— The beautiful mountain vista seen above is an excellent location for an FM
station, don’t you think? But what do you do when your leased tower site falls
through and no new tower construction is allowed?
beautiful location for an FM antenna
was my mountaintop challenge!
In early 2012, I set out to complete
construction of an FCC CP for a new station, WUMV(FM), with less than two
months before expiration. No big deal, I thought, until the tower owner we had
been dealing with for two years informed us that the tower couldn’t accept any
additional antennas, and he offered us no options. So I got to work — I like a
I found a nearby neighbor who has a love for
public radio, and some land on the side of the hill the previously-mentioned
tower sits atop of. I made a deal with him to install a temporary antenna on a
tree in his back yard! See the picture on the next page for the eventual
this arrangement, we would still provide full coverage of the city of license.
There was one problem: our effective
radiated power and our transmitter power output would have to be double what we
had planned at the first site, so I couldn’t use my spare 250 watt exciter as I
The station is associated with University of
Massachusetts Boston so I didn’t have a large budget to work with. I started
looking for cost-effective options. One potential problem — the transmitter had
to be small enough to fit into a weatherproof equipment cabinet I already had,
along with all the peripherals needed, and be efficient enough to need only
exhaust fan cooling.
there’s no tower, there’s always a tree!
Our Shively 6810-2-SS-DA antenna mounted easily
to a 4-inch pipe, which mounted to the tree with a special arrangement of
custom mounting brackets and straps designed by Chris Loycano of Broadcast
Tower Co. of West Bridgewater, Mass. We chose a nice, fat beech tree, and being
a directional antenna, the orientation stake was located by the surveyor,
according to Shively’s measurements. Chris’
mounting arrangement of rope and wood
lattice allows the tree to breathe and grow, and
doesn’t damage its sapwood layer or bark, while permitting the antenna to be
aligned to its required azimuth.
At a New England Radio Engineering Luncheon
(hosted by Broadcast Signal Lab), I saw one of Elenos’ cute little Indium
series transmitters put through its paces and fell in love. The 1,000 watt unit
is only 2 RU high, and its high efficiency results in little waste heat. Unfortunately,
the transmitter was a couple of inches too deep to fit within the donated
enclosure with the doors closed.
So I fabricated special brackets that allowed
the transmitter to be installed at a steep angle, with the front near the
bottom front of the cabinet and the back near the top. This sleight of hand can
be seen in the picture to the right. It provides a natural path for the air to
flow, because the transmitter exhaust heat appears near the exhaust fans in the
top of the cabinet.
the Shively antenna to a tree — landscape fabric under a wood and rope lattice
protect the tree from the mounting chains.
The equipment enclosure sits comfortably on two
pressure-treated wood, 6-by-6-inch boards staked into the ground with standard
ground rods. Even though there’s no steel structure in the air, I didn’t skimp
on grounding. The antenna, transmission line, and the enclosure and its
contents are well grounded, tied into the ground rods anchoring the enclosure.
The site is fed with power from the landowner’s
garage, using 400 feet of 10-3 SO cord. All communications with the site are through
a Verizon USB wireless data dongle. That includes program audio, remote control
and TCP/IP management. The tower we planned to be on is only half-a-mile away,
and I’ve got four bars of signal strength on the wireless router. We get around
the lack of a static IP address by setting up an SSH tunnel from the site back
to the studio, checking for existence of the tunnel every few minutes, and
rebuilding it if it collapses — a great idea from Rob Landry, well known in
these parts for his extensive bag of computer tricks.
author and his transmitter box. Note the steeply angled Elenos transmitter: Its
exhaust fans on the backplane are at the top of the box to vent excess heat.
Setup of the transmitter was a breeze, taking
less than five minutes to set frequency, power output and modulation level
directly from the front panel.
site has been on-the-air for nearly six months now, and we’ve been very
impressed with the operation.
transmitter site challenges sometimes require out-of-the-box thinking. This
project was no exception!
information about Elenos, contact Mary Ann Seidler in Florida at (855) 353-6670
or visit www.elenos.com.
For information about Shively
Labs, contact Bob Surette in Maine at (207) 647-3327 or visit www.shively.com.