Licence Plate on Derwent Radio - UK Vintage Radio Repair and Restoration Discussion Forum

Radio Tech · 10th Jan 2018, 8:08 pm

Hi Folks

I wonder if there is any way of locating the history of this information that is written on a plate attached to the cabinet of the Derwent Radio I am restoring. It reads; "This instrument is manufactured under licence granted by electrical and musical industries ltd, Hazelpat Ltd, Marconi wireless telegraph company ltd and Standard telephone company ltd in respect of their patents for the reception in Gt Britain, Northern Ireland, Irish Free State, The Isle of Man and The Chanel Islands of sound broadcast by wireless but only for private use and not for operation for any public or commercial or revenue earning purpose. A post office licence is required, HP 68487

Perhaps someone might know and it might even lead me to identifying the model number.

Best wishes

Ken

G6Tanuki · 10th Jan 2018, 8:17 pm

That's a pretty standard 'plate' showing the manufacturers have paid the royalties for using technology on which other companies [those listed] hold patents.

As an example, Hazeltine Corporation [Hazelpat] owned the patent on automatic-gain-control by rectifying the carrier and using the resultant DC component to vary the gain of variable-mu valves.

https://en.wikipedia.org/wiki/Hazeltine_Corporation

https://books.google.co.uk/books?id=...0nD1kQ6AEIFjAA

10th Jan 2018, 8:08 pm	#1
Radio Tech Nonode Join Date: Dec 2012 Location: Bocking, near Braintree, Essex, UK. Posts: 2,071	Licence Plate on Derwent Radio Hi Folks I wonder if there is any way of locating the history of this information that is written on a plate attached to the cabinet of the Derwent Radio I am restoring. It reads; "This instrument is manufactured under licence granted by electrical and musical industries ltd, Hazelpat Ltd, Marconi wireless telegraph company ltd and Standard telephone company ltd in respect of their patents for the reception in Gt Britain, Northern Ireland, Irish Free State, The Isle of Man and The Chanel Islands of sound broadcast by wireless but only for private use and not for operation for any public or commercial or revenue earning purpose. A post office licence is required, HP 68487 Perhaps someone might know and it might even lead me to identifying the model number. Best wishes Ken

10th Jan 2018, 8:17 pm	#2
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Licence Plate on Derwent Radio That's a pretty standard 'plate' showing the manufacturers have paid the royalties for using technology on which other companies [those listed] hold patents. As an example, Hazeltine Corporation [Hazelpat] owned the patent on automatic-gain-control by rectifying the carrier and using the resultant DC component to vary the gain of variable-mu valves. https://en.wikipedia.org/wiki/Hazeltine_Corporation https://books.google.co.uk/books?id=...0nD1kQ6AEIFjAA