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www.southgatearc.org
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Smith Chart Slide Rules presented to museumOn Sunday 12th August, Murray Niman G6JYB of the Chelmsford Amateur Radio Society (CARS) presented two Smith Chart calculators to Trish Robinson of the Sandford Mill Museum.
They were owned by Mr H M Chandler (known as Vic to his friends) who worked at the Gateshead plant from the late 1940s to late 50s. Vic died some years ago and they were found by his son Nick Chandler following the recent death of his mother and consequent house clearance. Nick, a Chief Scientist at BAE Systems, Great Baddow, Chelmsford gave them to Murray G6JYB.
Smith charts enable plotting of impedance, Z and its’ inverse (i.e. admittance, Y) for design of matching circuits - a process that is usually performed by computers nowadays rather than by hand. The central circular chart can be rotated and the picture shows them in the rarer Admittance position - as used in the Marconi and CARS roundel logos. Normally they are used 180 deg around in the Impedance position. The chart was developed by and named after Philip H Smith in 1938. His original book is a collectors item. In addition to the calculators the Marconi company printed a wide range
of graph papers and pads including Smith charts under the MG (Marconi
Graph) series. Murray is one of the tutors for the CARS Amateur Radio courses. Details
of the courses are available from the training organiser Clive
G1EUC
Related URL’s The Smith Chart Bill Quay, Gateshead Sandford Mill CARS at Sandford Mill
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