

Remarkably, all this went totally smoothly. Nobody got so much as a
splinter I cannot express my gratitude sufficiently. And for some reason,
this project did not require the usual three trips to the hardware store.

The new wire antenna is a 135 foot doublet, fed by window line. While not
exactly resonant on any ham band, it loads easily on all the bands with a
tuner. It is a popular configuration, if you Google it you will find dozens
of write ups on it.

I measured my wire (two 67 foot lengths) by putting two tent stakes into
the ground 11 feet appart, and making six turns around the stakes, plus a
foot or so. Then I wrapped the wire around rectangles of corrugated
cardboard to keep it out of trouble until deployed.
Hard to see wire staked out for measurement

The center insulator is a device called a Ladder-Loc, which is designed to
support the window line and reduce stress on the the wire-to-feedline
connections. The one I have has been in use for over four years it is a
little faded from exposure, but in fine shape and back in service.

When I reconnected the wire ends to the support ropes and pulled them up, I
realized something interesting the old antenna had been much shorter than
135 feet. I thought what I had was a 135 foot doublet, but it turned out to
be about 90 feet. I dimly remember doing a lot of calculations to come up
with a good doublet length because I thought 135 would not fit in my lot.
Apparently I was wrong, and am absent minded, but to good effect.
The new mast

I didnt make the final connections back to the shack until the sun had set.
The new antenna loads easily on all bands, and despite the prediction of a
geomagnetic storm this evening, 80 and 40 meters sounded lively. Im totally
thrilled that this job is done, and not a flake of snow has fallen yet this
season. Im looking forward to a winter of sitting snug in my shack, playing
radio with a beautiful piece of wire up in the air.

73,

de N2HTT