[TenTec] Balanced Tuners

[Carter Grabarczyk]

Dave Marling wrote:

> It feeds about fifty feet of balanced line to a 950' horizontal loop.  
> Driven by a Jupiter into a Dentron Cliperton L.
> 
> Note the insulated shaft to the knob in the second picture.
> 
> After building and installing this about a year ago my problems with rf 
> into the computer and alarm system disappeared.
> The previous setup used RG8 to a balun at the feedpoint.


Dave,

A beautiful job....thanks for sharing the pictures with us. However, a 
couple of questions:

Did you test the central vac pipe in a microwave oven to make sure it's 
not the kind of plastic pipe that heats up in the presence of RF?

For those of us that don't have access to the 1990 article, what is the 
value of the variable cap and its voltage rating? How is it connected?

Any idea if the inductance values presented will work for a 130 foot 
ladder line fed dipole rather than your 950 ft loop?

Finally, if I do use it with my dipole, it is a given that due to the 
limitations of the real world, the dipole is *not* electrically 
symmetrical. Therefore, when you tune this, do you just go by being on 
the same tap for each coil, or do you tune for equal current in each leg 
(conceivably resulting in being on different taps on each coil)?

Thanks, and again, a very nice job!

73/Carter/K8VT