{"id":1294,"date":"2013-01-27T15:27:00","date_gmt":"2013-01-27T04:27:00","guid":{"rendered":"https:\/\/www.homebrewradio.us\/blog\/2013\/01\/27\/a-filter-for-the-mighty-midgets-mate\/"},"modified":"2025-07-21T11:12:18","modified_gmt":"2025-07-21T01:12:18","slug":"a-filter-for-the-mighty-midgets-mate","status":"publish","type":"post","link":"https:\/\/www.homebrewradio.us\/blog\/2013\/01\/27\/a-filter-for-the-mighty-midgets-mate\/","title":{"rendered":"A Filter for The Mighty Midget’s Mate"},"content":{"rendered":"
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The story of my 80\/40 meter three tube (all 6U8) superhet receiver is recounted here: http:\/\/www.gadgeteer.us\/erart.htm <\/a><\/b>

<\/b> I’ve been playing with this RX on and off for many years now. Somewhere along the line I picked up a 455 kHz filter for it (I couldn’t find the 455 kc crystals that Lew McCoy used). Yesterday I finally got around to putting the filter into the receiver.<\/b>

<\/b> There is almost no info on this filter on the internet. Here are the details”<\/b>
Toyo Communications Equipment Company Ltd. CM FILTER<\/b>
Type: 455 — 2.4 — C Date: 8- 69<\/b>

<\/b> On the bottom, there are four terminals. They are marked “P” “B” “E” and “G”. Does anyone know what these letters signify? <\/b><\/p>\n

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I experimented and it seemed like putting a 455 kc signal into P and B, and taking the output from E was the way to go. I’ve left G floating. It works, and the improved selectivity is very evident. But I’m operating with no specs on the filter, so I may have it in there upside down and backwards. And of course, I am operating with my usual disregard for impedance matching issues. <\/b>

<\/b> Here’s how I’ve placed it in the circuit: <\/b><\/p>\n

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Ideas, suggestions and even admonitions would be appreciated. <\/b><\/p>\n

Our book: “SolderSmoke — Global Adventures in Wireless Electronics” http:\/\/soldersmoke.com\/book.htm<\/a> Our coffee mugs, T-Shirts, bumper stickers: http:\/\/www.cafepress.com\/SolderSmoke<\/a> Our Book Store: http:\/\/astore.amazon.com\/contracross-20<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

The story of my 80\/40 meter three tube (all 6U8) superhet receiver is recounted here: http:\/\/www.gadgeteer.us\/erart.htm I’ve been playing with this RX on and off for many years now. Somewhere along the line I picked up a 455 kHz filter for it (I couldn’t find the 455 kc crystals that Lew McCoy used). Yesterday I … Continue reading “A Filter for The Mighty Midget’s Mate”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":1295,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[262,100],"tags":[],"class_list":["post-1294","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-mccoy-lew","category-old-radio"],"_links":{"self":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/1294","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=1294"}],"version-history":[{"count":1,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/1294\/revisions"}],"predecessor-version":[{"id":1298,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/1294\/revisions\/1298"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media\/1295"}],"wp:attachment":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media?parent=1294"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/categories?post=1294"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/tags?post=1294"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}