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Ericsson F955 conversion
By Steef Koenen PA0IB and Paul Reuvers PE1BXL

Some time ago the Museum acquired a large number of transceivers, used in the now obsolete ATF-2/NMT mobile phone base stations, from KNP Telecom. As the ATF-2 network was operated at frequencies close to the 70cm amateur band, they can be modified for amateur use fairly easy.

In the past, the museum had another surplus base station available, the RS9044 (from Radio Systems of Sweden) but these have been sold out completely. The Ericsson F955 is a slightly older rig, build mainly from (standard) discrete components (no SMD!) which makes it ideal for amateur purposes and experiments.

Steef, PA0IB, found and tested many different methods to modify this rig and together with Paul, PE1BXL, he has put these on paper. The purpose of that manual is not to provide a uniform method of conversion, but more like a collection of hints and tips that you can use when modifying this rig. The manual has been setup in such a way that it can even be used by the new and unexperienced radio amateur. Many methods are described to use this rig on the 70cm amateur band as well as the 23cm band.

The building blocks
As you can see in the drawing above the rig is modular, which comes in handy when experimenting. A transceiver consists of 6 modules in a single rack. However, we do have models available with 12 modules in a single rack. The first one is called a single rig and the latter -surprise- a double rig as it houses two full transceivers. The following modules are available in a single rig:
  • RF, this is the receiver, also known as the font-end.
  • FGRX, the synthesizer for the receiver.
  • IF, the IF section of the receiver.
  • IU, the logic unit.
  • FGTX, the synthesizer for the transmitter.
  • TX, the transmitter, also known as the exiter (200 mW output).
Each of these modules are discussed in detail in the manual and block diagrams are used to explain the functionality. Full circuit diagrams of some important parts of this rig are also included in the manual.
In order to get you going with this nice rig, PA0IB has gathered a large collection of hints and tips. It is, for example, possible to use the rig in both a 12.5 Hz and 25 kHz grid. Although the rig was designed for use in the 70cm band, the manual shows how to make it work on the 23cm band as well. The manual is now available for download in PDF format. Please note that most of the information is in Dutch. Nevertheless it can be useful for browsing the ideas, circuit diagrams and PCB layouts.


More information
If you want to know more about this wonderful rig, please contact the museum directly, or ask one of the amateurs below.

Jan Corver (click for homepage) Any red coloured links are currently unavailable
© Copyright Museum Jan Corver Last changed: Last changed: Monday, 05 November 2007 - 18:54 CET.