Can you describe the construction of the top hat a little more?  
----- Original Message ----- 
From: "Phil Scovell" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, December 03, 2012 5:14 PM
Subject: A SHORT VERTICAL FOR THE TOP BAND


> This was published in WorldRadio, a monthly mag , years ago.  I even =
> receive 5 dollars for it.  The second article they published was about =
> talking devices for blind hams but I didn't get paid for that one.  I =
> was mildly famous for a day, haha.  Anyway, this small vertical really =
> worked well for me and though I have posted it here on blind-hams =
> before, it's been some time so I thought I'd do it again.  Send your =
> donations to... haha.
> 
> 
> 
> A SHORT VERTICAL FOR THE TOP BAND=20
> 
> 
> By Phil Scovell  K0NX
> 
>     Soon after purchasing a transceiver with 160 meter
> capability, I decided to go for the Top Band.  At that time, I was
> renting a bi-level duplex with the smallest backyard I had ever
> seen as a ham.  It was only about 30-by-40 feet and the front yard
> was even worse.  To complicate matters, I had 38 feet of Rohn 25G
> bolted to the back of the house at the 14 foot level, with a
> single set of guys at 35 feet  Perched on top was a 4 element 20
> meter yagi on a 24 foot. boom.  The tower itself was simply too
> short to shunt feed and a 160 meter inverted L was out of the
> question.  Even an adequate ground system in that limited space
> was impossible.  I did the only thing left to do - made a short
> top loaded vertical.
> 
>     Most of us have always considered 160 meters to be limited to
> those with miles of open range and super tall towers.  Few, in the
> city, have much more than 260 feet of yard space, the needed
> length for a half wave on 1.8 MHZ, or even enough room; not to
> mention the money, for a 130 foot tower - the length of a quarter
> wave for 160 meters.  For those of us with small yards and even
> smaller towers and limited budgets, there is no hope?  Not so!  My
> vertical was only 32 feet
> 
>     Short top loaded verticals for 160 are commonly used and
> their advantages are numerous.  Conveniently, they need almost no
> ground.  The nicest thing about top loaded verticals is their
> radiation pattern:  The antenna radiates from the top instead of
> the bottom; thus allowing the signal to be projected from above
> ground where it does the most good.
> 
>                          CONSTRUCTION
> 
>     Using the remains of a telescoping push-up mast from Radio
> Shack, I bolted 24 feet of vertical mast to the peak of the duplex
> on the west side of the house at the 20 foot level.  Sandwiching a
> piece of plastic between the house bracket and the edge of the
> roof helped insure the antenna was adequately insulated.  My
> telescoping mast was once about 40 feet. but only 24 feet remained
> after a 100 MPH plus wind storm - you use what you have. =20
> 
>     Setting the mast on a block of wood, again using a piece of
> plastic for insulation, I planted the antenna.  The braid, shield,
> goes to ground.  Your ground can be, as in my case, a nearby chain
> link fence, or a ground rod, or even a cold water pipe.  If there
> is room, lay out as many wires, no matter how short, as you can;
> and attach your shield to the wires.  The larger the diameter of
> wire, the better.  Yes, you can use insulated wire; in fact, it is
> preferred if you plan to bury it.  The center conductor goes to
> the base of the antenna.
> 
> TOP ASSEMBLY
> 
>     The top of the vertical was made up of A:- 4 feet of 1 inch
> aluminum tubing, B:- 3 feet of 2.5 inch plastic tubing: PVC pipe,
> and C:- an additional 7 feet of 1 inch aluminum tubing.  I used
> 2.5 inch diameter PVC for my coil form because I had no idea how
> large a 160 meter resonator should be.  Later, of course, I
> discovered I could have gotten along with something smaller.=20
> Learning is what home brewing is all about.
> 
>     I bolted both the 4 foot and 7 foot pieces of aluminum tubing
> to either end of my 3 foot PVC pipe - a few inches down inside
> either end to insure structural strength - the 4 feet length on
> the bottom and the 7 feet poking out the top.
> 
> RESONATOR
> 
>     The coil, or the 160 meter resonator, was a winding of 14
> gage insulated wire rapped around the middle of my PVC pipe.  How
> much wire did it take?  I wanted my antenna to resonate near the
> bottom of the band, 1800 KHZ, since I was mostly interested in CW.=20
> A quarter wave at that frequency is 130 feet. The total length of
> my vertical, I judged, would be about 32 feet; so I wound the
> difference, 98 feet around the plastic pipe and tied the ends of
> the wire to the bolts used to secure the aluminum tubing to the
> PVC coil form.
> 
>     HIGH VOLTAGE
> 
>     The voltage on such a coil is very high.  If high power is to
> be used, a heavier insulated wire, such as RG8U, should be used
> for the winding to prevent arcing.  Some hams even used quarter
> inch copper tubing wound on a coil form when running a KW.  My 100
> watts, however, presented no such problem; thus the 14 gage
> insulated wire was satisfactory.
> 
> CAPACITY HAT
> 
>     After dropping my top assembly a foot or two down inside the
> 24 foot vertical mast already bolted to the edge of the roof, and
> securing it with a U clap, I hurried to the basement and fired up
> the transmitter.  You guessed it...it didn't work!  I found that
> not only would the antenna not load, but there was no resonate
> frequency anywhere on the band.  I rechecked everything and made
> numerous adjustments but the results were the same.  I even added
> and subtracted wire from my coil, but nothing changed. =20
> 
>     Sitting on the roof, contemplating my dilemma, I suddenly
> recalled that trapped verticals used capacity hats.  Crawling over
> to my home brew 5 element 6 meter beam, which I had recently
> removed from the tower and left laying on the roof, I plucked off
> two elements.  Quickly clamping these 2 aluminum elements in an X-
> formation to the top of my vertical, I dropped the entire assembly
> - now looking like a giant TV antenna - back down inside the 24
> foot vertical mast and tightened it down.
> 
>     Hurrying to the basement, I once again tried to load the
> antenna.  It worked!  It resonated at about 1815 KHZ.  Playing
> with various lengths, I was able to raise the resonate frequency
> enough to allow me about 50 KHZ of room before the SWR became too
> unreasonable.  My capacity hat was over 9 feet in diameter but
> without it, the antenna would not resonate.
> 
> RESULTS
> 
>     Just because an antenna can be made to resonate, does not
> mean it will radiate.  I have made 3 feet of coax laying on the
> back of my desk resonate but could not talk across town with it.=20
> This antenna, however, worked; and worked well.
> 
>     I finished my antenna project in early May and operated
> almost nightly until mid July when I pulled down everything to
> move to a new location.  I made dozens of contacts during this
> period of time and worked both East and West coasts often.  On
> sideband, I often received reports of 10 and 20 DB over S9 from
> W5, W6, and W7.  Although the summer time conditions from Colorado
> are not the best for working the East Coast, do to high static
> levels, I worked a few, none out of the northeast however, with
> reasonable reports on the better nights.  Most think that 160 does
> not propagate during the summer because of the low frequency.=20
> Although this is certainly not true, you better plan on getting
> used to listening to the static.  Interestingly enough, the static
> level is almost nil a few minutes before sunrise each morning and
> the band goes long during that window opening. =20
> 
>     I found that the top loaded vertical is one of the most
> commonly used antennas on 160 meters and often are only 30-to-40
> feet in total length.  Simple 30-to-50 foot telescoping masts are
> often used for the vertical element which can be easily purchased
> from most radio and hobby stores.  Capacity hats range from 3-to-
> 10 feet in diameter and sometimes even greater.  A friend of mine
> in Texas has used 22 foot diameter cap-hats when using short
> verticals under 40 feet in height; thus getting as much signal
> above ground as possible.
> 
> GROUND SYSTEMS
> 
>     On 160 meters the greater your ground system, usually the
> better your signal.  This, however, is perhaps the greatest
> benefit of the top loaded vertical for the Top Band.  I have
> worked hams on 160 who have been using 40 foot push-up masts and
> 5 foot diameter capacity hats with no more ground system than a
> single short ground rod driven in at the base of the antenna.=20
> Some use nothing more than a wire running over to a nearby cold
> water pipe.  Top loaded verticals simply work well with little
> ground and signals from such antenni compare well with the larger
> base loaded antenni - shunt fed towers with large ground systems
> for example.
> 
>     There seems to be one additional advantage to a short top
> loaded vertical on the Top Band over many other antenni.  Because
> of its size, it has reduced signal capture area.  This means, in
> high static conditions, the shorter antenna often is able to hear
> the weaker signals, - perhaps do to the fact it is less resonate
> at the static frequency - compared to shunt fed towers for
> example.  I know some will take issue with this statement, but I
> have personally observe this to be true.  Many times, when
> comparing incoming signals with local stations using larger
> antenni who have not been able to copy a weaker signal, I have, on
> the other hand, with the shorter antenna, been able to hear and
> copy clearly.
> 
>                           CONCLUSION
> 
>     If you have a 160 meter position on your transceiver, now you
> can try it out.  In recent years, the top band has become more
> popular with hams who have discovered that short antenni indeed
> work well at low frequencies.  Of course, the winter conditions
> are the most favorable for 160 meter communications, but you will
> find even the summer to be good for under 1,000 miles.  An
> amplifier certainly helps on any band, especially during the
> noisy summer time, but I have no problem working the western half
> of the U.S. from Colorado even with 100 watts.  If you want to try
> the top band but are short on money, space, and tower; try the
> short top loaded vertical.  You won't be disappointed.
> 
> End of article.