Yaesu FT-990 Operating Manual page 24

(9)
AC
Line Cord Socket
Connect the supplied AC line cord to this
socket after ensuring that your AC mains volt-
age is within the range on the label. See the
Installation section for instructions on how to
change the AC power supply voltage range, if
necessary.
(10)
FUSE
Holder
This holder requires a 8-A fuse for operation
from AC voltages below 125 V, and a 4-A fuse
for AC voltages of 200 V and above. Only
normal fast-blow type fuses should be used
here.
(11)
ANT
Coaxial Jack
Connect your main antenna here, using a type-
M (UHF, PL-259) plug and coaxial feedline.
This antenna
is
always used for transmission,
and is also used for reception unless a separate
receive antenna is connected and selected from
the front panel. The internal antenna tuner af-
fects only the antenna connected here, during
transmission.
(12)
RX ANT IN/OUT
Phono Jacks
Both of these jacks have no connection unless
the
RX ANT
switch on the front panel is pressed.
The
OUT
jack connects through the
RX ANT
switch to the receive side of the main antenna
T /R relay, which is closed while receiving. The
IN
jack connects through the
RX ANT
switch to
the receiver front end. See the box on page 27.
These jacks provide you with several receiver
front end options. You can connect a receive-
only antenna to the
IN
jack and use the main
antenna jack for a transmit-only antenna, or
you can connect an external receiver to the
OUT
jack to function in place of the Ff-990's re-
ceiver, or you can connect a receiver preampli-
fier or bandpass filter between these two jacks
to affect reception on the main antenna (when
the
RX ANT
switch is closed).
(13)
EXT ALC
Phono Jack
This input jack accepts external ALC (Auto-
matic Level Control) voltage from a linear am-
plifier, to prevent over-excitation by the
transceiver. Usable input voltage range is 0 to
-4 VDC.
(14)
EXT SPKR
Mini Phone Jack
This 2-contact output jack provides receiver
audio for an external loudspeaker, such as the
Controls & Connectors -Rear Panel
SP-6. Inserting a plug into this jack disables the
internal loudspeaker. Impedance is 4 to 16
Q.
(15)
REMOTE
DIN Jack
This 8-pin input/ output jack provides connec-
tions
to
internal relay contacts and control in-
puts for transmit/receive switching of an
external device such as a linear amplifier (other
than the FL-7000). Pin 1 is connected together
with the
EXT ALC
jack, and pins 3 and 8 connect
to chassis ground.
Pin 6 may be used to control manual transmit-
ter activation using a footswitch or other
switching device. Its function is identical to the
MOX
button on the front panel (short pin 6 to pin
3 or pin 8 to transmit). The same line is avail-
able at the
PACKET
and
RTTY
jacks for tnc/tu
control. Open-circuit voltage is
+ 13.5 VOC,
and dosed-circuit current is 1.5 rnA.
Pin 7 provides + 13.5 VDC at up to 200mA for
powering an external device. However, this
line is not fused, so shorting this pin to ground or
drawing more than 200mA can seriously damage
the transceiver.
Pins 2 and 5 are connected together through
the contacts of a disabled relay inside the Ff-
990. Pin 4 is connected to the collector of a
transistor, which is off (high impedance to
ground) on receive, and on (low impedance to
ground) on transmit. The relay connected to
pins 2 and 5 is normally disabled to provide
maximum t/r switching speed and minimum
noise. However, by setting internal switch
S6801 to its RY position, the functions of these
three pins change so that the transistor that was
switching pin 4 now controls the relay at pins
2 and 5, and pin 4 now connects to the closed-
on-transmit contact of the relay (pin 5 is com-
mon, and pin 2 is dosed-on-receive: see the
diagram on page 9).
With switch S6801 in its factory default (TR)
position, the maximum current that pin 4 can sink
is
500 rnA, at up to 50 V (positive DC only!).
If
you are connecting an amplifier that requires
higher current or voltage to switch, or uses AC
voltage for t/r switching, you can move switch
S6801 to the RYposition, in which case the internal
relay contacts (via pins 2, 4 and 5) will be able to
handle up to 500 rnA @ 125 VAC, 300 rnA@ 220
VDC or 2 A
@
30 VDC. Before connecting an external
device, make sure its switching requirements will not
exceed these limits.
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