[ Introduction | Summary | Details]

Study of Patents Applied to Radio Sets as a guide to Date of Manufacture - Revised 30/04/2003

© Martin Francis, 2003

This document was inspired by a table published at http://www.tri.net/radio/patent.html showing the last US patent number granted in each year, as a guide to set earliest possible age calculations. I have produced an equivalent list for the UK which you can see here

The document you are now reading attempts to test the valididy of this dating technique for UK sets by listing patents claimed by radio manufacturers in association with their sets. If you are connected to the Internet you can actually read the online archives of the patents filed all those years ago by clicking on the patent numbers.

This tool gives somewhat variable results - note that the 342 Music Maid has a span of 14 years between the last patent and the release of the set. My explanation for the fact that the 206A/15 seems to have been released a month before the issue of an associated patent was that my set was produced after the initial release date - its serial number is M59793, if that helps.

Anyone who can provide other examples of UK sets and their patent numbers is very much encouraged to contact me with details and I will add these to this document. Since (with the sole exception of Philips) most UK manufacturers did not prominently display patent numbers for sets, any information for other manufacturers would be especially welcomed!

Summary

	588A4 1934	587HD ?	577A 1935	747A Aug 1937	753A-15 1938	206A/15 May 1940	186A-15 1946	462A-15 Mar 1947	342 Dec 1954
GB287958 (26/03/1928)
GB323823 (16/01/1930)
GB341403 (07/01/1931)
GB359168 (22/10/1931)
GB361450 (26/11/1931)
GB371057 (21/04/1932)
GB382481 (27/10/1932)
GB383073 (10/11/1932)
GB399400 (05/10/1933)
GB400490 (26/10/1933)
GB401022 (09/11/1933)
GB413946 (26/07/1934)
GB418932 (02/11/1934)
GB444723 (26/03/1936)
GB455121 (14/10/1936)
GB460871 (05/02/1937)
GB463604 (02/04/1937)
GB516286 (29/12/1939)
GB522731 (26/06/1940)

Details

Philips 588A4 [ Summary ]
Date 1934

Patent	Company	Applied for	Approved on	Details
GB359168	Philips	30/09/1930	22/10/1931	Improvements in or relating to screened coils provided with means for adjusting the self-inductance thereof
GB371057	Philips	23/01/1931	21/04/1932	Wound electric condenser and method of manufacturing same
GB382481	Philips	18/01/1932	27/10/1932	Process of making stack-condensers and condensers made by means of this process
GB383073	Philips	23/11/1931	10/11/1932	Improvements in or relating to the Manufacture of Electric Condensers
GB399400	Philips	06/03/1933	05/10/1933	Improvements in or relating to electrolytic condensers
GB400490	Philips	04/03/1933	26/10/1933	Improvements in or relating to electrolytic cells particularly condensers

Philips 587HD [ Summary ]
Date ?

Patent	Company	Applied for	Approved on	Details
GB287958	Philips	24/12/1926	26/03/1928	Improvements in or relating to circuit arrangements and discharge tubes for amplifying electric oscillations
GB341403	Philips	04/07/1930	07/01/1931	Improvements in or relating to amplifier circuits
GB400490	Philips	04/03/1933	26/10/1933	Improvements in or relating to electrolytic cells particularly condensers

Philips 577A [ Summary ]
Date 1935

Patent	Company	Applied for	Approved on	Details
GB287958	Philips	24/12/1926	26/03/1928	Improvements in or relating to circuit arrangements and discharge tubes for amplifying electric oscillations
GB341403	Philips	04/07/1930	07/01/1931	Improvements in or relating to amplifier circuits
GB359168	Philips	30/09/1930	22/10/1931	Improvements in or relating to screened coils provided with means for adjusting the self-inductance thereof
GB400490	Philips	04/03/1933	26/10/1933	Improvements in or relating to electrolytic cells particularly condensers

Philips 747A [ Summary ]
Date Aug 1937

Patent	Company	Applied for	Approved on	Details
GB287958	Philips	24/12/1926	26/03/1928	Improvements in or relating to circuit arrangements and discharge tubes for amplifying electric oscillations
GB323823	Philips	18/10/1928	16/01/1930	Improvements in or relating to arrangements for amplifying electrical oscillations
GB361450	Philips	30/08/1930	26/11/1931	Improvements in or relating to circuit-arrangements for the detection of high-frequency oscillations with subsequent amplification
GB400490	Philips	04/03/1933	26/10/1933	Improvements in or relating to electrolytic cells particularly condensers

Philips 753A-15 [ Summary ]
Date 1938

Patent	Company	Applied for	Approved on	Details
GB323823	Philips	18/10/1928	16/01/1930	Improvements in or relating to arrangements for amplifying electrical oscillations
GB361450	Philips	30/08/1930	26/11/1931	Improvements in or relating to circuit-arrangements for the detection of high-frequency oscillations with subsequent amplification
GB400490	Philips	04/03/1933	26/10/1933	Improvements in or relating to electrolytic cells particularly condensers
GB401022	Philips	23/05/1932	09/11/1933	Improvements relating to the production of electrically conducting coatings
GB413946	Philips	05/12/1932	26/07/1934	Improvements in or relating to radio receivers (relates to Hinged popup tuning dial)
GB455121	Philips	01/01/1936	14/10/1936	Improved method of adjusting the value of an inductance coil

Philips 206A/15 [ Summary ]
Date May 1940

Patent	Company	Applied for	Approved on	Details
GB400490	Philips	04/03/1933	26/10/1933	Improvements in or relating to electrolytic cells particularly condensers
GB418932	Philips	12/08/1933	02/11/1934	Improvements in or relating to electron discharge tubes
GB460871	Philips	15/07/1936	05/02/1937	Improved methods of manufactuting for Electric Condenser
GB522731	Philips	07/12/1938	26/06/1940	Improvements in or relating to Permananet Magnets

Philips 186A-15 [ Summary ]
Date 1946

Patent	Company	Applied for	Approved on	Details
GB400490	Philips	04/03/1933	26/10/1933	Improvements in or relating to electrolytic cells particularly condensers
GB455121	Philips	01/01/1936	14/10/1936	Improved method of adjusting the value of an inductance coil
GB460871	Philips	15/07/1936	05/02/1937	Improved methods of manufactuting for Electric Condenser
GB516286	Philips	20/06/1938	29/12/1939	Improvements in tone-control circuits for audio-frequency amplifiers
GB522731	Philips	07/12/1938	26/06/1940	Improvements in or relating to Permananet Magnets

Philips 462A-15 [ Summary ]
Date Mar 1947

Patent	Company	Applied for	Approved on	Details
GB400490	Philips	04/03/1933	26/10/1933	Improvements in or relating to electrolytic cells particularly condensers
GB455121	Philips	01/01/1936	14/10/1936	Improved method of adjusting the value of an inductance coil
GB460871	Philips	15/07/1936	05/02/1937	Improved methods of manufactuting for Electric Condenser
GB463604	Philips	05/08/1936	02/04/1937	Improvements in or relating to multi-position change-over electric switches
GB522731	Philips	07/12/1938	26/06/1940	Improvements in or relating to Permananet Magnets

Philips 342 [ Summary ]
Date Dec 1954

Patent	Company	Applied for	Approved on	Details
GB444723	Philips	07/06/1935	26/03/1936	Valve Electrode Coating deposition
GB460871	Philips	15/07/1936	05/02/1937	Improved methods of manufactuting for Electric Condenser
GB463604	Philips	05/08/1936	02/04/1937	Improvements in or relating to multi-position change-over electric switches
GB522731	Philips	07/12/1938	26/06/1940	Improvements in or relating to Permananet Magnets