Moving iron reed speaker driver rebuild - UK Vintage Radio Repair and Restoration Discussion Forum

PJL · 28th Apr 2019, 3:05 pm

I foolishly decided I would try restoring a few 1929 suitcase sets, a McMichael and a Selectors. They tend to suffer badly both externally and internally due to the acid batteries being kept inside the cabinet. Both had open circuit coils and interstage transformers.

I am working on rewinding the moving iron drivers first. My question is in the way in which the laminated core is attached to the iron magnet. In both cases they are tightly clamped which would seem to put a short between the laminations? Did they rely on an oxide coating to prevent this as the oxide coating is long gone?

Also, does anyone have a picture of a McMichael Super Range Portable Four cone as the paper cone in this one looks a bit suspect to me. It is black paper with a bit of cotton wool stuffed around the rim.

28th Apr 2019, 3:05 pm	#1
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Moving iron reed speaker driver rebuild I foolishly decided I would try restoring a few 1929 suitcase sets, a McMichael and a Selectors. They tend to suffer badly both externally and internally due to the acid batteries being kept inside the cabinet. Both had open circuit coils and interstage transformers. I am working on rewinding the moving iron drivers first. My question is in the way in which the laminated core is attached to the iron magnet. In both cases they are tightly clamped which would seem to put a short between the laminations? Did they rely on an oxide coating to prevent this as the oxide coating is long gone? Also, does anyone have a picture of a McMichael Super Range Portable Four cone as the paper cone in this one looks a bit suspect to me. It is black paper with a bit of cotton wool stuffed around the rim.