Quote:
Originally Posted by AdrianH
[...] It is the fundamental getting through that is my main concern when on 80m To do any Morse code I would be down near the bottom 1.75MHz which takes it out of the Amateur band and close to some coast guard stations.[...]
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Yes, the fundamental 1.8 MHz getting through on 3.6 MHz isn't attenuated by any low-pass filtering. But the acceptor circuit consisting of L3 and C9 makes it just about tolerable, especially if C9 is changed for a trimer and the fundamental is minimised for the bit of 80m used most often.
The AT5 is crude by today's standards, but even then it was a trade off between performance and complexity. Back in the day you'd have to be close (and unlucky!) to be a problem for any coast station.
Nevertheless, quite innovative and compact transmitter, borrowing some of the best ideas from the previous decade or so, with adding Codar adding some of their own.