[Amps] Link coupling

[R.Measures]

On Jan 9, 2005, at 12:04 AM, G3rzp at aol.com wrote:

> The problem with the fixed link and varying secondary turns is that 
> you  need
> the secondary impedance to vary. There's some compensation in that as 
> the
> number of secondary turns drops, the leakage reactance tends to 
> increase.
>
> The problem with all of these tuners is that it's quite hard to 
> control the
> working Q value. Too high a working Q pushes up the losses. Double the 
> working
>  Q, all other things being equal, and you double the circulating 
> current,
> pushing  the losses up by 4 times. Swinging links work by varying the 
> leakage
> reactance,  so you get a wide range of secondary impedances with 
> hopefully, a
> controllable  Q.
>
> One thing I don't like about the Matchbox, and that is the lack of a DC
> ground on the antenna for bleeding static away.

The trouble with a direct ground on a balanced feedline is increased 
risk of sudden discharge -- as in "big-bang".  To reduce this risk, 
slowly bleed down the static charge with  a 1-10 M-ohm HV-type resistor 
from each side of the feedline to ground.
>
> ...

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