Interfacing HAM radio
By a definition, an interface is a shared boundary or connection between two dissimilar objects, devices or systems through which information is passed. The connection can be either physical or logical.
The term is used in many fields, including chemistry, geology, electronics, computers (both hardware and software) and telecommunications.
The term “interface” can refer to either a hardware connection or a user interface. It can also be used as a verb, describing how two devices connect to each other.
A hardware interface is used to connect two or more electronic devices together. For example, a printer typically connects to a computer via Parallel port or via USB interface. Therefore, the USB port on the computer is considered as the hardware interface. The printer itself also has a USB interface, which is where the other end of the USB cable
connects. Several common peripherals connect to a computer via USB, while other devices use a Firewire connection or other interface. Ethernet connections are commonly used for networking, which is why most cable modems and routers have an Ethernet interface.
Today’s modern amateur radio devices are equipped with RS-232 port, (or with a derivation of RS-232 port), for a control via computer. Some amateur radio equipment manufacturers comply with the RS-232 standard, but some of them are implementing RS-232 using TTL voltage level, adhering to an RS-232 protocol, but not to the V.24 voltage level.
This creates the need for a different interfaces, cabling and conectors specific to each HAM radio manufacturer, often also for different radio devices of the same manufacturer.
A common name for such a specific port that allows you to manage your HAM radio through your computer is “CAT interface.”
CAT (“Computer Aided Tuning”, or “Computer Aided Transceiver”) connects your ham radio with a computer. For transceivers with a built-in RS-232C interface according to the V.24 standard, a serial cable will be enough for the computer connection. For all other radio devices, mostly with a proprietray interface, you will need a suitable electronic circuit (interface) for voltage level shifting.
The FT-8×7’s CAT System allows the transceiver to be controlled by a personal computer. This allows multiple control operations to be fully automated as a single mouse click, or it allows a third-party software package (such as GBCAT) to communicate with the FT-8×7 without (redundant) operator intervention. Yaesu CAT system using RS-232 standard modified with TTL voltage level. Cable 7: USB CT-62 CAT Cable for Yaesu FT-100, FT-817, FT-857, FT-897. Price under 10 USD. Works exellent with GBCAT.
The Optional CAT Interface Cable CT-62 is a connection cable for the FT-857D and your computer. The CT-62 has a built-in level converter, allowing direct connection from the rear panel CAT/LINEAR jack to the serial port of your computer, without the need for an external RS-232C level converter box.
Icom(tm) Communication interface-V (CI-V)
The transceiver can be connected through an optional CT-17 CI-V LEVEL CONVERTER to a personal computer equipped with an RS-232C port. Up to four Icom CI-V transceivers or receivers can be connected to a personal computer via RS-232C port. Icom CI-V using RS-232 standard modified with TTL voltage level. Specificity of the Icom CI-V connection is that both RxD and TxD lines are connected to the same wire. It is possible because a half-duplex RS-232 port will not receive while transmitting, so Icom CI-V using just single wire + ground for a radio management via RS-232 port.
Cable I/F 1: 3-rd party Icom CI-V cable, with USB to Serial TTL interface. Works exellent with GBCAT. Price under 10 USD. Cable Length: Approx. 1 m. Works with all ICOM CT-17 compatible radios including: IC-1275, IC-275, IC-375, IC-475, IC-575, IC-7000, IC-703, IC-706(all), IC-707, IC-718, IC-725,IC-726, IC-728, IC-729, IC-735, IC-736, IC-737, IC-738, IC-7000, IC-7400, IC-746(all), IC-756(all), IC-761, IC-765, IC-775, IC-78, IC-7800, IC-781, IC-820, IC-821, IC-910, IC-970, IC-R10, IC-R20 (please contact us), IC-R7000, IC-R7100, IC-R72, IC-R75, IC-R8500, IC-9000L.
Kenwood(tm) TS-2000 COM connector
This transceiver uses a full-duplex, asynchronous, serial interface for communicating through the male 9-pin RS-232C COM connector. Theoretically, only 3 lines (RxD, TxD, ground) are required to control transciver via computer, but from a practical
standpoint, when you are using a full-duplex, asynchronous serial interface, you will need a 5-wire straight through serial cable, with DB-9 female connector at both sides of the serial cable.
Cable 2: Home-made 9-wire straight through serial cable for Kenwood TS-2000. Works exellent with GBCAT.
USB to RS232C (V.24) converter (Cable 6)
If your computer is not equipped with a standard RS232C (V.24), the solution is to obtain an appropriate USB to RS232 converter supporting a V.24 voltage level, as well as Bandridge offers. It is a good and stable USB to RS232C converter, works exellent with home-made 9-wire straight through serial cable for Kenwood TS-2000.
USB to RS232 TTL converters
There are cheap solutions on the market for a quick build of CAT interfaces and cables for a various HAM radio devices. If you own several different HAM radio devices which uses CAT interfaces under RS232 standard, but with TTL voltage levels, and your computer is not equipped with serial ports, take advantage of cheap USB to Serial adapters that operates at TTL voltage levels. The cost of these solutions, which can be made as a universal for several different types of HAM radio devices, are from 2-10 USD, depending on the quality of the built chipset. Both converters works like a charm with GBCAT.
Text and photos: Ivan Držanić, 9A2GB