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Tech Arsenal (Arsenal Computer).ISO
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ST20T
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1992-09-15
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ST2OT
RECEIVE NOAA-WX FREQS ON SANTEC ST20T
From the mod sheet:
"The Santec ST-20T operates from 142-150.995 MHz as received from the
factory."
MODIFICATION:
Remove the six black screws from the back of the radio. Remove the
four screw which hold the battery retainer plate. Carefully remove the
battery latch and switch. Remove the keyboard lock switch cover (pull
it off).
Now lift the front of the radio away from the back, starting from the
bottom of the radio. Be careful not to tear the flexible printed
circuit material connecting the front panel to the front of the radio.
Locate the keyboard lock switch. Locate R423 which is a 33k ohm
resistor. It is about 1/4 to 1/2 inch from the top of the keyboard
lock switch, and is standing up from the circuit board. See the parts
layout diagram on page 24 of your owners manual for location of this
resistor.
Install a jumper wire from the top terminal of the keyboard lock
switch to the top of R423.
Reassemble the radio and install the battery.
OPERATION:
The receiver will now cover from 142-150.995 and 158.9-167.895 MHz.
However, the highest frequency the radio will actually receive is
dependent on the VCO range. If you enter a frequency above the stable
range of the VCO then the display will flicker and the receiver will
shift to the frequency stored in memory #1.
In order to use this new feature, you must program a frequency 16.9
MHz lower than the desired frequency. For example, if you wish to
receive the NOAA weather broadcast on 162.400 MHz you must subtract 16
.9 from 162.4 and enter 145.5 MHz into the Santec. SET THE OFFSET ON
THE SANTEC TO SIMPLEX (NOT + OR -).
To receive the weather channel, push the keyboard lock switch up and
the receiver will shift up 16.9 MHz. The frequency shown on the
display will remain at 145.500. If you transmit while using your
Santec this way, you will transmit on the displayed frequency.
The TX indicator on the display will show when you have the lock
switch up. This is normal. It happens because we have fooled the
microcomputer into thinking that it is transmitting, when it is
actually receiving up 16.9 MHz.
It is not a good idea to turn the radio off when the microcomputer
thinks the radio is in transmit mode, so remember to push the LOCK
switch down (off) before turning the radio off.