A Much Needed Antenna |
by
Ralph Taggart (WB8DQT) Mason, MI |
In
October of 2017, the FCC gave us back a piece of our
history by creating a new Amateur Radio band at 630
meters (472-479 kHz). The biggest challenge when you
start thinking about putting together a station for this
band is the antenna. A half-wave dipole for 630 meters
would have a span of over 1000 feet and a quarter-wave
vertical would tower-over 500 feet and require lots of
radials of comparable length! Any Amateur Radio antenna
will be very small (and very inefficient) when compared
against that standard.
Until recently there have been no commercial antenna
options and those constructing their inverted L or other
basic antennas strive to get as much wire into the air
as possible. It is not surprising that most operators
have property that is large enough to accommodate such
antennas. Those on smaller lots in town or other
residential situations seem to have few options.
That was all to change in 2021 with the introduction of
the Lowdown 630.PD, manufactured and marketed by
Information Stations Specialists in Zeeland, Michigan
(theRADIOsource.com). This antenna, illustrated in the
image below, has two characteristics
that make it
special: |
|
- It is small – the vertical monopole is just 21.5
feet tall, with a capacity top-hat of 6 aluminum
rods, and is mounted over a radial field that can be
as small as 20 feet in diameter.
- It works!
- A lowdown antenna at the Information Station
Specialists test range and
- Another antenna up against the trees at my
QTH. The first-class black anodizing on the
vertical tubing makes the vertical quite
stealthy!
The quality of the components and the care taken to
protect them in shipment is exceptional. Instructions
for assembling, mounting, and tuning of the antenna
(controlled trimming of the six radial rods) is clearly
documented and should provide no surprises. The tuning
process, which you do only once, involves lowering and
raising the antenna several times while tuning; and I
would strongly advise the use of an insulated tilt-base
like those sold by DX Engineering. Tuning also requires
the use of either a VMA (which MUST be calibrated prior
to making measurements) or antenna analyzer that works
on the Medium Wave band (all Rig Expert and some MFJ
units).
The units are only needed for the initial tuning and
thus can be borrowed if you don't have your own. The
help of another Radio Amateur makes everything easier
and safer! Once tuned, the job is done and there is no
need to endlessly tinker with a bucket variometer or
other vintage tuner. At that point the antenna is fed
from standard coax from the shack. Repeating the tuning
is only required if you change the radial field or some
other significant aspect of the mounting and you will
find the antenna tuning is very stable in all kinds of
weather.
|
So, I have a vertical that looks more like 20 or 30
meters instead of 630, it sits over a field of 32
radials that are each only 10 feet long, and is next to
a stand of trees, far from being in the clear. In the
end I was hoping for at least some marginal performance.
Needless to say, I was astonished to find that the
Lowdown 630 was completely serviceable and effective on
the 630 meter band. Below is the result of a 12-hour
WSPR run near the end of September: |
|
“Lowdown 630
continues to amaze! The latest WSPR count is a new
record - 42 hits, 41 of which heard me! Had seven
two-way FSt4 contacts, including W0SD for my 13th state
worked.” |
This
run was typical of the early Fall, with 34 WSPR hits.
During the Summer there is a much higher average noise
level and mostly ground wave propagation, so somewhere
around 20 hits is the rule with my setup. I was running
50 watts input, which probably resulted in about 1W ERP,
and every one of the 34 stations heard my transmissions!
WSPR can be fun and informative, but I wanted two-way
QSOs and I have just passed a total of 100 contacts
using FST4. By mid-winter, with much lower average noise
and more ionospheric propagation, I will expect to have
two-way QSOs with the West Coast and some very crowded
WSPR plots. I also expect Winter to bring the
opportunity for some CW that brings to life the nature
of the earliest activity of the first Radio Amateurs!
Information Station Specialists has designed an antenna
that permits those of us, with smaller lots and nearer
neighbors, the fun of working 630 meters. When you do,
you will meet a fine group of very friendly operators.
There is a lot to learn on this vintage band and it is
painless and fun. It will take a little time to settle
in, but patience assures success. |
|
Information Radio Stations is a generic term
synonymous with Travelers Information Stations (TIS), Highway
Advisory Radio Stations (HAR) / Highway Information Systems &
Low Power Radio Stations (LPR). Operation of the stations is
governed by FCC Part 90.242 Rules. A FCC license is required.
Information Radio Stations may be fixed or portable.
Subcomponents may include transmitter, antenna and ground
system, digital voice player, wattmeter, cabinet with
conventional or Corbin locks, lightning arrestors for RF, power
and telephone lines, coaxial cable. Most stations employ black
maximized antennas to discourage ice accumulation and security
measures to prevent unauthorized program access. Options include
synchronization, battery backup, solar power, remote programming
by local, network or telco, multi-station audio distribution via
RF or LAN / WAN or wireless network. |