UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

ChristianFletcher · 30th Aug 2019, 3:05 pm

Having removed the Interstage transformer I wanted to ensure that the radio would tune. Given I had found two open circuit transformers I feared for the tuning coils and hadn’t had any audio out So I have retained the -4.5 volt grid bias to the pentode output via a 500k resistor and also capacitive coupled to the detector output. The radio tunes and it’s as loud as I would ever want a radio to be. Sound quality is about as good as any 1930s radio I have owned. Now I’m still going to rewind the transformer, but cannot help thinking why did they bother to use a transformer when capacitor coupling works well and would have been cheaper.

Chris

30th Aug 2019, 3:05 pm	#39
ChristianFletcher Heptode Join Date: Dec 2003 Location: South Yorkshire, UK. Posts: 900	Re: Interstage Audio coupling transformer Having removed the Interstage transformer I wanted to ensure that the radio would tune. Given I had found two open circuit transformers I feared for the tuning coils and hadn’t had any audio out So I have retained the -4.5 volt grid bias to the pentode output via a 500k resistor and also capacitive coupled to the detector output. The radio tunes and it’s as loud as I would ever want a radio to be. Sound quality is about as good as any 1930s radio I have owned. Now I’m still going to rewind the transformer, but cannot help thinking why did they bother to use a transformer when capacitor coupling works well and would have been cheaper. Chris __________________ Every Silver Lining Has Its Cloud https://youtube.com/channel/UCvBpiuUUnErJlNBm6DWb3Ww Last edited by ChristianFletcher; 30th Aug 2019 at 3:20 pm.