Saturday, June 7, 2014

Reset...and a QRP DXCC Milestone

It's time for a reset, and some reflection. As the picture below shows, all of my antennas and supports are down. The time investment was 6 hours spread over the past week, which is a lot less time than I spent putting them up!

All of this antenna and support removal is in preparation for the raising of my recently acquired 14 meters tall new (used) tower. But it's more than just that. I decided that the mast that supports the multi-band inverted vee would also come down since, although it works much better after making improvements, it is inadequate for the longer term.

Of course this means I am QRT for a little while. Since it's summer I am perfectly fine with this. If I survived being QRT for 20 years I can manage a few more weeks.


Before I discuss my rebuilding plans I want to mention that I did succeed at reaching a milestone, a stretch objective I set for my small QRP station. I have now worked over 200 DXCC countries over the past 18 months.

I was stuck at 198 for a while when in the space of 48 hours I worked 3 more: A3, JY, 9G. Although I have worked some SSB -- mostly during the WPX contest this spring -- all 201 countries are on CW, using no more than 10 watts (5 watts in contests). It goes to show what can be done with a small station. Of course it wasn't easy, but what's the fun in making it easy?

Even so it is time to look onward and upward. I am not philosophically bound to QRP and small antennas.

Tower and antenna plans

By this fall I expect to have a more competitive station for DX and contest operating. I will begin with supports and antennas, and then, but I have yet to decide when, increase power to 100 watts. I purchased a 35 A power supply this spring as preparation. I have pretty much put the refurbishment of my venerable FT-102 off into the unknown future, if ever, and will look at purchase of something more modern. Newer rigs are just too attractive to overlook with regard to features and performance. The FT-102 has a truly great receiver but its time has come and gone.

The plans for my new suburban antenna farm are evolving. I will be assessing options even as I proceed to raise the new support structures.

DMX-52 tower:
  • The first task is to erect the DMX-52 tower. It will be guyed in the same fashion as the Golden Nugget tower it replaces in the same location (Site C). I am well along in preparatory work, of which I'll say more when I am further along. You can see a bit of this in the picture at the start of this article.
  • My objective is to place a 3-element tri-band trap yagi on top of the DMX-52. I am waiting for the right used antenna to come along. I am endeavouring to keep the tri-bander wind load below 4.5 ft², which is why my TH6 will remain in storage. I'll probably turn it with my ancient Ham-II rotator. The rotator has been well-serviced (by me) in the past and has upgrades, including a steel ring gear. The only other rotator I own is a underpowered for what I am planning.
  • I would like to stack a small 6 meters yagi on the tower. If I do this it'll be a cut-down 3-element version of the Cushcraft A50-6 I have in storage. (The 1λ boom of that antenna served as the upper half of the house-bracketed 14.5 meters tall mast for the inverted vee.) Since the DMX tower is 14.1 meters tall and I have to keep everything below 15 meters to remain exempt from municipal involvement stacking will be a challenge. Modelling will help.
  • For the interim I will likely reinstall the 40 meters delta loop on the tower. It will need to be lowered about 2 meters from its previous apex of 14.9 meters and "squashed" a bit to keep the bottom from becoming a safety hazard. I could reshape it as a narrow diamond loop, but only if the interaction with the tri-band yagi is small. I will use EZNEC to determine the potential extent of interactions. I would like to have a 2-element loop array but only if I can manage the interactions with other antennas and the tower. This will be challenging.
  • Further crowding the tower will be an antenna for 80 meters. My current plan is an inductively-loaded half sloper. Loading is needed due to the low height of the tower. This antenna can be an efficient and effective DX antenna since it is vertically-polarized and the current maximum is at the top of the antenna, not the bottom as in most 80 meter monopoles. This is antenna that will require modelling, including the capacity-hat effect of the yagi(s).
  • I am playing around with the idea of resonating a modified yagi boom on either 30 or 40 meters. Other hams have accomplished this with some success. The elements become loading elements of the lower-band dipole, and the yagi performance is not affected because the antennas are orthogonal. I can only work on this after the yagi is bought and installed.
Golden Nugget tower:
  • The 30' Golden Nugget tower will be house-bracketed in the same place as the steel & aluminum mast I just took down. In addition to being stronger and more reliable it will allow me to work on antennas and access the upper roof of my 2-floor house without ladders and pulleys. An added benefit is less wear on the roof shingles.
  • The multi-band inverted vee that was supported by the house-braketed mast will not continue in the same form. One alternative is to replace the 15 meters element with one for 40 meters. This would allow continued resonance on 15 and give me a better antenna for short-paths on 40. The latter will help me in contests I need to work the US, especially the QSO-rich northeast and mid-west. 
All this said my first priority is to get the towers in the air. Once I've done that I'll check their performance in wind and violent weather before putting up any antennas. However I may put up a dipole just so I can do some operating during the early summer.

I'll next post another article on this blog when I've made progress in executing my plan, or if I learn something interesting from the modelling of antenna interactions.

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