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First 30 Meter Antenna

first 30 meter antenna

My first 30 meter antenna is up and running.

30 meters is one of the lesser used ham bands, mainly because it is restricted to digital modes – no voice. Half of the band is used for Morse Code communications, the other half for computer-based digital signals. The frequency allocated to 30 meters is 10.10 to 10.15 MHz – a relatively small slice.

So, I leaned my new magnetic loop antenna against the lilac bush beside my house and gave it a try. My first contact on my first 30 meter antenna was with Gerry W0GV near Denver, Colorado. I used low power – 10 watts and my Morse Code was a bit rusty. But it worked. Nice to know I can communicate 1,000 miles with less power than a small light bulb using a piece of copper stuck in a lilac bush. Smile

First 30 meter antenna – a work in progress

Several changes were made to my magnetic loop antenna after yesterday’s tests. In order to get better frequency coverage with the loop, I reduced the spacing between the butterfly capacitor plates. This increased the variable capacitance to range between 10-60 pF, which let me tune the loop to 30 meters without difficulty. Next, I replaced the feed with a simple loop of wire and some proper mounting brackets.

The picture above shows the modified butterfly capacitor on the top left, and the new feed loop on the bottom left. Then, I tuned the loop to 10.109 MHz by hand adjusting the capacitor. The loop tuned up nicely, as shown in the graph at the top right. The magnetic loop is a very narrowband antenna – whenever you change frequency by any appreciable amount, you need to retune.

Finally, I hooked the antenna up to my radio. Low and behold, you can see (and I can hear) a bunch of signals from my first 30 meter antenna on the radio spectrum display, lower right.

Now that I know my proof of concept works, it’s time to get on with finishing the motorized control for the butterfly capacitor. In addition to the remote control, I need the reduction gearing to properly move the capacitor. It is very touchy to tune by hand – and at ten feet in the air, difficult to reach!

3 comments

  1. Randy Hollingsworth - K0FA says:

    John – Have you determined the max power that you can use with this antenna? A good friend and fellow ham just moved to a neighborhood that tightly restricts outdoor antennas and he is looking for alternatives to the vertical he used at the old house. I thought this might be a viable option for him.

    Randy – K0FA

    • John VE6EY says:

      Hi Randy. Depends on the spacing of the plates in the capacitor and the ability to handle the 4KV or so that builds up. There are various calculators online that can guide you through this. I built a second capacitor with wider spacing that easily handled 100 watts. If he is going to run a linear, probably needs a vacuum variable. Cheers.

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