The Cranky Sysadmin A world of technology, fun, and ignorant rants.

June 9, 2013

A Field Day Antenna for 80 Meters part 2

Filed under: ham radio — Cranky Sysadmin @ 2:32 pm

I’ve made some progress on my short vertical for 80 meters. I put it up in the air and added the guy wires. Some pictures and commentary are after the fold.

The Guy wires are made of that nylon “antenna cord” you can get at HRO and other places. I used a piece of 3/4 inch inner diameter pvc pipe about an inch long to keep the guy wires from sliding down. Here is a picture of the whole thing in the air at operational height (the capacitance hat is at about 29 feet). I use standard plastic tent stakes from Wallmart to secure the guy wires.

IMG_0032Below is a picture of the interconnect, and the radial system. That ring is supposed to be around the mast, but I forgot to place it before standing it up.

IMG_0031Next is a closeup of the interconnect panel. I haven’t decided on a way to weatherize it yet. It’s a simple bit of aluminum from a discarded bit of electronics.


The antenna seems to be resonant at 5.48 mhz, which is amazing to me considering the antenna is only 29 feet high. The velocity factor of the radiator wire and the capacitance hat in this case seems to add 13 feet to the antenna length assuming my calculations are right (468/5.48/2 for 1/4 wavelength).

My next step is to build a loading coil. If I want to hit 160 meters, the loading coil will be about 80 to 120 uh depending on how high I place the coil.I’ll tap it for 80 meters afterward.

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