Originally posted by iamnothere
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Trial Runs for Comparison of FRANKLIN SPIDER (With Impedance Matching added), Spider, and Franklin Spider.
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This is my 2nd quarter wave antenna with 8 legs, new build have not install yet , first one is on duty .
IMG_5535.jpg
Another antenna I made month ago , it prove my solder skill pretty bad .
IMG_5463.jpg
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Originally posted by AzKo View PostI made also this Franklin Spider antenna today. Lets see how it performs. And thanks abcd567 at good antenna tips
Today I have tried two tweaks in values of the two parameters of impedance matching as below:
(1) Soldered a third 1 pF Capacitor in parallel with existing two, increasing the total value of Capacitor from 2 pF to 3 pF
(2) Tried two different lengths of transmission line between the Antenna & the Capacitor. Original was 210 mm (including length of connectors at both ends). I made two more, one 225 mm (including length of connectors at both ends), other 240 mm (including length of connectors at both ends).
The combination of 3 pF Capacitor & 240 mm Transmission Line (including length of connectors at both ends) between Capacitor & Antenna resulted in Franklin Spider surpassing the performance of Spider.
Since each built of DIY antenna is slightly different, these values (240 mm / 3 pF) may not be optimum for every one, but sure will be close to optimum, provided RG6 Coax cable (with VF 0.83 to 0.85) is used as transmission line piece between Antenna & Capacitor, shown in photo in my post #2395.Last edited by abcd567; 2015-07-20, 01:29.
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I made also this Franklin Spider antenna today. Lets see how it performs. And thanks abcd567 at good antenna tips
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