parallel inductance

[bob85]

can i use a parallel inducter from antenna feedpoint to ground to bring the impedance of my 1/4wave tube up to 50ohms from the 39 ohms its reading now and at the same time get the lower static and lack of lf radio station breakthrough like a shuntfed base loaded antenna????? thanks

 

[Moleculo]

You'd have to figure out the right amount of inductance, but I'd say it should work. I use a coil inductor at the feedpoint in paralell to ground on my screwdriver antenna for matching. Of course, I'm doing it for 40 and 80 meters, not 11, but the principle should be the same.

 

[W5LZ]

bob85,
Can you? Sure, that's how a lot of antennas are matched to the feed line. Simplest way is to mount the coil at the base of the antenna (connected tot he antenna) and run a shorting strap to ground. Aligator clip on the end of the strap, keep tapping the coil at various points till you fine the 'right' one. It depends on the antenna though. A 102" whip is easy. An antenna with a base coil is NOT easy (best thing to do is change the tap on the internal coil of the antenna).
You can also do the same thing with a capacitor between feed pont and ground. Bit more difficult cuz you gotta have a bunch of capacitors to find the 'right' one. Tapping a coil is just easier for me (ain't got the capacitors).
Good luck...
- 'Doc

 

[FL Native]

could you explain how to do this on a 102 whip and maybe pictures if you have them ???

 

[bob85]

wind a coil say several turns on inch and half former, connect one end of this coil to the coax center connection on your antenna mount then take the other end of the coil along with a short piece of wire with a croc clip on one end and connect them to a good ground near the mount, using the croc clip to short turns on the coil to ground you should be able to get a flat vswr on an antenna whos feedpoint impedance is below 50ohms you just need to find the right place to clip the croc, once you have the right place you can cut the croc clip off and solder the wire at the right tapping point, i think thats how it goes :?: but will the signal performance be better than leaving a 102" at 1.5:1 vswr?????

 

[mrcoily]

could you explain how to do this on a 102 whip and maybe pictures if you have them ???

This should help you this is for a 102" whip you can see how it works its a blurry but it helps.matching network
this is another one both kinda the same setup should give you some ideas and get you going in the right direction.73sss Dan
bottom of 102" ball mount section and loading matching network.

 

[bob85]

ahh the dollar match from the arrl antenna handbook thats what i mean FL

 

[mrcoily]

ahh the dollar match from the arrl antenna handbook thats what i mean FL

You are correct! I thought thats what you were thinking of 73sss Gota love them digital cameras..Have a good day...DAN

 

[Moleculo]

Here's a picture of mine:

See the little red coil coming off the base? The aligator clip method is a real easy way to find the right inductance. Once you get pretty close, you can also change the inductance by changing the distance between the coils (spread them out, or squeeze them together).

Also a wound torroid is another way to do it, but I think the coil is probably the easiest.

Will your signal be any stronger than at 1.5 SWR? Nope.