OK, equal time for the lowry power choke.
Get out the Ny-Quil to enjoy this dissection.
This one is a Thordarson 20C55, which of course, is the only one not in my catalog. All the more reason to hack it! I had all the details in one short hour.
The victim:
This guy measures out at 4.78 Henries on the Sencore bridge, 5.1 Henries on the B-K, and 2.7 Henries on the Gen Rad. The lower reading is because the Gen Rad osillator is running at 1000 hertz, where-as the other machines probably estimate inductance at 60 hz.
DCR was about 72 ohms.
This choke is made for high voltage tube type power supplies.
It weighs 3 lbs.
Bottom view, two leads, black goo on the lams, two end bells:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_2.jpg
Bell covers off. Those are fake keeper lams on the outside, made out of paper. They "block" the coil for tightness:
The I bars are all stacked together. Not a lapped lam construction like audio transformers. This is in order to handle DC . There was no paper gap between the E and I lams:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_5.jpg
The coil was just back and forth windings with 0.0025 kp (kraft paper) in between the layers:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_7.jpg
Using the plastic persuader to seperate the core from the coil. Along with the always present heat gun:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_8.jpg
Coil off the core:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_9.jpg
Leads are secured and insulated with some tape that runs thru the coil:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_10.jpg
Varnish impregnated coil:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_11.jpg
Interlayer paper:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_paper.jpg
Lam type. 0.018 barn roof steel, (non grain oriented silicon), type MH 112,
1.115 inch stack, 62 lams:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_lam.jpg
Pressboard former:
That's about it. Oh yeah, turns: 24 layers, 85 turns per layer, back and forth winding of 0.013 in. enameled copper, 28 gauge, 65 ohms per 1000 ft, 72.7 turns per inch, 2040 turns total.
Wire length: about 1140 ft.
OK, easy construction, but still not really something you would DIY, unless you were trapped on a small desert island and needed a choke. Much easier/cheaper to buy one, as they make them by the thousands.
cj
Get out the Ny-Quil to enjoy this dissection.
This one is a Thordarson 20C55, which of course, is the only one not in my catalog. All the more reason to hack it! I had all the details in one short hour.
The victim:
This guy measures out at 4.78 Henries on the Sencore bridge, 5.1 Henries on the B-K, and 2.7 Henries on the Gen Rad. The lower reading is because the Gen Rad osillator is running at 1000 hertz, where-as the other machines probably estimate inductance at 60 hz.
DCR was about 72 ohms.
This choke is made for high voltage tube type power supplies.
It weighs 3 lbs.
Bottom view, two leads, black goo on the lams, two end bells:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_2.jpg
Bell covers off. Those are fake keeper lams on the outside, made out of paper. They "block" the coil for tightness:
The I bars are all stacked together. Not a lapped lam construction like audio transformers. This is in order to handle DC . There was no paper gap between the E and I lams:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_5.jpg
The coil was just back and forth windings with 0.0025 kp (kraft paper) in between the layers:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_7.jpg
Using the plastic persuader to seperate the core from the coil. Along with the always present heat gun:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_8.jpg
Coil off the core:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_9.jpg
Leads are secured and insulated with some tape that runs thru the coil:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_10.jpg
Varnish impregnated coil:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_11.jpg
Interlayer paper:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_paper.jpg
Lam type. 0.018 barn roof steel, (non grain oriented silicon), type MH 112,
1.115 inch stack, 62 lams:
http://vacuumbrain.com/The_Lab/TA/Thordarson/Choke/ck_lam.jpg
Pressboard former:
That's about it. Oh yeah, turns: 24 layers, 85 turns per layer, back and forth winding of 0.013 in. enameled copper, 28 gauge, 65 ohms per 1000 ft, 72.7 turns per inch, 2040 turns total.
Wire length: about 1140 ft.
OK, easy construction, but still not really something you would DIY, unless you were trapped on a small desert island and needed a choke. Much easier/cheaper to buy one, as they make them by the thousands.
cj
