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 connectors).

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
follows:
 

                  2-----------------TX GND - to KEY-IN
               4     5
   +13V---o---1   6   3----------------GND - two shields
          |     7    8---o------TX INHIBIT - to KEY-OUT
          |              |
           ----10kOhm----

(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 additional
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 during
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). Acom
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.