By Glen Rickerd, no6w@arrl.net

A few weeks back I had occasion to test a power supply transformer in a piece of equipment I was repairing.  The DC winding resistance measurements on the old transformer, which was blowing fuses, showed the SAME readings as the “new old stock” replacement.

However the inductance measurements I made with my cheap $20 Chinese L/C meter showed a radically different story.  The replacement went in and the old transformer went to e-waste.

To get the WHOLE picture, I would have been better served by a high-potential resistance meter… sometime referred to as a megger by some old-timers.

I would recommend you check out something like the Estone BM500A 1000V 1999M Digital Insulation Resistance Tester Meter Megohmmeter.

Another megohmmeter that gets better reviews but comes with a flimsy case that is easy to reinforce is the Samyo VC60B.  There are several different “brands” that look identical.  Likely all made in the same factory in China.

At about $50 the price is still reasonable.

Test voltage is up to 1 KV.  Also good for checking feedlines, extension cords,
etc.

I would recommend you check out the Samyo VC60B+ Digital Insulation Resistance Tester Megohmmeter MegOhm DCV ACV Meter.

Glen Rickerd NO6W
no6w@arrl.net
http://www.qrz.com/db/NO6W