INVENTOR TALKS ABOUT HIS MOST FAMOUS INVENTION AND ONE OF ITS MOST IMPORTANT APPLICATIONS. LEE DE FORESTHANDWRITTEN LETTER SIGNED, Faithfully/Lee de Forest, on a card 4.5 x 3, 1/12/1916, by the American inventor, self-described Father of Radio , and developer of sound-on-film recording used for motion pictures. He handwrites a letter in which he talks about his most famous invention, the tree-element Audion(Triode) vacuum tube, the first practical amplification device which made possible radio broadcasting, long-distance telephone lines, and talking motion pictures, among countless other applications. In full: Dear Mr. In long-distance communications it renders you service. This excellent content handwritten letter is in fine condition , with minor age toning. This item has been authenticated and is accompanied by a Certificate of Authenticity issued by our parent company, History Makers Autographs. We financially stand behind our COA. Ask us about our PSA/DNA and JSA authentication guarantee. YES, WE DO OFFER A LAYAWAY PLAN. THIS IS AN ORIGINAL HAND SIGNED AUTOGRAPH. We do not sell reprints or facsimile autographs. We closed our retail galleries and noware totally internet sales oriented. We are a long-time member of UACC #RD337, PADAH, and the Manuscript Society. Our collectibles make for fantastic additionsto long standing collections, great starting points for new collectors lookingfor trusted authentic material, and make for a truly unique gifts for thatspecial person in your life or corporate gift for a special client. History Makers Autographs offers one of the strongestguarantees available by any dealer. Weunconditionally guarantee the authenticity of the document/artwork , withouttime limit, to the original purchaser. Every item we sell comes with a Certificate of Authenticity clearlystating this guarantee. International Buyers Please Note. The item “LEE DE FOREST HANDWRITTEN LETTER SIGNED, FATHER OF RADIO, INVENTOR, GOOD CONTENT” is in sale since Sunday, August 8, 2021. This item is in the category “Collectibles\Autographs\Other Collectible Autographs”. The seller is “stevnowli_0″ and is located in Nokomis, Florida. This item can be shipped worldwide.