EAS-3
Emergency Alert System Receiver
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This is a new twist on the EAS Series of receivers that I've built. By Federal law, broadcast stations must monitor for NOAA/NWS Emergency Alerts. They can be
found in three places; AM and FM broadcast and from the Government stations in the 162 MHz band on narrow-band FM. The
EAS-1 and EAS-2 accomplish that,
but in slightly different ways. After playing with these radios for a few months, it occurred to me that the best place to listen for EAS Alerts was on the AM
broadcast band. It is indisputable that the AM band has so much greater range than broadcast FM or the Government narrow band FM. If you have occasion to
track the conditions of an approaching storm, it is best to have as much info as possible, and as early as possible ... for obvious reasons.

So I decided to build an AM-only version receiver with the EAS protocol operating system. In this case, I had the freedom to add all the features that I wanted,
which the 3-band versions didn't allow.
One thing is a "dual-watch" system that allowed for maintaining a Primary station while searching for a secondary station.
I can get reports here in Connecticut from Michigan, Indiana, Ohio, Pennsylvania, etc. while listening to the local broadcaster.
To that end, this had to be a real DX machine! I increased the input sensitivity to a fraction of a microvolt ... about 20 dB. I also added some selectivity with a very
sharp, Hi-Q, preselector that has good 10 KHz (one broadcast channel) skirt rejection.
Here is a screen shot of the front panel decal graphics artwork.
I had to print the decal in
two sections since it has
to span a full rack mount
panel of 19 inches and the
printer only does 11
inches.

From left: an antenna
shunt and static bleed
circuit and an input
impedance selector. A
digital meter for S-Units
and microvolts of antenna
signal. A
preamp/attenuator control.
A tunable preselector, a
sub-detector to indicate a
carrier or carrier with data
and a "hold" or standby
switch for on-line cue
purposes. An audio
control section for feed
level, monitor level and
noise (hash) filter. An
internal or external
monitor speaker switch.
The power input switch
also has a power source
display for battery or
generator or mains line
status.

Note that the Primary and
secondary tuning methods
are accomplished in
different ways: the primary
uses decimal rotary
switches that make
surfing the band easy and
the secondary tuner uses
thumbwheel decade
switches for a
more-or-less fixed
monitoring condition.
Left: The laminated decal
ready to be cut out once
the panel is machined and
painted.
The panel is a fresh piece
of aluminum with only the
rack holes milled and the
control positions prick
punched and marked for
hole diameter.
Here is what the meters and
the thumbwheel BCD
switches look like. The pic
of the switches is taken
from the
EAS-1 Project.
Counter
With my other activities, it took
a week to get to machine and
paint the panel. The actual
hole-making took about 2-hours
to machine the holes for the
switches, pots, displays, and
meters.

Since the panel was raw
aluminum, it needed a good
cleaning with 400 emory, a
good alkali cleaning (mild lye
solution), but a good scrub with
acetone will do, then priming
and finally satin black enamel.
Later in the day I cut out the
various decal sections, affixed
the thin double-sided tape
and positioned the graphics
over the panel holes. Here is
the proof to see if everything
lines up correctly ... phew.
This radio is an
AM DXer's
dream. It has
super sensitivity
and very good
channel filtering,
basic noise
(hash) filtering, a
dual-watch
headend (2
receivers) and a
nice 7-watt audio
monitor system.

Here are some
snaps of the
finished unit.

If you would like
to see a demo of
the radio, it's on
my Youtube site
at the link at the
top of the page,
or just view all of
my videos by
going directly to
my Youtube
channel  
"
N1KPR."
Thanks for looking.