Beacon
AOH
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Frequency:
27.125 MHz.
Frequency Stability: +/-
.5 PPM.
Modulation: USB
w/carrier. Amplitude
-90%, +150%
Audio: CW I.D. 'AOH'
using tone freq. of 1000
Hz.(1 kc.) at 8 WPM.
Location: Near Mt. Diablo
in Northern California.
Nearest city: Brentwood,
CA.
Elevation: 2,500 feet
ASL.
Final amplifier input: 5
volts DC @ 20 milliamps
(peak).
Output power: 16
milliwatts carrier.
Antenna: Antron 305 end
fed 1/2 wave vertical.
Feedline: 25 feet 1/2
inch Andrew LDF-50
Heliax. |
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This is the first
ever full-time part 15 beacon on
the CB band, 'AOH'. This
historical beacon has been on the
air 24/7 since April 1st,
2001. It has been copied in
almost every state and several
continents. The main
purpose of beacons is to help
gather information about band
conditions, propagation
conditions, and since they are a
reliable, steady signal source,
they are handy when testing
antennas and experimenting with
radio systems.
The
AOH beacon consists of a power
supply, controller, transmitter,
RF filtering, and antenna.
All components except the antenna
are located within this
unassuming watertight
cabinet.
AOH
transmits the morse code letters
A, O, H, (dit dah, dah dah dah,
dit dit dit dit) once every 8
seconds using modulated CW. You
can hear it on a regular SW or CB
radio, no BFO or CW detector
needed. If you have a SSB capable
receiver, it will be easier to
hear the beacon if you switch to
USB mode.
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| Inside the cabinet,
you see the RF shielded
box in the lower left area
that contains the radio
transmitter and the
controller/audio
source. At the very
top of the cabinet is the 12
volt, 7.2 Ah battery for backup
in case of power failure at the
site. Continuing clockwise,
the tan rectangular box on the
right is a Bird L/P harmonic
filter. Below the filter,
the small silver box is the
Polyphasor for lightning
protection. In the middle
of the cabinet is the
battery charge/float controller
which monitors and maintains the
gel cell backup battery and keeps
it from overcharging. This
battery gets changed every 2
years to make sure it is always
ready to go. All internal coax
cable is LMR-200, double shielded
for added RF protection. The
metal chassis inside the cabinet
is well grounded.
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The AOH antenna is a
modified Antron 305, once
commonly found in almost any CB
or amateur radio shop.
Modifications include filling
voids in the fiberglass structure
with expandable foam, and a
coating to help resist long term
exposure to harsh sunlight,
freezing rain, and other
conditions found on the mountain
top. If you copy the
beacon and would like to receive
an e-QSL card, please Or, . Be sure to include a valid return email address with your report.
Authorization:
FEDERAL COMMUNICATIONS
COMMISSION PART 15--RADIO
FREQUENCY DEVICES--Table of
Contents Subpart C--Intentional
Radiators Sec. 15.227
Operation within the band
26.96-27.28 MHz. (a) The field
strength of any emission within
this band shall not exceed 10,000
microvolts/meter at 3 meters. The
emission limit in this paragraph
is based on measurement
instrumentation employing an
average detector. The provisions
in Sec. 15.35 for limiting peak
emissions apply. (b) The field
strength of any emissions which
appear outside of this band shall
not exceed the general radiated
emission limits in Sec. 15.209.
AOH has
been inspected by a private
professional engineer, and the
FCC field office in San
Francisco. Emmissions were found
to comply with 15.227.
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