Bible
Verse
Ephesians 5:1-2 / “Be ye therefore imitators of God, as beloved children; and walk in love, even as Christ also loved you, and gave himself up for us, an offering and a sacrifice to God for an odor of a sweet smell.” (ASV)
President's Report
Greetings from the fair, the Neshoba County Fair that is. First off let me say that the meeting for August will be the second weekend instead of the first, as I will be packing up on the first Saturday to come back to Meridian.
An update on the repeater. We have determined that the final is out on the 146.700 machine and all that is running is the exciter. I have borrowed a machine from Dennis NO5C. It was planned to be back up with this machine before I left to be at the fair but I didn’t find the software in time to make sure it was programmed. I hope to have it back on before the meeting and we can discuss the next steps for the repeater.
Plan on being there the second Saturday in August. Hope to see you at the business meeting.
73' Charles Grisham, KB5SZJ
MARC 2-Meter Net
Until we are able to get the repeater back up and running properly, please check into the MARC 2-meter net on the W5LRG repeater 145.410- (97.4 Hz PL Tone) on Tuesday evenings at 7 pm.
Reminder the W5LRG net is held on Tuesday nights at 8 pm.
Next MARC Business Meeting
The next business meeting will be held at the Checker Board Restaurant on 2nd Saturday, August 14th beginning at 10 A.M. Come join us for breakfast, coffee and fellowship.
MARC 2-Meter Net
Until we are able to get the repeater back up and running properly, please check into the MARC 2-meter net on the W5LRG repeater 145.410- (97.4 Hz PL Tone) on Tuesday evenings at 7 pm.
Reminder the W5LRG net is held on Tuesday nights at 8 pm.
Amateur radio based VLF comms gear used in Thailand cave rescue
If you have been following the news much lately, you are very likely aware of the international effort to pull off the cave rescue in Thailand of the
12 children and one coach trapped underground.
if you thought about it much you probably wondered how someone could find them underground in a maze of cave passages dozens of miles long and find their way back out again to tell the other people involved in the rescue effort in other parts of the caves and above ground that " I found them", much less coordinate communications back and forth and allow divers and rescuers deep deep underground to communicate with people back on the surface to keep them informed as to the action plan.
The answer is extremely low frequency or vlf radio systems. .
See below for some links and history regarding the development of this system by amateur radio operators, for precisely this sort of reason. Cavers all over the world use systems like this, largely designed by amateur radio operators, because spending money developing this technology isn't of interest to the big corporate cellular carriers. They see no profits to develop this type of equipment, nor is military equipment available to or affordable by the everyday citizen.
One of the primary inventors of this form of technology and the person who made it capable of communicating for far greater distance than previous systems ever had was an amateur radio operator and design this system through the knowledge and skills he gained as an amateur radio operator.
His name is John Hey, call sign G3TDZ
This kind of rescue, and the emergency communications skills, techniques, and engineering, that amateur radio operators do is exactly why we build and develop the skills that we have. And this while more one of the unusual cases, is exactly why we do it. you can talk all you want about cell phones and cell towers in the internet, but a plain fact is that reliable cell phone communications, and the ability to access the internet without thousands of dollars in Satellite equipment, exists only in about 10% of the surface of planet Earth and practically not at all underneath it. if you want to communicate far out at sea, underground, and probably even in outer space, you better find yourself a ham operator.
https://hackaday.com/2018/07/11/ham-designed-gear-used-in-thailand-cave-rescue/
http://www.scavalon.be/avalonuk/technical/radio1.htm
Get your free copy of A Field Guide to Simple HF Dipoles
by Dan Romanchik, KB6NU
A link to A Field Guide to Simple HF Dipoles (http://www.dtic.mil/dtic/tr/fulltext/u2/684938.pdf) was posted to reddit recently, and I liked this document so much that I thought I would share it with you. It was originally written for the military, but is now available for free from the Defense Technical Information Center.
The preface to this document reads:
“Under project Agile, Stanford Research Institute has supplied several teams to assist operating personnel in improving the performance of field radio networks. In this work, it has been observed that U.S. military and civilian antenna manuals often contain misleading information regarding the operation of field antennas and tend to be overly complex. Consequently, this guide has been prepared to assist in training personnel concerned with the construction of simple HF antennas in the field.”
I must say that A Field Guide to Simple HF Dipoles does this very well. It not only explains how dipole antennas work, it also does a very good job of describing the basics of radio waves and propagation. And it does this without getting overly technical.
For example, below is Figure 10. It’s used to describe current flow in a dipole antenna.
The Field Guide reads:
“Electric current in a conductor consists of the flow of small particles called electrons. Figure 10(a) represents a dipole with electrons in it. When the transmitter is turned off, the electrons distribute themselves evenly throughout the dipole, as shown. All electrons repel each other and try to get as far from each other as possible; that is how they achieve the uniform distribution show in Figure 10(a). When the transmitter is turned on, the electrons flow back and forth from end to end as shown in Figures 10(b) and 10(c). First the electrons flow to the left and crowded at one end as shown in Figure 10(b). Second, since the electrons repel each other, the push off to the right and get crowded together at the other end, as in Figure 10(c).”
It then uses this description to talk about voltage and current distribution along a dipole antenna:
“The difference between voltage (volts) and current (amperes) in a dipole is also illustrated by Figs. 10(b) and 10(c). You can see that the maximum flow of current is going to be in the middle of the dipole. An observer at the center of the dipole would see the electrons rush past, first one way and then the other. The center is the maximum current point. Very little current flows near the end of the dipole; in fact, at the extreme ends there is no current at all for there is no place for it to go. However, at the ends of the dipole, there is a great change of voltage; when the electrons are densely packed, this represents a negative voltages, and when there is a scarcity of electrons, it represents a positive voltage. Thus you can see that the voltage at each end swings alternately positive and and negative. An end of the dipole is a maximum voltage point.”
A Field Guide to Simple HF Dipoles is packed with all kinds of goodies like this.
Download it (http://www.dtic.mil/dtic/tr/fulltext/u2/684938.pdf) right now.
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When he's not building dipoles or teaching ham radio classes, Dan blogs about amateur radio, writes exam study guides (www.kb6nu.com/study-guides), and operates CW on the HF bands. Look for him on 30m, 40m, and 80m. You can email him about your experiences with simple HF dipoles at cwgeek@kb6nu.com.
Quote of the Month
Watch your thoughts; they become words.
Watch your words; they become actions.
Watch your actions; they become habit.
Watch your habits; they become character.
Watch your character; it becomes your destiny.”
—Lao Tzu
Have a great month
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