The obligatory rant about the
equipment that makes Northern Community
Radio run . . . enter
the land of the supergeek.
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. We play audio from CD players,
recorded and live feeds off the Public Radio
Satellite System, turntables, an ENCO
automation system, and other devices.
Heart of the Beast
Northern Community Radio's on air system is a marriage between a
Logitek audio router system and Mosiac
control surface tied into the ENCO "Digital
Audio Delivery" system. The Logitek
router system puts the correct inputs to the
correct outputs, at the command of the ENCO
system. ENCO serves as a centralized place to
store any audio which is either locally
produced (like Real Good Words) or from the
satellite (like the World CafÃ©). 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.
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 Aphex Systems. This box
handles equalization, and does some
multi-band compression to make us sound
louder while still staying within legal
modulation limits. Now that
the audio has been processed, it goes to the
transmitter site. We use an analog microwave STL
(Studio to Transmitter Link) operating in
the 950 megahertz band, specifically, a
Moseley PCL 6000. KAXE broadcasts 2
subcarriers... a 57kHz RDBS signal for the
Now Playing data displayed on receivers
capable of RDS/RDBS data and also the MN
Talking Books on a 67kHz subcarrier using
the FMeXtra digital subcarrier.
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: 9.6kv
Plate Current: 2.20a
Transmitter final efficiency: 78.6%
Final TPO (Transmitter Power Output):
16.500kw (The transmitter is rated up to
Final ERP (EFFECTIVE Radiated Power): 100kW
Now you have
it . . All the gory details of how
Northern Community Radio gets
from our studios to your radio.