Thursday, June 16, 2011

The Alpha Delta DX-EE is up..............

20m dipole that was taken down
Well before I left for Europe I was contemplating another antenna for my attic. At this point I have a 20m dipole, a 40m dipole made from two mobile whips as well as the same for 30m. It is getting very crowed up there. It would be nice to replace them all with one antenna. I did try using my High Sierra Sidekick but the results were very poor to say the least. So that came down and on once again on went my thinking cap. I some how stumbled across the Alpha Delta DX-EE. It's only 40 feet in length, covers 10,15,20 and 40 meters with the tuner in my K3 I can also get 12, 17 and 30 meters. With this antenna I could  remove the other antennas to make room for 6m's, put my Discone antenna back up and possibly an active antenna. This past
40m dipole still up for now
Saturday I assembled the antenna, it is made from 12 gauge solid wire which makes it very easy to work with. I had to do the assembly in the basement as the antenna is 40 feet in total length. I got Julie to help me get it up into the attic. From there is was bumping my head, crawling around on all fours and weaving between the rafters. Each leg is in a "Z" configuration as the attic is not 40 feet in length. Most of Saturday was spent assembling the antenna and getting it into the attic. Sunday was spent getting the SWR readings and fine tweaking the antenna. Below are the  SWR readings before adjustments.
40 meters
7.000=5.7                                 7.030 = 6.1                              7.060= 10.7     (lowest SWR @ 6.788 1.5)

20 meters
14.000= 1.97                           14.030= 1.9                              14.060= 1.9     (lowest SWR @ 14.551 1.)

15 meters

21.000= 1.7                             21.030= 2.0                              21.060= 2.3  (lowest SWR @ 20.730 1.1)

10 meters

28.000= 2.2                            28.030= 2.2                               28.060= 2.4  (lowest SWR @ 27.711 1.1)

So now its time to tweak the SWR which was made very easy ( except for the up and down from the attic) with my MFJ antenna analyzer.  Below are the final results I was able to achieve, now having said that I did have a slightly better result but I got greedy and wanted to further improve on what was a very good over all SWR. In doing so I ended up never getting it back to that sweet spot......so lesson learned "when the SWR is what you think to be the best LEAVE IT ALONE"
Final SWR readings
7.000= 2.52                            7.030= 1.60                                 7.060= 1.59

14.000= 1.88                          14.030= 1.98                               14.060= 2.0

21.000= 1.39                          21.030= 1.46                                21.060= 1.54

28.000= 1.4                            28.030= 1.61                                 28.060= 1.76

So over the weekend I am going to do some tests between the new Alpha Delta antenna and the only remaining antenna in the attic my 40 meter mobile whip dipole antenna. I will post them when the results are in.

6 comments:

  1. Hi Mike, you are lucky with such a nice attic. I am curious what the results are with your new antenna. Good luck, 73 Paul

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  2. Hello Mike,

    Wish you the best of luck with the antenna.

    For me, 40 meters is always the problem with a multi-band antenna. Simple mathematics sez when you start cutting it down to less than 66', performance drops quickly. But I rarely work long distances on 40 anyway....

    I bet the other bands will work just fine... Lets hope the sun spots hold out just a little longer. Current predictions are worrisome...QRP could become even more of a challenge.

    ps....you must have a really great wife. That insulation is quite a obstacle for anyone. My wife said I was on my own when it came to working around that itchy stuff. hihi

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  3. Hello Mike,
    If it's anything like our attic, at this time of year,I bet it was as hot as a sauna up there.. :0)

    Good luck with the new antenna 73... Mark

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  4. Good evening Paul, I too am hoping that the new antenna on 40 meters (as this is the only antenna I have left from the dipoles) will out preform the mobile whip 40 meter dipole.

    "J" Julie is a real sport when it comes to my hobby. She is very supportive as I am with her photography hobby as well. As for the 40 meter portion of the multi-band mix yes I too have not really done any DX with the mobile whip setup I will be very please if the multi-band on 40 does a bit better.

    Mark you got that right the attic is unbelievable when it comes to heat. I was up and down just to cool down and that really adds time to the setup and the SWR setup as well. But having said that I know I can always get up there and not have to worry about weather affecting the antenna setup.

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  5. Hi Mike,

    I have a DX-EE in my attic as well. How did you lower the SWR's as shown above in your post? I have very high SWR's on 40 m only.

    Thanks. Mike, N3ZHA, Centreville, MD

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  6. Good evening Mike, Im not sure if I did anything special with the 40 meter section. I do use the MFJ antenna analyzer as to get the lowest SWR. I did start out on 10 meters and worked my way up to 40 looking for the lowest SWR. Also the antenna is in a "Z" configuration due to space troubles. Also there is no ducting and very little wiring in the attic as well. That's all I can think of what I did. Thanks for stopping by the blog hope you enjoyed.....

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