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Re: [Amps] Link coupling

To: G3rzp@aol.com
Subject: Re: [Amps] Link coupling
From: R.Measures <r@somis.org>
Date: Sun, 9 Jan 2005 01:48:46 -0800
List-post: <mailto:amps@contesting.com>

On Jan 9, 2005, at 12:04 AM, G3rzp@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


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