Doublet – Straight and simple

Even though I partly disassembled my horizontal loop antenna before I left for Germany in January, the wind and the trees had ripped it into three parts. One of the three parts fit exactly between two trees and was used for a 2 x 13m doublet. Fed with a ladder line and tuned to resonance at 50 Ohm with the S-match it should keep me radio-active until I have thought out new and hopefully more efficient antennas.

I tested my new antenna during a few hours of operation during Saturday and Sunday in the IARU HF Championship. In total I made 328 contacts with low power and mixed mode. It turned out that the doublet could not be tuned good on 80 meters. I need a larger coil on the S-match, or a longer antenna. But there were also problems on 15 meters with HF in the shack. I have some ideas but need to think and make some research to figure out if it is the right solution.


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Slack loop

Something has happened with my horizontal loop antenna.  Instead of being straight at 8 meters over ground at its lowest point it is slacking 3 meters over ground.


A close look at the above image reveals the slacking loop wire reflecting the evening sun.

During my inspection walk along the loop I noticed a slacking wire all the way around, but the suspension ropes were all looking good.

As I tried pulling the suspension rope going up the birch tree to the highest point about 20 meters above ground it was was solid stuck. Pulling hard resulted in a little more than 3 meters of rope loosening and after thst the rope was again completely stuck, not going up, not going down. Pulling the suspension rope did not result in any movement at all in the antenna wire.

The foliage makes it difficult to see what has happened.  My guess is that the wind moved the birch so that somehow the suspension rope has left its original position and got tangled up a few meters lower in the tree top.


Somewhere up there hidden in the green is the answer. The antenna is still very functional, but with an aesthetic challenge. I need to fix this eye sore, let’s hope that I don’t have to wait for the winter and the leafs to fall before I can see how to solve  it.

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8S7GL Garpen 2013


The weekend of great radio fun is over, back to everyday-life and reality. A big thank you to SM7PXS and SM7XWM for good company and making the weekend so fun and relaxing.

Also a big thank you to SM7PIK and the other members of ‘Garpens vänner‘, the non-profit association keeping the old lighthouse and the buildings on Garpen Island open to the public. Without their dedication and positive attitude towards us radio amateurs this operation would not have been possible.

The radio operations went well, conditions on Saturday could have been better. Friday night and Sunday offered fair to normal propagation. An estimated QSO count of around 900 and all continents from ILLW SE0004 and IOTA EU-037. Within about a week there will be a summary on the 8S7GL blog.

From the QSO’s I worked during the weekend I would like to mention three: ZL3XDJ on 80m CW, 8S0GL on 80m SSB, and LA9IAA on 80m CW.

ZL3XDJ was the best DX for me. I could barely copy Brian as his signal was doing the QSB dance on the noise floor. But to my joy and surprise I was able to reach him through the pile-up and we were able to have a QSO. Brian proved good sport not giving up on the first partially received GL from our call when other stations with and without G in the suffix also were responding to his ‘GL?’-call. After exchanging report and names I thanked him and ended the QSO, the signal level on my side was not good enough to continue. Five minutes later I could no longer hear Brian’s signals. I hope to hear Brian again from home and have a longer QSO on my loop antenna.

8S0GL, another ILLW expedition, was fun to work since I almost talked with myself. 8S7GL op Ronny (SM7RRF) in QSO with 8S0GL op Ronny (SM0XMX). Ronny is not a very common name in Sweden and we were both amused and confused trying to keep the call signs straight.

It is always a pleasure to work QRP stations. LA9IAA Björn was operating with 1/2 Watt and under slight QSB we were able to perform a QSO. This QSO reminded me that I use my SW30+ 1 Watt kit far too seldom. QRP brings the best of operating skills and stubbornness.

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The coming weekend 16th to 18th of August I am looking forward to a large mass of amateur radio fun. Together with SM7PXS and SM7XWM I will operate 8S7GL from lighthouse Garpen during the International Lighthouse Lightship Weekend. This operation is of course a part of the activities of our local club, Kalmar Radio Amateur Society, SK7CA.

SM7PXS started a blog for the event, where there also are links to pictures from previous activites.

Last time we operated from Garpen was during ILLW 2007. The little island is a truly great QTH surrounded by salt water. Hopefully completely free from man-made noise.

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Hentenna and MS

I write this post during the Perseids, using the Hentenna to work meteor scatter Just now trying to work DL2IAN on JT6M. So far this evening I have had two MS QSO’s, both random, with LY2CP and F1GTU. I cannot say more about the performance of the hentenna for MS than it works. In the current test position, only about 3 meters above ground, making QSO’s is good enough.


My thoughts over the Hentenna is whether I to build a more permanent installation in copper tubing and somehow place it higher up, or go for testing another antenna for next year’s 6 meter season. Maybe HB9CV? I will give it some thought. On one hand I would like to have a directive antenna, and on the other hand, I am so far satisfied with my wire Hentenna and would like to try it higher up and possibly rotable to see if there is any usable directivity in practice,


Any suggestion or thought about 6 meters antenna choice is welcome. At the moment I do not have any possibility for the large Yagi array we all dream about.

The attempted QSO with DL2IAN did not go through, Now I will call CQ on 227 JT6M.

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Have you seen the video link “Waves, an instructive film” in my link list on the right hand side of this page?

If not, you should look at the film. Understanding wave behavior is very relevant to the radio amateur. Especially if you connect your radio to an antenna.

Are you sure you understand standing waves and the standing wave ratio (SWR) ?

Click to wwatch Similarities of wave behavior

Click to watch Similarities of wave behavior

In my high school we had the same equipment and did the very same experiments. Now I would want a wave machine at home to play and learn with.

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Hentenna experiences

I have been using the 6m hentenna (see The hentenna proved to work) for a couple of months. So far I am happy with how easy it was to build and trim to resonance, and with the contacts I have made using it. But was it worthwhile to spend the extra meters of antenna wire compared to my old 6m dipole?

I decided to make a quick comparison, but as there was no opening and no traffic to hear I found a somewhat stable but weak man-made noice signal to listen to. Compared with my vertical half wave dipole the hentenna is perceived as slightly better for receiving, but there is not a huge difference. I should ask one of the local hams to help me out with a more stable signal source and to listen for differences in my transmitted signals.

Here are the far field plots for the hentenna:

hentenna2 hentenna1
















A friend helped me simulate the radiation plots for the hentenna. The simulation was made with measurements from this description, shorted with 3% for wire dimension and insulation. This was same as I used for building the hentenna, except that the feed point in practice was found by trial and error.

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