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Beautiful coils

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Forum » Technique, Repair, Restoration, Home construction ** » Radios: how to get parts for old radios » Beautiful coils
           
Joe Sousa
Joe Sousa
Editor
USA  Articles: 664
Schem.: 214
Pict.: 434
16.Nov.09 04:20

Count of Thanks: 42
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John Bruckner makes very nice RF coils that he sells on ebay under "noseknowsnose".

He also has this web page: http://www.crystalradiocoils.com/index.html

He measures his coils and sells each coild with the measured inductance and Q at stated frequencies in the AM band.

He also offers a coil winding service. Perhaps he can make a replacement or missing coil.

His web page also shows RF transformer, and coils with ticklers.

You can contact John at mail[A*T]crystalradiocoils.com

I just bought these 4 coils to experiment with. They are beautiful, electrically and visually. The quoted text in blue was taken from his ebay listing coil descriptions after I bought the coils. I edited out some of John's text and marked the edits with [snip].

"Diamond-weave Cloth Wire COIL for Crystal Radio SetsAka Spider-web Coil Formless 15 pins – 246.9uH This is a Diamond-weave hand-wound coil for crystal radios using #24 synthetic silk cloth covered enameled copper wire.  The design is sometimes mistaken as a spider-web coil but since it has no included spokes, it is called a diamond-weave. Coil color is antique green.[snip] Wooden stand shown for demonstration purposes only and is not included. [snip] There are no forms, coil is held together with GC Q-Dope and lightly sprayed with crystal clear acrylic to strengthen the coil.  Lead length is approximately 6”, and is pre-tinned using a solder pot. This coil wound using a 15 pin Kipgen former, a 36% increase over the 11 pin former, meaning more crossovers for better inductance performance, less inner capacitance. One two-inch nylon screw and 3 nylon nuts provided to mount the coil on your set. Each coil measured for proper inductance using an AADE IIB Precision LC meter. Coil Dimensions: Coil ID:2.1875 inchesCoil OD:3.75 inches Coil width:0.375 inches Inductance:246.9uH Coil Q:210[A*T]790kHz"

 

"Diamond-weave COILS-240uH for Crystal Radio Sets Aka Spider-web Coils Formless 15 pins – 240uHThis is two Diamond-weave hand-wound coils for crystal radios using #26 silver-plated Kynar insulated wire. [snip] The design is sometimes mistaken as a spider-web coil but since it has no spokes, it is called a diamond-weave.[snip] There are no forms, coil is held together with genuine GC Coil Dope and sprayed with Crystal Clear acrylic to strengthen the coil. Lead length is approximately 6 inches. This coil wound using a 15 pin former, a 36% increase over a 11 pin former, meaning more crossovers for better inductance performance, less inner capacitance. A two-inch nylon screw and 3 nuts provided for each coil to mount the coils on your set. Each coil measured for proper inductance using an AADE L/C Meter IIB precision meter. [snip] I do have multiples of this coil. Email for information. Coil Dimensions:Coil ID: 1.375 inches Coil OD: 3.00 inches Coil width: 0.3125 inches Inductance: 240uH +/- 1% Coil Q: 200[A*T]790kHz. Q measured using my calibrated TS-617C/U Q Meter."

 

"HONEYCOMB LITZ COIL FOR CRYSTAL RADIO SETS Made with 180/44 Litz, High Q, 245.2uH - Free diode! Nicely hand-wound by me using brand-new American made-Bridgeport Insulated Wire Co.-180/44 litz wire; coil is formless, and air-wound for low losses. Coil is held together by genuine GC Q-Dope and lightly sprayed with Crystal Clear acrylic to strengthen the coil. One free 1N34A diode included. See photos. Coil specifications: ID 2.187 inches OD 3.125 inches Width 0.750 inches, Coil Inductance 245.2uH, Coil Q 700 @ 790kHz Lead length >5.5 inches and pre-tinned using solder pot. All measurements made with AADE IIB Precision L/C Meter and TS-617C/U Q-meter. All coils come with a two-inch long ¼-20-nylon bolt and three nylon nuts to mount the coil in your set."

 

"Diamond-weave COIL 180/44 LITZ  - Crystal Radio Spider-web Coil Formless 15 pins – 258.9uH [snip] My best selling coil!  This is a Diamond-weave hand-wound coil for crystal radios using 180/44 Litz wire. The design is sometimes mistaken as a spider-web coil but since it has no former spokes, it is called a diamond-weave. [snip] Wooden stand shown for demonstration purposes only and is not included. Used with a 365pf variable capacitor this will tune from 500kHz up. There are no forms, coil is held together with genuine GC Q-Dope and lightly sprayed with Crystal Clear acrylic to strengthen the coil.  Lead length is approximately 6”, and is pre-tinned. This coil wound using a 15 pin Kipgen former, a 36% increase over the 11 pin former, meaning more crossovers for better inductance performance, less inner capacitance. A two-inch nylon screw and 3 nuts are provided to mount the coil on your set. Each coil measured for proper inductance using an AADE L/C Meter IIB precision meter. See photos. Coil Dimensions: Coil ID: 1.4375 inches, Coil OD:   3.675inches, Coil width:0.3125 inches, Inductance:258.9uH. Coil Q is measured on a calibrated TS-617C/U Q-meter with coil 5.5 inches above meter, unloaded: @ 500kHz Q>750,  @ 790kHz    Q>750, @ 1495kHz  Q=735"

I have no commercial interest in this post and no commercial connection with John, other than having just bought these 4 beautiful coils.

Regards,

-Joe

Joe Sousa
Joe Sousa
Editor
USA  Articles: 664
Schem.: 214
Pict.: 434
18.Nov.09 16:33

Count of Thanks: 37
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The following is from an email I received from John about his coils.
Regards,
-Joe
 

Date: Sun, 15 Nov 2009 22:37
Hi Joe;
 
First of all, thank you for your purchase. 
 
I am not an engineer but an experimenter and a copy-cat. In that when I find a particular coil that looks interesting or a coil description in a vintage book, I re-create the coil according to the original instructions, but using modern litz wire or other wires that I can find.
 
I am of the firm belief that using formers in the coil lowers the Q, as well as tapping the coil and have limited myself to making non-tapped coils for that reason.  Tom Kipgen makes all of my coil formers for me and thus they are all air-wound, by hand.
 
The 180/44 litz is used because that is what I can afford to buy to make my coils.  I paid over $50 a pound for the last shipment. Just increasing the litz count to #46 would cost me $97 a pound, both being a 10 pound minimum.  Living off a pension, that is a lot of money.
 
The first coils I made were bifilar coils, using #24 twisted pair telephone wires.  I do have some #30 bifilar kynar insulated silver-plated wire that I could experiment with.  Trying to separate the litz into two bundles would be quite a task, especially with my 67 year old eyes.
 
As far as loose or tight coupling between the coils, I can tell you what I have done on other spec coils.  I use waxed twine as a spacer between the coils to achieve whatever spacing the order called for.  I basically copied what I found in a vintage TRF coil I found at a garage sale. It used twine as a spacer between the coils.  I have seen wooden and bakelite spacers used as well in other coil designs. I suppose acrylic or plastic could be used as well but then it would detract from the vintage look of the coil.
 
The best coil design I have found is the diamond-weave, with a close second being the duolateral. One can wind a lot of wire in a small (1920's small) size with very high inductance. I have wound duolaterals up to 2000uH, 3-inch ID,  for a customer in Switzerland. 
 
I hope this answers some of your questions, I hope my coils do as good in the flesh when you get them.
 
John
  
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