Review of the Titanex Lowband Dxpedition Antenna
On a recent DXpedition to Kure (K7K), we used one of the new Titanex
antennas. Some people have been asking me for details on how it goes
together. Here are some random notes.
Erik (SM0AGD) and I did most of the assembly work. I think that, from start
to finish, it took us about four hours to get the antenna up and working.
Precutting the guys
We did not have time to precut the guy ropes. I would recommend doing this,
if you can. It only took Erik and I about a half hour to cut them.
The antenna is fairly easy to assemble. The current translated (to English
from German) version of the assembly manual leaves a lot to be desired. When
I read the manual on the plane ride over to Midway, I was concerned that we
might have some problems. Fortunately, once we got the antenna unpacked and
laid out, it was fairly obvious how everything fit together.
Preparing the antenna base
The antenna mounts on a piece of galvanized channel steel. The channel is
about four feet long, 3 inches wide, with roughly one-half inch sides. There
are two mounting holes drilled through the center of the channel. One near
the top, the other about one foot from the bottom. The roughly one foot long
portion of the channel, below the second mounting hole, is supposed to be
driven into solid ground, or mounted in concrete. There is no "solid" ground
on Kure. We drove two 3-foot long pieces of 5/8 inch rebar into the ground
right next to each other, leaving about one foot of each sticking out above
ground. Then, we drove the channel into the ground next to the rebar, to a
point at which the lower mounting hole was still just above ground. We then
used a couple of steel hose clamps to connect the channel to the rebar. When
we were finished, we had a very solid mount for the antenna.
The antenna itself is connected to the steel channel base with two identical
insulating clamps. These clamps are shaped roughly like a lower-case letter
"p". The base section of the antenna slips through both clamps (through the
circular part of the letter "p"). The clamps are connect to the steel
channel base using a bolt that corresponds to the tail portion of the letter
"p". More on this in the next section.
Assembling the antenna
The antenna itself consists of nine separate pieces of Titanium-Aluminum
Alloy tubing. If memory serves me correctly, there are four 40 mm diameter
tubes ( 3 meters long each), two 30 mm diameter tubes (3 meters long each),
and three 20 mm diameter tubes that are a combined length of about 8 meters
(two are 3 meters long, one is just over 2 meters long). The key to the
whole antenna is the Titanium-
Aluminum alloy. You won't believe how flexible this antenna is.
Assembly is straight forward. The English translation called some of the
hardware "ring screws." We quickly realized that these are better known as
eyebolts. Each of the four large tubes connect together with a short piece
of splice tubing, or a machined reducer piece, that goes inside the two
pieces being joined. Eyebolts go completely through each main tube and the
splice. The eyebolts serve a dual purpose of holding the antenna together,
and also acting as an easy place to tie on the guy ropes.
The entire antenna fits together to very close tolerances. We found that the
top 40mm tube that connects via a reducer to the bottom 30mm tube was "upside
down." The reducer piece was connected to the wrong end. As a result, one
joint didn't fit very tight, and the other end wouldn't fit because it was
too tight. When we flipped this piece around and put the reducer at the
other end, both joints now fit very snug. If you have a problem with pieces
that don't fit, try flipping them around. I have a feeling that each antenna
is manufactured individually, and there is only one way for all of the tubes
to connect together with snug joints. If you have problems pushing the tubes
together, use some anti-oxidant grease to
lubricate the joint.
Erecting the Antenna
After you finish assembling the antenna, you then erect the antenna WITHOUT
the top 8 meters of 20mm tubing. This "trial" erection is done so that the
amount of time you spend erecting the complete antenna, including the stinger
section (top 8 meters), is minimized. When we put the antenna up, we had
steady 10-15 mile per hour trade winds blowing, so this seemed like a good
idea.
The bottom of the antenna is clampled and bolted to the lower hole in the
steel channel. The antenna is then lifted until the upper clamp can also be
attached to the steel channel. At this point, the antenna actually bends
around all the way back to the ground, kind of like a rainbow. Apparently,
the titanex alloy is extremely flexible, yet strong!
With no winds, you might be able to erect this antenna with two people. I
would recommend at least three people. We had five people, which made things
go easily and quickly. The trial run took us about 30-40 minutes. The final
erection took about another 30 minutes, mainly because we got really picky
about having the vertical "exactly" vertical.
Attaching the Guy Ropes
All guy ropes are pre-attached to the antenna at the 6, 9, 12, 15, and 18
meter levels. We pre-cut them to the lengths suggested in the manual, and
placed our attachment points 10 meters from the base of the antenna. Titanex
supplies individual aluminum rope ratchets for each guy so that they can be
easily tightened or loosened individually. Most of the ratchets work OK, but
two of the ones we received did not turn freely. The brackets are roughly
"O" shaped, with the ratchet mechanism mounted inside the "O." The guy rope
goes out a hole in the middle of the top of the "O", while the guy stake goes
through the gap on the other side of the "O" between the bracket and the
ratchet mechanism.
They also supply three nifty looking stakes that are supposed to hold the
ratchets at each guy point. Unfortunately, the stakes are only about one
foot long, and each ratchet (which slips over the stake) is about one inch
wide. This leaves only 6-7 inches of stake (there are 5 levels of guying)
below ground when it is driven in, which is not nearly enough holding power.
Furthermore, there are two horizontal stubs that stick out at the top of
each stake that are meant to keep the ratchets from slipping off the top of
the guy stake. Since the stubs prevent the ratchets from slipping off of the
top, this makes it much more difficult to lower and raise the antenna. My
advice is that you leave the fancy stakes at home and use at home and use
rebar instead. We ended up using two pieces of two foot long 5/8 inch rebar
at each guy point. One rebar held the bottom three ratchets, while the other
rebar held the two top ratchets. We drove each rebar in at about a 45 degree
angle, with the rebar pointing towards the antenna. This system simplifies
everything. The ratchets slip easily over the top of the rebar, which means
that, once you have each guy rope tightened (ratcheted) to the right length,
you can just pull a little on the guy rope to slip it on or off of the rebar.
The ridges in the rebar hold the brackets from slipping over the top fairly
well, but you still need to tie some rope around the top ratchet and the
rebar to keep it from slipping off. The angle of the top guy rope up to its
attachment point is about 55 degrees.
You erect the antenna by pulling it up, one section of guys at a time, until
you have it completely in the air. The guys are carefully adjusted at each
level so that the antenna is as close to vertical and straight as possible.
Tuning the Titanex
A separate, waterproof box is provided containing the tuning unit. This unit
consists of a large coil, two relays, and two variable capacitors.
We ran eight 130 foot long radials out around the base of the antenna. Being
fairly close to the ocean, we figured that eight radials was enough.
Besides, we didn't want to create any more of a clutter than we had to with
the fish and wildlife people also sharing the island with us.
Tuning of this antenna is fairly critical. There are three wires that must
be soldered to the matching coil, plus two separate variable capacitors to
adjust. Erik brought along a compact antenna matcher, which was a real
timesaver. We would have spent hours trying to tune the antenna if we had to
actually apply power from one of the rigs, with an SWR bridge at the antenna.
I would insist on having one of these
devices if I were going to use this antenna again on another trip. Besides,
the thing came in handy when we were jury rigging some simple wire antennas
for 15 and 20 meters.
First, you match the antenna on 160 meters. The ONLY adjustment is to move
the tap point of 160M wire on the coil. The 160M relay must be energized
while making this adjustment. We just pushed the relay down with a
screwdriver handle. We must have fiddled around for 15 or 20 minutes trying
to find a tap point that would give an SWR under 3:1. Finally, by accident,
we found that if we tapped the coil and
shorted out one turn of the coil at the same time, we could get an SWR of
1.8:1. We decided to live with that.
Next, you set the tap point for 80M operation. A variable capacitor is also
adjusted for minimum SWR. It was easier to find an 80M tap point, but we
still were only able to get the SWR down to about 1.8:1. No relay is used for
80M operation.
Lastly, you set the tap point for 40M operation. It took a long time to find
a good tap point. Finally, we found that if we tapped into the coil at the
bottom (the most inaccessible part of the coil, of course!), we could achieve
an acceptable SWR. You also must activate the 40M relay for this step, and a
second variable capacitor is
adjusted. If I remember correctly, the SWR ended up around 1.5:1.
During these adjustments, we found that we had to temporarily shut down the
20 meter CW station, which was running about 500W out into a nearby R-7.
Otherwise, whenever that station transmitted, we got false readings on the
antenna analyzer.
I should add that, when we actually checked the SWR on each band with a
wattmeter back at the shack end of the coax, the SWR was better in all cases
than the antenna analyzer had shown. Bottom line was that, for 160M, 80M,
75M, and 40M, this antenna worked fine and did not cause excessive reflected
power at any time.
Changing Bands
Once the antenna has been pretuned, you change bands by plugging a banana
jack with +12V into either the 160M female connector (for 160M operation), or
into the 40M female connector (for 40M operation). You leave the jack
unplugged for 80M operation.
Conclusions:
This is an excellent low band antenna. It may not be suitable for all
Dxpeditions because of its size, in that most pieces are 3 meters long. It
performed very well on 160M, although I would guess that a Battle Creek
Special has a slight edge on that band. The battle creek does not use base
loading on 160M. Instead, it uses a top loading wire in conjunction with an
80M trap at the top of the antenna. The cost of
the antenna may also be a factor. I think the list price is around US $1400.
For a permanent installation, I believe that Titanex makex a different
antenna, but only have heard rumors of this from ZS6EZ. I would not choose
this antenna for a "home" station. You can probably build your own 26 meter
high vertical using something less expensive such as irrigation tubing. For
strictly 160M operation, it would be better to add some top loading wires to
eliminate the need for the base loading coil. By the way, the 26 meter
height was chosen because it makes the antenna a 5/8 wave vertical on 40M,
which gives an excellent low angle radiation pattern on that band.
73,
Randy K0EU
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