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

greenkit · 8th Oct 2018, 9:02 pm

Thanks Sean,
I found the driver's 82k anode load resistor had drifted up to just over 100k: the screen feed had fared better, only up to about 230k from the nominal 220k. Both replaced anyhow.

Today I substituted an old 8" speaker for the (very modern) 4" unit I had been using, and no doubt the audio does sound better. Tuning to our local BBC Radio on MW, I still need the AF gain at close to 100% to get what I consider a good listening level in my workshop. Maybe this is normal, and I can live with it.

After 60+ years I'm surprised these two radios run so well. I don't know what the difference is in their exact build dates, but one has much tidier wiring than the other, with laced looms and 90 degree bends that can only be described as artistic. This unit also has component-reference ID painted on individual capacitors, etc., with nice blobs of protective lacquer. Someone took a lot of pride in his/her work!

Noel

8th Oct 2018, 9:02 pm	#5
greenkit Tetrode Join Date: Aug 2007 Location: Belfast, Northern Ireland, UK. Posts: 80	Re: Murphy B40D Audio Output Thanks Sean, I found the driver's 82k anode load resistor had drifted up to just over 100k: the screen feed had fared better, only up to about 230k from the nominal 220k. Both replaced anyhow. Today I substituted an old 8" speaker for the (very modern) 4" unit I had been using, and no doubt the audio does sound better. Tuning to our local BBC Radio on MW, I still need the AF gain at close to 100% to get what I consider a good listening level in my workshop. Maybe this is normal, and I can live with it. After 60+ years I'm surprised these two radios run so well. I don't know what the difference is in their exact build dates, but one has much tidier wiring than the other, with laced looms and 90 degree bends that can only be described as artistic. This unit also has component-reference ID painted on individual capacitors, etc., with nice blobs of protective lacquer. Someone took a lot of pride in his/her work! Noel