View Full Version : Figured I'd try my hand at antenna building...

04-29-2013, 04:19 PM
And what better to start with than a 1/4 wave center loaded large coil?

http://i292.photobucket.com/albums/mm9/anickode/20130429_173158_zps34f781ef.jpg (http://s292.photobucket.com/user/anickode/media/20130429_173158_zps34f781ef.jpg.html)

The overall length is 58", and the overall element length is 54. The coil is 5 turns, 3.75" dia by 3.75" long. Hope my math came out right. The insulator is 3/4" SCH80 pvc, with 1/2" NPT threads tapped into the ends. The bottom of the coil is soldered into a 3/8" hole drilled in the side of the threaded adapter. The top of the coil is soldered into a 3/8" hole drilled into the side of a 1/2" NPT to 5/8"OD compression fitting (1/2" copper pipe is 5/8" OD). After the coil was soldered in place, I ran a 5/8" drill bit though the compression fitting, cutting the stub of copper from the coil off flush with the inside of the fitting, and removing the stop lip inside the fitting, allowing the top half of the antenna to slide freely in and out up to 4 inches for tuning purposes.

Guess we'll see if it works. If not, at least it looks cool.

High Voltage Mobile NJ
04-29-2013, 05:29 PM
very nice , I like it . how heavy is it ? :rockon:

04-29-2013, 05:57 PM
I'd estimate maybe 3 lbs... Very light, all type m Copper tube.

04-29-2013, 09:42 PM
looks to have potential :)

how did you do the threads to allow it to screw into a typical 3/8x24 mount ?

Silverado 996
05-04-2013, 06:35 PM
Have you tried it yet? It looks great!

Super Slab
05-06-2013, 08:50 PM
I like new toys...give me a price after you test it out and build some more

05-11-2013, 08:29 AM
Well, I tried it out, and it seems to work nicely. The compression fitting tuning works like a charm, but you have to make sure not to snug it too tight, or the ferrule will be crimped down on the copper, making it immovable.

My house is in a lousy spot for transmitting from. It sits at the very bottom of the lowest spot within probably 10 miles of here, and I'm not allowed to put up a tower, so I threw together a quick tripod, stuck it on my roof, stretched out 4 102" ground radials, and had a go. I managed to get it down to 1.2 SWR with minimal effort. Probably could get it lower, but I was tired of climbing up and down.

With 4 watts, I was able to make contact with a friend of mine 27 miles due north. He said my signal was faint, but audible. I could hear him loud and clear, as he's pushing 300 watts through an Antron 99 on a 30 foot mast.

The design could definitely use some refinement. The biggest issue I have is putting together the top end of the insulator, because I'm currently required to thread the compression fitting in, and then solder the coil into the side. I'm thinking the best solution is either a slip fit, instead of threaded, or a bolt-on coil, instead of permanently fixed.

Silverado 996
05-11-2013, 09:40 AM
Awesome! Thanks for the report. How long did it take to fabricate the antenna? How much will you be charging if someone would like one? How much would you charge if you made one with a shaft length that measured 30" from the bottom of the coil to base / mount and an overall length of 5' to 6' with the stinger? I'm running a 2 pill amp, do you think it will handle it? Have you done a test with linears yet?



How much $$$.$$ do you have tied up in this project in materials??

Moonchild 747
05-20-2013, 09:54 PM
Nice antenna...Great Job on the build...