EEVblog Electronics Community Forum
Electronics => RF, Microwave, Ham Radio => Topic started by: Dom13c on August 01, 2018, 11:23:28 am
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Transmitting voice over shortwave is quite fascinating to me. But whenever I google for shortwave AM phone, the results turn out as cw transmitters.Well, I've already made and played with them. So my next goal is to transmit voice over shortwave. Well ,don't recommend the SSB stuffs. They are just too hard to be bulit. Output power may stay within one or two watt as I'm planning to drive a class B linear amplifier with it.( If possible suggest a circuit that is based on crystal oscillator) And I'm not talking about AM radio( 550-1500khz in India) transmitter , I'm talking about shortwave transmitter(3-30 mhz) with amplitude modulation
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https://www.google.com/search?q=short+wave+am+transmitter&tbm=isch (https://www.google.com/search?q=short+wave+am+transmitter&tbm=isch)
Some are CW but there's a lot AM too.
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Try it with a NE602: http://www.elektronikbasteln.pl7.de/am-modulation-mit-einem-sa612-oder-sa602-ne612-ne602.html (http://www.elektronikbasteln.pl7.de/am-modulation-mit-einem-sa612-oder-sa602-ne612-ne602.html)
with the trimmer you adjust the carrier suppression (if wished for SSB), otherwise it outputs an AM signal
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You might be better off googling "AM modulation circuit".
AM is nothing more than CW transmitter that is keyed down and power to the final section modulated. There are much fancier way to do it but that's the basics of it.
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http://www.phonestack.com/farhan/bitx.html (http://www.phonestack.com/farhan/bitx.html)
Check out how this ham did it. Very popular simple design.
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What you want to do is google DSB Double Sideband, double sideband suppressed carrier. Its the easiest method of generating vioce RF. Peter Parkers Beach 40, the MDT by ozqrp etc are rigs that use direct conversion of audio to RF.