Thoughts on Grounding

Ground the main strike at the tower base.  Worry about protecting your equipment (and people) from what’s left over.

My tower and my equipment shack are 100 feet apart.  Bonding the two would be fruitless because of the inductance of the bonding conductor.   So don’t bond when the two are that far apart.  Ground the tower.   Ground the shed.  Worry the most about protecting the equipment in the shed.

Accomplish the first part by putting a ufer ground* in the concrete base and spacing ground rods around the tower, all bonded in a wagon wheel ring.  That should divert just about any lightning strike.  Do not bond to the equipment shed when it’s 100 feet away.

At the shed install spaced ground rods and bond them in a wagon wheel ring.  Install protection on all cables at their entry point, coax, Internet, power, rotator, etc. and bond together.

 

 

*The Ufer Ground is an electrical earth grounding method developed during World War II. It uses a concrete-encased electrode to improve grounding in dry areas. The technique is used in construction of concrete foundations.   –Wikipedia

More…

The principle of the Ufer ground is simple, it is very effective and inexpensive to install during new construction. The Ufer ground takes good advantage of concrete’s properties. Concrete absorbs moisture quickly and loses moisture very slowly. The mineral properties of concrete (lime and others) and their inherent pH means concrete has a supply of ions and free electrons to conduct current. The soil around concrete becomes “doped” by the concrete, as a result, the pH of the soil rises and reduces what would normally be 1000 ohm soil conditions (hard to get a good ground). The moisture present, (concrete gives up moisture very slowly), in combination with the “doped” soil, make a good conductor for electrical energy or lightning currents.   —psihq.com

Cable entrance cabinet with single point ground plate and protectors.  All cables pass through this box before entering the shed in an attempt to stop all strike current from going inside.  The copper plate is bonded to a ground rod and eventually a ground ring around the shed with spaced ground rods.

June 28, 2017: John picked up 100 feet of No. 2 Solid Copper today to serve as the ground ring.  Yay.

 

Tower Base Ready For Concrete

Finally got to this point  (see bullet point 4, below).  It seemed like the digging would never end, but it did and now the hole is ready for the concrete pour.

One of the rebars is allowed to protrude upwards and will be bonded to the tower along with ground rods to make up the ground system. The rebar is the “ufer ground”.

 

 

Station Upgrades

Nothing reinvigorates interest in operating a ham station more than an upgrade.  Finally some upgrades and changes are in progress.  (All we want is more, right?)

• Two 40 meter dipoles at a height of one half wave length (65 ft.), one for Europe, the other for Asia
• Decommissioning Parker site
• Replacing one TS-480 with a Elecraft K3 and K3/0 Mini
• Erecting a 60 foot tower with a 20 meter monoband yagi, web access for the rotor control
• Web access for a coax switch
• A 630 meter station
• A reservation for a Icom IC-7610 for the future because it has a builtin remote base server and an excellent performance sales pitch.

These upgrades and changes should make this station significantly more competitive.  Some of these upgrades are a culmination of what has been previously discussed in this blog. Others, like 630 meters, are a result of new happenings in the world of amateur radio.

Progress report on 40 meter dipoles:  South support pole is up and waiting for the north support pole to be readied.  South pole is in the foreground and the other pole is in the distance behind the shed. The pole is 65 feet tall.  Picture a dipole running between the tips of these two poles for 40 meters.

Update:  It blew down 3 days later.  What’s left of the aluminum is now a support for a 6 meter dipole for the sporadic E season.  It’s windy out there on them thar’ plains.

June 8, 2017:  Big progress on hole for tower.  Today we finished digging the 4’X4’X4′ hole and got a rebar cage built and lowered inside the excavation.  Next step is to put the tower base in.  My rotator cuff suffered minor damage and was quickly repaired by a little physical therapy.  My advice is next time get someone younger to do the digging.

Another Disaster

Whoosh. There goes Strasburg. It can be a real challenge to keep a bunch of aluminum up in the air.  Witness the results of the March 24 blizzard on the eastern plains of Colorado.  It wasn’t much of a blizzard as blizzards go but it was enough to take down the main vertical.  It was my fault, of course.  I should have replaced the temporary tree stakes anchoring the guys with steel T-posts.  Sure enough one of the tree stakes broke in the wind yesterday and aluminum poles don’t stay up very long without guy wires.

Only two aluminum sections were damaged. It was a pleasant surprise to find the exact replacement sizes in my spare stock.  The mast was also bent but my friend, John Neilson, KC0RF has a spare length of galvanized pipe.  Total cost of disaster is $0.  That’s a good kind of disaster.  Repair work can begin once the mud dries in a few days.  Almost a non-event.  Meanwhile there is a 20 meter vertical available so we can stay on the air for one band at least.

First Measurements

Today we measured the actual height and the resonant frequency of the big vertical for the first time since it’s been installed. Amazingly the resonant frequency is exactly what it was designed to be, 2.9 MHz and the impedance is an ideal 35 ohms.   These measurements were taken with the tuner out of the circuit.

Height   56′ 3″

Resonant Frequency   2.9 MHz

Impedance         35 ohms

The top hat consists of the first 16 feet of the top guy wires.  We are assuming the effective area of a drooping top hat is a function of the sin of droop angle.  If so, a nominal droop of 45 degrees provides a factor of .707 effective area (.707 is the sin of 45 degrees).  A resonance of 2.9 MHz indicates the vertical is electrically 80.7 feet tall (468 div by 2 = 234.  Divide 234 by 2.9 = 80.7 feet.).  Subtract the actual height of 56.25 feet from the electrical height of 80.7 = 24.45 feet.  Compare this to the actual top hat diameter of 32 feet and multiply it by .707 which equals 22.6 feet.  Our assumption proves to be pretty close, off by only two feet which could be accounted for by the difference of the actual slope with the estimated slope. Or it could be just dumb luck, who knows.

The main purpose of today’s site visit was to restore the vertical to it’s original height.  Two sections had slipped down inside their adjacent sections by about 18 inches and the tuner could no longer find a match for 160 meters.  It’s hard to tell any difference with the naked eye but here is the restored appearance.  The tuner is able to once again resonant on 160 meters as well as all other bands.

The Nighthauler

This massive vertical is called the Nighthauler because it’s the antenna that can haul ass on the night time bands  — the bands that are open at night.

We’re definitely out on the prairie.  The radiating element is a DX Engineering ATK65A Telescoping Aluminum Antenna Tubing Kit, described here:

ATK65A kits consist of 11 slow-taper 6-ft. sections and one heavy-wall section of DX Engineering’s rugged 6063-T832 aluminum tubing and include all stainless-steel element clamps. The bottom section is the 2.0-in. outside-diameter heavy-wall that mates up to 2-1/8 in. diameter tubing, and then back to 2-in. diameter for the first 12-ft. length. The sections continue to taper down to 7/8-in. diameter at the top.

Of course hams are never happy with a stock product so it’s modified slightly for improved performance.  A couple of additional tubing sections are added at the top for a total of 69 feet of height along with four top hat wires.   The four wires that make up the top hat are 16 feet long and are the first 16 feet of the top guy wire.  The remainder of the guy is Dacron “Antenna Rope” as are all the other guys.

The 16 foot top hat elements, which are actually the guy wires at the top, can be seen in this photo.

A raising fixture was constructed to help with tilting up the slightly unwieldy mast.   It’s the red thing on the left in the picture above.   The mast is just too much to handle alone without some additional leverage.  The fixture consists of a ten foot pole ( which no one would touch, lol )  a pulley at the top and a winch at shoulder height. A rope goes from the winch to the pulley to an attachment point on the aluminum element about half way up.  The point was picked to allow the top half to flex but not too much and to allow the bottom half to sag but not too much.  Kind of what Goldilocks was looking for.

Unfortunately even the raising fixture was not enough.  The mast bowed out sideways as it was raising, damaging the tilt up base.  A single set of guys was placed at the midpoint of the intended mast.  Most of the top half was left on the ground for a while.  We had to settle for a 45 foot antenna due to not being able to raise the mast with the top 25 feet attached. The top hat didn’t make it either.   Back to the drawing board.

December 27, 2016 Update – Two more sections were added successfully; that is, the mast didn’t bow out as it was being raised.  The four top hat radials were added, too.  It’s now 56 feet tall and an electrical equivalent of 67 feet with the top hat included.  We heard China on 80 meters the next morning.  Batteries were too weak to attempt a call which was the perfect excuse to upgrade to a new set of golf cart batteries. Future plans include adding a second winch and rope to the raising fixture.  This might bring the excessive bending under control while lifting and lowering.   -0-

An antenna analyzer should show the resonant frequency to be 2.9 MHz.  This frequency between the 160 meter band and 80 meter band is about perfect for a tuner to match on multiple bands.  An SGC SG-230 automatic antenna coupler is connected at the base between the radial field and the vertical radiating element.

Performance is expected to be good.  The first qso will probably be on 80 or 160 meters with Afghanistan or Somalia or something like that. Ya, right.

Progress On New Site

Today was a milestone because we got Internet installed and made the first remote base qso on a test antenna.  It is the vertical on the right in this picture which is a EF-20 end fed half wave on a fiberglass pole. Notice the new Internet dish on the roof. It brings in Internet from 7 miles away but it also produces a birdy in the center of the 60 meter band. That birdy will have to be worked out. ( Clamping on a couple of ferrite toroids completely eliminated the birdie.)

Progress was also made today on the main low band vertical antenna by completing the radial field.  It is made up of 4 radials each 4 feet wide consisting of welded wire fencing laid flat and held in place with landscape pins.  Below is one radial.  The vertical element will  be 60 feet tall with a top hat.

The equipment has been moved up from the Elizabeth site and re-used.   Even the welded wire fencing was painstakingly removed and brought up to Strasburg.

Terrain Profiles

How well our signals will emanate from this new location can be estimated by using software called HFTA (High Frequency Terrain Analysis – from any recent ARRL Antenna Book ) to produce a map of the terrain.  It looks promising because we slope down toward the northeast, which is direction of Europe.  This screen snap is what the terrain looks like as we look to the northeast, or 45 degrees, using a dipole on a 60 foot tower.  Slopes down for 2 miles.  Nice.

Next is a plot of Colorado to Europe using a dipole at 60 feet elevation.  Looks good but could be better.  About 5 dBi gain at the take off angle where most of the Europeans stations come in.   The dipole peaks at 15 degrees, a good all around takeoff angle and very usable but not optimum for Europe.  Four or five degree take off angle is perfect but not likely attainable at this installation.

 

New Coat Of Paint

The pale green shed is now a vibrant barn red with tan trim.  Painting something is a good way to make it one’s own.  No longer drab, now it has sparkle.

It’s ready for the move-in.  First item is solar panels and batteries so there is power to have the Internet installed.  Radio equipment comes after the Internet is up and running.  Finally antennas, which always seem to be work in progress forever.  Ever changing for that extra db.

Raw Farm Land Purchased

This beautiful 40 acre piece of farm land became available this fall, complete with enough space for any antenna, no covenants, nor hoa’s, and perfectly flat and unobstructed. Lucky me, the property is now mine.  Having one’s own land upon which to put a remote base has a much nicer feel than having to borrow from friends.  As gracious as my friends have been it’ll be relaxing to use my own land instead.  This is what the acreage looks like when still a blank sheet of paper.  The mountains are just barely visible in the distance.

A Tuff Shed “barn” is scheduled for delivery tomorrow and then the equipment can begin to be moved in.  Off grid solar power has served us well in Elizabeth and those panels will be moved up here.  A Direct Link internet tower is 7 miles north for Internet access and we should be able to reach that easily.  This acreage is located near Strasburg, Colorado about 25 miles east of Denver in the heart of farm and ranch country.  Access is quick by I-70 and the county roads are paved all the way except for the last mile.  Testing for RF noise showed no S-meter movement off the S-zero level on 20 meters.  The plan is to slowly move the other two remote bases here.  The Tuff Shed will house the remote base equipment and also serve as an operating location on occasion.  It will be big enough to accommodate a camp cot and a sleeping bag.  If a used tower and beam comes on the market that could also be in future plans.   For now the antennas will be verticals.   Lots and lots of verticals.  With lots and lots of radials.

The cost of this land is looked upon not as an expense but as an investment that I can get some ham radio use out of.  Investing in land is almost never a bad thing.   Lucky for us, Colorado is one of the sought after places these days and some say almost any real estate here is a good investment.  We’re fastening our seat belt for the next exciting ride.  Here we go.

November 21, 2016 – Tuff Shed arrives. It doesn’t look so much like a barn as a shed.  From a distance I thought it looks like a yurt until my wife corrected me.  She says yurts are round.  I guess I’ll have to find a better name than “Little Yurt On The Prairie”.

At the closing I asked what the address will be since there was no address on the paper work.  The answer was, “Oh, the County will give you an address when you apply for a driveway permit.”  Reality sets in.   Permits?  We don’t need no stinkin’ permits.  Do we?  Oh, maybe we do.  I’ll put that on my Christmas list.  (February update:  still no permits and still no address )