{"id":1114,"date":"2018-02-13T08:31:32","date_gmt":"2018-02-13T08:31:32","guid":{"rendered":"http:\/\/storycase.co.uk\/radio\/?p=1114"},"modified":"2024-07-02T18:29:10","modified_gmt":"2024-07-02T18:29:10","slug":"champion-trf-784-bakelite-valve-radio","status":"publish","type":"post","link":"https:\/\/storycase.co.uk\/radio\/radio\/champion-trf-784-bakelite-valve-radio\/","title":{"rendered":"Champion TRF 784 Bakelite Valve Radio"},"content":{"rendered":"

Champion Electric Corporation manufactured this 4 valve radio in the mid 1950s at their factory in Newhaven East Sussex. This one is serial number 44986. Encased in cream Bakelite the single waveband radio receives only MW (600 – 1500 kHz).<\/p>\n

It\u2019s a pretty basic design being TRF (tuned radio frequency) which is essentially like a crystal set with a variable frequency RF amplifier and an audio amplifier to drive the loud speaker. Better radios use a super-hetrodyne design which mixes the higher radio frequency down to an intermediate frequency (IF) amplifier which improves reception and allows automatic gain control.<\/p>\n

A long length of wire is required for an aerial like that used on the Alba Midget see separate post<\/a>. These are sometimes referred to as ‘throw out’ antennas and were replaced by internal ferrite aerials.<\/p>\n

There\u2019s no sign of cracks in the Bakelite case and the tuning dial has not yellowed or faded and looks original. This set is better suited as a display piece and was used as a prop. The mains cable has been removed.<\/p>\n

\"Champion<\/a>

Champion TRF 784 Dial<\/p><\/div>\n

“Important on no account must the mains lead be shortened\u201d appears on the rear as this set was fitted with a 300 ohm resistive cable to reduce the mains voltage down to run the valve heater circuit. Simply replacing the mains lead with a standard twin flex would damage the valves and components without the resistive feed.<\/p>\n

\"Champion<\/a>

Champion TRF 784 Back<\/p><\/div>\n

Like many radios of this period, no mains transformer was used and so the chassis is not isolated from 240v mains. It\u2019s possible to replace the old mains lead by inserting a resistor inside the radio but typically a 30-40w dissipation is required which heats up the case and can cause discolouration and cracking. A later model 784 from Champion had the dropper inside the case instead of the resistance mains lead and you find many cases have cracked. Alternatively a capacitor could be used to avoid the heat dissipation but must be rated for continuous a.c.use and ideally fail open circuit to avoid damaging the valves if the capacitor fails. The UK Vintage Radio forum<\/a> has many posts and a good guide on dropper calculations<\/a> for anyone wishing to try such a repair.<\/p>\n

Repairs or modifications to old valve radios should not be attempted unless you have experience due to the high voltages these sets have internally.<\/p><\/blockquote>\n","protected":false},"excerpt":{"rendered":"

Champion Electric Corporation manufactured this 4 valve radio in the mid 1950s at their factory in Newhaven East Sussex. This one is serial number 44986. Encased in cream Bakelite the single waveband radio receives only MW (600 – 1500 kHz)…. Continue Reading →<\/a><\/p>\n","protected":false},"author":164,"featured_media":1190,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"class_list":["post-1114","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-radio"],"yoast_head":"\nChampion TRF 784 Bakelite Valve Radio - Radio Retro<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/storycase.co.uk\/radio\/radio\/champion-trf-784-bakelite-valve-radio\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Champion TRF 784 Bakelite Valve Radio - Radio Retro\" \/>\n<meta property=\"og:description\" content=\"Champion Electric Corporation manufactured this 4 valve radio in the mid 1950s at their factory in Newhaven East Sussex. 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