{"id":5239,"date":"2020-11-19T11:50:00","date_gmt":"2020-11-19T00:50:00","guid":{"rendered":"https:\/\/www.homebrewradio.us\/blog\/2020\/11\/19\/diode-ring-magic\/"},"modified":"2025-07-21T18:35:28","modified_gmt":"2025-07-21T08:35:28","slug":"diode-ring-magic","status":"publish","type":"post","link":"https:\/\/www.homebrewradio.us\/blog\/2020\/11\/19\/diode-ring-magic\/","title":{"rendered":"Diode Ring Magic"},"content":{"rendered":"<\/p>\n
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I continue to work on the product detector of my Lafayette HA-600A. This work has caused me to brush up on my understanding of how mixers really work. <\/b><\/div>\n

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I think one of the most interesting mixer circuits is the diode ring. With just four diodes and one or two transformers, this device manages to take an incoming signal and multiply it by either 1 or -1 depending on the polarity of the local oscillator signal. That is pretty amazing. <\/b><\/div>\n

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Alan Wolke W2AEW did an excellent video on this: https:\/\/www.youtube.com\/watch?v=junuEwmQVQ8<\/a><\/b><\/div>\n

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Inspired by Alan, I took my most recent homebrew diode ring mixer (with transformers from Farhan, diodes from Jim W8NSA, and a PC board base from the CNC mill of Pete N6QW) and hooked it up to two signal generators and an oscilloscope. I had the local oscillator at 10 MHz and the signal oscillator at 7 MHz. You can see my results in the pictures (above and at the end). You can see the resulting difference frequency (3 MHz) in the broad up and down pattern. And you can see the sum frequency (17 MHz) signal in the faster oscillations. All you would need is some filtering to separate them out. <\/b><\/div>\n
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I really like the RSGB Handbook diagram (above). I think the bottom schematic with its crossed diodes really explains how the phase reversal takes place: when the LO turns on D1 and D3 (the horizontal ones), multiplication by 1 takes place. But when the LO turns on D2 and D4 (the crossed diodes), up goes to down and down to up, creating phase reversal, or, in math terms, multiplication by -1. <\/b><\/div>\n

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At a more basic level, mixing takes place whenever — in a non-linear circuit — one signal is controlling the gain or attenuation experienced by the other signal. A complex waveform results, a waveform that contains sum and difference products. A circuit like the diode ring, that alternately multiplies by 1 and -1, is non-linear in the extreme, and the multiplication is controlled by the LO. The results can be seen in the diagram’s complex waveforms, on Alan’s Tek ‘scope, and on my Rigol. And in those complex waveforms you can SEE the sum and difference frequencies. That is really cool. <\/b><\/div>\n<\/p><\/div>\n
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I continue to work on the product detector of my Lafayette HA-600A. This work has caused me to brush up on my understanding of how mixers really work. I think one of the most interesting mixer circuits is the diode ring. With just four diodes and one or two transformers, this device manages to take … Continue reading “Diode Ring Magic”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":1672,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[66,41,106,34,119],"tags":[],"class_list":["post-5239","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-farhan","category-juliano-pete","category-lafayette-ha-600a","category-mixer-theory","category-uk"],"_links":{"self":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5239","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/comments?post=5239"}],"version-history":[{"count":1,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5239\/revisions"}],"predecessor-version":[{"id":5242,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5239\/revisions\/5242"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media\/1672"}],"wp:attachment":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media?parent=5239"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/categories?post=5239"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/tags?post=5239"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}