OT - Source for Air Variable Capacitors
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OT - Source for Air Variable Capacitors
 
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With the tutelage of a friend I am putting together a mag loop but have had no luck finding a source of air variable capacitors up to the task. Vacuum variables aren’t hard to find, but the $200 and up price tag is offputting. I have seen a couple of AVCs on E-bay that looked pretty ratty; and the commercial types for sale new look like low-power trimmers. Anyone know of a source -- or even have any they’d sell? Specifically I would like a range of 6 to 120 pf or more, butterfly or split stator, with plate spacing sufficient to take a kilovolt of RF. And ideally with reduction gear tuning though that’s optional.
Thanks for any info anyone can provide . . . Ted, KN1CBR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: OT - Source for Air Variable Capacitors
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I bought a Cardwell 500PF 3.5KV on eBay last year. As a bonus I discovered
that it had a reduction drive when I opened the box. :) Not sure if it fits your requirements - it's pretty ratty looking, and was obviously pulled from some electronic equipment. I sort of resigned myself to needing to 'spiff it up'. Keep your eyes open on eBay, that's the best advice I can offer. On Sat, Jun 16, 2018 at 8:05 PM Dauer, Edward <[hidden email]> wrote: > With the tutelage of a friend I am putting together a mag loop but have > had no luck finding a source of air variable capacitors up to the task. > Vacuum variables aren’t hard to find, but the $200 and up price tag is > offputting. I have seen a couple of AVCs on E-bay that looked pretty > ratty; and the commercial types for sale new look like low-power trimmers. > Anyone know of a source -- or even have any they’d sell? Specifically I > would like a range of 6 to 120 pf or more, butterfly or split stator, with > plate spacing sufficient to take a kilovolt of RF. And ideally with > reduction gear tuning though that’s optional. > > Thanks for any info anyone can provide . . . > > Ted, KN1CBR > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] -- 72, Rich Hurd / WC3T / DMR: 3142737 PA Army MARS, Northampton County RACES, EPA-ARRL Public Information Officer for Scouting Latitude: 40.761621 Longitude: -75.288988 (40°45.68' N 75°17.33' W) Grid: *FN20is* ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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I searched far and wide for high voltage air variables a year or so ago
for a tuner. I needed some quite specific values rated up to about 1 kV. The only place I could find them was Surplus Sales of Nebraska. They weren't cheap. 73, Scott K9MA On 6/16/2018 20:30, rich hurd WC3T wrote: > I bought a Cardwell 500PF 3.5KV on eBay last year. As a bonus I discovered > that it had a reduction drive when I opened the box. :) > > Not sure if it fits your requirements - it's pretty ratty looking, and was > obviously pulled from some electronic equipment. I sort of resigned > myself to needing to 'spiff it up'. > > Keep your eyes open on eBay, that's the best advice I can offer. > > On Sat, Jun 16, 2018 at 8:05 PM Dauer, Edward <[hidden email]> wrote: > >> With the tutelage of a friend I am putting together a mag loop but have >> had no luck finding a source of air variable capacitors up to the task. >> Vacuum variables aren’t hard to find, but the $200 and up price tag is >> offputting. I have seen a couple of AVCs on E-bay that looked pretty >> ratty; and the commercial types for sale new look like low-power trimmers. >> Anyone know of a source -- or even have any they’d sell? Specifically I >> would like a range of 6 to 120 pf or more, butterfly or split stator, with >> plate spacing sufficient to take a kilovolt of RF. And ideally with >> reduction gear tuning though that’s optional. >> >> Thanks for any info anyone can provide . . . >> >> Ted, KN1CBR >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > > -- Scott K9MA [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Edward A. Dauer
Actually, MFJ has lots of air variables, but they're not easy to find on
their web site. Search on "air capacitors". 73, Scott K9MA On 6/16/2018 21:33, Walter Underwood wrote: > MFJ sells butterfly capacitors. They are rated at 1.5 kV. > > 12-67 pF http://www.mfjenterprises.com/Product.php?productid=MFJ-19 > > 18-136 pF https://www.mfjenterprises.com/Product.php?productid=MFJ-23 > > wunder > K6WRU > Walter Underwood > CM87wj > http://observer.wunderwood.org/ (my blog) > >> On Jun 16, 2018, at 5:05 PM, Dauer, Edward <[hidden email]> wrote: >> >> With the tutelage of a friend I am putting together a mag loop but have had no luck finding a source of air variable capacitors up to the task. Vacuum variables aren’t hard to find, but the $200 and up price tag is offputting. I have seen a couple of AVCs on E-bay that looked pretty ratty; and the commercial types for sale new look like low-power trimmers. Anyone know of a source -- or even have any they’d sell? Specifically I would like a range of 6 to 120 pf or more, butterfly or split stator, with plate spacing sufficient to take a kilovolt of RF. And ideally with reduction gear tuning though that’s optional. >> >> Thanks for any info anyone can provide . . . >> >> Ted, KN1CBR >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] -- Scott K9MA [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: OT - Source for Air Variable Capacitors
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In reply to this post by K9MA
These look interesting & $38 incl shipping. I'd be inclined to check this out before MFJ..
https://m.ebay.com/itm/High-Voltage-Air-Variable-Capacitors-20-95pF-Amplifier-Tuner-REPAIR-DIY-/161247381436 73 Josh W6XU Sent from my mobile device > On Jun 16, 2018, at 7:34 PM, K9MA <[hidden email]> wrote: > > I searched far and wide for high voltage air variables a year or so ago for a tuner. I needed some quite specific values rated up to about 1 kV. The only place I could find them was Surplus Sales of Nebraska. They weren't cheap. > > 73, > Scott K9MA > > >> On 6/16/2018 20:30, rich hurd WC3T wrote: >> I bought a Cardwell 500PF 3.5KV on eBay last year. As a bonus I discovered >> that it had a reduction drive when I opened the box. :) >> >> Not sure if it fits your requirements - it's pretty ratty looking, and was >> obviously pulled from some electronic equipment. I sort of resigned >> myself to needing to 'spiff it up'. >> >> Keep your eyes open on eBay, that's the best advice I can offer. >> >>> On Sat, Jun 16, 2018 at 8:05 PM Dauer, Edward <[hidden email]> wrote: >>> >>> With the tutelage of a friend I am putting together a mag loop but have >>> had no luck finding a source of air variable capacitors up to the task. >>> Vacuum variables aren’t hard to find, but the $200 and up price tag is >>> offputting. I have seen a couple of AVCs on E-bay that looked pretty >>> ratty; and the commercial types for sale new look like low-power trimmers. >>> Anyone know of a source -- or even have any they’d sell? Specifically I >>> would like a range of 6 to 120 pf or more, butterfly or split stator, with >>> plate spacing sufficient to take a kilovolt of RF. And ideally with >>> reduction gear tuning though that’s optional. >>> >>> Thanks for any info anyone can provide . . . >>> >>> Ted, KN1CBR >>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[hidden email] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to [hidden email] > > -- > Scott K9MA > > [hidden email] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Edward A. Dauer
I believe Palstar sells their air variable capacitors.
Dale, K9VUJ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
OT - Source for Air Variable Capacitors
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In reply to this post by Edward A. Dauer
If you are making a home-brew loop why not make the capacitor too? My loop works fine at 100 W input but not yet tested at 500 W. I borrowed the capacitor design concept but the implementation details are mine. Capacitor components are hardware store copper pipe, copper pipe couplers, and PEX tube.
http://www.w7tbc.org/downloads.php?do=file&id=369 73, Andy k3wyc ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
OT - Source for Air Variable Capacitors
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In reply to this post by Edward A. Dauer
Many thanks to all who replied, both on-list and off. Apparently these things are available even if I couldn't find them. I guess I need to improve my research skills, and maybe make more visits to hamfest flea markets. In any case, once again the group on this reflector came through. My thanks. 73 all, Ted, KN1CBR ------------------------------ Message: 14 Date: Sat, 16 Jun 2018 23:57:06 -0700 From: Walter Underwood <[hidden email]> To: Elecraft Reflector <[hidden email]> Subject: Re: [Elecraft] OT - Source for Air Variable Capacitors Message-ID: <[hidden email]> Content-Type: text/plain; charset=utf-8 For a magnetic loop, the contact resistance of the wipers on typical air variable capacitors causes big losses. That is why he?s specifically looking for vacuum, butterfly, or split stator variable capacitors. The MFJ butterfly capacitors are reasonably priced, at $70 and $90. MFJ uses them in the mag loop tuners they sell. wunder K6WRU Walter Underwood CM87wj http://observer.wunderwood.org/ (my blog) ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by ANDY DURBIN
There is a Canadian Ham on the magnetic loop list who makes first class
butterfly caps(you assemble) less than $100 to my home. Leroy AB7CE -----Original Message----- From: ANDY DURBIN Sent: Sunday, June 17, 2018 11:02 AM To: [hidden email] Subject: [Elecraft] OT - Source for Air Variable Capacitors If you are making a home-brew loop why not make the capacitor too? My loop works fine at 100 W input but not yet tested at 500 W. I borrowed the capacitor design concept but the implementation details are mine. Capacitor components are hardware store copper pipe, copper pipe couplers, and PEX tube. http://www.w7tbc.org/downloads.php?do=file&id=369 73, Andy k3wyc ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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