rom: aa1nd@aol.com Reply-To: acom-list@yahoogroups.com Date: Wed, 30 Jan 2002 14:29:53 EST For ICOM transceivers, you should preferably use the PTT and CW keyer (and parallel computer) connected to the respective inputs of the transceiver. For amplifier control use the semiconductor control input/output "HSEND" on the round "ACC" connector of the transceiver. For some ICOM models it is named "SEND". Connect it directly to the "KEY-IN" input of the amplifier via a shielded cable. You don't need any relay between ICOM transceivers and the ACOM1000 or ACOM2000A. Generally, the HSEND (SEND) signal on the ACC connector of ICOM models is bidirectional. If you connect it to the ground, the transceiver will go to transmit, i.e. it acts like an external PTT input. A 20mA "output" current will flow through your external PTT contact. This direction of the HSEND (SEND) however is not used for external amplifiers control. Another function of the same signal is an output, that goes to the ground when you activate a transmission using the front panel SEND button, mike PTT, VOX, or CW keyer. In this direction, it will withstand 100-200mA "input" current (drawn from amplifier's control input) and is suitable to control ACOM amplifiers. If you would simply wire the CW key line from your keyer (and parallel computer) directly to both the Icom and the A1000 (in parallel), the amplifier would be OK. Most of the ICOM models would however only change to transmit but without emitting any carrier (they would wait for a closure of their input "CW KEY"). For SSB, such connection is OK to a foot switch. Note however, that the foot switch should be bounce-free since some asynchronous timing may arise. You could also use the foot switch for CW, with the keyer connected to the transceiver's "CW KEY" input. You will lose however the possibility of operation in QSK/FULL-BK-IN mode. More information about the connections KEY-IN and KEY-OUT follows below. Briefly, the amp is keyed by grounding the KEY-IN jack. The keying voltage is typically 12VDC and the keying current is less than 15mA. Both amplifiers ACOM1000 and ACOM2000A are QSK-compatible with all QSK-capable transceivers on the market. The keying circuit requirements for the ACOM1000 and the ACOM2000A are identical. 1. The amplifier's T/R-control input for the antenna relay is called "KEY-IN". When in OPERATE mode, on this input appears a DC signal that is to be held low to activate the amplifier to the transmit mode. This can be done via either a relay contact or a semiconductor (transistor or integrated circuit) with suitable polarity (plus to the ground). NOTE: You should prefer a semiconductor output when it is available on your transceiver, since relay contacts on some models are slow with respect to their RF output. You may see a "Hot-Switching Warning" or "RF detected at wrong time" message otherwise. This message means that an eventual hot switching has been prevented by the amplifier's protection system. You should change to the semiconductor output in such conditions. In addition, utilizing the semiconductor output, you may disable the transceiver's relay clicking (on some models there is a switch intended for a case when the relay is not needed). The electrical specifications of the amplifier's KEY-IN input are as follows: - Switching voltage (open circuit): 15V max (12V typ.), plus to the ground; - Closed-circuit current: 15mA max; - Voltage drop / resistance of the control output @ 15mA (closed circuit): 1.5V/250 Ohm max. You can control the KEY-IN signal in two different methods. Look at (3) for a second way. For the preferred mode, you have to connect the KEY-IN socket to the transceiver's output that goes to the ground when you transmit. Practically all transceivers have such an output, and their electrical specifications exceed the amplifier's requirements. Transceivers producers give different names to this output, and they are for instance: TX-GND, SEND, *T/R-LINE, KEY-OUT, etc. Some transceivers require that their signal "ground on transmit" be implemented via a software command, or by changing of a switch on the rear panel, or interior of the transceiver. Some models generate a "+12V on TX" signal. Then, you may need a simple n-p-n or n-mos transistor, controlled through a 10kOhm resistor to the base or gate, in order to "invert" the available signal in a "GND on TX". Look in your transceiver's manual or contact your dealer or ACOM directly for details about a particular model. Please use always shielded cables for these connections. 2. The KEY-OUT socket on the rear panel is a "phono" type (RCA) connector. When you don't use the second method of the connection (see p.3), this is an extra output signal from the amplifier, that could be either used or not. When used, it would improve the T/R process of switching and would increase the exploitation reliability. The KEY-OUT output is usable when the transceiver has available a respective input to disable transmitting when the amplifier may need it. If your transceiver has no such input (for instance ICOM models), or you use the second way of the KEY-IN connection (p.3), please don't worry: the amplifier will be fully protected and will function normally, so the KEY-OUT may remain unused. If your transceiver however possesses a suitable input that is capable to disable transmission, we recommend that you utilize that feature. Just connect this input of the transceiver to the KEY-OUT socket of the amplifier. Transceiver producers give different names to this input, and they are for instance: TX-INHIBIT, MUTE, LINEAR, KEY-IN, etc. It is available sometimes on BAND-DATA, ACC, EXT, LIN, ATU, and etc rear-panel connectors. Some transceivers may require that a "transmit disable" function is implemented via a software command, or by changing of a switch, or via adding an external pull-up resistor, etc. Look in your transceiver's manual. You have to use the preferred connection of the KEY-IN socket (p.1) to utilize this feature. The output KEY-OUT of the amplifier is an open-drain circuit and it can hold a positive DC signal to the ground. During all the periods when the amplifier is ready to transmit, this line will always pattern the requests "GND on TX" in order to enable transmission. When transmitting is not permissible, the output becomes open (for instance, while the antenna relay is in process of switching-over) and the transceiver would stop RF driving. The electrical specifications and timing of the amplifier's KEY-OUT output are as follows: - Switching voltage (open circuit) - up to +50V, - Switching current (closed circuit) - up to 20mA, - Internal resistance @ 20mA (closed circuit) - 120 Ohm max, - Delay time - 5ms max (2...3ms typically). While the amplifier is not powered, and in STANDBY mode, this output is directly connected to the KEY-IN socket. Thus, the amplifier will send back the "ground on transmit" signal to the "TX enable"-input of the transceiver always during OFF and STBY modes in order not to disable any transmission. In OPERATE mode the signal KEY-OUT will pattern the signal "ground on transmit" that is coming on the socket KEY-IN, always when the antenna relay is in safe position and when no other warning is present. The signal KEY-OUT will reject transmitting if the amplifier detects any risk condition. Besides, the amplifier contains an independent self-protection that looks after the relay safety during a T/R-switching, regardless of taking or not an advantage of the KEY-OUT signal. 3. If your transceiver has not a suitable connector providing an output signal "ground on transmit" nor "+12V on transmit", you can use the second connection method as described below. Connect the PTT or CW-keying contact to the amplifier's socket KEY-IN on the rear panel. Then connect the amplifier's socket KEY-OUT to the input PTT or CW-KEY of the transceiver. Always use shielded cables for these connections. CAUTION: Please check up, that the parameters of the signals PTT and CW-key of the transceiver met the specifications of the "KEY-OUT" output of the amplifier (see p.2 above). Some very old transceivers models may require buffering if the requirement is higher than 50V/20mA. With the second way of connection, the amplifier will just pass the PTT or keying signal directly to the transceiver always when powered off and during STBY mode. During OPERATE, the signal will pattern your PTT/keying after the antenna relay reaches a safe position, and will disable transmission during relay's motion as well as during any risk condition. The second way of controlling the transmit/receive process could be very useful also if the transceiver has an incorrect timing sequence of its T/R signals. For instance, if the RF power appears before a "ground on transmit" is fed to the amplifier. 73 Krassy K1LZ 29 January 2002.