[Elecraft] RE: balanced tuner

[O. Johns]

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: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of list1
> Sent: Saturday, August 16, 2008 3:43 PM
> To: elecraft at mailman.qth.net
> 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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