[Hammarlund] HQ-120-X crystal filter patent

[ve4feb at gmx.ca]

That is cool info :)------ Original message------From: Richard Knoppow<1oldlens1 at ix.netcom.com>Date: Wed, Dec 4, 2019 22:41To: Hammarlund at mailman.qth.net;Cc: Subject:[Hammarlund] HQ-120-X crystal filter patent    I think I mentioned the Hammarlund patented crystal filter in
an earlier thread. I found it again (from an old post by me).
The patent is _Selective Wave Transmission_, USP
2.222,043 applied for in 1939 and issued in 1940. I had
thought it was earlier. The inventor is Donald K. Oram.
--
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL
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