Series 1 Evershed Testing Set Bridge Megger Repair - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Uncle Bulgaria · 4th Mar 2022, 10:35 pm

Thanks for all the replies. I'll investigate the practicalities as suggested.

I did get one reading back to the inner terminal, and it was close to 12k as printed on the outer varnish before I removed it. I've (of course) managed to snap it off at the point it goes under the insulation layer to become the next winding beneath, so I'll have to try winding the whole outer layer.

Ed, thank you very much for the suggestion. A foot is about 75 ohms. Does that sound like a standard value? I was able to scrape off some insulation and it appeared more silk than enamel. Perhaps it's decayed since manufacture, and a modern enamel type would be more reliable.

Ed_Dinning · 5th Mar 2022, 2:46 am

Hi Yes silk was a standard covering for precision resistors, enamel was often used if it got hotter. 75 R/ ft sounds a standard value and I should have some. note that different alloys had different diameters for the same R/ft.

I'm away at present so if you PM me the wire details I'll see if I can find something suitable on my return

Ed

4th Mar 2022, 10:35 pm	#21
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,336	Re: Series 1 Evershed Testing Set Bridge Megger Repair Thanks for all the replies. I'll investigate the practicalities as suggested. I did get one reading back to the inner terminal, and it was close to 12k as printed on the outer varnish before I removed it. I've (of course) managed to snap it off at the point it goes under the insulation layer to become the next winding beneath, so I'll have to try winding the whole outer layer. Ed, thank you very much for the suggestion. A foot is about 75 ohms. Does that sound like a standard value? I was able to scrape off some insulation and it appeared more silk than enamel. Perhaps it's decayed since manufacture, and a modern enamel type would be more reliable.

5th Mar 2022, 2:46 am	#22
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: Series 1 Evershed Testing Set Bridge Megger Repair Hi Yes silk was a standard covering for precision resistors, enamel was often used if it got hotter. 75 R/ ft sounds a standard value and I should have some. note that different alloys had different diameters for the same R/ft. I'm away at present so if you PM me the wire details I'll see if I can find something suitable on my return Ed