04-29-2019, 03:34 PM
Over the past two weeks after a few issues I have been able to wind the field coil.
I erroneously assumed that with the relatively stiff .032” FR4 material epoxied to the FR4 tube that I would not need additional side supports. So, I set up an old prototype coil winder using a wooden spool support, and some old Meccano parts to make a hand guide to allow me to move the wire feed back and forth to fill the winding width. The pipe cleaner in the guide loop adds dampening and some tension.
It began winding fine until I got about half way filled (about 5000T) when the side force of the winding broke the epoxy and forced the sides out in a keystone shape. I should have taken Phlogiston's advice. So, I scrapped that winding and decided to re-use the original bobbin after cleaning it up a bit. Now with added side supports, I began again.
Below is the bobbin with about 1000T wound:
With the side supports the coil wound perfectly and I wound a total of 10,000T. Here is the finished wound coil. It measured 1100Ω which is a tad higher than the original which was 1060Ω but with today’s higher line voltage the small extra drop is beneficial.
I coated the winding with a few coats of Glyptal varnish and installed the original covering/termination contacts. Here is the coil after terminating the magnet wire and lead wires to the contacts:
I used the original insulating fish paper over the contacts and then covered the whole coil with friction tape, exposing the original RCA part number. See next post for finished photo.
Steve D
I erroneously assumed that with the relatively stiff .032” FR4 material epoxied to the FR4 tube that I would not need additional side supports. So, I set up an old prototype coil winder using a wooden spool support, and some old Meccano parts to make a hand guide to allow me to move the wire feed back and forth to fill the winding width. The pipe cleaner in the guide loop adds dampening and some tension.
It began winding fine until I got about half way filled (about 5000T) when the side force of the winding broke the epoxy and forced the sides out in a keystone shape. I should have taken Phlogiston's advice. So, I scrapped that winding and decided to re-use the original bobbin after cleaning it up a bit. Now with added side supports, I began again.
Below is the bobbin with about 1000T wound:
With the side supports the coil wound perfectly and I wound a total of 10,000T. Here is the finished wound coil. It measured 1100Ω which is a tad higher than the original which was 1060Ω but with today’s higher line voltage the small extra drop is beneficial.
I coated the winding with a few coats of Glyptal varnish and installed the original covering/termination contacts. Here is the coil after terminating the magnet wire and lead wires to the contacts:
I used the original insulating fish paper over the contacts and then covered the whole coil with friction tape, exposing the original RCA part number. See next post for finished photo.
Steve D
