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Author Topic: Homebrewing 1/4" Tuned-Slug Coils  (Read 21689 times)
KB1WSY
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Posts: 724




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« Reply #15 on: March 17, 2012, 02:33:09 AM »

>>Strange, I salvaged a lot of slug-tuned coils of every size imaginable from discarded electronic circuits over the years... A few years ago, I bought a sack of 100 of just such coils from All Electronics near downtown LA.<<

Being new to all this, I have found there is a big difference between veteran homebrewers who have had opportunities to build up a decent "junk box" (from salvaging their own existing equipment, picking up stuff at hamfests and surplus dealers, and and so on) and newcomers like me who have nothing to start with. It was also, apparently, somewhat easier in the past than it is now. For instance you now seldom see tube TVs being dumped with the garbage.... and although I have managed to find a limited amount available online, it is sometimes pricey (and occasionally ridiculously so) and I have been waiting for an opportunity to pay more reasonable prices. Anyway, I am assuming that after a few years, I will be in a better position than now.

>>I'd gladly mail you a couple dozen of them that you could pull apart and rewind.<<

That would be terrific. The ones I am currently looking for are the 1/4" type (Miller 4500 or equivalent) with the "red" cores (suitable up to 20 MHz) plus a smaller number with the "green" cores (20 MHz to 50 MHz) but the size isn't critical, obviously. Please contact me via email (it's in my eham profile) and we can talk turkey. Thank you very much.

73 de Martin, KB1WSY
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AA2JZ
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Posts: 18


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« Reply #16 on: May 10, 2012, 07:40:04 PM »

I have used plastic drinking straws to hold the slug...theyre soft enough to "thread" by using the core as a tap......they come in various diameters, so its up to you to drink enough soda to find the correct one....
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KC9KEP
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« Reply #17 on: July 10, 2012, 08:34:27 AM »

The Gingery Coil Winder

http://www.youtube.com/watch?v=FIOocMoRsYQ

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N2XJN
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Posts: 4




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« Reply #18 on: October 04, 2012, 07:21:09 AM »

someone  ( ham) playing with coils
http://www.youtube.com/user/govane2?feature=results_main
 

or this one

coil winders, my new treasure, Old Good USA QUALITY No Chinese
http://www.youtube.com/watch?v=GsEBfDNRFhM&list=UU1ZrGlkxBvG9WOwIs2eApLA&index=6&feature=plcp

by the way is there anyone who knows how did they make coil formers from ceramic and Bakelite originally at the first place?

 How to repeat the same process in home lab environment for one who wants to?
« Last Edit: October 04, 2012, 07:30:19 AM by N2XJN » Logged
G3RZP
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Posts: 4494




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« Reply #19 on: October 04, 2012, 09:33:13 AM »

Some three or four - maybe more years ago, but this century - there was an article in the RSGB RadCom magazine by a guy who made his own ceramic coil formers. These were fairly big for TX use, but doubtless the principle could be applied to smaller ones.

Bakelite ones were moulded, hopefully without a filler of wood flour, but rather of powdered mica.  (Millen's 'Micalex', I believe) Paper ones are just wound: the better resin bonded paper would be filled with resin after vacuum treatment.
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W8JI
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« Reply #20 on: October 04, 2012, 04:01:46 PM »

If I wanted new little 3/8th inch slug tuned coils, I'd order some from Ameritron.  :-)
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KD0REQ
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Posts: 900




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« Reply #21 on: October 04, 2012, 04:54:21 PM »

I'd start looking at McMaster Carr for ceramic or phenolic, and scout around for iron powder rod, probably Amidon.  cut a chunk, square up the ends, drill a hole in the end with a Dremel and set a brass ready-rod in there... the only real excitement, after getting some core and iron powder stock cut without shattering or bad edges, would be making a header and chassis mount on the end that stays put.  no lathe
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KB1WSY
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Posts: 724




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« Reply #22 on: October 04, 2012, 06:22:09 PM »

There are commercially available supplies for raw forms and tuning slugs but I haven't tried them yet. For instance:

http://tinyurl.com/8pv2buq

I actually contacted that supplier but got confused about which slugs fit into which forms so didn't order....

73 de Martin, KB1WSY
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N2XJN
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Posts: 4




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« Reply #23 on: October 04, 2012, 08:23:12 PM »

Some three or four - maybe more years ago, but this century - there was an article in the RSGB RadCom magazine by a guy who made his own ceramic coil formers. These were fairly big for TX use, but doubtless the principle could be applied to smaller ones.

Bakelite ones were moulded, hopefully without a filler of wood flour, but rather of powdered mica.  (Millen's 'Micalex', I believe) Paper ones are just wound: the better resin bonded paper would be filled with resin after vacuum treatment.

I have made my homework:
In this difficult time understanding is the key to the future.
It may trigger an ideas.

ferrites,ceramics,metal parts have something  in common;
 POWDER



Easy introduction to the technology of powder compacting into product
-coil formers
-metal formers
-metal tooling
-metal parts



what is
Sintering:

Solid state sintering is the process of taking metal in the form of a powder and placing it into a mold or die. Once compacted into the mold the material is placed under a high heat for a long period of time. Under heat, bonding takes place between the porous aggregate particles and once cooled the powder has bonded to form a solid piece.
Sintering can be considered to proceed in three stages. During the first, neck growth proceeds rapidly but powder particles remain discrete. During the second, most densification occurs, the structure recrystallizes and particles diffuse into each other. During the third, isolated pores tend to become spheroidal and densification continues at a much lower rate. The words Solid State in Solid State Sintering simply refer to the state the material is in when it bonds, solid meaning the material was not turned molten to bond together as alloys are formed.[11]
One recently developed technique for high-speed sintering involves passing high electrical current through a powder to preferentially heat the asperities. Most of the energy serves to melt that portion of the compact where migration is desirable for densification; comparatively little energy is absorbed by the bulk materials and forming machinery. Naturally, this technique is not applicable to electrically insulating powders.
To allow efficient stacking of product in the furnace during sintering and prevent parts sticking together, many manufacturers separate ware using Ceramic Powder Separator Sheets. These sheets are available in various materials such as alumina, zirconia and magnesia. They are also available in fine medium and coarse particle sizes. By matching the material and particle size to the ware being sintered, surface damage and contamination can be reduced while maximizing furnace loading.





1. YouTube videos

a.
http://www.youtube.com/watch?v=0kksTTeAxU4
Gasbarre 30 Ton CNC Hydraulic powder compaction press

b.
http://www.youtube.com/watch?v=QUarWqjEPD8&feature=related   this one is for me manual processing.
Metal powder injection molding

c.
http://www.youtube.com/watch?v=n_FW7Q2xO5o&feature=related

Powder Metallurgy Touches Your Life, Part 1

d.
http://www.youtube.com/watch?v=T0pNySWH6Us&feature=channel&list=UL
2010 MPIF PM Design Excellence Awards: Grand Prizes !!!!!

e.
http://www.youtube.com/watch?v=qzGBPEoZKSM
Baldwin Defiance 75A Compacting Press from Detroit Process Machinery

f.
http://www.youtube.com/watch?v=avks-yELhBg
Y30E Rotary Powder Compaction Press

g.
http://www.youtube.com/watch?v=MTtHxYyfy2c
Dorst TPA-45 Powder Compacting Press "For Sale" at Detroit P


=====================================================================================================




2. More complex science and lectures:

 a.
http://www.youtube.com/watch?feature=endscreen&NR=1&v=uRVaLUQUmA8
Mod-1 Lec-1 Powder Metallurgy - 1
this is lecture of what it is with heavy accent.

b.
Celadon Ceramics Making.avi - YouTube
this link is to skip the only important here is that ceramic is needed of 800 Celsius for 4 hours


c.
Cold Isostatic Pressing.mpg - YouTube
that one is not for home small production but is good for all of powder based products.










3.http://www.engineeringtoolbox.com/melting-temperature-metals-d_860.html
melting temperature table for various materials.
Note that for sintering there is no need  for such high temperatures


4.Powder metallurgy - Wikipedia, the free encyclopedia
Powder production techniques

Powder compaction


5.Loomis - Inside Page


LOOMIS PRODUCTS piston extrusion presses are used to process powdered ceramics, metals, and plastics into a wide variety of profiles ranging from simple cylinders and tubes, to complex honeycomb shapes. With capacities exceeding 800 tons, our piston extrusion presses are available in 9 standard configurations, and are capable of producing parts per customers specifications.














Cold compaction
Cold compaction is a process in which powder is compressed at a temperature where deformation mechanics like dislocation or diffusional creep can be neglected







6. Ceramic Materials Mechanical and Electrical Properties - Du-Co Ceramics Company
Mechanical and Electrical Properties of Ceramic Materials


7.Extrusion Press Ceramic,Buy Quality Extrusion Press Ceramic from Manufacturers and Suppliers on Alibaba.com
high alumina ceramic
Min. Order: 100 Pieces
FOB Price: US $0.05-1.00 / Piece


Best quality ceramics for oil

FOB Price:   US $ 399 - 436 / Ton






8.Used- Stokes Single Motion, Single Punch Compacting Press, Model 511.6. Maximum
desktop press


9.http://www.antiqueradios.com/forums/viewtopic.php?f=12&t=47085

Ham radio forums coil formers



11.Detroit Process Machinery - Inventory of Kilns, Furnaces, Ovens - Buy and Sell Detroit Process Machinery Ceramic Kiln, High Temperature Furnace, Elevator Kiln, Vacuum Sintering Furnace, Sinter Hip
powder industry used machinery.


At the end someone who has good lab and small mechanical lab can move to area of use of both.
so for ebay and  military auction hunters it takes  less than some of you spend for restaurant and entertainment
including  cigarettes withing 2 years to get to all this guy was able to get.
kind of impressive.
http://www.youtube.com/watch?v=QHBEHOOsxT4
look at minute:
2:33 to 5:22
and
35:34 to 37:51

 
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KD0REQ
Member

Posts: 900




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« Reply #24 on: October 05, 2012, 11:05:48 AM »

I have walked past a sintering line many a time in the 2 years I worked contract at a major HVAC company.  lot of natural gas used in the ovens there.  lot of pressure in the molds.

I consider going that far into DIY is not worth the effort when there are places selling bulk stock that I can cut down and use.
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N2XJN
Member

Posts: 4




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« Reply #25 on: October 05, 2012, 12:20:20 PM »

Some three or four - maybe more years ago, but this century - there was an article in the RSGB RadCom magazine by a guy who made his own ceramic coil formers. These were fairly big for TX use, but doubtless the principle could be applied to smaller ones.

Bakelite ones were moulded, hopefully without a filler of wood flour, but rather of powdered mica.  (Millen's 'Micalex', I believe) Paper ones are just wound: the better resin bonded paper would be filled with resin after vacuum treatment.


I have gone through   everything RSGB RadCom magazine  on line was giving me and I did not find it
the only note I found is



10 January 2010.doc - Radio Society of Great Britain
File Format: Microsoft Word
Jan 10, 2010 ... On Tuesday 12 January Loughborough and District Amateur Radio Club is having a Bakelite bits show and tell evening. Contact Chris, G1ETZ ...
www.rsgb.org/gb2rs/public/archive/2010/10%20January%202010.doc


24 August 2008 - Radio Society of Great Britain
File Format: Microsoft Word
On Thursday 28 August Yeovil Amateur Radio Club is spending the evening discussing Bakelite and associated equipment. Contact Gary, 2E0BFJ, by email to ...
www.rsgb.org/gb2rs/public/archive/2008/24%20August%202008.doc

If  Peter Chadwick G3RZP by the chance will be able to find this article I would be happy to contact designated person for benefit of all general knowledge  of ham radio community. I might be even considering visit such ham and take documentary.
Bakelite is  art of the past but art of the beauty.
So is ceramic coil formers, ceramic variometers ans so on.
The best of it is,...........
 that next QSO with one, might be  not about "Burger-king trip" but about something that is more educational to our young SWL's and maybe  some of them will get ideas for the future.

Thanks again

N2XJN
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N2XJN
Member

Posts: 4




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« Reply #26 on: October 05, 2012, 01:08:31 PM »

I have walked past a sintering line many a time in the 2 years I worked contract at a major HVAC company.  lot of natural gas used in the ovens there.  lot of pressure in the molds.

I consider going that far into DIY is not worth the effort when there are places selling bulk stock that I can cut down and use.


Interesting
I have been is science since.............. hm.....as long as I can remember.
I would love if you can give me some hints of how to make it in lab environment.
There are two of us  KC2WGB my Friend just go to his QRZ.com page, you going to love it.
My lab is not smaller at all.
Between two of us there is probably one of the the largest ham owned/ham dedicated, noncommercial   lab in USA

John is more  into GHz I'm operating in 1Mhz and below VLF UVLF


question:
can you show me any place  where I can buy  ceramic coil former at any given length diameter and wall thickens?
 


question:
If you  have need for one particular box 3x3x5 made from  Aluminium.
Than
small 50T  hydraulic press is about (ebay, about $200-1000)
than
you mill  stamp and base(ebay, universal milling machine is about $500-2000)
 
powder cost : ? hm........ it looks like $1-10 but I wait for  you to correct me.

iron for ferrite core is no problem
old cast iron pipe from scrap yard and grinder.
You can make  as much as you wish.

Now you make the cold pressed mold with addition of ?
what kind of silicone you suggest?

Than sintering.
cost of 1200 degrees of  Centigrade furnace ( kiln)  is $100-700) (but  for AL you need only 550 degrees C)
cost of electrical energy?
6kWH = around $10 for one time process.


The same process can be applied to  ceramic ham radio PA coil formers and variometers
The only difference is that  around 2KWh is required at 1200 C and around 4h
 than total cost is around 0.40 x4 say around $2
at 220V In

I will appreciate if you can correct any factors that are not included or not properly  calculated.


So what is the benefit of doing it by yourself?

well/...........

What is the difference of buying the painting and painting it by yourself?

education, EDUCATION, E D U C A T I O N
fun
pleasure
and for some additional source of income out of his own garage if you will................




N2XJN








  
« Last Edit: October 05, 2012, 01:57:25 PM by N2XJN » Logged
G3RZP
Member

Posts: 4494




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« Reply #27 on: October 06, 2012, 03:46:43 AM »

Radcom, 2002, Volume 78, August, page 38, 'making a ceramic coil former'.

Further back than I thought, but that is what advancing age does for one!

You have to search the on line yearly indexes.
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K8AI
Member

Posts: 58




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« Reply #28 on: October 13, 2012, 07:55:08 PM »

Just throwing this out there and I don't know what inductances you're needing. I've bought coils and slugs here:

Www.hamtronics.com
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