My last post was in January this year. It’s August now. Lots of things have changed around here.
First of all i changed QTH. I now live in a place where i can mount a larger antenna IF I WANTED TO. In fact, if i wanted to get back into some serious radio i WILL have to build a new antenna because my previous antenna got lost in the move. But do i want to? This i will explain later.
Then i changed job. Where before i was working from home and never left the house, read: lots of time for radio, now i have to travel every week. So when i am at home i want to be with the family, work on the garden, the pool, the BBQ and not lock myself up in my office again to do some radio.
Then, and that’s the most important at the moment, the sun has gone really quiet lately. I know the cycle is going down, but i didn’t expect it to go down this dramatically. This was a very short and very unpredictable sun cycle. So to spend money on a tower and an antenna when there is hardly anything to listen to, no. That’s not the plan.
Let’s see. For the moment i just let my SDR create some daily heatmaps and maybe at some point, when the winter comes and conditions pick up again, i will decide to build or buy something.
A second heatmap server has been installed. This time i used a leftover Raspberry Pi and a RTL-SDR adapter. This one is going to cover everything from 24MHz to 1.7GHz. At least, that’s what i understand the RTL adapter can handle.
As you know, antennas are a critical part of any HAM radio setup. Where i live we are not allowed to build any decent size antenna because of the view. Yes, they are that picky here. So i’m always struggling and fiddling with either mobile antennas or wire antennas.
This time i built a wire dipole out of scrap material i had lying around.This antenna is very wide banded and is useful on any band between 40 and 6 meters. Here is what i did:
First the feed line.
I took a bunch of normal loudspeaker twin-wire and connected one end to my MFJ 941-E antenna tuner. This tuner has connections for ladder lines and has a 4:1 balun integrated. My speaker wire is my ladder line with very little spacing between the elements.
At the end of the feed line i connected a choke balun (thanks, Mark PA5MW for winding and sending it) and created two hookup “eye” pieces to clip the radials in. These “eye” pieces are just a piece of wire in the form of a circle which i completely soldered to give it structure.
As you can see i hooked everything up with regular connector block electricians use.
On my terrace i fixed two hooks on the outside wall to fix the end of the radials. The radials themselves are the same speaker wire i used for the feed line.
Of course there are two issues i have to deal with. One it isolation of the radials from ground. That’s why the tie-wrap is there.
The other issue i wanted to deal with is the tensioning of the radials so they remain sort of straight. I used simple springs to hook up the wires. Now i am able to define the tension with the tie-wrap without having to change the length of the radials and therefor changing the resonance frequency.
The other end of the radial created a sort of “hook” so i can clip the wires into the “eyes”
So this is what the antenna looks like now. The center under the gutter, the radials spread out to the farthest points of the terrace wall.
SWR of the antenna is 3:1 on 8 MHz, 1,1:1 on 11.500 MHz, 1,5:1 on 18,400 MHz and 1:1 on 27,555 MHz. That, BTW, is just a coincidence…
I don’t know how effective the antenna is, but i have made contacts on 20, 17, 15, 12 and 10m with stations inside and outside of Europe, so for me this antenna works. Sort of.