Post by Richard on Feb 7, 2020 16:55:42 GMT 12
I acquired this "JBC National" (John Burns & Co) a few years ago, it wasnt in a good state. On removing the rear cover, I discovered it was an AC/DC Mains Chassis, meaning it didnt have a power transformer, so that it could run on both AC or DC Mains as was available apparently in central Auckland in the old days. The radio being manufactured by "Radio Ltd 1936" Auckland. The 7 Valve chassis was used in a number of other Radio's produced by Radio Ltd, most of them had a slight improvement of having a power transformer, so a little bit safer than this particular one.
I cant find a photo of its original condition, but here are a few of it being restored, including the installation of a Power transformer and Choke to bring it up to electrical standards. There was no way I was going to operate it in its current form, the mains being directly rectified, the fillaments in series with a large resistor wirewound on a large porcelain former.
The original Valve line up being 6K7 (RF AMP), 6K7 (Mixer), 6C5 (Osc) 6K7 (IF Amp), 6Q7 (Detector, AGC, Ist AF), 18 (Audio Output), 25Y3 (Rectifier) 6G5 (Magic Eye Tuning). I swapped out the 18 Audio Output for a 6F6 and the Rectifier changed to a 5Y3, rewired the Heater Bus from series to parallel. Replaced an open circuit output transformer and Speaker and refinished the cabinet. All the Capacitors were changed out and a faulty Detector load resistor hiding in the second IF can.
I cant find a photo of its original condition, but here are a few of it being restored, including the installation of a Power transformer and Choke to bring it up to electrical standards. There was no way I was going to operate it in its current form, the mains being directly rectified, the fillaments in series with a large resistor wirewound on a large porcelain former.
The original Valve line up being 6K7 (RF AMP), 6K7 (Mixer), 6C5 (Osc) 6K7 (IF Amp), 6Q7 (Detector, AGC, Ist AF), 18 (Audio Output), 25Y3 (Rectifier) 6G5 (Magic Eye Tuning). I swapped out the 18 Audio Output for a 6F6 and the Rectifier changed to a 5Y3, rewired the Heater Bus from series to parallel. Replaced an open circuit output transformer and Speaker and refinished the cabinet. All the Capacitors were changed out and a faulty Detector load resistor hiding in the second IF can.
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