Improvements in or relating to superheterodyne radio- receiving arrangements whose selectivity is controlled bu hand or auto- matically and which comprises an intermediate frequency band pass filter constituted by a number of tuned circuits which are coupled to each other

Read the whole patent

Listed from its IP Australia record in Patent Yard's archive of Australian patents past their term. Its claims, description and drawings are in the AusPat record and on Google Patents, and the Claude kit works from them.

Why it's free to use

• Filed May 24, 1939. Even if it was granted, its term would have ended by May 24, 1960.
• A pharmaceutical extension adds at most five years, so even that would have ended by May 24, 1965.
• We check Australian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.