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 Post subject: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Wed 16, 2018 8:19 pm 
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Joined: May Wed 16, 2018 6:58 pm
Posts: 15
Hello,
I am here for the first time and live in the Netherlands and I have a question right away. I'm building the improved 4-circuit tuner and running into a problem.
Who can explain me (preferably with photos) how to wrap the antenna coil.
The first layer with the branches is not the problem but the second layer.
I hope someone can help me.
I know someone in Holland who has him and I would like to be the second to play this beautiful radio.

Best regards, Henk


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Thu 17, 2018 3:52 pm 
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Joined: Nov Tue 14, 2017 5:09 am
Posts: 640
Location: Austin, Texas
Henk,

Welcome to the forum.

I have not made a Cockaday coil so I may not be helpful. One thing I have found useful for winding coils is double sided package wrapping tape. If you put some strips of tape across the coil form, it will hold the wire turns in place until you can coat them with sealer.

Jay


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Thu 17, 2018 6:13 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 12610
Location: S. Dartmouth MA 02748-1225 USA
Try this:

http://theradioboard.com/rb/viewtopic.php?t=4946

If no joy, coax me to peruse my library, FWIR there is an article how to build in a 1920's handbook.

BTW your question is a bit vague. FWIR the larger winding on the larger coil is bank wound. There are turns over it then the antenna input winding is but one turn of large insulated magnet wire. Turns, location and direction of turns, wire size is very important anlog with the correct tuning capacitor range.

If you are wishing in Europe for full range of the BC best to review if there needs to be turns added/removed to cover standard broadcast. The Cockaday is not a long wave receiver by design. There are other designs, not Cockaday or four circuit that will cover long wave in Europe. These circuits were popular build in the late teens and 20's. For receiving shipping and time. Some only exist as radios as there was no compendium for such receiver circuits in great detail.

FWIR Consolidated Radio may have published "blue prints" for the 4-circuit.

Also: http://www.antiqueradios.com/forums/vie ... highlight=

Chas


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Sat 19, 2018 7:09 pm 
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Joined: May Wed 16, 2018 6:58 pm
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Hi jay and Chas,

Thank you for your response, I'm going to try to wrap a coil and show you the result. I take pictures and I wonder what you think of it.

Best regards, Henk


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Sat 19, 2018 9:13 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 12610
Location: S. Dartmouth MA 02748-1225 USA
Do use a coil form material that has low loss. Avoid coating the completed coil if you can, as that will change the "Q". Keep iron/steel hardware out of the working area of the coil. Use brass fasteners and brackets and as few as possible. A one-turn loop around a small O.D. pin will create a tap. When the coil is completed, unravel the cotton covering to make the connection. Bees wax, sealing wax and collodion were the 20's builders choice for securing coils, taps and wire ends. Some also used white shellac. Test on scrap of wire to see the result as all will stain the cotton.

YMMV

Chas


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Sat 19, 2018 9:57 pm 
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Joined: May Wed 16, 2018 6:58 pm
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Hello Chas,

Thank you for your advice. I hope I can get shellac here. Do you have experiences with the Cockaday radio?

Greeting, Henk


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Sun 20, 2018 1:17 am 
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Location: S. Dartmouth MA 02748-1225 USA
hebo wrote:
Hello Chas,

Thank you for your advice. I hope I can get shellac here. Do you have experiences with the Cockaday radio?

Greeting, Henk
Most any home supply store will have shellac. It can be used on coils but orange shellac will turn the coil, well, orange. Use white shellac. Seal a coil only it if has been impossible to wind it tightly.

I have Cockaday 4-circuit radio with the Push-Pull amp, unfortunately, the audio transformers are open.

Chas


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Sun 20, 2018 7:17 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1733
Location: Monroe, NC 28112 USA
There is a book. Coil Design & Construction Manual
by B.B. Babani on Archive.org but my Norton Security says that the .pdf version of this file is a known dangerous file!! Do not think I have ever seen that warning before...

There is another publication: https://nvlpubs.nist.gov/nistpubs/nbste ... erT298.pdf Figure 3 shows the winding sequence.

Here are some pictures of my little one tube version. I can provide higher resolution images if that will help. AND measurements...

Yours,
Robert


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800-Cockaday-on-bench.jpg
800-Cockaday-on-bench.jpg [ 126.8 KiB | Viewed 667 times ]
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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Sun 20, 2018 7:29 am 
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Joined: May Wed 16, 2018 6:58 pm
Posts: 15
I am going to order it at a webshop. I start by making the coils and then the tuner. If that works then I make the closet. I'll keep you informed.


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Sun 20, 2018 9:49 am 
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Joined: Apr Mon 18, 2016 11:03 pm
Posts: 12
Location: Berlin, Germany
Several years ago I was wondering about the special Cockaday Coils and examined them. I bought the original issue of Popular Radio Magazin October 1924, covered with: "This Number contains a Complete Description of the Latest Development in Receivers - The FOUR-CIRCUIT TUNER with A RESISTANCE-COUPLED AMPLIFIER. I made a funny video about this magazin, but without the Cockaday article concerning the special circuit descriptions. https://www.youtube.com/watch?v=xsuuIBRm4hw

Then I built a model and made various measures in the hope of understanding the functions of the coils, found a very surprising solution to the Cockaday phenomenon and have posted it in the well known German Radio Forum WGF:

http://www.wumpus-gollum-forum.de/forum ... 116&page=1

There you can find the experimental equipment, geometry and material that I used. It is extremely important to make the right connections within the coils. My built model was fully functional as Cockaday described its benefits.

Image

Note that there is an enhancement of the resonance curve in the main circuit due to the 90 degree phase shifted signal from second tank circuit resonating at exactly twice the frequency. Be sure, the cockaday effect is not an energy absorption "dip" as assumed by some publications in the past.

I look forward to a successfully development with your Cockaday receiver!


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Sun 20, 2018 9:20 pm 
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Joined: May Wed 16, 2018 6:58 pm
Posts: 15
Thank you for your response, the photos look fine. I will definitely read your report that you posted at German Radio Forum WGF.
If I have any questions during construction, can I then report, and also to the other people who have responded to my question?
I appreciate your reactions to help me further.
My English is not 100% but I do my best.
I hope that I can bring this project to a successful conclusion with your help,


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Mon 21, 2018 10:08 pm 
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Joined: Apr Mon 18, 2016 11:03 pm
Posts: 12
Location: Berlin, Germany
Hi Henk, of course we will help you if we can. Welcome to the club of non native speakers :)
Greetings from Berlin


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Mon 21, 2018 11:22 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 12610
Location: S. Dartmouth MA 02748-1225 USA
Hebo & JPascal,

Please continue in English, though a part of me is Bohemian, Dutch and a smattering of other parts of Europe. I'm stuck...

I would like to learn more about this radio and have bookmarked the topic and look forward to Henks progress.

The slot wound regenerative coil used in the Browning-Drake is well documented in the 20's this Cockaday is not.

BTW beautiful textile covered wire on your Cockaday 4-circuit coil. Is it a European source?

Oh, have you noticed any had capacity effects while tuning?

Regards,

Chas


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Tue 29, 2018 6:07 pm 
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Joined: May Wed 16, 2018 6:58 pm
Posts: 15
Hello Cockaday friends,

Almost all parts have now been collected. Virtually everything is original. I will make the tube feet with bayonet connection myself.
I have to rewind 1 LF transformer, but that is no problem.
First I'm going to make the chassis, preferably brass. Then the receiver, then the amplifier part.
If you want to see pictures of the progress here, I'll post them at the next update.

Regards, Henk


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Tue 29, 2018 6:46 pm 
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Location: S. Dartmouth MA 02748-1225 USA
Henk,

Be aware that the brass chassis could have a detrimental effect on the Cockaday coil.

I would suggest you build on a wood base first, a prototype then insert below, brass sheet and evaluate. It would be a shame to create a receiver work of art that works poorly. Same would apply for a front panel shield to reduce hand capacity. That may explain why the coil is far to the rear with tap wires extending some length to the panel.

If the brass chassis has been done with good results then no worries.

YMMV

Chas


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Tue 29, 2018 7:02 pm 
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Joined: May Wed 16, 2018 6:58 pm
Posts: 15
Hello Chas,

I'm thinking about how I'm going to make the chassis. What you quote is a valid comment. Ok, no brass. Then I go for a wooden floor plate, an ebonite front plate (which I still have) and various brackets. I would like to see photos from that time how they have put together things.

Regards, Henk


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Tue 29, 2018 7:07 pm 
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Joined: May Wed 16, 2018 6:58 pm
Posts: 15
Is aluminum usable here or can you expect the same problems as with brass?

Regards, henk


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Tue 29, 2018 8:19 pm 
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Location: S. Dartmouth MA 02748-1225 USA
hebo wrote:
Is aluminum usable here or can you expect the same problems as with brass?
Regards, henk
Any metal will cause a loss, the larger the coil, the greater the RF field extends around it.

Ebonite (FWIR is hard rubber) is O.K. so is most other modern sheet insulating materials. The wooden base is fine as long as the wood is dry and sealed and not painted with a metallic paint.

I have used, in other radios, to prevent hand capacity effects, tin plated sheet steel metal salvaged from large olive oil cans. Carefully cut, flattened and labels removed with solvent. Again only enough metal to do the job behind the front panel and connected directly to the Earth terminal. All well away from the coils.

I do not want to plant the seeds of doubt, trying a prototype wooden base board then transfer to metal if you wish.

Or, if you know of a metal based Cockaday success then go ahead.

IMHO, the Cockaday coil is what 3" diameter? I would mount at least 4" away from the bottom larger coil, if a metal chassis, opposite the perpendicular tapped coil from any metal base (chassis). That is going to look rather strange that far above. The fact that the tapped coil is all within the field of the base coil gives some idea how far away and not have influence.

GL

Chas


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: May Thu 31, 2018 8:04 am 
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Location: Tucson, Arizona U.S.A.
The explanation is that metal, any kind, too close to a coil acts like a shorted turn in the coil.

_________________
Jim Mueller


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 Post subject: Re: How to make the Cockaday coil for the 4-circuit tuner.
PostPosted: Jun Tue 12, 2018 2:08 pm 
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Joined: May Wed 16, 2018 6:58 pm
Posts: 15
Hey,
I am now on holiday in Luxembourg, it is raining here so I have some time for an update.

The coils and valve base are ready.

The next step is to create a test setup of the receiver. Then test the receiver.
To be continued.


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