Saturday, July 9, 2011

An exceptional little 10m attic dipole

I had no plans this Saturday morning so instead of lying around in bed I decided to get going early. I was glad of the opportunity to get on the radio firstly, especially as I was able to nab JX5O on a further four band slots, bringing my total to five band slots since yesterday. Great stuff.

My homebrew dipole centre with the dipole legs attached
For a long time now, in fact for at least a decade, I have had some sort of short wave radio at the bedside with a random wire flung up in a very haphazard fashion around the attic. Before I was licenced I used to enjoy listening to HF aeronautical and the amateur bands and at times I heard the Auckland volmet in New Zealand early in the mornings. Just shows what a piece of wire can do!

To take this further I decided to (finally, after months of thinking about it) construct an attic dipole. All I have space for is a 10m dipole, and in fact barely just!! But nevertheless I wanted to have something that I could actually use to TX on from the bedroom shack (shack B as I call it) if needed.

I found a black circular piece of plastic (see photo) which has been lying in the shed for years. I cannot even remember what it belonged to, but I have a tendency to keep apparently useless items lying around the place, as my good XYL will attest to LOL!!!

Anyway I measured out two legs of wire 8 feet and approx 2.5 inches long. That's 2.503 metres for those metric fanatics among you! I am still an imperial man. And I love miles, not kilometres! Anyway, I digress.

I strung the dipole up in extremely cramped and warm conditions. I was sweating buckets. It's a very warm muggy day here in EI land. I then ran coax up from the bedroom into the attic and took some time connecting it to my homebrew dipole centre. After all that was done it was time to connect the antenna to my old Icom IC-735 which I use as a listening rig in Shack B. It seemed to be hearing well. But it does not transmit well for some reason.

So I nabbed the FT-897 from Shack A and also my MFJ 941E manual tuner and brought them upstairs and hooked them up to the "attic dipole". There are other metallic objects in the attic so the SWR doesn't quite sit down on 28.500 Mhz which is where I intended it to be resonant. But, to my delight, with the manual tuner I was able to tune it flat on the SSB portion and the CW portion of 10m. Not only that, but it also tunes quite flat on 12m, 15m, 17m and even 20m! Although how efficient it will be on 20m remains to be seen. It even tuned nicely on 6m. Yes!!

10m and 12m were pretty dead so I decided to try to nab a few contacts on 15m. I didn't have to try very hard. The IARU contest is on and there were some strong stations. Using just 50 watts into my attic dipole, I managed to nab the following in a short space of time: EF8HQ Canary Islands, LS1D Argentina, N4AF North America, VE2EJ Canada and ST2AR Sudan. Most of those took just one or two calls, but I was trying for a while for Sudan. So the antenna is certainly working. And doing well on 15m which it is less efficient on. I will let you know what it's like on 28 Mhz when 10m opens, and also I will give it a run on 6m.


  1. Nice idea Anthony. My XYL would never allow the bedroom to be the 2nd HAM shack. Actually, she just barely allows 1 shack in the house ;-).
    Nice catches on the attic dipole. 73, Bas

  2. Bas, I am lucky because I have always had a radio in "Shack B". It's as much for listening as anything but now at least if I hear something late at night I can work them. Maybe only on CW with the headphones on though, HI HI !!!


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