"Jim Shorney" <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- On Sun, 11 Dec 2005 15:36:01 -0500, [EMAIL PROTECTED] wrote:
>I can see the MFJ method as a possibility. The 5 Ohm load provide purely >resistive load at a fixed value. The meter relies on a 5 Ohm load. >The method described in the magazine article, utilizing a GDO is not >impedance dependent. I think the 50 ohm resistor in series is to allow calculating the velocity factor of lines that are other than 50 ohm characteristuc impedance. With a 1/4 wave open line, the "dip" would appear at 50 ohms on the analyser. If the line is 50 ohms, the resistor can be elimintated and the dip will be at 0 ohms. This worked for my 144.39 stub filter. Actually, I'm still not at all sure that the series resistor is needed at all. An open line, regardless of it's impedance, will reflect a short at it's 1/4 wave resonant frequency. 0 ohms is 0 ohms, regardless of the source impedance of whatever is feeding it. Maybe someone with more education than I am can enlighten me. -- Jim Shorney -->.<--Put complaints in this box jshorney (at) inebraska.com Ham Radio NU0C Lincoln, NE, USA EN10ps http://incolor.inetnebr.com/jshorney/ ---------------------------------------------------------------------- Submissions: drakelist@www.zerobeat.net Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net ----------------------------------------------------------------------
