{"id":22710,"date":"2025-07-01T09:40:18","date_gmt":"2025-07-01T08:40:18","guid":{"rendered":"https:\/\/www.crowave.com\/blog\/?p=22710"},"modified":"2025-07-01T09:40:18","modified_gmt":"2025-07-01T08:40:18","slug":"maximal-model-8708","status":"publish","type":"post","link":"https:\/\/www.crowave.com\/blog\/2025\/07\/01\/maximal-model-8708\/","title":{"rendered":"AM\/FM Radio Maximal Model 8708"},"content":{"rendered":"<p>Danas je nabavljen AM\/FM radio prijemnik model 8708, originalno japanski ili kineski proizvod proizveden vjerojatno 1980-tih godina za njema\u010dkog distributera potro\u0161a\u010dke elektronike Maximal. Isti model prijemnika mo\u017ee primjerice imati oznaku Crown \u0161to je japanski proizvo\u0111a\u010d potro\u0161a\u010dke elektronike, no tu robnu marku su mogu\u0107e koristili i neki drugi proizvo\u0111a\u010di\/distributeri.<\/p>\n<p>&nbsp;<\/p>\n<p><a href=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_01.jpg\" rel=\"lightbox[22710]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-22711\" src=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_01.jpg\" alt=\"\" width=\"1300\" height=\"821\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_01.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_01-768x485.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p><a href=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_04.jpg\" rel=\"lightbox[22710]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-22714\" src=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_04.jpg\" alt=\"\" width=\"1300\" height=\"685\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_04.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_04-768x405.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p><a href=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_02.jpg\" rel=\"lightbox[22710]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-22712\" src=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_02.jpg\" alt=\"\" width=\"1300\" height=\"807\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_02.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_02-768x477.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p><a href=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_03.jpg\" rel=\"lightbox[22710]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-22713\" src=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_03.jpg\" alt=\"\" width=\"1300\" height=\"442\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_03.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_03-768x261.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<p>AM\/FM Radio Model 8708 se mo\u017ee napajati preko baterija (4&#215;1,5 V \/ C-tip) ili preko mre\u017ee 220 V, a pokriva \u010detiri frekvencijska opsega:<\/p>\n<ul>\n<li>UKW\/FM: 87,5 \u2013 108 MHz<\/li>\n<li>KW\/AM: 5,9 \u2013 18 MHz<\/li>\n<li>MW\/AM: 535 \u2013 1605 kHz<\/li>\n<li>LW\/AM: 155 \u2013 260 kHz<\/li>\n<\/ul>\n<p>Ugra\u0111en je i jednostavan pasivni audio filtar (KLANG \u2013 ton, zvuk) kojim se mogu naglasiti vi\u0161e (HOCH) ili ni\u017ee (TIEF) audio frekvencije. Ova kontrola bi trebala pomo\u0107i boljoj razumljivosti i \u010disto\u0107i audio prijema s obzirom na vrstu emisije (govor, muzika) i s obzirom na propusnu \u0161irinu audio opsega na pojedinim radio opsezima.<\/p>\n<p>&nbsp;<\/p>\n<hr \/>\n<p>&nbsp;<\/p>\n<p><a href=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_05.jpg\" rel=\"lightbox[22710]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-22715\" src=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_05.jpg\" alt=\"\" width=\"1300\" height=\"414\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_05.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_05-768x245.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p><a href=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_06.jpg\" rel=\"lightbox[22710]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-22716\" src=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_06.jpg\" alt=\"\" width=\"1300\" height=\"1227\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_06.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_06-768x725.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p><a href=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_07.jpg\" rel=\"lightbox[22710]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-22717\" src=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_07.jpg\" alt=\"\" width=\"1300\" height=\"669\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_07.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_07-768x395.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p><a href=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_08.jpg\" rel=\"lightbox[22710]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-22718\" src=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_08.jpg\" alt=\"\" width=\"1300\" height=\"844\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_08.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_08-768x499.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p><a href=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_09.jpg\" rel=\"lightbox[22710]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-22719\" src=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_09.jpg\" alt=\"\" width=\"1300\" height=\"546\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_09.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_09-768x323.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<p>Prijemnik Model 8708 se bazira na integriranom krugu TA 7613AP (Toshiba) u koji su implementirani gotovo svi sklopovi AM\/FM superheteroidnog prijemnika sa izlaznim audio poja\u010dalom (<em>One Chip AM\/FM Radio with Audio Power Amplifier<\/em>). Intenzivni razvoj ovakvih integriranih krugova zapo\u010deo je krajem 1970-tih godina te su od po\u010detka 1980-tih godina ve\u0107 mnoge tvrtke proizvodile identi\u010dne, kompatibilne, ili vrlo sli\u010dne \u010dipove za AM\/FM prijemnike: HA11224 (Hitachi), HA12402 (Hitachi), TDA1083 (Telefunken), A283D (HFO), KA2242x (Samsung), ULN2204 (Sprague), CD7613 (PRC) da nabrojimo samo neke. Ovakvim integriranim krugovima bilo je mogu\u0107e dizajnirati male AM\/FM radio prijemnike koji bi se lako ugra\u0111ivali u najrazli\u010ditije prijenosne (baterijske) radio ure\u0111aje ili druge vi\u0161efunkcionalne audio\/video komponente i ure\u0111aje sa ugra\u0111enim radio prijemnikom.<\/p>\n<p>Tako u razdoblju od po\u010detka 1980-tih godina pa sve do po\u010detka 2000-tih godina nalazimo najrazli\u010ditije tipove i izvedbe komercijalnih radio prijemnika u koji je ugra\u0111en upravo \u010dip TA 7613. Od ostalih aktivnih komponenti potrebno je dodati samo FM tuner (obi\u010dno sa dva tranzistora), no na TA 7613 su se bazirali i neki modeli \u010distih AM prijemnika. Vrlo sli\u010dan prijemnik sa \u010dipom HA12402 (Hitachi) opisali smo u objavi <a href=\"https:\/\/www.crowave.com\/blog\/2021\/08\/23\/grundig-mini-boy-400\/\" target=\"_blank\" rel=\"noopener\">Grundig Mini-Boy 400<\/a>.<\/p>\n<p>&nbsp;<\/p>\n<p><a href=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_10.jpg\" rel=\"lightbox[22710]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-22720\" src=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_10.jpg\" alt=\"\" width=\"700\" height=\"436\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<p>Integrirani krug TA 7613 sadr\u017ei AM tuner (RF poja\u010dalo, lokalni oscilator i mje\u0161a\u010d), AM\/FM MF poja\u010dalo i demodulatore, AM AGC\/FM AFC kontrolu, te izlazno audio poja\u010dalo koje radi u B-klasi. Zahvaljuju\u0107i ugra\u0111enom regulatoru napona (zener-dioda) HA12402 se mo\u017ee napajati naponima u rasponu 3 \u2013 13 V. Preklapanje izme\u0111u AM i FM prijema izvedeno je jednostavnim preklapanjem napona napajanja izme\u0111u AM i FM sklopova \u0161to samu sklopku za ovu funkciju \u010dini vrlo jednostavnom (obi\u010dna jednopolna DC sklopka).<\/p>\n<p>Unato\u010d tome \u0161to je u TA 7613 implementiran veliki broj AM\/FM sklopova jo\u0161 uvijek je za kompletiranje prijemnika potrebno dodati vanjske RF i LO titrajne krugove, pojasne MF filtre i MF transformatore te kompletni FM tuner, a sve ove komponente tra\u017ee i dobru pode\u0161enost na ulazne i MF frekvencije. Kod kasnijih ina\u010dica One Chip (Single Chip) AM\/FM integriranih krugova te\u017eilo se \u0161to vi\u0161e smanjiti broj potrebnih vanjskih komponenti, tako da su razvijeni \u010dipovi kojima je za potpuno funkcionalan prijemnik bilo dovoljno dodati desetak malih kondenzatora i jednu ili dvije jednostavne zavojnice. Kako je srednjevalni AM opseg polako po\u010deo gubiti na popularnosti zbog sve ve\u0107eg broja postaja na UKV opsegu, isti je \u010desto izostavljan iz One Chip konfiguracija pa su one postale jo\u0161 jednostavnije, posebice \u0161to su zahvaljuju\u0107i naponski kontroliranim varikap diodama potpuno izba\u010deni nezgrapni spregnuti promjenjivi kondenzatori za izbor prijemne frekvencije.<\/p>\n<p>Elektroni\u010dku shemu za na\u0161 prijemnik Model 8708 nisam na\u0161ao, no ovdje mo\u017ee poslu\u017eiti ve\u0107 i tipi\u010dna shema AM\/FM prijemnika iz tvorni\u010dke dokumentacije za \u010dip TA 7613 ili pak shema bilo kojeg AM\/FM prijemnika sa tim \u010dipom. Razlike se najvi\u0161e o\u010dituju u broju i tipu ugra\u0111enih MF filtara (kerami\u010dki filtri ili MF transformatori) te donekle u izvedbi FM tunera te ulaznih AM krugova (ovisno o pokrivenim AM frekvencijskim podru\u010djima).<\/p>\n<p>&nbsp;<\/p>\n<p><a href=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_11.jpg\" rel=\"lightbox[22710]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-22721\" src=\"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_11.jpg\" alt=\"\" width=\"1300\" height=\"997\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_11.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_11-768x589.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<p>FM prijemnik je jednostruki heterodin sa MF na 10,7 MHz. Ulazni FM krug (tuner) sastoji se od svega dva tranzistora gdje jedan radi kao RF poja\u010dalo, a drugi radi kao lokalni oscilator i ujedno kao mje\u0161a\u010d (samoosciliraju\u0107i mje\u0161a\u010d).<\/p>\n<p>AM prijemnik je tako\u0111er \u00a0jednostruki heterodin sa MF na 455 kHz. Sve aktivne komponente AM prijemnika implementirane su unutar integriranog kruga TA 7613 (RF poja\u010dalo, mje\u0161a\u010d, lokalni oscilator, MF poja\u010dalo), dok su izvana dodani samo promjenjivi titrajni krugovi tunera i MF filtri.<\/p>\n<p>Izlazna snaga internog audio poja\u010dala unutar \u010dipa TA 7613 je 280 mW (5,5 V \/ 8 \u2126).<\/p>\n<p>&nbsp;<\/p>\n<hr \/>\n<p>&nbsp;<\/p>\n<p>U 1990-tim godinama naj\u010de\u0161\u0107i su bili AM\/FM prijemnici za UKV i srednjevalni radiodifuzni opseg, no bilo je i modela takozvanih \u201emultiband\u201c ili \u201efull band\u201c radio prijemnika koji su imali dodane kratkovalne i dugovalne radio opsege. Jeftini modeli multiband prijemnika, a posebno d\u017eepni modeli, mogli su imati samo jednostavne ulazne AM krugove bez nekih posebnih pojasnih filtera ili aktivnih selektivnih RF poja\u010dala. Tako\u0111er, zbog samih fizi\u010dkih dimenzija, mogli su imati ugra\u0111enu samo malu fiksnu internu feritnu antenu za prijem AM podru\u010dju.<\/p>\n<p>Stoga se takvim prijemnicima na kratkovalnim i dugovalnim AM podru\u010djima i nije moglo puno toga uhvatiti, barem ne dovoljno selektivno. Ipak, za vrijeme povoljnijih propagacija i u no\u0107nim satima, u podru\u010djima gdje nije bilo puno vanjskih elektromagnetskih smetnji, sasvim sigurno se moglo zabavljati poku\u0161ajem prijema nekih dalekih radio oda\u0161ilja\u010da.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Danas je nabavljen AM\/FM radio prijemnik model 8708, originalno japanski ili kineski proizvod proizveden vjerojatno 1980-tih godina za njema\u010dkog distributera potro\u0161a\u010dke elektronike Maximal. Isti model prijemnika mo\u017ee primjerice imati oznaku Crown \u0161to je japanski proizvo\u0111a\u010d potro\u0161a\u010dke elektronike, no tu robnu marku su mogu\u0107e koristili i neki drugi proizvo\u0111a\u010di\/distributeri. &nbsp; &nbsp; AM\/FM Radio Model 8708 se [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":22711,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[],"class_list":{"0":"post-22710","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-radio","8":"czr-hentry"},"jetpack_featured_media_url":"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2025\/07\/maximal_8708_01.jpg","_links":{"self":[{"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/posts\/22710","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/comments?post=22710"}],"version-history":[{"count":1,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/posts\/22710\/revisions"}],"predecessor-version":[{"id":22722,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/posts\/22710\/revisions\/22722"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/media\/22711"}],"wp:attachment":[{"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/media?parent=22710"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/categories?post=22710"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/tags?post=22710"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}