ARDI-1001 - a versatile Amateur Radio Data Interface

Heinz Bolli, HB9KOF

New digital operating modes such as PSK31 or MT63, but also the established modes such as RTTY, SSTV or Fax enjoy increasing popularity. One of the main reasons for this is the fact that ever more applications appear, wich are based on the soundcard of current personal computers.

This article describes a versatile Data Interface for Amateur Radio Stations.

The PC as a part of the Amateur Radio Station

The PC has established it's presence in amateur radio station. Thanks to its versatility of service and usages, the PC has mutated from the "mysterious wonder box" for digimode specialists to an ordinary part of current station equipment of the average radio amateur too.

The PC is so versatile like our hobby in general. So, among other things, it's job can be keeping the log , QSO- statistics and -management, as well as the use of many digital operating modes witch are based on the soundcard. Specially these new modes are appreciated by many people, which are using a whole number of efficient and beautiful made programs, available often free of charge. The fact, that the PC is also useful to control the transmitter (TRX) or and/or antenna systems, is not only interesting under technical aspects. It brings also much more comfort to the operating of the station. And not to mention in this regard is the excitement that goes along with the optimization of the technical-functional aspects of our stations.

The electrical connection - not always without problems

The connection of a PC and a amateur radio transceiver is of course not always free of trouble and it has worn out amateur nerves many times. We have to take into account the questions of audio frequency signal levels to avoid the overdrive of the transmitter, which can result in signal distortions or intermodulation products. But also humming effects, caused for example by different zero potentials, are sure to avoid. Further the keying of the TX has to be considered and finally the solution has to resist to the electromacnetic fields within the legal power limitations.

So, many radio amateur publications published many different ideas and instructions for the self construction of the connecting device between the PC and the TRX. Also the market offers some products, that should assure a connection without or with less complications.

Not all solutions I have seen are marked with outstanding functionality. Noticiable is that obviously none of these solutions solves the entire communication needs of PC, modern transceiver systems and other ham devices. I just found solutions for solving a problem at a time and with more or less other disadvantages in the effective and comfortable use of the modern station resources.

ARDI-1001 - a universal Amateur Radio Data Interface

The above mentioned situation was the reason for the developement of the ARDI-1001, a versatile data interface for amateur radio stations. ARDI-1001 allows the utilization of the entire functionality, which is included in todays PC and transceiver systems without restrictions. ARDI-1001 makes possible the simple and correct connection of the PC (RS232 and soundcard) with the transceiver (specially the brand Icom, see footnote 1) through its ACC and CI-V connectors. It allows the operation with all digital operating modes, which are based on the PC-soundcard, and it makes possible to control all the whole functionallity of the entire transceiver system and other station equipment.

Through optional and subject t ofuture development it will be possible to control other devices such as antenna rotators, antenna coupling units and so on, see Footnote 2.

ARDI-1001 consists mainly of two functional blocks:

ARDI-1001 allows to work with every audiofrequency based modulation mode together with the PC. This applies of course all the digital modes like PSK31, RTTY, SSTV etc., but also voice modes running on the computer. For the imaginative ham there are practically no limitations....

Through the use of ARDI-1001 all connections between the PC and the HF-side are galvanically separated. This happens generally via optocouplers, the so needed electronic circuits are allowing also the adjustment of signal levels in a wide range. This results in optimal adaption to the specific needs of each amateur radio station and its environment.

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ARDI-1001 block diagram

The electric power for ARDI-1001 is supplied by the TRX, which supplies the HF-side directly and the PC-side via a DC/DC converter.

All the electronic components, including the connectors, are mounted directly in the printed circuit board. The pcb is made of double side laminated expoxy, the component layout ist marked with a silk screen. Just the six pushbuttons are mounted into the frontpanel and they are connected via miniature plugs.

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The ARDI-1001 pcb

The circuit design was following to professional criteria. Stability and a high immunity against electromagnetic fields have been most important points of consideration. A robust, compact an nice model aluminium die cast case with excellent HF-shielding is used as assembling platform.

Connection and Operation

ARDI-1001 contains the following elements in its frontside:

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ARDI-1001 front side

The backside has the following elements: