Oct 21, 2009

The MPV project

"Most Pitiful Vertical"

It's time to become active on Top Band again!
Since the move to my new QTH there have been several options investigated on how to implement a vertical antenna for 160m. Discussions, software antenna models, wild ideas etc.. all with no result yet.
A recent article in QST described a "No excuses" home brew vertical by John K6MM. This helically wound vertical is only 25ft(7.6m) high, see details at his website
Sure, delivering a puny little signal this is no pileup-killer. But you make qso's and at right times you work some dx as well.
So why keep dreaming about that larger, but still compromise antenna in the woods behind the house, which by today remains not feasible and due to practical restrictions will still be a compromise?
Then there's this remote farm site available for serious 160m operation, but that's more than an hour drive from here. You want to check Top Band when you pee at nights right?. Maybe I can have fun even with a ridiculous small antenna.

On october 14th there was a cool presentation during a joint webinar from PVRC-NCCC by K6MM.

The MPV idea
Let's put up a vertical and see what I can accomplish. I sure can use the experience for future field operations. There is and have been so many reasons in the past to not put up a small vertical for 1.8MHz, both at home and on field locations.
As my garden measures only 8x7mtrs (600sq feet) there is another requirement: the vertical must be unobtrusive for the neighbourhood during daylight hours. This means I need to be able to take it down to a max 3m(10ft) level in a matter of minutes.

First steps
From DJ6NI I have the 10m version fibre-glass mast for more than 10 years now. It has served me on many occasions as mast for antennas like Inverted Vee, Vertical, K9AY etc. This very tough material and can carry a lot of weight. Each section can be locked and has a micro adjustment.
Why not install a 12, 18 or even the new 26m Spiderpole fishing rod? I have seen that big sucker at the Friedrichshafen Ham-Fair, but the 15 segments become quickly too heavy to lift. It's ok for any field day occasion, but not the daily install I have planned in my backyard. Not to mention it costs 549 euro.

10m heavy duty mast. Can be set up within 2 minutes at minimal effort.
The top section is 22mm dia so there's opportunity for additional length.
Guying is done at the 6m level, using 2mm dynema.

No; for several reasons there is no possibility for a vertical in those trees behind.

  • Find an extension like old fishing rod
  • Explore option for possible inverted L
  • Or helical windings
  • Create ground screen
  • Find the final resonance and add a tuning network at the bottom
I need to clean up the garden first.

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