{"id":10457,"date":"2017-11-22T11:20:00","date_gmt":"2017-11-22T00:20:00","guid":{"rendered":"https:\/\/www.homebrewradio.us\/blog\/2017\/11\/22\/iphone-direct-conversion-receiver-with-variable-ceramic-oscillator\/"},"modified":"2025-07-22T04:32:35","modified_gmt":"2025-07-21T18:32:35","slug":"iphone-direct-conversion-receiver-with-variable-ceramic-oscillator","status":"publish","type":"post","link":"https:\/\/www.homebrewradio.us\/blog\/2017\/11\/22\/iphone-direct-conversion-receiver-with-variable-ceramic-oscillator\/","title":{"rendered":"iPhone Direct Conversion Receiver with Variable Ceramic Oscillator"},"content":{"rendered":"
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A while back Bob N7SUR got us talking about winter projects. Receivers. Of course, Pete and I quickly went down different paths. Pete is making great progress with lots of interesting digital circuitry. He is going over to the dark side. Check it out here: <\/b><\/div>\n
http:\/\/n6qw.blogspot.com\/2017\/11\/21st-century-homebrew-sdr-ssb.html<\/a><\/b><\/div>\n

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I went with simplicity. Extreme simplicity. Direct Conversion (thanks Wes!). Discrete components. No chips. Analog Oscillator. 40 meters — monoband. <\/b><\/div>\n

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Schematic updated 29 November 2017<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
There it is. You can click on the picture to make it larger. Here is an outline of the circuitry: <\/b><\/div>\n

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— Single tuned circuit bandpass filter preceded by a simple pot that serves as a gain control. <\/b><\/div>\n
— JFET RF amp<\/b><\/div>\n
— Singly balanced passive mixer inspired by F5LVG’s RX-20 in SPRAT 100. For the coil I used one of the many trifilar toroids that Farhan gave me. <\/b><\/div>\n
— The local oscillator is the coolest stage. I used a 7.37 MHz ceramic resonator and a circuit inspired by Miguel PY2OHH. With a polivaricon I can tune the entire 40 meter band. I put a reduction drive int here to make tuning easier. <\/b><\/div>\n
— The AF amp is an op-amp free design. It works well into ear buds or into a computer speaker. <\/b><\/div>\n
— Perhaps in an effort to catch the attention of the younger generation, I built it into an iPhone box. <\/b><\/div>\n

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Please let me know if you spot any flaws in the circuit, or see any places where it might be improved. <\/b><\/div>\n

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More to follow. This prototype is now in the mail, en route to my nephew John Henry who will be testing it for me. <\/b><\/div>\n
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A while back Bob N7SUR got us talking about winter projects. Receivers. Of course, Pete and I quickly went down different paths. Pete is making great progress with lots of interesting digital circuitry. He is going over to the dark side. Check it out here: http:\/\/n6qw.blogspot.com\/2017\/11\/21st-century-homebrew-sdr-ssb.html I went with simplicity. Extreme simplicity. Direct Conversion (thanks … Continue reading “iPhone Direct Conversion Receiver with Variable Ceramic Oscillator”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":1438,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[42,217,35,66],"tags":[],"class_list":["post-10457","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-40-meters","category-brazil","category-direct-conversion","category-farhan"],"_links":{"self":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/10457","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=10457"}],"version-history":[{"count":1,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/10457\/revisions"}],"predecessor-version":[{"id":10462,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/10457\/revisions\/10462"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media\/1438"}],"wp:attachment":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media?parent=10457"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/categories?post=10457"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/tags?post=10457"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}