Linear Amplifire Interfacing - Yaesu FT-897 Operating Manual

I
NSTALLATION
The FT-897 provides the switching and drive-control lines
required for easy interfacing to most all commonly-avail-
able amplifiers sold today.
These include:
Ì The Antenna Jacks ("HF/50MHz" and "144/430MHz");
Ì A T/R control line (open circuit on RX, closure to ground
on TX); and
Ì A negative-going ALC jack (control voltage range: 0V
to –4V DC).
Ì When interfacing to the VL-1000 Solid State 1 KW Lin-
ear Amplifier, the optional CT-58 Interface Cable pro-
vides for easy interconnection (requires that the Menu
Mode No-020 [ CAT/LIN/TUN ] setting changes to "LIN-
EAR").
The rear-panel /LINEAR jack is an 8-pin, miniature
CAT
DIN type, with the "TX GND" pin providing a closure to
ground on transmit, for T/R control of your linear amplifier.
The ACC jack is a miniature stereo type, with external ALC
input capability on the tip connection. The main shaft is the
ground return. The ring connection of the ACC jack, when
closed to ground, places the FT-897 into the transmit mode,
and sends a steady CW carrier, for amplifier (or antenna
tuner) adjustment purposes.
Typical amplifier interface circuits are shown below.
Note that some amplifiers, particularly VHF or UHF "brick"
amplifiers, offer two methods of T/R switching: application
of +13V or a closure to ground.
Page 10
L A
INEAR MPLIFIER
ANT 1
ANT 2
CT-58 BAND DATA Cable
CT-58 ALC Cable
I
NTERFACING
Be sure to configure your amplifier so that it switches via a
closure to ground, as provided by your FT-897's
EAR jack ("TX GND" pin). Alternatively, many of these
amplifiers use "RF Sensing" to control their relays; if yours
is in this category, you may then use the T/R control line
from the "TX GND" pin of the
control of your HF linear amplifier, and RF sensing for your
VHF or UHF amplifier.
The "TX GND" T/R control line is a transistor "open col-
lector" circuit, capable of handling positive amplifier relay
coil voltages of up to +50V DC and current of up to 400
mA. If you plan on using multiple linear amplifiers for dif-
ferent bands, you must provide external band-switching of
the "TX GND" relay control line from the
jack.
Important Note!
Do not exceed the maximum voltage or current ratings
for the "TX GND" line at the
line is not compatible with negative DC voltages, nor
AC voltages of any magnitude.
Most amplifier control relay systems require only low
DC voltage/current switching capability (typically, +12V
DC at 25 ~ 75 mA), and the switching transistor in the
FT-897 will easily accommodate such amplifiers.
VL-1000
REMOTE
ON
OFF
BAND DATA 1
BAND DATA 2
FT-897 O
CAT /LIN-
CAT /LINEAR jack for
CAT /LINEAR
CAT /LINEAR jack. This
INPUT 1
PTT 1
PTT 2
INPUT 2
ALC 1
CONTROL
ALC 2
DC48V IN
GND
M
PERATING ANUAL