Assembling a LightningBolt Quad
The next step is to install the reflector elements. During
element assembly you will work with the aluminum alloy wire that is
supplied on two spools, one for the reflector loops and one for the
driven element loops. It is solid wire, about 1/16 inch in
diameter. Eye protection is recommended because the wire is like
a big spring. Once you unreel it from the spool it will snap back
with a lot of force if let go and could potentially cause some harm if
you are not careful. If you can have some help during this phase,
it will save some time. It is possible to do this by yourself
( I have) if planned carefully. If you have a helper, he/she needs
to hold one end of the wire at all times so it does not snap back.
If released, the wire will coil back up and make it very difficult to feed
through the wire holders.
Element assembly begins with measuring and cutting to length the 20
meter reflector loop. Cut each wire an inch or two longer than
needed to allow for mistakes. The aluminum alloy wire
is very strong under tension, however, it breaks if bent back on itself
or in too tight a loop. If you make a mistake bending the
attachment loops, don't unbend it, just cut that portion off and start
over. Use long nose pliers and bend the wire gradually to form
the loop as shown in the instructions. If you see any hint of
cracking on the surface of the wire, start over. Some practice in
bending the wire before hand is recommended.
the wire lengths for each element. You should use a 100 foot tape
pull the wire tight when measuring and cutting.
| The wire holders allow the wires to move freely when the spreaders flex in the wind.
Before unreeling and cutting the 20 meter loop, bend the first
attachment loop. Attach the plexiglass insulator to the loop you
just made using the stainless steel nuts, bolts, and washers.
Make sure the wire is between the two washers as shown in the
instructions and tighten it enough to hold it in place. Final
tightening will be done after the reflector elements are all
done. Also do not overlap the wire, bend it exactly as shown in
the instructions or it will break at the point of overlap after the
nuts are tightened. Next, take note of where the paint mark (blue
or red) is on the hub. You must string the wire so that when you
are done, the plexiglass insulator will be centered under the paint
mark. Take the unbent end of the wire and feed it through a 20
meter wire holder located under the paint mark, then work your way around
the spreaders, feeding the wire through the outer most wire holders.
Don't let the wire coil up during this process or you will wind up with
a kink and a potential breaking point. Once you have the wire
threaded through all four wire holders, you can let go of it. Cut
off any extra wire and bend the attachment loop on the other end of the
wire. At this point you will need to loosen one of the wire
holders to allow enough slack to attach the free end of the wire to the
plexiglass insulator. Once the second end is attached, to the insulator,
it should be approximately centered between the ends of the adjacent spreaders.
Move the loosened wire holder back into place to take the slack out of the
wire but do not tension it yet. At this point you have completed the
assembly of the 20 meter reflector loop.
|A properly formed attachment loop.|
Repeat this process for the 17, 15, 12, and 10 meter reflector
loops. Bend the attachment loop, unreel the wire, cut it to length,
attach the insulator to the looped end of the wire, feed the wire through
the wire holders, bend the second attachment loop on the free end of the
wire, loosen a wire holder, attach the free end of the wire to the insulator,
reposition wire holder to remove slack, and center the insulator between the
ends of the adjacent spreaders.
Now a side note...
The wire installation process can be completed by one
person. To do this, here is the procedure I have used.
First, I drive a large
nail (I use pole barn nails found at Lowes) into the ground. I locate the
nail so that when you unreel the wire, the loose end will be close to the
spreader which is at this point assembled and laying on the ground.
Next I clip a 100 foot tape measure to the nail and reel out enough tape to
measure the length of wire needed. Next, take the spool of wire and
bend the attachment loop with needle nose pliers and hook it to the nail in
the ground. Then insert a large screwdriver through the hole in the
spool of wire and walk along the tape measure toward the spreader unreeling
the wire as you go. When you have enough wire unreeled, pull it and the
tape measure tight and cut the wire as described above. At this point
you will need something heavy to lay on the wire temporarily while you work
on the end hooked to the nail. I use a few bricks for this purpose.
Next, unhook the wire from the nail and attach the plexiglass insulator
to the looped end of the wire.
I use a vise grip plier (locking jaw pliers, preferably a large pair) to
hold down the loose end of the wire (to prevent it from coiling up)
while threading the wire through the wire holders. Next, clamp
the vise grip onto the plexiglass insulator, on the end opposite to
where the wire is attached. The vise grip needs to be tight
enough so you can drag it on the ground with the wire to keep the slack
out, but not so tight that the plexiglass becomes cracked. Drop
the vise grip plier on the ground and pick up the free end of the wire
under the bricks. Pull the length of wire over to the spreader
and thread the wire through the wire holders (as described above) while
keeping tension in the wire with the weight of the channel locks
holding the other end of the wire. Once the wire is threaded
through all four wire holders, bend the attachment loop on the free
end, remove the channel locks and attach the wire to the insulator.
This completes installation of the wire. Repeat this
process for all of the other wires.
End of side note...
Once you have all five reflector loops installed, check to make sure
all of the loops are evenly spaced on the spreaders and tension the loops
so that the spreaders have a slight bow to them. Then tighten all
the nuts on all five of the plexiglass insulators. A little
advice here... While the element is laying on the ground, the wires
will have more tension in them than when they are in the air. If
you put too much tension in the wires, it can cause
problems later that will eventually break a wire. I shoot for
about 1 foot of bow in the spreader when it is laying on the
ground. This foot is the distance from the ground to the end of
the spreader with the element laying level on the ground. More
tension than this will put excess stress on the wire and wire holders
under high wind loading and will eventually break a wire. Less
tension will cause too much slack in the loops once the antenna is in
the air and the loops could potentially flap in the breeze and touch
each other and lead to breakage due to excess flexing of the wire
around attachment points. A good indication that you have the
tension right will be seen once the antenna is in the air. I have
found that with high wind loading and with the reflector pointed into the
wind, it can snap inside-out, or stay bowed in the opposite direction
in gusty wind. If the reflector snaps back easily, you have the
tension about right. If it stays inside-out for long periods of time,
the wires are too tight. If you have guy wires at the top of your
tower his condition can cause interference between the guy wires and the
ends of the spreaders. The driven element is less susseptible to this
when the wire are tensioned properly. It is stiffer since all of the
loops are tied together at the balun.
|The completed reflector with wires tensioned and shorting stubs installed.
| Once installed, the spacing between the elements should be checked and adjusted for even spacing.
Once all of the elements are tensioned, the reflector shorting stubs
are installed on the plexiglass insulators. I find that the stub
lengths given in the instructions work just fine. A second
set of washers and nuts is used to secure the shoring stubs. Although
not as critical as the other attachment points, the same guidelines for
wire bending and placement should be followed. After everything
has been properly tensioned and tightened, all of the shorting stubs
should be centered under the paint mark on the spreader hub.
|The completed reflector with shorting stubs installed.
|The reflector shorting stub hardware.|
Assembly of the driven element is much the same as the reflector.
The major difference is in the order of installation of the loops.
Following the recommended antenna feed point configuration, all five
driven element loops are fed in parallel through the supplied 2:1 balun.
This requires that the 15 meter loop be installed first, followed
by the 10, 12, 17 and 20 meter loops. The ten meter loop should
attach to the balun closest to the body of the balun, and the 20 meter
loop should be the farthest from the body of the balun, with the rest of
the wires in band order from inside to outside. The balun is
installed with the coax connector pointing toward the ground and the
wire mounting stubs pointing up. Each wire should be placed between
washers and the entire assembly tightened once all of the wires have been
attached. On the driven element, a bit more effort is needed to
position the feed point in the center of the bottom of the loop.
The balun should be under the paint mark on the spreader hub.
Partial tensioning of the wires of each element as it is installed helps
keep the balun in place. Otherwise tensioning of the wires on the
driven element is done the same way as the reflector.
|The completed driven element with balun installed and wires tensioned.
all of the driven elements installed, the wires on the balun should be
in the following order, 10, 12, 15, 17, and 20M starting closest to the
body of the balun.|
With both elements assembled, check that all the loops are centered and
all the wire holders are tight. The clamps on the wire holders are
not as heavy as the other hose clamps. They do not have to be super
tight to stay in place and can be over tightened to the point of breaking
if you get "too enthusiastic" about making sure they are tight.
|The completed driven element with the balun and wires tensioned.
Once the elements are assembled, the boom to mast plate is installed on
the rotator mast and the boom is centered with the paint marks pointing towards
the ground. Pre-marking the center of both the boom and boom-to-mast
plate before installation makes this step easier. The nuts clamping
the boom are just finger tight at this point. Each element is installed
by inserting the hub into the end of the boom and securing it with a bolt.
When doing this step by myself, I have found it to be a big help to polish the
spreader hubs and the inside of the ends of the the boom with steel wool and
then apply a little lubricant like WD-40. This makes the hub slide
into the boom easily. If you have a helper for this step you may not
need to do this.
Once the elements are installed, the antenna is leveled and the boom to
mast clamp nuts are tightened. Be careful when tightening the boom
clamps. The boom is thin walled aluminum and will collapse if the clamps
are overtightened weakening the boom.
With the antenna assembled all that is left is connecting and securing
the feed line and rotator loop. I weather proof the coax connection
with vulcanizing tape and seal the potted side of the balun with R.T.V.
|The completed installation on 60 feet of AB-577.
I have found that following these procedures results in an installation
that is correct the first time with no other adjustments needed.
The antenna has good front-to-back, signals virtually disappear off the
ends of the elements and the standing wave ratio is good on all
bands. Click here to see the SWR plots
for each band. I originally had some concern about running 1500
watts through the supplied balun, but have not had any problems doing
so. With an SWR less than 2:1 on any frequency on the 5 bands,
my amplifier puts out the legal limit.
This project requires some work, but with proper planning it can all
be done in one weekend by one person. I have successfully
assembled this antenna and made repairs to it in this time.
I did however, learn some of the lessons described above the hard way.
So I hope you find this information useful if you are planning to purchase and install
a LightningBolt quad.
One last thing ... The one weak point in the design of this antenna
is the boom. The supplied boom is a 2 inch outside diameter thin
wall aluminum alloy which will bend over time. The original
boom on my antenna had a large set in it after two plus years in the air.
This was most likely caused by an ice storm we had in December 2001
and was made worse by over tightening the boom clamps. The antenna
survived the ice storm with no apparent damage (½ inch
diameter of ice over a 24 hour period) but the boom had a noticeable curvature
to it when I took it down for repair the following summer. Since
then I have reinforced the boom by inserting a length of PVC pipe in
the boom to stiffen it. I recently had the antenna down to
replace a faulty rotator and found that the boom still was bending a
little, most likely from wind loading.
The plus side of this is that replacement parts can be purchased from
LightningBolt at a very reasonable price. Any of the parts
supplied with the antenna, right down to the washers, can be
purchased. LightningBolt makes a four element quad which has a
heavy duty boom. You can buy a version of the two element quad
which uses this heavier boom and allows the antenna to be upgraded to
the four element version. I looked into doing this, however, the
heavy duty boom nearly doubles the weight of the antenna. This
does not lend itself to my installation so I tried reinforcing the boom
with a PVC pipe to keep the weight to a minimum.
My quad sits on top of an AB-577. The AB-577 is a crank-up mast used
by the military. It was available on the surplus market and has become
a very popular item among hams in recent years. The performance of the
antenna is excellent. I frequently receive unsolisited comments on the
strength of my signal, even while running 100 watts. When I installed
the quad in June 2001, I had 286 countries worked using only wire antennas.
Since then, I have added 43 countries and have over 330 countries confirmed on
CW and SSB.
I hope you have found this information useful. I welcome any comments you
may have. Just drop me an e-mail from the link at the botom of the main
page or at firstname.lastname@example.org.