One of the best tools in the engineer’s lightning protection toolbox is a tried, true and frequently underutilized friend, the ferrite toroid.

The principle is quite simple. If you have two (or more) conductors passing through a ferrite, such that the net sum of their currents is zero, then the ferrite is an inert object, just sitting there waiting for something to happen.

If, as in the case with a surge or lightning strike, the current on any conductor increases, such that the net current is no longer zero, then the ferrite core saturates, creates a magnetic field and attempts to induce an equal and opposite current flow in the other conductor(s) — in effect, trying to maintain the zero net total current.

For this reason, ferrites are a very good tool in many ways, not the least of which is lightning protection. Used on a coaxial cable going out to the antenna system, they can also be useful for finding ground loops.

If you have a ground loop, such that not all of your return current is through the coax shield, the ferrite will saturate — and quickly (depending on the amount of the imbalance between feed and return) get physically warm … in extreme cases, I’ve even seen them explode!

Easy to Install

You want ferrite toroids at the output of the transmitter, preferably before the point where the coax shield is connected to the station reference ground (usually where the coax enters the building, but not always, so keep an eye out).

In the course of the installation, ferrites can and should be placed on pretty much every current carrying conductor, including AC lines, remote control feeds and audio/AES lines (don’t forget the STL antenna cable).

For any cable where there is a safety ground connection (for example, the antenna feedline ground referenced above, or an AC mains surge protector), ensure the ferrites are installed between the ground and the equipment being protected. That makes the reference ground connection look like a better path than the equipment, by raising the effective impedance lighting or surge current has to overcome to get to the equipment.

Another use for toroids is helping to reduce pickup (for example, the RF from your AM station getting onto the audio feed for your FM station). The principle is much the same as for lightning protection: The ferrite will help to filter any signal that is not present in equal amplitudes in both the feed and return paths.

Nautel offers several ferrites that can help, and you can order them via our Parts Quotation Request form at http://support.nautel.com/parts.

Some useful part numbers:

• LXP38 — this is a 3/4-inch inside diameter toroid, good for RF rejection and lightning protection on small signal cables.

• LP23 — a 2-1/8-inch inside diameter toroid, good for most heavier AC cables and coax up to 1-5/8 inches (as long as the connectors aren’t already installed!)

• LP32 — a 4-1/8-inch inside diameter toroid, good for the really big AC and RF cables (again, this won’t fit over a 3-1/8-inch EIA flange, so keep that in mind when planning)

• LA52 — a small (1/4-inch inside diameter) clip on ferrite that helps to keep higher frequency (FM) RF out of control and signal wiring. Impedance curve shows 320 ohms at 100 MHz, so it wouldn’t be so good for an AM station, but definitely useful for a higher power FM.

These are RF band-pass filters/shorted quarter wave shorted stub traps. They are a DC short that will pass an FM radio frequency with little or no attenuation. //

Above is the test setup required to calibrate the trap to the correct frequency. A return loss bridge is used in conjunction with an RF spectrum analyzer and 50-ohm dummy load. The analyzer display is a VSWR picture of the performance of the trap at the frequency of interest.

These filters are normally used at the output of an FM (88 - 108 MHz) solid state broadcast exciter as a voltage spike protector. It is, in essence, a shorted quarter wave stub made of 50 ohm transmission line. They are needed on FM transmitters where the next stage of amplification is a tube. An arc in that tube could send a spike of hundreds or thousands of volts back to the exciter causing failure of the exciter's output stage.

Since the filter is DC shorted at the end, it presents a direct short to any DC voltages. It passes the FM frequency of interest because the cable is cut to an exact length. Each filter is cut and tested using a spectrum analyzer with tracking generator and return loss bridge. The return loss at the specified frequency is typically 45 dB, which a VSWR of 1.01:1.

Sometimes they are used at the output of a low power FM station or an FM translator to give lightning protection to the final amplifier. They will also help reject second harmonic radiation as well as offer some attenuation to carriers that are not on the frequency they are cut for. //

By practically any measure, the world today is more peaceful and less war-torn on a global scale, relative to the past.

For instance, declarations of war between nations and soldier casualties have both dropped drastically since the 20th century. Yet, military spending has not followed this trend.
The Top 10 Military Spenders

According to SIPRI, global military spend reached almost $2 trillion in 2020. The top 10 countries represent roughly 75% of this figure, and have increased their spending by $51 billion since the year prior. //

The U.S. isn’t labeled as a global superpower for nothing. The country is by far the largest military spender, and its $778 billion budget trumps the remainder of the list’s collective $703.6 billion. On its own, the U.S. represents just under 40% of global military spending. //

Military expenditures as a percentage of GDP can be used to compare military spending relative to the size of a country’s economy.

When looking at things this way, many of the top spenders above do not appear. This may be an indication of their economic prowess or a demonstration that the money might be used for other vital areas such as education, healthcare, or infrastructure.

#1 🇴🇲 Oman Middle East 11.0%
#2 🇸🇦 Saudi Arabia Middle East 8.4%
#3 🇩🇿 Algeria North Africa 6.7%
#4 🇰🇼 Kuwait Middle East 6.5%
#5 🇮🇱 Israel Middle East 5.6%
#6 🇷🇺 Russia Europe/Asia 4.3%
#7 🇲🇦 Morocco North Africa 4.3%
#8 🇮🇶 Iraq Middle East 4.1%
#9 🇺🇦 Ukraine Europe 4.1%
#10 🇵🇰 Pakistan South Asia 4.0%

While the name of Singapore Airlines debuted in the 1970s, the carrier’s history traces back to a few decades prior amid the creation of Malayan Airways Limited in 1947. This airline became Malaysian Airways Limited in 1963 before taking on the name of Malaysia-Singapore Airlines Limited in 1966. Singapore Airlines began operations under its current moniker in 1972, going on to become a global powerhouse and achieving numerous awards thanks to its welcoming service. //

The Ocean Steamship Company of Liverpool, Straits Steamship Company of Singapore, and Imperial Airways came together to incorporate Malayan Airways Limited (MAL). The region where this outfit started flying was the recently-formed Malayan Union, which was a combination of the Malay states and the Straits Settlements of Penang and Malacca. The Federation of Malaya was formed in 1948, which underwent several transitions in the following years. //

After launching flights to the United States a few years before, 1972 saw the launch of two names that are still influential forces today. Malaysia-Singapore Airlines split to give both to Singapore Airlines and Malaysia Airlines Systems, with operations of both commencing on October 1st. Notably, Malaysia Airlines System also still flies today, under the brand of Malaysia Airlines. //

Singapore got the 1990s going with the opening of Changi’s Terminal 2. There was also a series of fleet renewals as the airline expanded, such as the $10.3 billion order for 22 747-400 and 30 A340-300 jets in 1994. //

Singapore Airlines stopped flying the 747 for passenger services in 2012, but the family remains in its fleet as a freighter. //

Continuing its trend of experimenting with widebody aircraft, Singapore Airlines introduced the Airbus A380 to the world on October 25th, 2007. This behemoth flew commercially for the first time between Singapore and Sydney. This inaugural flight had 455 passengers and 30 crew members on board. It was joined by the A330 just two years later.

Another piece of protection equipment you may want to consider is a shorted quarter-wave stub. One can be placed on the output of an FM exciter, ahead of a tube transmitter, so that any tube arcing is shorted to ground and will not be fed into the exciter.

Our Radio World colleague Mark Persons has an interesting article on his website www.mwpersons.com describing its use. Select “Tech Tips” and look for “Stub Protector for FM Exciters and Transmitters” under the FM Tips column.

The quarter-wave shorted stub connects between your transmitter and your antenna system to short the center conductor to ground. This provides lightning protection for your transmitter. Should lightning strike your tower, the high-voltage pulse travels down your transmission line and meets the stub, where it is shorted to ground.

The stub is virtually invisible to your transmitter and offers 0 dB of insertion loss and an input VSWR better than 1.01. Return loss values are typically greater than –50 dB. Both fixed and frequency-agile models are available.

A real benefit is that the stub is maintenance-free, even after a discharge. There are no parts to replace.

The shorted stub acts as a broadband filter, and in sites where FM is collocated with AM, the latter signal is reduced by more than 30 dB. //

https://www.xenirad.com/

To see how burgeoning lumber prices are impacting the U.S. housing market, we’ve calculated the number of single family homes that could be built with $50,000 worth of lumber. First, we established the following parameters:

• Lumber requirements: 6.3 board feet (bd ft) per square foot (sq ft)
• Median single family house size: 2,301 sq ft
• Total lumber required per single family house: 14,496 bd ft

Based on these parameters, here’s how many single family homes can be built with $50,000 worth of lumber:

Date* Lumber Price Total Lumber Purchased Total Homes Built
2021-05-05 $1,635 per 1,000 bd ft 30,581 bd ft 2.11
2020-05-04 $343 per 1,000 bd ft 145,773 bd ft 10.05
2015-05-01 $234 per 1,000 bd ft 213,675 bd ft 14.74
2010-05-01 $270 per 1,000 bd ft 185,185 bd ft 12.77

If you look at the inner-city areas of Los Angeles, San Francisco, Seattle, Chicago, or New York, you find a laundry list of issues, from homelessness to rampant crime to cold-blooded murder, almost exclusively attributable to a liberal-socialist policy that has been codified into law. And what does the progressive-left say is the answer? Whaddya know! More Government. More Socialism.

That doesn’t mean that Conservative policies don’t often require force to implement or that those policies don’t create problems bigger than those they intended to fix; it’s just that Conservative policies do those things less often. If Conservatives stuck more often to Conservative principles, they would seek to remove the barriers and triggers which create the problems we are seeing in the first place, the majority of which can be sourced back to the government. Libertarian-leaning conservatives, such as me, are so often frustrated because we watch so-called “conservatives” believe that the answer to the problems caused by socialist policies is simply more government, in the hands of these “conservatives.” What makes conservatives who engage in this action hypocrites is that they are acting like the very liberals they criticize. //

This brings us back to the statements made by the Former President on Monday at COP 26 Climate Summit in Scotland. As always, Obama started with some pandering nonsense which led him to commit what is, to my people, a grievous cardinal sin:

“Since we’re in the Emerald Isles here, let me quote the bard, William Shakespeare, ‘What wound,’ he writes, ‘did ever heal but by degrees.'”

Yes, while the President spoke in Scotland, he suggested they were in Ireland and quoted an Englishman. //

“I can afford to give up a lot of my current lifestyle to benefit the planet because I’ll still have a lot left over. A lot of folks don’t have that cushion. So that means that any climate plan worth salt has to take these inequities into account.”

That leaves me with just one question: What the hell is stopping you? //

If, again, climate change was such a grave threat to our existence, and immediate action is necessary, why would you only give up some? Why would you not give it all up? Why wouldn’t you take the totality of the action available to you, with as much immediacy of which you were capable, to combat climate change? And why is it that Obama thinks he can state so openly and plainly that he just isn’t doing anything and is waiting for others to tell him what to do when he is there, demanding action? Would not the sentence, “I have given everything up to help contribute to climate change goals,” or even “Here is the immediate action I am taking to help combat climate change,” serve his agenda better than, “Welp, someone hasn’t made me do anything yet.” Is the left’s only motivation for an action done so at the end of a barrel of a gun? //

No one in socialism sees themselves as “the worker.” They all envision themselves as some grand societal architect, and that they, in their endless benevolence, will do what is best for the rest of the plebes. It is only when they realize that they too will have to live under the rules they are setting, that they seek ways to create exemptions for themselves, because well, their benevolence has earned it. Obama’s words are no different. He wants to plan. He wants to discuss. He wants to pontificate. But when the sustainable rubber hits the road, he has less than zero intention of ever committing to, let alone engaging in, any meaningful change in his life.