Ron,
Very pretty job! Do you recall the (approx) capacitance range of the
split-stator and link capacitors? Also, your pdf file says 3" acrylic
tubing for main coil. Is it 3" or 2" ? How many turns on your 10
meter and 160 meter coil and link? (I assume the pictures show the
80-10 version.)
I'm becoming more and more convinced that a current balun either at
input or output of even a true BALANCED-L tuner will NOT insure a
balanced system, even if the ladder line and antenna are balanced
(which they seldom are). The brute fact is that, with or without a
balun, you're connecting one side of the line to ground at the rig,
making it unbalanced by construction. Current baluns will impede
common-mode current, true. That will keep RF off of the rig. But
they will not give the other benefit of a balanced system, that the
ladder line to the antenna won't radiate, or pick up noise on
receive. So your kind of tuner is very appealing. Old ideas
sometimes work. Now all you need is an electrostatic shield between
the link and the main windings, hi hi.
73,
Oliver W6ODJ
On 16 Aug 2008, at 8:21 PM, Ron D'Eau Claire wrote:
Very nice, Steve!
You can see my homebrew balanced tuner in the picture with my
listing on
www.QRZ.com/ac7ac.
The alligator clips attached to the wires above the coil are for the
antenna
feeder connections. There are two alligator clips nearer the bottom
that
short out turns as needed. The knob on the end operates a split stator
capacitor directly under the coil. The knob on the front operates the
variable in series with the link to control the coupling. That coil
actually
plugs in. It works FB from 80 through 10. I have a larger coil for 160
meters. The coil form is a 2" acrylic tube with four 1/4" tubes
glued to it
to space the turns away for easy tapping with the alligator clips.
The "case" is 1/8" hardened masonite (a pressed wood product) with a
1/2"
wood base and uses aluminum angle for the corner fittings. The top is
acrylic sheet to handle whatever RF voltages might appear between the
fittings. The variable has 1/4" plate spacing for high voltages. It
works
very well.
A PDF file with close-up photos and more details is available at
www.cobi.biz/ac7ac.pdf
Ron AC7AC
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of list1
Sent: Saturday, August 16, 2008 3:43 PM
To: [email protected]
Subject: [Elecraft] RE: balanced tuner
Hi All,
Just finished mine.
Works Well so far.
I have some pictures here:
http://www.pituch.net/Steve%27s%20Page/Radio/Link%20Coupled%20Tuner/tuner1.h
tml
or just drill down from:
http://www.pituch.net/
No documentation yet......later.
Elecraft should make it a kit... hi hi.
Steve, W2MY
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