Yes, the stator-stator 15-120pF range applies to the mag loop
butterfly configuration. stator-stator is equivalent to 2 stator-rotor
capacitances (20-250pF) in series, approximately.
Bob NW8L
On Mon, 18 Jun 2018, Walter Underwood wrote:
Here is a link to a butterfly capacitor at Radiohaus,
Here is a link to a butterfly capacitor at Radiohaus, without the eBay
middleman.
http://www.radiohausamerica.com/produto.php?prod=1703
It looks nice, but I’m not sure I understand what they mean by the three
different capacitance ranges. The normal mag loop configuration would be to
connect
I just bought one on eBay from "Radiohaus". It is beautiful, high quality, ball
bearings, it spins freely so the torque requirements for a stepping motor are
almost non-existant.
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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: elecraft@mailman.qth.net
Subject: [Elecraft] OT - Source for Air
. My thanks.
73 all,
Ted, KN1CBR
--
Message: 14
Date: Sat, 16 Jun 2018 23:57:06 -0700
From: Walter Underwood
To: Elecraft Reflector
Subject: Re: [Elecraft] OT - Source for Air Variable Capacitors
Message-ID: <506d8e2a-6eb9-4
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
I believe Palstar sells their air variable capacitors.
Dale, K9VUJ
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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
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 wrote:
>
> I
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
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
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,
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
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;
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