INTRODUCTION
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These
pages will describe the technical aspects of the KE8RV Repeater System
on 147.285 MHz. Follow the links above for more information about
the indicated topics.
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The
Repeater System is located in London OH at the Madison County
Hospital in central Madison County. There are also three remote
receiver sites located in Plain City, West Jefferson, and Mt Sterling
at
the north, east, and south ends of the county respectively. This
enables low-powered handheld coverage throughout the entire county, and
mobile coverage over most of the adjoining counties. (See Coverage for more information.) All
sites have emergency backup power available.
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The
Repeater System is operated by the Madison
County Amateur Radio Club (MCARC),
and is open for all amateurs to use. For more information about
our club, click here
to visit the
club's web site.
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Welcome!
- You are encouraged to use the system. |

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WEEKLY
"GET TOGETHER" NET
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Every
Tuesday evening at 8:00 PM we host a very friendly net and all
amateurs are welcome and encouraged to check in. Hear about the
latest club news and other items of interest from the members.
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CURRENT
REPEATER STATUS -
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Repeater temporarily located in West Jefferson, with
remote receivers in Galloway, Plain City, and Mt Sterling.
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MAINTENANCE HISTORY:
- September 1, 2017 - The repeater now transmits a 82.5 Hz CTCSS tone
during any RX activity, but not during tail or hang time. This
will help remote linking to other repeaters or remote EchoLink
connections. A 150 ms audio delay has been added as a squelch tail
eliminator.
- August 14, 2017 - The repeater is back on the air at W8DPK's QTH in
Lilly Chapel until a new permanent location is found. The remote
receiver links from Plain City and Mt Sterling are not strong enough at
Lilly Chapel, so the only receivers now online are at West Jefferson and
the local receiver in Lilly Chapel. The antenna is only 33 feet
high so coverage is limited.
- August 1, 2017 - MAJOR! The Madison County Hospital (now
called Madison Health) where the repeater tower is located is under
major renovations and the tower will be permanently removed. The
repeater will be off the air until a new location can be found.
Here's a 5 minute video of the tower being removed:
https://youtu.be/I1fsnhyo-XA
- Entire Year 2016 - No maintenance or repairs required!
- Entire Year 2015 - No maintenance or repairs required!
- December 14, 2014 - Repeater is back on the air with the new DB-224E
VHF antenna, 1/2" Heliax feedline, and a new omnidirectional DB-404 UHF
link antenna to replace the 3 individual yagi antennas that were used to
receive the remote receiver links. Here's a 36-minute video of the
antenna replacement project:
https://www.youtube.com/watch?v=HDBTCP403fs
- December 7, 2014 - Antenna replacement at the main site in London.
The repeater will be off the air until the antenna replacement is
complete. The old antenna, a 10-year old Phelps-Dodge DB-224 was
installed in 1985 when the repeater was moved to the tower at the
Madison County Hospital.
- September 17, 2013 - The West Jefferson receive site is now
fully operational at its new location near the high school. It
has new antennas and feedlines for the 2M receiver and UHF link
transmitter, and is about 20 feet higher than the old location (now
about 50 feet AGL.) Tests have confirmed that this installation
works very well! (The WJ receiver site was temporarily located in Lilly
Chapel for the past 9 months while this new site was being prepared.)
- May 10, 2013 - The main site in London was damaged by a
power surge during a thunderstorm. The Astron 35A power supply
bore the brunt of the damage, destroying the OVP crowbar, the main
rectifier diodes, and also melted the fuse holder and some of the
wiring. The microprocessor's reset circuit in the REP-200
controller failed, requiring replacement of the 6803 microprocessor.
Some routine preventive maintenance was also performed - The cooling fan
on the 100W amplifier was replaced, and a new fan was added to the
Astron power supply. The repeater was back in service two days
later on May 12, 2013.
- Entire Year 2012 - No maintenance or repairs required!
- November 17, 2011 - The power switch on the REP-200
controller suddenly and mysteriously failed during a QSO.
Repeater was down for only a few hours before repairs could be made.
- Entire Year 2010 - No maintenance or repairs required!
- June 30, 2009 - The Plain City receive site was hit by
lighting on June 19th or early morning June 20th, damaging the power
supply, receiver, and
controller. The backup battery suffered unrecoverable damage due
to complete discharge. A new power supply and backup battery (13AH)
were installed. A dual-gate mosfet for the receiver RF front end and an
op-amp on the controller board were replaced.
- June 27, 2009 - The Mt Sterling receive site link antenna
was mis-aligned by strong winds earlier this year. The link antenna has
been re-aimed, securely tightened, and is now fully functional.
Many thanks to Jim Bingham - KC8ARZ (son-in-law of club members Art
& Betty Eberle - K8JBF & N8KPZ) for his work on the tower!
- January 5, 2009 - The West Jefferson receive site has been
updated with the new microprocessor-based controller. All three remote
receive sites are now controlled with this new hardware. See
the Equipment page for the details.
- November 30, 2008 - A new microprocessor-based
controller has been installed at the Plain City receive site.
- October 25, 2008 - The South receive site has been
installed at the firehouse in Mt. Sterling, providing coverage to the
southern parts of Madison County. This new microprocessor-based
controller has multiple CTCSS and carrier access modes, several timer
modes, and a DSP based CTCSS decoder.
- September 14, 2008 - Added a backup battery to the main
repeater site in London. The controller would sometime
malfunction when the AC power glitched during a transfer to the backup
generator. The battery will allow the controller to survive these
power interruptions.
- June 30, 2008 - A new dual circulator/isolator was added to
the main transmitter in London
- June 15, 2008 - We did not get permission to install the
south receive site at the new firehouse in Sedalia. Plans are being
made to move the south site to Mt Sterling.
- January 25, 2008 - The Sedalia receive site was removed
from service and the tower and antennas disassembled because of the
pending demolition of the firehouse. The new firehouse is under
construction and should be completed by the end of February 2008.
Hopefully we'll have the tower and antenna re-installed later this
Spring.
- March 19, 2007 - The West Jefferson receiver site was
damaged by lightning this morning, killing the power supply. The backup
battery died sometime later. The regulators and diodes in the power
supply literally exploded. The backup battery suffered unrecoverable
damage due to complete discharge. Receiver and link transmitter were
not damaged. The power supply has been repaired and battery replaced on
March 20.
- February 12, 2007 - Fan replacement completed and 100W
amplifier is back online. Also, the "kerchunk" filter has been turned
off for instant carrier access.
- February 5, 2007: Routine inspection revealed that
the cooling fan on the transmitter's power amplifier has died.
Last inspection was June 10, 2006, so it quit sometime in the last 8
months. To avoid risking damage to the amplifier, the amp is
off-line and the repeater is running barefoot at 25 watts. A new
fan has been ordered and should be installed next week.
- February 5, 2007: Programming Changes - Due to increasing
amounts of DX and other noises hitting the Sedalia and Plain City
receivers, the repeater now has the "kerchunk" filter turned on.
If the repeater has been idle for more than several minutes, it will
take one second of continuous carrier to activate the repeater. Keep
this in mind so that the first second of your transmission is not
chopped off.
Also, the pitch of the CW reset beeps have been changed to make it
easier to tell how many receivers you have "hit" during your
transmission. The range used to be from 523 Hz to 1046 Hz; now
the range is from 350 Hz to 1185 Hz.
- June 12, 2006: The new and improved Sedalia receiver
site is back in service, sporting a new microprocessor-controlled
controller and CTCSS decoder. See the Equipment
page for more information.
- June 8, 2006: The main repeater site in London was
hit by lightning, damaging the power supply and the Plain City link
receiver. Repairs were completed by June 10.
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FREQUENTLY ASKED
QUESTIONS (FAQ)
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Q.
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How
does the voter work?
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A.
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At
the main transmit site, there are are three receivers that listen to
a set of UHF link frequencies in addition to the main 2-meter receiver
on 147.885 MHz. Remote receiver sites also listen on
147.885 MHz and transmit what they hear back to the main site on a UHF
link frequency. The voter decides which one of the four receivers is
receiving the best
signal by continuously measuring the signal to noise ratio. The
quietest
signal (the one with the least amount of
high-frequency white noise) will be voted, and its signal is sent
to the 147.285 MHz transmitter. The voter may vote different receivers
several times a second if the signal is rapidly changing or
fluttering. The best signal is always sent to the transmitter,
assuring the best possible signal to the transmitter.
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Q.
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Where
are the receivers located?
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A.
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The main receiver is located at
the transmitter site in London, OH, at the Madison County Hospital.
The north receiver is located in Plain City, OH at the Pleasant Valley
Joint Fire District Firehouse.
The south receiver is located in Mt Sterling, OH at the
Firehouse.
The east receiver is located in West Jefferson, OH near the High School.
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Q.
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What
is the meaning of the CW
(Morse Code) at the end of each transmission?
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A.
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It is the indication of which
receiver was voted the most during a user's transmission by sending a
specific letter in Morse Code at the end of each transmission:
- "L" (*-**) for the London receiver
- "W" (*--) for the West Jefferson receiver
- "S" (***) for the Mt Sterling (South) receiver
- "P" (*--*) for the Plain City receiver
A microcomputer samples the voter output 20 times each second and
counts how many times each receiver is voted during a user's
transmission. The receiver with the highest vote count determines
which letter is sent.
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Also, the pitch of the CW
character indicates how many of the receivers you "hit" during your
transmission. The lowest pitch indicates only one receiver, and
the highest pitch means that you have a strong signal and are hitting
all four receivers. The intermediate pitches indicate that two or
three receivers are receiving your signal.
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Q.
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Why am I sometimes
voted into a receiver that is not the closest to me?
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A.
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The voter will always choose the
receiver with the best signal. However, if you have a very good
signal (full quieting) into more than one receiver, the voter cannot
choose which one is best because there is no difference to detect (it's
a tie.) In that case, the voter will lock onto the first receiver
that comes up. Usually that will be the local London receiver
because there are no link delays with that receiver.
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Q.
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Is
an Autopatch available to
make telephone calls?
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A.
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No. The repeater has the
necessary hardware, but no telephone line is available at the repeater
site.
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Q.
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How
much power is the repeater's
transmitter?
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A.
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100 watts at the transmitter,
but with losses in the isolator, duplexer and feedline, there's less
than 40
Watts at the antenna. However, the antenna has 6-9dB of gain in
its best direction, so the Effective Radiated Power (ERP) is greater
than 100 Watts in most directions.
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Q.
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So,
the repeater's antenna is
directional?
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A.
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Yes, sort of. Since the
antenna is closely side-mounted to its tower, there is a weak null to
the southwest of London.
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Q.
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Is
a subaudible tone (CTCSS, PL,
etc.) necessary to access the system?
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A.
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No. However, the remote
receivers are designed to have a higher sensitivity (actually, a looser
squelch) if you are using a 82.5 Hz subaudible tone on your
signal. If you are out in the fringes with a weak signal, then
using 82.5 Hz subaudible tone may improve your signal quality into the
repeater.
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