FT-920 Operating Manual
33
transmit. Check with the
manufacturer
of your ampli-
fier (or other device) to confirm the switching voltage
and current, if it is not clearly stipulated in the docu-
mentation for your equipment.
þ Be absolutely certain to check the position of the
TR-RY switch prior to connecting any external de-
vice to the TX GND jack. Never connect an AC
voltage, or a negative DC voltage, to the TX GND
jack if the TR-RY switch is set to TR. The Limited
Warranty on this product does not cover damage
caused by improper connections (excessive or im-
proper voltage) to the rear panel jacks of the FT-
920.
(8) 13.5V Jack
This jack provides +13.5V DC at up to 200 mA for
use with low-power peripheral devices. The jack is
fused, and the current is limited by the size of the
copper foil on the internal circuit boards; do not ex-
ceed the 200 mA current limitation.
(9) E
XT SP Jack
This 3.5 mm, 2-pin jack provides speaker audio out-
put for an external speaker. The audio output im-
pedance at this jack is 4 Ω ~ 16 Ω, and the level
varies according to the setting of the front panel’s AF
GAIN control.
(10) AF OUT Jack
This is a fixed-level audio output jack for connection
to a peripheral device such as a TNC, Morse code
reader, or WeatherFax decoder. The audio output
level provided is 100 mV at 600 Ω, and the front-panel
AF GAIN control has no effect upon the audio level
present at the AF OUT jack.
(11) PATCH Jack
This RCA jack is wired in parallel with the front panel’s
microphone input jack, providing a convenient input
port for connection of a phone patch or other audio
input. The audio input impedance is 600 Ω, and the
signal applied to the PATCH jack is affected by the
setting of the front panel’s MIC GAIN control.
(12) AFSK-FSK Switch
This switch determines the method of (transmit) Data
input to Pin 1 of the DATA jack (described below). If
AFSK is selected, then Pin 1 should be connected to
the “TX Audio” line from the TNC. If FSK is selected,
then Pin 1 should be connected to the “FSK Out” line
from the TNC or TU.
(13) D
ATA Jack
This five-pin DIN jack accepts AFSK input or FSK
(closure to ground) input from a Terminal Node Con-
troller (TNC) or Terminal Unit (TU); it also provides
fixed-level Audio Output, PTT, and Ground lines. The
optimum AFSK Input level is 30 mV at 3 kΩ, while
the Audio Output level provided is fixed at 100 mV at
600 Ω.
(14) E
XT ALC Jack
This RCA type connector may be used for connec-
tion to a linear amplifier’s ALC cable. The specified
control voltage range is 0V ~ -4V DC, with -4V corre-
sponding to the maximum degree of power reduc-
tion being applied to the FT-920.
(15) RX A
NT Jacks
These RCA connectors provide convenient access
to the receiver input line for a number of applications.
They are active only when the front-panel [RX A
NT]
key is pressed.
The OUT jack is connected to the “RX” lead from the
main T/R relay for the transceiver.
The IN jack is connected to the input port of the FT-
920 receiver section.
Accordingly, a separate receive-only antenna, or a
VHF receive converter’s 28 MHz output, may be con-
nected to the IN jack. Alternatively, a receive
preamplifier’s Input jack may be connected to the OUT
jack, and the preamp’s Output jack may be connected
to the IN jack. See page 35 for interface instructions
and ideas.
(16) ANT Jacks (A - B)
These SO-239 (“M”) jacks should be connected to
an appropriate coaxial connector for the antenna or
a 50 Ω dummy load. Antenna selection is made via
the front-panel [ANTENNA A/B] switch.
(17) DC 13.5V Jack
This is the main DC input jack for the transceiver.
The specified voltage is 13.5V DC (negative ground)
at 20 Amps.
(18) GND Lug
For best performance and safety, this Ground Lug
should be connected to a good earth ground, using a
short, heavy, braided cable.
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