Connecting the FT-1000MP to Acom 2000A or other QSK Amp (N1EU)
(information provided by Acom)
1. You will need the following materials to prepare a control cable:
- a piece of two-lead shielded (audio) cable, maximum 3m/11ft long,
- a resistor 10kOhm 0,125W,
- an male DIN-8 (8 pins) connector (mating to FT1000MP BAND DATA connector),
- two phono type (RCA, CINCH) connectors (mating to ACOM2000A KEY-IN and KEY-OUT
2. Look into the FT1000MP OPERATING MANUAL. Find the layout of the BAND DATA
connector, located on the top-right corner of page 4. Note that the DIN-8
connector pins are numbered in a special order: not successively but as
2-----------------TX GND - to KEY-IN
+13V---o---1 6 3----------------GND - two
7 8---o------TX INHIBIT - to KEY-OUT
(DIN-8, as viewed from the transceiver's rear panel "BAND DATA" and from
the soldering side of the male cable connector)
pin1 (+13V) - left from the center,
pin2 (TX GND) - on the top,
pin3 (GND) - right from the center,
pin4 (BAND DATA A, not used) - above pin 1,
pin5 (BAND DATA B, not used) - above pin 3,
pin6 (BAND DATA C, not used) - the central,
pin7 (BAND DATA D, not used) - below pin 1,
pin8 (TX INHIBIT) - below pin 3.
3. First solder the 10 kOhm resistor between pins 1 (+13V) and 8 (TX
INHIBIT). This "pull-up" resistor may be needed for the FT1000MP in
order to activate its "TX INHIBIT" input. Now, if you connect this DIN-8
connector to the BAND DATA, the transceiver won't transmit until you
pull pin 8 (TX INHIBIT) to ground. This is controlled by the ACOM2000A.
Before trimming the cable end, thread on it the DIN-8 protective cap.
Solder cable shields together and then to pin 3 (GND). Solder one of the
active leads to pin 8 (together with one of the resistor leads). Mark
the other end of this active lead as KEY-OUT. Solder the second active
lead to pin 2 (TX GND). Mark its second end as KEY-IN. Take care that
all leads are well insulated when assembling DIN-8 protective cap to
avoid any shorts. Split the second cable end and thread the two phono
connector accessories. Solder the active KEY-IN and KEY-OUT leads to the
central pins and their shields to the outer connector rings. Assembly
the connector's protective caps and your control cable is ready.
4. Before connecting or disconnecting cables always switch off both the
transceiver and the amplifier. Look in the FT1000MP OPERATING MANUAL.
Find the Rear Panel Controls & Connectors on page 19/20. Slide the LIN
switch (21), located in a slot on the FT1000MP rear panel, to the OFF
position. This will disable the internal TX GND relay of the
transceiver and your QSK-CW timing will get better. Using this mode is
possible as the amplifier's input KEY-IN is sensitive enough and does
not require any relay buffering. Connect the DIN8 connector of the
prepared control cable to the BAND DATA (16) connector of FT1000MP. Now
look in the ACOM2000A OPERATING MANUAL. Find Fig.2-2 "Connections" on
page 8. Connect the cable KEY-IN and KEY-OUT to the same name connectors
(d) and (e) of the amplifier (bottom left corner as seen from rear). See
also the respective paragraphs (d) and (e) on page 9.
5. Now you can use the QSK feature of both FT1000MP and ACOM2000A with
maximum switching safety and timing quality. You don't need to do
anything else. The following information is only intended to give some
technical information about the ACOM2000A KEY-IN and KEY-OUT signals.
a) The KEY-IN socket on the rear panel is the antenna relay
transmit/receive control input of the amplifier.
When in OPERATE mode, a DC signal appears on this input which must be
held to ground to activate transmit mode in the amplifier. This can be
done via a relay contact or semiconductor (transistor or integrated
circuit) with suitable
polarity (positive to ground). The electrical specifications for the
respective transceiver's output are: -
switching voltage (open circuit) minimum 12V; - switching current
(closed circuit) minimum 12mA; - voltage drop or resistance @ 12mA
current (closed circuit) maximum 1.5V/250 Ohm.
FT1000MP output exceeds all of them. You can control the KEY-IN signal
in two different ways. The preferred mode is to connect the KEY-IN
socket with a shielded cable to the transceiver's output which goes to
ground on transmit. The FT1000MP corresponding output is named TX GND
(pin 2 of BAND DATA connector) and its electrical specifications exceed
the needs without any buffering.
You don't need to use the other alternate method with the FT1000MP. It
may be useful with an older type of transceiver which may not provide a
suitable "ground on transmit" output signal. Connect with a shielded
cable the PTT or CW keyer contact to the amplifier rear panel KEY-IN
socket. Then connect with a shielded cable the amplifier rear panel
KEY-OUT socket to the PTT or CW-KEY transceiver input. In this mode the
amplifier will just pass directly the PTT or keyer signal to the
transceiver when not powered and in STBY. In OPERATE mode it will follow
it always when the antenna relay
and/or band switch are in safe position and will disable transmitting
their motion or any risk situation.
Have in mind that the second way of transmit/receive control could be
very useful also if a transceiver has improper sequencing of its T/R
signals. For instance, in some old type transceivers, the "ground on
transmit" signal is late at beginning (RF power appears before it); or
it competes at the end of transmission (disappears before RF power).
b) The KEY-OUT socket on the rear panel is an extra output signal from
the amplifier to the transceiver. It could be used to improve the T/R
switching process or reliability of the amplifier as well as the
transceiver. This output can be used in two cases: - when your
transceiver has the respective input to disable transmitting and the
preferred connection of the KEY-IN socket is made - see (a). For
FT1000MP this is the TX INHIBIT input (pin 8 of BAND DATA connector).
recommends that you connect it with a shielded cable to the KEY-OUT of
the amplifier. - when the second method of transmit/receive control is
used with any old-type of transceiver - see (a).
The output KEY-OUT of the amplifier is an open drain circuit and it can
hold to ground a positive DC signal. At the instant the amplifier is
ready to transmit this line is held to ground. If transmitting must be
disabled for any reason, the output is open (for instance when the
antenna relay is in process of switching or the band switch is rotated).
The electrical specifications of the amplifier's output are: switching
voltage capability (open circuit) up to +50V; switching current
capability (closed circuit) up to 20mA; resistance @ 20mA current
(closed circuit) maximum 120 Ohm. When the amplifier is not powered and
also in STANDBY mode this output is directly connected to the KEY-IN
socket. Then the amplifier will return the "TX GND" signal back to the
"TX INHIBIT" in order to enable transmitting.