Date: Wed, 30 Apr 2003 22:46:33 +0200
Message-ID: <200304302046.h3UKkXq08170@mailgate5.cinetic.de>
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From: "Hans-Albrecht Haffa" <haffaha@web.de>
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: LF Tuning meter
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Dear Jim, please send me a copy of Your pdf-file.
Hans-Albrecht DK 8 ND 


rsgb_lf_group@blacksheep.org schrieb am 29.04.03 16:43:02:
> 
> Dear LF Group,
> 
> For tuning LF antennas, I have for some time been using an oscilloscope to 
> monitor the current and voltage waveforms at the TX output. Resonance 
> occurs when V and I are in phase, and the load resistance is 50ohms when 
> V/I = 50. This is very easy to use provided a scope is to hand, but not 
> very useful if it isn't. An SWR bridge can be used, but it only indicates 
> the degree of mismatch, so tuning is still a matter of trial and error. So 
> with a mind towards future /P operations, I have built a self-contained 
> tuning meter.
> 
> The prototype has 2 meters - one indicates phase, while the other can be 
> switched between voltage and current to determine the load resistance. The 
> circuit is slightly more complex than an SWR bridge, but not by very much - 
> it uses 12 diodes, 3 toroid cores and a few other passive components. It 
> does not require an external power supply, and is usable with TX power 
> between about 20W and 1.8kW. I have written a 3 page article about it - it 
> is a pdf file of about 190k, so too big for the reflector, but I can e-mail 
> it as an attachment to those who are interested. If someone would like to 
> put it on their web site, they would be more than welcome!
> 
> Cheers, Jim Moritz
> 73 de M0BMU
> 
> 


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