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Coverage
Area
The Technology...Everything you could ever possibly want to
know about the technical nuts and bolts that make KAXE run (or just how to get a better
signal...)
Signal
"Hey! How can I get a better signal from KAXE?"
Lets start off with how you can get better reception of KAXE. Everyone could use better
reception, right? To start with, many people ask us if we can increase our power. The
short answer is, no. We broadcast with the maximum amount of power allowed by the FCC for
an FM broadcast station. KAXE’s 100,000 watt signal (see "Transmitter site"
later in this page) can be picked up with no trouble for a radius of about 35 miles around
Grand Rapids. This is the area that the FCC has designated as our "protected"
contour. Anything outside this 35 mile radius is considered the "fringe" of our
coverage area. The size of this "fringe" area depends on many factors, including
the atmospheric conditions on any particular day. On a good day, we’ve been known to
reach clear into Canada. One night, we even had a report of our signal being received in
Anchorage, Alaska.
"All this is great, but how can I get a better signal?"
OK, on to the good part. The best way to improve your signal is to improve your
antenna. The first, and probably the best option, is to put up an outside antenna pointed
straight at KAXE. (Stay away from antenna amplifiers though, particularly if you live
close to other broadcast stations. They have a tendancy to overload, and then you
won’t receive ANYTHING.) Putting up an outdoor antenna isn’t always the most
practical option, but it will give you the best possible signal if you’re about 70 to
80 miles away from KAXE. The second option, which works in most cases, is just a simple
wire antenna. The most common type is a "dipole" (pronounced DIE-pole).
"Uhhh…What’s a dipole?"
A dipole is just a wire antenna that points in two directions…It looks like a
"T". To make a simple wire dipole, take a piece of lamp cord, or speaker wire
(the zip cord type that can be split down the middle). Split it, and pull it apart until
you have about 3 feet split apart. (3 feet is the recommended amount, but the longer the
better…) Leave the rest together. You may want to tie the point where it splits so it
doesn’t split any further. Hang the ends that you’ve split apart as high as you
can get them, then attach the free end (the bottom part of the "T") to your
receiver. Play around with positioning to get the best signal. Its generally best to open
the "T" toward the station you’re trying to receive. (In this case, KAXE,
we hope…)
Okay, now time for the obligatory rant about the equipment that makes KAXE run. If
you have no desire to hear about equipment specifications, and terms like ERP and TPO,
turn back now.
I warned you….No going back now…Enter the land of the supergeek.
Studio Facilities
Our studios aren’t fancy by anyone’s definition, but thanks to money raised
through the Capital Campaign, we’ve been able to update some of our equipment.
Everything starts at the studio, specifically with some sort of playback device. There is
the usual mix of CD players, cassette decks, a reel to reel deck, a DAT player and even a
couple of turntables, but the most recent addition to KAXE is an Enco DAD Pro 32
automation system.
About the Enco:
This system serves as a centralized place to store any audio which is either locally
produced (like Loran DeShaw’s pieces on Chief Busticogan) or from the satellite (like
the World Café). It cuts down dramatically on the number of tapes shuffled around the
station, and since the audio stays in the computer, it is of much higher quality. It also
allows us the capability to run all night long unattended. The hardware for this system is
fairly simple (at least compared to some other automation systems…). Two industrial
grade rack mounted Pentium II-300 PCs with high quality audio cards make up the studio
part of the hardware. These machines run Enco’s DAD Pro 32 software under Windows NT.
One machine is dedicated to the on-air studio and the other is for the production studio
and recording satellite feeds. A third PC runs a Novell Netware server to store all the
audio on a quad of mirrored 70 gig drives. The drives are mirrored for reliability. In case
we lose a drive, the other drive takes over without anyone even noticing. All three machines are
networked via a 100 megabit network, so either studio has access to any of the audio that
has been stored.
The mixing console
All audio that goes on the air has to come through a mixing console. Our current console
is an Arrakis Systems 12,000 series. (Supergeek wishlist item #1: A PR&E Airwave
console)
Airchain
Once the audio comes from the console, it goes through some electronic gymnastics before
it finally gets to the transmitter site. Our current audio processing is made by CRL
Systems, and consists of several parts. The first box in line is an Audio Signature four
band processor. This box handles equalization, and does some multi-band compression to
make us sound louder while still staying within legal modulation limits. The next box is
an SMP-850 Stereo Modulation Processor. This device controls the overall gain of the
audio, does some stereo enhancement, and has a peak limiter for additional modulation
control. Next is the stereo generator, an SG-800A. This takes the stereo audio coming in,
combines it to a single signal, and generates a pilot signal so your radio can decode the
stereo information. (Add another item to the supergeek’s wishlist…A CRL DP100.
It does everything that our current airchain does, only it includes 5 band processing, and
is fully digital.) Now that the audio has been processed, it goes to the transmitter site.
We use a microwave STL (Studio to Transmitter Link) operating in the 950 megahertz band,
specifically, a Moseley PCL 6000.
Subcarrier
We also broadcast the Minnesota Radio Talking Book service for the blind on one of our
subcarriers. The signal is received via satellite, fed into a subcarrier generator
(similar to a stereo generator, except it generates the pilot signal at a different
frequency), then sent to the transmitter via our STL.
Transmitter Site
The signal is received by the STL receiver at the transmitter site, then fed into the
exciter of our transmitter. Our transmitter is a Harris HT-25FM. The exciter is a small
transmitter operating at a relatively low power level. This drives the intermediate stage
of our transmitter, which in turn drives the final stage. All stages in the transmitter
are solid state, except for the final tube. The final tube in our transmitter is a rebuilt
Econco 4CX20,000A. If you know anything about tubes, you know that this is one BIG tube.
Once the signal comes out of our transmitter, it goes through a filter to prevent
interaction with the other FM transmitter at our site. Finally, it is fed through 315 feet
of 3" rigid copper transmission line to our antenna. The antenna we use consists of
12 circularly polarized antennas stacked on top of each other.
Nominal Transmitter specifications
Plate Voltage: 9.3kv
Plate Current: 2.25a
Transmitter final efficiency: 78.6%
Final TPO (Transmitter Power Output): 16.447kw (The transmitter is rated up to 25kw)
Final ERP (EFFECTIVE Radiated Power): 100kw
How do they come up with 100kw output from 16.447kw in? Some mathematical formula which
I don’t even pretend to understand takes into account our height on the tower, how
many antenna bays we have, and the input power, then PRESTO! 100kw of EFFECTIVE radiated
power.
Now you have it…All the gory details
of how KAXE gets from our studios to your radio.
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