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Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
Hello,
I found this very nice website with a section about Homebrew Butterfly Capacitor with many photographs. http://hps.infolink.com.br/py1ahd/gallery21.htm Does anybody knows where in UK (preferrable in Dorset or London) can I get aluminum foil, 0.5 centimeters thickness? 73's DX Marcelo LW3EOV/GB |
Where can I get aluminium foil (0.5 cm thickness) for Homebrew Butterfly Capacitor
wrote in message ... Hello, I found this very nice website with a section about Homebrew Butterfly Capacitor with many photographs. http://hps.infolink.com.br/py1ahd/gallery21.htm Does anybody knows where in UK (preferrable in Dorset or London) can I get aluminum foil, 0.5 centimeters thickness? 73's DX Marcelo LW3EOV/GB Hi Marcelo, I think that 0.5 centimeter is a typo, it seems to thick, I think it should say millimeters. As a reference compare the thickness of the brass nuts to the plate thickness. Mike |
Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
I wouldn't call 0.5 cm "foil"...more like aluminum "plate"...that's
almost 3/16 inch thick. Try http://www.aircraftspruce.com Scott wrote: Hello, I found this very nice website with a section about Homebrew Butterfly Capacitor with many photographs. http://hps.infolink.com.br/py1ahd/gallery21.htm Does anybody knows where in UK (preferrable in Dorset or London) can I get aluminum foil, 0.5 centimeters thickness? 73's DX Marcelo LW3EOV/GB -- Scott http://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version) |
Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
In article ,
wrote: I found this very nice website with a section about Homebrew Butterfly Capacitor with many photographs. http://hps.infolink.com.br/py1ahd/gallery21.htm Does anybody knows where in UK (preferrable in Dorset or London) can I get aluminum foil, 0.5 centimeters thickness? I think that figure, cited on the web site, must certainly be a typographical error. There's no way that aluminum sheet which is 0.5 centimeters (5 millimeters) thick would make sense in this application. I'd believe that it's supposed to be 0.5 mm (rather than 0.5 cm). I can't offer a specific source, since I'm in the United States, but a well-stocked hardware store might carry something of about that thickness. When I look up aluminum sheeting at www.use-enco.com (a U.S. mailorder supplier) the thinnest I see is 0.032", which is around ..8 mm I believe. I do have one specific concern about the butterfly capacitor design you're interested in. Capacitors used for resonating small magnetic transmitting loop antennas need to have low resistive losses, due to the high Q and the high currents in the loop. Butterfly capacitors are often preferred to typical stator/rotor capacitors because they have no "wiping" contacts (which have a relatively small contact area and thus potentially a relatively high resistance). The most-favored type use an all-welded or all-soldered construction, in order to ensure a low-resistance path to all of the plates. Unfortunately, the homebrew cap you're looking at uses threaded brass rods, brass nuts, and aluminum plates. None of the connections are soldered. The connections to the stator plates will be interference/friction mating (i.e. brass nut, tightened onto aluminum plate) and I'd be concerned that the aluminum will soon oxidize and that the connections may rise in resistance, leading to increased losses over time. This issue could be largely eliminated if you were to use sheet brass, rather than sheet aluminum, for the stator plates. You could then flux and solder the rods, nuts, and plates together (before installing the acrylic endplates, of course :-) and ensure a solid, reliable, low-resistance current path. I think you could continue to use aluminum for the rotor plates, if you wish, since the current flow will be across the plate and there will be little or no need for current flow between adjacent plates. If you do use aluminum plates for the stators,, I'd consider adding a thin smear of a conductive aluminum-compatible anti-oxidant grease (Penetrox, NoAlOx, or a similar product) around the hole in each stator plate, before tightening down the brass nuts. This would help make a reliable contact, and exclude oxygen from the aluminum surface. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Where can I get aluminium foil (0.5 cm thickness) for Homebrew Butterfly Capacitor
I found this very nice website with a section about Homebrew Butterfly Capacitor with many photographs. http://hps.infolink.com.br/py1ahd/gallery21.htm Does anybody knows where in UK (preferrable in Dorset or London) can I get aluminum foil, 0.5 centimeters thickness? Make contact with the Flight Refuelling Amateur Radio Society (www.frars.org.uk), based near Poole. They will tell you where to find sheet metal in Dorset. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
On Nov 27, 1:41 am, (Dave Platt) wrote:
In article , wrote: I found this very nice website with a section about Homebrew Butterfly Capacitor with many photographs. http://hps.infolink.com.br/py1ahd/gallery21.htm Does anybody knows where in UK (preferrable in Dorset or London) can I get aluminum foil, 0.5 centimeters thickness? I think that figure, cited on the web site, must certainly be a typographical error. There's no way that aluminum sheet which is 0.5 centimeters (5 millimeters) thick would make sense in this application. I'd believe that it's supposed to be 0.5 mm (rather than 0.5 cm). I can't offer a specific source, since I'm in the United States, but a well-stocked hardware store might carry something of about that thickness. When I look up aluminum sheeting atwww.use-enco.com(a U.S. mailorder supplier) the thinnest I see is 0.032", which is around .8 mm I believe. I do have one specific concern about the butterfly capacitor design you're interested in. Capacitors used for resonating small magnetic transmitting loop antennas need to have low resistive losses, due to the high Q and the high currents in the loop. Butterfly capacitors are often preferred to typical stator/rotor capacitors because they have no "wiping" contacts (which have a relatively small contact area and thus potentially a relatively high resistance). The most-favored type use an all-welded or all-soldered construction, in order to ensure a low-resistance path to all of the plates. Unfortunately, the homebrew cap you're looking at uses threaded brass rods, brass nuts, and aluminum plates. None of the connections are soldered. The connections to the stator plates will be interference/friction mating (i.e. brass nut, tightened onto aluminum plate) and I'd be concerned that the aluminum will soon oxidize and that the connections may rise in resistance, leading to increased losses over time. This issue could be largely eliminated if you were to use sheet brass, rather than sheet aluminum, for the stator plates. You could then flux and solder the rods, nuts, and plates together (before installing the acrylic endplates, of course :-) and ensure a solid, reliable, low-resistance current path. I think you could continue to use aluminum for the rotor plates, if you wish, since the current flow will be across the plate and there will be little or no need for current flow between adjacent plates. If you do use aluminum plates for the stators,, I'd consider adding a thin smear of a conductive aluminum-compatible anti-oxidant grease (Penetrox, NoAlOx, or a similar product) around the hole in each stator plate, before tightening down the brass nuts. This would help make a reliable contact, and exclude oxygen from the aluminum surface. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Thanks for taking the time to give me an explanation, I will try to find sheet brass, but still don't know where in UK. |
Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
On Nov 27, 7:30 am, Ian White GM3SEK wrote:
I found this very nice website with a section about Homebrew Butterfly Capacitor with many photographs. http://hps.infolink.com.br/py1ahd/gallery21.htm Does anybody knows where in UK (preferrable in Dorset or London) can I get aluminum foil, 0.5 centimeters thickness? Make contact with the Flight Refuelling Amateur Radio Society (www.frars.org.uk), based near Poole. They will tell you where to find sheet metal in Dorset. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)http://www.ifwtech.co.uk/g3sek Thanks Ian, I sent an email to M1FBB, Steve Smale, from the Flight Refuelling Amateur Radio Society. |
Where can I get aluminium foil (0.5 cm thickness) for Homebrew Butterfly Capacitor
wrote in message ... [...] Thanks for taking the time to give me an explanation, I will try to find sheet brass, but still don't know where in UK. I buy Aluminium and Brass sheet from ebay. Last buy was item number 160183295588. Not cheap though!. Probably much easier to buy a TF801 for a fiver and dismantle/rebuild the magnificent Gold and silver plated turret capacitors. There's also a bonus of about 2 square feet of Gold plated, brass sheeting in there. |
Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
On Nov 26, 8:41 pm, (Dave Platt) wrote:
Unfortunately, the homebrew cap you're looking at uses threaded brass rods, brass nuts, and aluminum plates. None of the connections are soldered. The connections to the stator plates will be interference/friction mating (i.e. brass nut, tightened onto aluminum plate) and I'd be concerned that the aluminum will soon oxidize and that the connections may rise in resistance, leading to increased losses over time. This issue could be largely eliminated if you were to use sheet brass, rather than sheet aluminum, for the stator plates. You could then flux and solder the rods, nuts, and plates together (before installing the acrylic endplates, of course :-) and ensure a solid, reliable, low-resistance current path. In the real world, most non-miniature variable capacitors were made with spacers and plates that weren't soldered all together, and generally didn't use star washers or anything except at the connecting posts. But these are generally either all-brass, all-aluminum, all- steel, etc., and not a mismash of different materials. You don't explicitly say so, Dave, but are you implying that it's the dissimilar materials that are the problem, or that it's the use of aluminum? My personal taste would be to make it out of all-brass. After the 50's, for the miniature variable capacitors, they seem to be made out of material that has been silver-soldered together without any explicit spacer components. (Maybe brazed or spot-welded, in some cases.) This seems to be either an improvement made for VHF/UHF work (remember when 50MHz was UHF?) or an admission that using spacers doesn't make economic sense when components are so tiny. Tim. |
Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
In article ,
Tim Shoppa wrote: In the real world, most non-miniature variable capacitors were made with spacers and plates that weren't soldered all together, and generally didn't use star washers or anything except at the connecting posts. But these are generally either all-brass, all-aluminum, all- steel, etc., and not a mismash of different materials. You don't explicitly say so, Dave, but are you implying that it's the dissimilar materials that are the problem, or that it's the use of aluminum? It's a combination of both, I think. A cap of this sort would work quite nicely indeed if it were made out of aluminum, and welded together. I believe that such capacitors are available even today (perhaps on special order). Aluminum's conductivity is certainly high enough, and the thin layer of aluminum oxide on the surface would have no effect on the cap's usability. The biggest problem with a hybrid aluminum/brass capacitor is that it's hard to get a reliable, low-resistance bond between the two metals. It's certainly not impossible - there are some fluxes and solders which can bond to aluminum - but it's not necessarily easy for the hobbyist to make this work reliably. Non-welded aluminum air-variable capacitors seem to work find in most applications... but in most applications, the currents flowing through the cap are relatively low, the circuit impedances are relatively high, and thus the resistive losses in the plate/spacer connections are negligible. In magloop transmitting antennas, the radiation resistance is small (often just a fraction of an ohm) and the resistive losses in the tuning capacitor can significantly effect the efficiency of the antenna. My personal taste would be to make it out of all-brass. After the 50's, for the miniature variable capacitors, they seem to be made out of material that has been silver-soldered together without any explicit spacer components. (Maybe brazed or spot-welded, in some cases.) This seems to be either an improvement made for VHF/UHF work (remember when 50MHz was UHF?) or an admission that using spacers doesn't make economic sense when components are so tiny. The highest-quality seem to use silver-plated brass, soldered or welded together. This would assure a good electrical connection, and I believe that this combination of materials and methods also helps reduce the tendency of the capacitor to drift in value as a result of temperature changes, or exhibit microphonic effects. People who build low-drift VFOs seem to favor this style of air-variable capacitor. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Where can I get aluminium foil (0.5 cm thickness) for Homebrew Butterfly Capacitor
wrote in message
... Hello, I found this very nice website with a section about Homebrew Butterfly Capacitor with many photographs. http://hps.infolink.com.br/py1ahd/gallery21.htm Does anybody knows where in UK (preferrable in Dorset or London) can I get aluminum foil, 0.5 centimeters thickness? 73's DX Marcelo LW3EOV/GB Small Parts, Inc in Florida carries Aluminum sheet, as well as K&S Engineering/Metals. Most well stock hobby stores (R/C models, model RR, etc.) will have that in stock!! w9gb |
Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
On Dec 5, 12:29 am, charlie wrote:
wrote: Hello, I found this very nice website with a section about Homebrew Butterfly Capacitor with many photographs. http://hps.infolink.com.br/py1ahd/gallery21.htm Does anybody knows where in UK (preferrable in Dorset or London) can I get aluminum foil, 0.5 centimeters thickness? 73's DX Marcelo LW3EOV/GB Marcello, Talk to Squires Models & Craft Tools, 100 London Rd, Bognor Regis, West Sussex, PO21 1DD. Tel: 01243 842424, Fax: 01243 842525 They have: Brass sheet, 4" x 10" X 0.005, 0.010, 0.015, 0.032, inches thick Copper sheet, 4" x 10" X 0.025 inches thick Aluminium sheet 4" x 10" X 0.016, 0.032, 0.064, inches thick. Sorry, I will leave you do convert to metric :) I think that you will find this kind of material at any decent model shop. Rapid Electronics,www.rapidonline.com, has aluminium sheet 0.5m x 0.5m x 0.8mm & 1.2mm, also 0.1mm brass sheet x A4 or A3. Charlie. -- M0WYMwww.radiowymsey.org- Hide quoted text - - Show quoted text - Rough and ready. One inch is 'about' 25mm? So 0.5 mm = 1/50th of inch? Which = 0.02 inches? That correct? So 0.016" would be close???????????? |
Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
Here in the USA, 0.020" aluminum is a standard thickness.
http://www.aircraftspruce.com/catalo...eet_2024t3.php Scott http://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version) terry wrote: Rough and ready. One inch is 'about' 25mm? So 0.5 mm = 1/50th of inch? Which = 0.02 inches? That correct? So 0.016" would be close???????????? -- |
Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
On Dec 10, 6:58 am, Scott wrote:
Here in the USA, 0.020" aluminum is a standard thickness. http://www.aircraftspruce.com/catalo...eet_2024t3.php Scotthttp://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version) terry wrote: Rough and ready. One inch is 'about' 25mm? So 0.5 mm = 1/50th of inch? Which = 0.02 inches? That correct? So 0.016" would be close???????????? -- Uuuh, I thought the OP said .5 CM, not MM... Slight difference by X10 denny |
Where can I get aluminium foil (0.5 cm thickness) for Homebrew Butterfly Capacitor
On Mon, 10 Dec 2007 05:16:28 -0800 (PST), Denny wrote:
On Dec 10, 6:58 am, Scott wrote: Here in the USA, 0.020" aluminum is a standard thickness. http://www.aircraftspruce.com/catalo...eet_2024t3.php Scotthttp://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version) terry wrote: Rough and ready. One inch is 'about' 25mm? So 0.5 mm = 1/50th of inch? Which = 0.02 inches? That correct? So 0.016" would be close???????????? Uuuh, I thought the OP said .5 CM, not MM... Slight difference by X10 Uuuh, if you had been reading _all_ the thread. |
Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
In article , Denny wrote: Uuuh, I thought the OP said .5 CM, not MM... Slight difference by X10 He did say .5 cm. So did the web page he was citing. It's pretty clear from looking at the picture of the capacitor that .5 cm is out of the question, and must be a typo on the original web page, while 0.5 mm is quite reasonable for a capacitor of that construction and size. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
The post has been out there a while and we all assume it's a typo (I've
never seen the original poster reply about that) but 1/2 a centimeter would make HUGE plates...1/2 a mm sounds MUCH more realistic... Scott Denny wrote: On Dec 10, 6:58 am, Scott wrote: Here in the USA, 0.020" aluminum is a standard thickness. http://www.aircraftspruce.com/catalo...eet_2024t3.php Scotthttp://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version) terry wrote: Rough and ready. One inch is 'about' 25mm? So 0.5 mm = 1/50th of inch? Which = 0.02 inches? That correct? So 0.016" would be close???????????? -- Uuuh, I thought the OP said .5 CM, not MM... Slight difference by X10 denny -- Scott http://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version) |
Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
On Dec 10, 6:25 pm, Scott wrote:
The post has been out there a while and we all assume it's a typo (I've never seen the original poster reply about that) but 1/2 a centimeter would make HUGE plates...1/2 a mm sounds MUCH more realistic... Scott Denny wrote: On Dec 10, 6:58 am, Scott wrote: Here in the USA, 0.020" aluminum is a standard thickness. http://www.aircraftspruce.com/catalo...eet_2024t3.php Scotthttp://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version) terry wrote: Rough and ready. One inch is 'about' 25mm? So 0.5 mm = 1/50th of inch? Which = 0.02 inches? That correct? So 0.016" would be close???????????? -- Uuuh, I thought the OP said .5 CM, not MM... Slight difference by X10 denny -- Scotthttp://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version)- Hide quoted text - - Show quoted text - Ahhhh jeez, there you go again - wanting reality! And on usenet to boot... denny / k8do |
Where can I get aluminium foil (0.5 cm thickness) for HomebrewButterfly Capacitor
Who, me? ;)
Scott N0EDV Denny wrote: On Dec 10, 6:25 pm, Scott wrote: The post has been out there a while and we all assume it's a typo (I've never seen the original poster reply about that) but 1/2 a centimeter would make HUGE plates...1/2 a mm sounds MUCH more realistic... Scott Denny wrote: Ahhhh jeez, there you go again - wanting reality! And on usenet to boot... denny / k8do -- Scott http://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version) |
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