Film-Tech Forum ARCHIVE: Looking for coil rewind recommendations

This is topic Looking for coil rewind recommendations in forum Film-Yak at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=8;t=001488

Posted by Paul G. Thompson (Member # 655) on 11-26-2002, 02:38 AM:

This is a 800-turn inductor using 22AWG wire. It was in the plate circuit of the Collins transmitter I spoke of in the "Editing Autoexec.bat" thread a couple of weeks ago. I might add that this coil is in the plate circuit of the RF drivers that have about 2,500 volts or so. This thing is about 3.7 mh in value. The coils are wound in a cross-hatch pattern, so nobody I know of will touch it. Any suggestions?

Oh, by the way - here is a picture of the 6,000 volt capacitor that was in the plate circuit of the finals on the 1KW ITA that died two days after the Collins blew its coil. This capacitor knocked me off the air, and was off the air for about 2.5 hours or so.

Posted by Tim Reed (Member # 137) on 11-26-2002, 10:51 AM:

Paul, where'd you get the replacement that got you back on the air? Is getting a new one not an option?

You know SMART can rewind transformers... don't know if their equipment can do the cross hatch trick, though.

Posted by Paul G. Thompson (Member # 655) on 11-26-2002, 11:52 AM:

Tim, I had one that had a broken coil form, and one of the coils were damaged. I was able to use it, but it is strictly a stop-gap fix. Getting a new coil is not an option, because I have not located one. The transmitter was manufactured in 1964. [Frown]

Posted by Oscar Neundorfer (Member # 458) on 11-26-2002, 11:57 AM:

Paul,

SMART does make transformers and inductors, but I am not sure we could make that particular part. I suspect it takes some special tooling to get the separation between the sections just right and to hold it all in place for the encapsulation of each section. Also, I am not sure if our equipment could do the crosshatching in the layers of each winding. I suspect that insulation requirements are pretty severe, so it might use a special magnet wire with high voltage insulation. Even though the dc voltage across the coil is probably quite low, the rf voltage may be considerable and might break down if not properly insulated.

Posted by Sam Hunter (Member # 1119) on 11-26-2002, 02:54 PM:

Try this site out Paul,
http://www.surplussales.com/
http://www.besco-int.com/

They will most likely have it.

Posted by Mark Gulbrandsen (Member # 72) on 11-26-2002, 09:45 PM:

Paul,
Coulda got you that cap at Salt Lake Instrumment....the coil will probably hvae to come out of another Collins though. Millen made a small bench winder that one could wind coils on but I don't know if they are still available or not. You could check with them on that. With the glut of used transmitters(many stations have gone solid state in the last 5 or 6 years) out there you should be able to find another Collins xmitter for parts quite easily. You might also get ahold of the guy that put this web site together too.....
http://hawkins.pair.com/wlw.shtml
Mark