Connecting A Linear Amplifier - Yaesu FT-890 Operating Manual

Station Installation
Connecting a Linear Amplifier
For all linear amplifiers, connect the ALC output from the linear to the
EXT ALC
jack on the rear of
the transceiver. After making the RF and t/r switching connections described below, you will
probably need to adjust the ALC output level of the linear so that it is not overdriven by the IT-890.
Your linear's manual should describe how to do this.
If using an FL-7000 with the FT-890, use optional cable CT-11 to provide automatic band selection
for the linear, as well as QSK t/r switching control. If using another QSK linear, and if it can be
switched with less than 100 mA of DC voltage below 15V, you can connect the the t/r switch line
for the linear to pin 2 of the
BAND DATA
jack, and the linear's exciter-enable output to pin 8 of the
BAND
DATA
jack. This line must be held high (+5 to 15 V) to inhibit transmission until the linear is ready
for excitation by the IT-890. If your QSK linear requires more than 100 mA or uses more than 15 V
for t/r relay switching, you will have to provide a suitable external interface transistor, controlled
by pin 2.
The FT-890 provides the
TX GND
jack on the rear panel, connected to an internal relay, for non-QSK
t/r switching of linear amplifiers that use AC voltage, or DC voltage above 15 V, or require more
than 100 mA for t/r switching. This relay is disabled at the factory to avoid the click sound when
the transceiver is used alone or with a QSK linear. To enable the relay for non-QSK linears that
exceed the above t/r switching requirements, you will need move switch S2001, located in the large
hole near the rear center of the bottom cover, to its forward position (see the photo on page 8). Turn
the FT-890 on its side or upside down and use a thin, sharp object to move the switch. Then connect
the center contact of the
TX
GND
jack to the positive line to your linear, and the outer contact to the
negative line or the linear's chassis ground (if there is no separate negative line).
With the relay enabled, the FI'-890 can support
non-QSK
linear t/r switching voltage up to 125 VAC
@
200 mA, or DC voltage up to 220 V
@
300 mA, or closed-circuit current up to 2 A with DC voltage
up to 30 V. Use the
TX
GND jack after setting S2001 to the forward (on) position.
Do not attempt QSK
operation with a linear
if
its switching requires the relay enabled.
Caution!
The FT-890 is designed for use with the FL-7000 when QSK operation with a linear amplifier is required,
and with the internal t/r relay enabled for non-QSK operation with all other amplifiers. Using pins 2
and 8 of the
BAND DATA
jack for other amplifiers will not work unless the control line signals are carefully
matched, and damage may result otherwise. Your warranty does not cover damage resulting from
improper connections to this jack, so
if
you are unsure, use the
TX GND
jack and operate non-QSK only.
TX GND
(on rear panel)
P
D2063
U
1 SS270
C2014
BAND DATA
Q2061
(socket viewed from rear)
FAlA4P
Linear Amp TIR Switching in the FT-890
page
11