{"id":174,"date":"2010-05-23T21:24:50","date_gmt":"2010-05-23T21:24:50","guid":{"rendered":"http:\/\/ve2cuy.wordpress.com\/"},"modified":"2010-05-23T21:24:50","modified_gmt":"2010-05-23T21:24:50","slug":"project-3-superheterodyne-octal-tubes","status":"publish","type":"page","link":"https:\/\/ve2cuy.com\/blog\/index.php\/vacuum-tube\/project-3-superheterodyne-octal-tubes\/","title":{"rendered":"Project 3 – Superheterodyne octal tubes"},"content":{"rendered":"

This is a work in progress. The radio will probably be completed in the first half of 2010.\u00a0\u00a0\u00a0<\/p>\n

It will have 5 section; rf, lo-mixer+if, if-amp2, det+first-af and af-amp.\u00a0\u00a0\u00a0<\/p>\n

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January 8 2010\u00a0\u00a0\u00a0<\/p>\n

Well, I had time to complete my 5 tube radio project.\u00a0\u00a0\u00a0<\/p>\n

[youtube=http:\/\/www.youtube.com\/watch?v=PFwE5W0Id50]\u00a0\u00a0\u00a0<\/p>\n

I have opted for a 1940\u2019s classic, an all American 5 superheterodyne AM receiver.\u00a0\u00a0\u00a0<\/p>\n

I had a few 12SA7, \u2026, 50L6 series lying around the shack and two old 455kc \u2018IF\u2019 transformer.\u00a0\u00a0\u00a0<\/p>\n

The schematic is quite straight forward, the usual RF\/MIXER, IF amp, DET\/AF amp and power amp.\u00a0\u00a0\u00a0<\/p>\n

The strength of the signal \u2013 from the detector section – is use to AGC.\u00a0\u00a0\u00a0<\/p>\n

Tube heaters are connected in series and a 35Z5 is use to provide the B+ from an isolation transformer connected to 117AC.\u00a0\u00a0\u00a0<\/p>\n

It was quite fun to revisit an old part of radio history.\u00a0\u00a0\u00a0<\/p>\n

Oh yes, tuning was a bit tricky using a scope.\u00a0 When the scope was disconnected, the circuit was detuned!\u00a0 Measuring the AGC negative voltage and using my ears was much more effective.\u00a0\u00a0\u00a0<\/p>\n

A frequency counter was use to calibrate the L.O.\u00a0\u00a0\u00a0<\/p>\n

By the way, Max Robinson has a lot of valuable information on his site \u2018<\/strong>FUN WITH TUBES\u2019 about tube radios and AA5 theory at http:\/\/www.angelfire.com\/electronic\/funwithtubes\/<\/a>.\u00a0\u00a0\u00a0<\/p>\n

And Dave N2DS has build very nice radios http:\/\/makearadio.com<\/a>.\u00a0\u00a0\u00a0<\/p>\n

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\u00a0<\/div>\n","protected":false},"excerpt":{"rendered":"

This is a work in progress. The radio will probably be completed in the first half of 2010.\u00a0\u00a0\u00a0 It will have 5 section; rf, lo-mixer+if, if-amp2, det+first-af and af-amp.\u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 January 8 2010\u00a0\u00a0\u00a0 Well, I had time to complete my 5 tube radio project.\u00a0\u00a0\u00a0 [youtube=http:\/\/www.youtube.com\/watch?v=PFwE5W0Id50]\u00a0\u00a0\u00a0 I have opted for a 1940\u2019s classic, an all […]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":12,"menu_order":0,"comment_status":"open","ping_status":"open","template":"","meta":{"footnotes":""},"class_list":["post-174","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/ve2cuy.com\/blog\/index.php\/wp-json\/wp\/v2\/pages\/174","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ve2cuy.com\/blog\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/ve2cuy.com\/blog\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/ve2cuy.com\/blog\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/ve2cuy.com\/blog\/index.php\/wp-json\/wp\/v2\/comments?post=174"}],"version-history":[{"count":0,"href":"https:\/\/ve2cuy.com\/blog\/index.php\/wp-json\/wp\/v2\/pages\/174\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/ve2cuy.com\/blog\/index.php\/wp-json\/wp\/v2\/pages\/12"}],"wp:attachment":[{"href":"https:\/\/ve2cuy.com\/blog\/index.php\/wp-json\/wp\/v2\/media?parent=174"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}