[Amps] Line Isolators for RF feedback

[R.Measures]

On Aug 11, 2004, at 7:17 AM, Harold B. Mandel wrote:

> Dear Peter,
>
>
> Some fourteen years ago, Rich Measures wrote an article that appeared 
> in
> QST magazine called A BALANCED BALANCED ANTENNA TUNER.
>
> This design firstly moves the balun to the input of the impedance 
> transformer
> network and then incorporates two separate but symmetrical variable
> inductors
> to operate on both halves of the open-wire feed line arrangement.
>
> In applying Mr. Measures' design

He unabashedly stole the idea of the balanced-L network from Bell Labs 
research done in the 1930s.

> to my shack the first problem
> encountered was the QRO-O and the fact that mostly RTTY is favored 
> (with attendant
> long-winded periods of transmission).  The balun coil to provide the
> balanced 50-ohm feed to the impedance transformer needed to be made of
> 10AWG silver-teflon, closely wound on a PVC core.
>
#10 silver-TFE would probably handle 10kW 24/7.  For most of us, 
RG-213/u will do.

cheerz, Hal

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org