©2005 Hamtronics, Inc.; Hilton NY; USA. All rights reserved. Hamtronics is a registered trademark. Revised: 11/11/05
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GENERAL INFORMATION.
The R139 is a commercial-grade,
five-channel, crystal-controlled vhf
fm receiver optimized for operation
on the 137 MHz weather satellite
channels. It features wide i-f filters
(38 kHz modulation acceptance to
accommodate the wide deviation
used for wefax), low-noise dual-gate
FET rf amplifier and mixer stages,
and an integrated circuit i-f strip.
The R139 is crystal controlled,
and it has five channel oscillators.
All five popular satellite frequencies
are installed in the receiver. You can
easily substitute other channel crys-
tals if you choose.
You can select a particular satel-
lite simply by stepping the SCAN
switch on the front panel. LED's on
the panel indicate which channel is
active. An adjustable squelch circuit
allows you to determine how weak a
signal you want to hear.
If you prefer automatic scanning,
the R139 will continually scan the
five channels looking for a satellite
signal it can hear. When it hears
one, the receiver locks onto that sat-
ellite.
A tape recorder control output
can be used to activate a tape re-
corder automatically whenever a sat-
ellite is heard, even if you are not
home at the time. This allows you to
play back the tape whenever you
have time to reproduce the satellite
images on your computer.
The R139 is powered by 12Vdc. If
you purchase the unit wired and
tested or buy the kit with the cabinet
option, a 115Vac-12Vdc power adap-
ter is supplied as well as a 9-pin plug
for the power, audio, and tape con-
trol connections.
CRYSTALS.
Channel crystals for the 137.100,
137.500, 137.62, and 137.9125 MHz
US NOAA satellites and the 137.400
MHz Meteor satellites are installed in
the R139 Receiver. The following
chart correlates fundamental crystal
frequency with channel frequency for
the five popular satellite frequencies
installed in the receiver.
CHANNEL
CRYSTAL (MHz)
137.100 14.044444
137.400 14.077778
137.500 14.088889
137.620 14.102222
137.9125 14.134722
We can provide crystals for any
other frequencies you may want. If
you order your own crystals, be sure
to order only close-tolerance com-
mercial grade crystals, and supply
the following specs. The receiver
uses 30 pF parallel resonant crystals
in HC-49/u holders. Crystals oper-
ate in fundamental mode at a fre-
quency of (F-10.7)/9. Frequency tol-
erance is .0005%.
Note that R139 receivers manu-
factured before June 2005 have a
different channel lineup based on
older satellites as follows.
CHANNEL
CRYSTAL (MHz)
137.300 14.066667
137.400 14.077778
137.500 14.088889
137.620 14.102222
137.850 14.127778
EXTERNAL CONNECTIONS.
Plug Assembly.
The R139 Receiver has a DB-9
male jack. The mating plug with fe-
male contacts is provided with the
cabinet kit option if you purchased a
kit receiver, or with the wired/tested
receiver, which comes in a cabinet.
If you purchased a receiver kit with-
out the cabinet, you can provide your
own plug or not use the jack on the
board and solder wires directly to the
pc board.
The plug looks just like a jack,
except it is the opposite sex and has
a plastic hood. Hardware to assem-
ble the hood is included. Nuts fit in
recesses in the plastic hood shells,
and one screw is installed from each
side.
Also included is hardware to as-
semble a clamp to fit around the ca-
ble inside the plug to provide strain
relief. It is easiest to do
this by laying one metal
clamp piece in the rear of
the shell, setting the
plug/cable assembly in
place, and then attaching
the other metal clamp
piece with a short screw.
This will position the
clamp properly. With the
one screw tightened, you can flip the
cable assembly over and install the
second screw in the other side of the
clamp.
Additional hardware is provided
for occasions where the plug is used
on a computer; the hardware being
long screws and backup plates to
hold the plug on the rear of the com-
puter. These are not needed for this
application; so they can be dis-
carded.
Making Connections.
Following are descriptions of the
three major connections you may
need to make. Note that the hot
wires connect to the top row of pins,
with tape recorder control connected
to pin 2, audio for a speaker and the
line input on your computer’s sound
card connected to pins 3 and 4, and
dc power connected to pin 5. All the
ground returns are connected to the
bottom row on pins 6-9. These con-
nections are illustrated in figure 1.
Connections can be made most
easily with #22 solid or pretinned
hookup wire. It is easiest to solder
wires to the pins if you clamp the
plug in a vise and solder one row of
pins at a time. The solder cups can
be preloaded with solder. Then, to
make each connection, strip the end
of the wire about 1/8 inch, melt the
solder in the solder cup, insert the
wire, and allow the solder to cool.
DC Power.
The R139 Receiver is designed to
operate on +12 to +18Vdc. It re-
quires about 50 mA of current with
no audio output and up to 100 mA
with audio turned all the way up.
Ideally, the R139 only needs
12Vdc. You can operate from any
12Vdc regulated power supply if you
wish. If you purchased the receiver
with a cabinet and 12Vdc power
adapter, the actual voltage will be
higher than 12Vdc, but the receiver
HAMTRONICS® R139 REV C WEATHER SATELLITE RECEIVER:
INSTALLATION, OPERATION, & MAINTENANCE
1 2 3 4 5
6 7 8 9
Figure 1. Terminals on Rear of Plug
TAPE CONTROL
+
_
12 VDC POWER
COMPUTER
SOUND CARD
SPEAKER
Note: Pins 2 thru 5 are hot leads, pins 6 thru 9 are ground.
