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public:radio:topics:arduino:30m_phasing_rx [16/07/26 23:13 BST] – johnpublic:radio:topics:arduino:30m_phasing_rx [16/07/26 23:28 BST] (current) – [The design] john
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 I recently found an old project that had been left in the junk box unfinished. It's a direct-conversion phasing receiver for 30m. I recently found an old project that had been left in the junk box unfinished. It's a direct-conversion phasing receiver for 30m.
  
-Inspired by my current binge-listen to the Soldesmoke Podcast [[https://www.soldersmoke.com/]] archives (I'm starting at the beginning and listening to them all.. currently I'm at around Episode 30) I thought I'd restart the project and build it into the planned-for 30m CW transceiver. There's a 5W PA strip that's recently been used in my QRSS "MEPT" [[qrss_tx|]] but I'll build a new PA for the MEPT and use the original one for it's original purpose.+Inspired by my current binge-listen to the Soldesmoke Podcast [[https://www.soldersmoke.com/]] archives (I'm starting at the beginning and listening to them all.. currently I'm at around Episode 30) I thought I'd restart the project and build it into the planned-for 30m CW transceiver. There's a 5W PA strip that's recently been used in my [[qrss_tx| QRSS MEPT]] but I'll build a new PA for the MEPT and use the original one for it's original purpose.
  
 I repaired a few broken wires and dry joints and the RX is working. I've checked that the phasing opposite-sideband rejection is working and given it a tweak to check that the adjustments are doing the right things. All looks good. I repaired a few broken wires and dry joints and the RX is working. I've checked that the phasing opposite-sideband rejection is working and given it a tweak to check that the adjustments are doing the right things. All looks good.
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 Coming soon.... FIXME Coming soon.... FIXME
 +
 +The basic format is
 +
 +  * Band pass filter for 30m
 +  * RF amplifier
 +  * Signal splitter to feed the RF ports of a pair of home-made passive 4-diode balance mixers
 +    * the 2 mixers are also fed with 90° I & Q local oscillator signals from an arduino/Si5351 IQ VFO
 +  * The outputs of the 2 mixers is a pair of baseband audio signals in quadrature which then pass through the phase-delay circuits
 +  * The 2 paths combine such that the audio from the unwanted sideband is cancelled and audio from the wanted sideband is presented to to an op-amp audio BPF centred on 700Hz.
 +  * Then there's a audio amplifier that can drive a speaker.