Taking Stock, continued

Where was I? Oh yes, we left off at the 2nd operating position up in the main house. It's on the second floor, the loft as we call it, with a balcony that faces NNW towards the Cerro de La Muerte (Hill of Death, nice name, huh?), which is about 1/3rd of the way towards San José. This is the other K2, with DSP filtering and its outboard ATU. 


The pliers are not one of the tools I regularly use when operating. :)



Up here I mounted a mast to the peak of the roof from which my 20 meter EDZ hangs.



It's always a bit difficult getting good shots of single wire antennas, but I think you can see the cockeyed mast and the messy window line tuning section OK. The property drops off very fast to the left of the photo and there is just nowhere to run a guy wire on that side. This is where I want to put up the dual EDZ beam, but before I do that I'm going to make a couple of solid supports from rod to hold the mast 90 degrees vertical. 

This EDZ is cut to spec with about a 16' tuning section that converts straight into a 1:1 coax balun and then about 35' of coax to the rig. On 20 meters it presents a 2:1 SWR, which takes off about 0.4 dB from the 10+ dBi signal that 4nec2 claims I have. The weird shape of the pattern plot is due to the wires not being horizontal to the (sloping) ground and being bent back slightly. 

Due north is at about 340 deg. on this plot

Big caveat here when I talk about any of my antennas: there is a lot of metal clutter in the near field, mostly metal roofs, that I don't yet know how to account for, so all plots should probably be taken with the proverbial grain of salt.

Before I get the dual EDZ beam built, I want to convert this 20 meter EDZ wire to a doublet. This involves first running a longer feed of window line, less coax, and adding a couple of coax capacitors (about 20 pf) in-line on each leg to help flatten the SWR across the bands. I'm betting that I can get 40 through 10 meters without losing my strong gain EDZ pattern on 20 meters. Less coax means less signal loss on those bands with a greater mismatch.




As it is now, I can use this EDZ to work on 10, 12, and 17 meters with high SWR (5:1, 7:1, 7:1, respectively) and on 15 meters with a 1.5:1 match. Worst case there, 12 meters, gives me a  loss of about 1.3 dB.

The other antenna up here, just recently put up, is a VK2ABQ. Essentially it's a full-wave loop turned on its side with small gaps between the driven and reflector elements. If you look really closely at the photo (click it to enlarge) you can see the Rube Goldberg mast I put it on, complete with a small cable winch to help raise and lower it. It has a hinge point about 4 feet below the top so that as I bring it close to the ground I can keep the antenna in a horizontal position for working on it.

 As you may know, the VK2ABQ is the predecessor to the Moxon. I was attracted to it because of its 2-way symmetry and to the fact that it is much more amenable to multi-banding than the Moxon. 

I'll write another post describing this antenna and its construction in more detail. Frankly, I'm rather disappointed in it, but I have plans to re-use it pretty much intact as a different kind of antenna (folded yagi). 

I had a gap in my antenna modeling activity after the move from Oregon, because Free EZNEC wasn't going to work for the more complex antennas I was preparing to build and it took me a while to find and learn to use 4nec2.  Suffice it to say that if I had modeled this VK2ABQ before building it, I most likely would not have made it.

73,  Casey  TI2/NA7U

4 comments:

  1. Good morning Casey, very nice blog and nice setup with the K2. I have the auto tuner still waiting to be assembled.I have been busy with antenna setup's. Very nice antenna setup and very nice place your living in. I woke up to 15 cm's of snow this morning...I have also added you to my blog. Cheers and looking forward to your posts in the future. Have a nice weekend.

    ReplyDelete
  2. Thanks Mike for the nice comments. The setup in your picture looks awesome. One thing I didn't plan for in my shack was wall space to hang up my ham awards, hi. Not that anyone here would care anyway!

    We miss the snow sometimes (especially my son), but it's hard to beat the climate here and it's year 'round. More than a little too much rain this last winter, though!

    Looking forward to your blog posts and maybe working your station some day.

    73,

    Casey

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  3. Hi Casey, just discovered your blog through a comment you made at G4ILO's blog. I like the picture you made for your header. I use kind of a "cloudwarmer" antenna myself in wintertime. It is a 84m horizontal loop. My interests are also building and experimenting with HF antennas. Although in wintertime I like to do a nice contest as well besides chasing DXCC. I did add you to my blogroll and will keep an eye on your nice blog. 73, Bas

    ReplyDelete
  4. Thanks Bas for stopping by. I'll be adding your blog to my blog roll as well, looks like you're into some interesting stuff. I must get on WSPR some day! I think it would be a perfect mode from here in Central America.

    Did you choose 84m for your loop or (as in my case) was it just the space provided by nature, hi?

    vy 73,

    Casey, TI2/NA7U

    ReplyDelete

Thanks very much for your comment! 73, Casey

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