Lightning Protection Basics for the HF Station

By Walt Mahoney, KC1DON

With spring (hopefully) just around the corner, late winter is a great time to evaluate our station lightning protection arrangements prior to lightning season. This short article is not a comprehensive review of the subject, but does suggest some basic protective measures we can all take. The suggestions are based on my experiences as an AM broadcast engineer, and later in my career with industrial plant control systems. Two comprehensive resources are Grounding and Bonding for the Radio Amateur (2nd Ed., ARRL), and a three-part series, "Lightning Protection for the Amateur Radio Station," by Ron Block, KB2UYT (now NR2B), which was published in the June, July, and August 2002 issues of QST. The later articles are available for free online at http://www.arrl.org/lightning-protection. A good explanation of lightning can be found at https://www.nssl.noaa.gov/education/svrwx101/lightning/

Lightning as a natural phenomenon is usually (~90% of the time) a downward negative electric discharge, with the earth as the anode. The length of the discharge is usually 1 second or less, and the potential can vary between 40 and 120 kV. Once the arc is established, the rise time to peak current is about 0.3 seconds, during which time the peak current flow can be from 5 to over 200 kA. If we consider the time integral of the lightning current over the entire flash duration, the energy released is something on the order of 10 billion watts. The key takeaway with this amount of energy is, we don't need to take a direct hit to cause harm to people or damage equipment. A lightning strike will induce hazardous voltages in nearby conductors through induction or via any reasonably conductive material.
I am assuming that nobody will be operating their station when lightning is anywhere in the vicinity, and all equipment is de-energized and grounded per recommendations in the ARRL Handbook. Even in this condition, the two routes that damaging amounts of energy can be coupled to a transceiver are via the power supply and the antenna connections, with the antenna connection being far more vulnerable. These two routes require different protection strategies.
On the power input side, obviously the best protection is to unplug the power supply from the branch circuit. I realize this isn't a practical solution for everyone, and we may not even be at our operating location when the storm arrives. The next best thing in this case is to use a quality surge protected power strip having an on/off switch. The quality and effectiveness of these surge protective devices (SPDs) vary greatly, and as always one "gets what they paid for." I recommend the Tripp Lite "Isobar" power strips.
Look for units that are circuit breaker protected and provide a minimum of 900 joule protection, and be aware that some imported power strips offer zero surge protection beyond a simple fuse. Our most common transceiver configuration now uses an outboard 14 V dc power supply. Obtain a broadband ferrite ring and wind as many turns as can comfortably fit of the dc transceiver cable through the ferrite. It's important to wind the positive and negative conductors together, and locate the ferrite as close as possible to the transceiver.
Protecting the antenna connection is a little more challenging. As a kid I would unscrew the feed line PL-259 and stick it in a pickle jar, which sort of worked. In modern times we have coax antenna switches, and it goes without saying your transceiver should always be switched to a dummy load of an appropriate power rating when not in use. The dummy load is highly recommended to avoid transmitting into an open circuit when one inevitably forgets to throw the switch. Some switch manufacturers such as Alpha-Delta and Daiwa also incorporate gas discharge tube (GDT) surge protection. Look for a switch that grounds all unused connections, and be sure to ground the switch body itself. 450-ohm ladder line can be protected by old-time knife switches, which are getting scarce. The second step is to add a GDT- type lighting arrestor which will shunt current to ground when the gas ionizes at a given voltage. As with SPDs, not all GDT arrestors are suitable for amateur use. Ideally, we want a device having a low let-through energy and minimal insertion losses. As part of my professional work with industrial radio modems, I found the Polyphaser IS-NEMP series offers the happy combination of low VSWR from 1.8 MHz through low-band VHF and a very fast-acting GDT. The housing and connectors are built to mil-spec standards. Again, there are less expensive arrestors of dubious provenance available through online sources. I caution some of these will demonstrate much greater VSWR than is advertised.

From the ARRL ARES Letter of March 15, 2023:
A Brief History of Amateur Radio EmComm Organization
In the early days, amateur radio and hams were considered irritations and nuisances to the "real" communicators -- the commercial sector and the military. We were almost outlawed, and ultimately relegated to the "useless" frequencies of "200 meters and down." That was until it was demonstrated that we could actually be of use as a service. In 1913, college students/hams in Michigan and Ohio passed disaster messages when other means of communications were down in the aftermath of severe storms and flooding in that part of the country. A Department of Commerce bulletin followed, proposing a dedicated communications network of radio amateurs to serve during disasters. Five special licenses were reportedly issued. A magazine article noted that amateurs were now considered to be essential auxiliary assets of the national public welfare.
ARRL was formed in 1914, and disaster response communications as provided by radio amateurs became organized and useful. In 1920, amateur radio was used to help recover a stolen car, of all things! Soon, the use of amateur radio for natural disasters that we traditionally think of now emerged with hams active in responding to deadly flooding in New Mexico and an ice storm in Minnesota.
More organization followed, with a memorandum of understanding emerging with the American railroad system for amateur radio support when the railroad's wire lines were down: There was an ARRL Railroad Emergency Service Committee. There was even a Q-signal designated: QRR, a kind of land SOS. More reports of disaster response communications provided by amateurs appeared in QST, much as they do there and here in this newsletter today. A major New England flood had amateurs supplying the only efficient means of communications from the devastated areas to the outside world, prompting the chairman of the Federal Radio Commission to say the future of radio depended on the amateurs.
Hams worked with the Burgess Battery Company for emergency radio power. Many of us old-timers, including myself, used those batteries when we were kids for our electrical experiments and kits. They looked like tall, thick candle columns! We learned our electrical principles from them. More organization followed, and traffic handling was recommended as the best way to gain discipline and proficiency to prepare for the efficiency and effectiveness needed in response communications situations.
ARRL Field Day was started to prepare amateurs for portable operation, as was necessary in disaster situations when commercial power and means of communications were down. In 1935, the ARRL Emergency Corps was formed with the goal of having an Amateur Radio Emergency Station in every community -- a goal that remains just as urgent today as it did then! To wit, just look at today's emphasis on the neighborhood and community as "first responder" and on self-reliance in the post-disaster survival chain. More "served agencies" emerged as potential partners, including the Red Cross. In 1936, major flooding across a 14-state region served as the ARRL Emergency Corps' first major testing, serving well, and solidifying amateur radio's status as a critical disaster response communications asset and public service. Communications operating protocols and the appointment of Emergency Coordinators followed.
Technical advances supported this evolution. Spark-gap transmitters gave way to the vacuum tube, making portable operations more viable. Articles on portable transmitters and receivers appeared in QST. Exploration and experimentation in the VHF region also spurred more development of portable equipment. The development of the variable frequency oscillator, or VFO -- something that modern generations of hams take for granted -- was at the time a liberating breakthrough offering more versatility and flexibility, and of course more efficiency in meeting the demands of a disaster response communications situation.
World War II meant a shutdown of amateur radio, but many hams joined the War Emergency Radio Service, which did provide some communications during the war period for natural disasters. After the war, ARRL reconstituted its disaster response communications programs and networks, and the first Simulated Emergency Test was run in 1946. The Cold War followed, and the government formed the Radio Amateur Civil Emergency Service (RACES) for civil defense (CD) purposes. It served as the forerunner of the modern emergency management model that we know so well today.
Throughout the 1960s and later up to today, the role, procedures, protocols, equipment, and techniques of amateur radio in public service, disaster, and emergency communications continue to evolve, ebb and flow. This evolution is fueled by advances in Amateur Radio technology and its application, lessons learned from each and every incident that involves amateur communications support. - Rick Palm, K1CE, based on an excellent article titled "QRR: The Beginnings of Amateur Radio Emergency Communications" by Gil McElroy, VE3PKD, that appeared in the September 2007 issue of QST