Mr Boleslaw Sosin OBE died on 7th January 2024 at the age of 102.
He was born in Poland, what follows is a summary of his career:-
August 1949
Having completed war time service in the Army (Signals) and University studies, I joined the Marconi Wireless Telegraph Company in the Antenna Development Group under Mr. C. Gillan and was promoted to Section Leader in November 1955.
The VHF sound and television broadcasting was rapidly expanding and with common antenna working there was need for various VHF filters capable of operating at the high power generated by the transmitters. The techniques for designing such filters were not known and I developed design methods and designed varieties of those filters which were used throughout the world.
These included FM transmitter combining filters, sound and vision combining filters, vestigial sideband filters, harmonic filters, as well as a very precise filter for a VHF radar transmitter for suppression of interference. The design principle and optimisation laid down by me are still used and are also applied today to UHF filters operating at high powers.
Suitable test equipment was not available and I developed specialised measurement equipment using directional couplers. It is of interest to note that the modern Vector Impedance Meter of H.P. is based on the same principle.
Ferrites became available but any previous attempt to design RF transformers were not successful until I analysed the fundamental properties and again laid down design principles. Not only are the transformers which I designed then still being sold, but the design principles are generally used nowadays.
February 1957
Transferred to Transmitter Development Group under Mr. V.O. Stokes. This was a complete change of speciality. The first job I completed was the design of 20 kW UHF (200 MHz ) television transmitter which was previously abandoned as impossible. The design was very successful, the transmitter incorporating many novel features, later adopted for general application.
One of the features was the use of quarter-wave phasing between the two output valves to obtain a ‘reflectionless’ effect. The main reason for the success was the very careful design of the anode tune and grid circuits after measurements of static characteristics of the valve and optimising circuit parameters, a technique which is today standard practice at microwave frequencies but which was not used previously.
The major achievement of this period was the development of HF wideband transmitters which at the power of 1 kW covered the whole HF band without any tuning and was suitable for operation with various modern systems from CW to SSB. The transmitter was the major step forward and a large number of new techniques had to be employed. The transmitter was also well ahead of its time, as indicated by the fact that a version designed in the next period (H1OOO) is still a current Company product.
Furthermore, the complete design, without changes, was repackaged into the Navy's cabinet and became their standard equipment (NT 203 series). Also, the most modern ICS-3 HF transmitter equipment contains the wide band amplifier with practically no changes.
July 1963
Promoted to Group Leader of a newly formed Advanced Development Group, comprising 5 to 10 engineers and being part of the Transmitter Development Department. The completion of work on the wideband transmitters was the major task of the group, as well as many new technology areas (such as wideband penultimate stage, neutralising and auto-tune pick-up transformers etc.) in a 7.5 kW transmitter (HIIOO) which was being developed in another group.
The initial work on 30 kW SSB transmitter (H1200) revealed problems with anode tune circuits due to the requirement of a very high VA with consequent high component costs and difficulty in servo tuning.
This problem was resolved by optimisation of a complete pi-L network. The method I developed is still in use today and contributes to the success of the present Hl140 transmitter.
During this period my attention also changed to low power equipment auxiliary to transmitters. In this content the work on wideband mixer was not successful and was overtaken by a modulated synthesiser (Hl500) developed elsewhere. However, under my direction, the group developed a complete HF drive system utilising the synthesiser and developing a comprehensive modulator and medium power wideband amplifier (H1600 series). A large number of these drive systems have been sold and only recently new equipment is becoming available.
The group also developed a failure proof 1 MHz reference distribution system which was again widely used, not only at transmitter stations, but also at the receiving sites.
October 1965
With the re-organisation I became Engineering Manager of the Special Technique Department responsible to Mr E.F. Cranston, Technical Manager. The department consisted of some 10 to 23 engineers, also some design office staff.
Continuation of work started in the previous period was the main task at first. With the introduction of larger transistors, design techniques for medium power HF wideband amplifiers were developed and are again widely used. However, research into power varactor frequency multipliers reached a successful conclusion but the 'technique was not used because of the advent of power UHF transistors.
At this time I initiated study work on a digital synthesiser.
October 1967
I took charge of the High Power Transmitter Department forming a High Power and Special Techniques Department. The department now consisted of 37 engineers and design office staff for part of the time.
A large part of the resources were allocated to various major communication projects, 'Maro' being an example, and necessitated the development of control systems and remote control equipment for both transmitter and receiver stations. With a large range of equipment on sale (MST and others) post design work, and particularly contract development, occupied considerable resources of the department.
The department also provided a test equipment service for the whole engineering area of the Radio Communication Division.
A laboratory model of solid state 1 kW transmitter was produced but the design was not continued because of the estimated high cost of a solid state transmitter, as compared to the equivalent valve equipment.
I introduced computer aided design facilities into the department.
The H2900 receiver needs special mention. The old valve communication receivers had good reception performance but were lacking in frequency stability with consequent difficult tuning. The introduction of transistors allowed a design of "synthesised" receiver (MST), which lacked in performance. My terms of reference was to design a point-to-point transistorised receiver to replace the MST receiver, which would have a reception performance better than the old valve receivers, but containing a built-in synthesiser. The target was achieved, although the receiver was not a commercial success because of the collapse of the point-to-point HF communication market and by not taking advantage, by sales, of our two year lead in other markets,
Our competitors were by then able to produce a much cheaper version of a high performance receiver. The design of this equipment was a particularly difficult task for me because, due to the high performance needed, we were pushing technology to the limit. A new digital synthesiser had to be designed with a very high signal purity, various mixers and amplifiers needed to be of high linearity and miniature components had to be used, e.g. micro-circuits for the first time.
The staff available to me for this work consisted mostly of inexperienced engineers; Italian graduates who left after training to be replaced by British graduates who then had to be trained again. I had to "carry" the team.
The ICS-3 contract was won against stiff competition, although we would have been suppliers of transmitters anyway, because of my wideband transmitter. It was necessary to convince ASWE that technically we were able to produce a receiver and drive equipment to the exceedingly high performance necessary for co-sited working on a warship.
Armed with the H2900 receiver, I set-up a team to show successfully that we could improve the critical areas to the new high standard. The design program, development cost and equipment cost was carefully prepared and has since been proved to be remarkably accurate.
March 1972
By the inclusion of the Low Power Departments to my responsibility, an HF Department was formed consisting of some 60 engineers in six groups. In addition to a steady load in the field of HF communication, I was now responsible for the development of all ICS-3 equipment (receivers, drives, transmitters and auxiliary units) to be produced in MCSL. The year saw rapid progress. Whilst managing this large department in the programming of work, financial control, staff administration, preparation of budgets etc.
I found that the department lacked a sufficient number of skilled and experienced engineers to lead various teams. I had to assume technical responsibility of this exacting project and laid out the basis of the design on nearly all major parts of the ICS-3 equipment. In fact, in that year I was doing two jobs simultaneously. I left the project well on the way to success (as is proving now) and the department which was well organised, capable of completing the ICS-3 project and able to undertake the rapid development of new commercial equipment (which it did under new management).
March 1973
Appointed Chief Scientist for HF, Broadcasting Transmitters and Microwave Departments. Responsibilities extended to cover all engineering areas of Marconi Communication Systems being responsible directly to Mr. I.B. Alexander, Engineering Director.
I conducted an analysis of the HF communication systems and have shown a number of controversial points. My findings are now at last being accepted in Europe and outside.
I have also successfully completed management, both contractually and technically, of Project Definition Study (Stamp) for ASWE, which included subcontracted work to Baddow Research and also MSDS Frimley and MSDS Portsmouth.
1985
Awarded the O.B.E and also the Nelson Gold medal for personal contribution to GEC. Author of 19 technical papers and over 40 patents. I was a consultant until 1990.