Tech Net Notes July 8, 2009

On the day of the Net we had a bit of unexpected rain. For most of us, rain, and especially lightning, affects our radio activity. To reduce my exposure to lightning, I usually will move my radio operation to a battery powered radio hooked to an attic antenna. The base radio gets unplugged from AC. I physically unplug my power supply from the wall. In addition, I unscrew the PL-259 connector from the back of the radio and let it dangle, not allowing the antenna connector to touch anything. I do not ground the plug.

My question, to those who check in tonight is: What do you do with your radio equipment during a storm?

Ron, kb5vdb, said that he didn't know if there is anything you can do to protect yourself from a lightning strike. Air is the best insulator that we know of, and lightning passes through air easily. He mentioned that he unplugs from the AC source and may hook to a magnet mount antenna. He mentioned that he had a friend that was hit by lightning while driving a tractor. The lightning hit him in the head and came out of his foot; he lived.

The story below was found at: http//www.dailycognition.com/index.php/2007/04/27/story-of-a-man-who-was-struck-by-lightning-7-times.html.

"US Park Ranger Roy C. Sullivan from Virginia holds the record for the person most struck by lightning - and living to tell the tale. Between 1942 and 1983, Roy has the dubious distinction of being struck by lightning seven times. He was known as the Human Lightning Rod.

The first lightning strike in 1942 happened as he was working in a lookout tower and the lightning bolt shot through his leg and knocked his big toenail off.

In 1969 while he was driving along a mountain road a second strike burned off his eyebrows and knocked him unconscious. Another strike just a year later, while he was walking across his yard to get his mail, left his shoulder seared.

He was standing in the office at the ranger station in 1972 when lightning set his hair on fire and Roy had to throw a bucket of water over his head to cool off. A year later, after his hair had grown back, a lightning bolt ripped through his hat and hit him on the the head, setting his hair on fire again. It threw him our of his truck, knocked his left shoe off and seared his legs. A sixth strike hit him in 1976 while he was checking on a campsite, injuring his ankle.

The last lightning bolt to hit Roy in 1977 happened while he was fishing. It sent him to the hospital with chest and stomach burns.

Roy Sullivan was never killed by lightning - he committed suicide while in his 70's in 1983 reportedly distraught over the loss of a woman."

Mike, ke5yoo, added that on a direct hit, there's not a lot that you can do. As long as you have a good solid single point ground at your antenna, then you shouldn't have a problem. As the voltage increases from a surge, the potential may rise in all of your equipment, but your equipment needs to be unplugged. If you get hit by lightning in another part of the house, and the lightning finds another path through your equipment, you'll have damage.

It stands to reason that your exposure to lightning, or subsequent power surges resulting from lightning, is related to the exposed inputs into your equipment. For most of us there are two avenues that allow this. The AC input to your equipment is one and the antenna input to your equipment is the other. If you have computer or other devices connected to your equipment, they may also provide an avenue.

The ARRL has a two-part article that addresses Lightning Protection. The first part is found at: http://www.arrl.org/tis/info/pdf/0206056.pdf . The second part can be found at: http://www.arrl.org/tis/info/pdf/0207048.pdf .

Tim, ke5vas, mentioned that American Power Conversions has a number of Uninterruptable Power Supplies that provide a level of protection against surges, particularly power drops. He said that he is at the end of a line and suffers a lot of power drops.

APS UPSs are available from office supply stores such as: Office Depot, Office Max, and Staples. They can also be found at electronics stores, like Best Buy.

More can be found on APS at: http://www.apc.com

Paul, ae5pb, suggested the use of Polyphaser as a source for protection. "Various amateur catalogs (AES for sure) stock some Polyphaser products. Electronics supply houses generally stock a more comprehensive inventory. You can find bunches of them on the internet. These are the industry standard - USACE uses tons of them in radio and also remote sensing applications. I'll bet I've written purchase orders for over a hundred of them. Their lightning protection handbook is the best out there.

Hoffman boxes are NEMA (National Electrical Manufacturers Association) spec enclosures. Though this is a specific brand, it's kind of like kleenex or band aid, and has come to mean any such box.

AES sells one that will hold Polyphaser copper single point ground panel, with in/outs for two coax lines. I'm going to use one with three coax ports, with the Polyphasers on the ground panel inside."

Polyphaser's website is located at: http://www.polyphaser.com .

Dave, ke5lnn, said that he has extensively used Polyphasers on his rig on every coax. He had the electric company put in a surge suppressor on the other side of the meter. During a storn he unplugs everything that has a wire in it. The idea is that the coax comes into a connector outside with a copper plate. He said that he's also heard that you can use a glass insulator, like a bottle to put your connector into inside. But that could create a glass bomb!

Note: I couldn't find anything on the internet that mentioned the use of glass insulators for isolating your PL-259 connector. If anyone knows anything about this, I'd be interested in hearing about it. I imagine that unless the glass is pure with virtually no air pockets, then the heat from a lightning strike could possibly cause the air in the pockets to expand, quickly, causing a "glass grenade", much like what Dave mentioned above.

Hank, ae5mn, mentioned that his exterior antenna gets disconnected during a storm and that in the future he intends to disconnect the power as well.

Ron, kb5vdb, added that most antennas are DC grounds anyway, but that Hank's, being a j-pole, will not be.

NTS - National Traffic System

In this post we will attempt to explain NTS, what it is and what it does. The information here was taken from: http://www.arrl.org/FandES/field/nts-mpg/ and loosely paraphrased. My deepest apologies!

What did I just hear?

Do you remember the game where you would pass a message around a group of folks standing in a circle? One person would whisper a message into the ear of the next person, who would then whisper the message into the ear of the next person, until it made it all around the circle and back to the originator. Oftentimes it was humorous and sometimes amazing to see how badly the message was maligned during it's trip around the room.

In that instance, the entire group of people was like a conduit and each person was an interface that had to re-transmit the message as if a link in this chain of communication. And, as said in the proverbial analogy, "the chain was only as good as it's weakest link". It was a fun game and well illustrated how perverted a message can get when relayed down numerous "links".

In an emergency situation communication becomes supremely important and is often viewed with solemnity and reverence. When lives hang in the balance, the time for frivolity has passed, and the time for focus and sobriety is at hand. To be a link in the chain of emergency communications becomes a serious matter. If you have the opportunity to be a link in that chain, at that time, you will likely want to be a strong link.

This is much of what NTS does. It organizes, trains, prepares, and tests the links of communications. When the time comes, you just revert to your training, instead of trying to re-invent the wheel. If done correctly the information you pass along may make a difference in someone's life.

The ARRL manages and operates the National Traffic System to assure a continuing and reliable structure to handle formal message traffic in the US. Though it may not be as "lay-back" as a comfortable ragchew on an informal net, there is great value to be had knowing that you can pass traffic effectively and efficiently. When time is of the essence, there may be no valuable substitute for effectiveness and efficiency.

We, as amateur radio operators, have many resources at our disposal for communicating. Not only to we have a number of bands available, but we also have a variety of modes available, such as voice, CW, SSB, and digital, and we have a multitude of delivery systems, horizontal, vertical, NVIS, or reflected off satellites. When an emergency occurs, we often have the means to relay vital information.

"The Fingerbone's connected to the Wristbone, and the Wristbone's connected to the Armbone"

So how do we all connect to each other in order to facilitate effective and efficient emergency communication? It all starts at the local level with ARES. The Amateur Radio Emergency Service. When you affiliate with ARES, you become a link in this recognized chain of communication.

Local ARES Nets link to
District Nets who link to
Section Nets and Traffic Managers who link to
Region Net Managers who link to
Area Net Managers who link to
NTS who links to
ARRL HQ

Of course, it may be a bit more complicated than that, but that is a general idea of how it works.

Tech Net Notes May 29, 2009

On this evening's net the topic was NVIS. After a brief description of Near-Vertical Incident Skywave (much like the post below this one), we opened the net for check-ins.

ke5okt, Jim, checked in with a question. He has a KendeCom, model KRP-5000 repeater and can't find much information on it. He asked if anyone has information on this brand, such as how to find parts and documentation. kb5vdb, Ron, mentioned that aa5v, Steve, may have a repeater of that brand in his garage, and may know something more about them. Steve is a member of TRO and may be contacted through the club. If anyone has information they think Jim might be able to use about the KendeCom repeaters, he can be contacted at jim@mounds.org.

n5tda, Rex, mentioned that he has a G5RV up at about 25 ft., which would be less than 1/4 wavelength and would fall into the NVIS category. He mentioned that he was not able to get within the 500 mile skip zone at that height.

ke5lnn, Dave, asked if NVIS is in wide use by any particular amateur radio groups. In addition, Dave has a TE Systems 1412G, 2 meter amplifier. He says it works fine on two meter but doesn't work on 70cm. He has heard of a mod that can be done to allow it to work on 70 cm and wants to know if anyone knows how to install that mod. w5ydl, Dan, says he also has one of those amplifiers and that he too would like it to work on 70 cm, but doesn't know how to install the mod. Dave mentioned that he may be able to reach someone at TE tech support who can help.

ka0oxn, Rich, said that he had a 160M installed at about .o4 wavelength height that was good out to about 400 miles. He also had a 40M installed at 10 ft. that was good to about 300 miles.

na5dw, Dan, said that he would like to find a way to get his HF signal from Fairplay, CO to Denver, CO, about 90 miles. He tried a dipole hooked up to his truck's tailgate, on one end, and to a signpost on the other end, about 3 ft. high, 20M or 40M, and couldn't quite make the trip.

ae5ft, Gene, said that n5fem, Steve, was talking into the Dallas, Texas area on 40M, on the NVIS dipole mounted at 5 ft. at the last Route 66 event in Chandler Park. He also mentioned that he uses an NVIS antenna every day to check into the Oklahoma Sooner Traffic Net, which is a part of the National Traffic system Net. His antenna, he calls an "extreme" NVIS antenna, which is a G5RV mounted along the top of his wooden fence at about 6 ft, with about 10 ft. of wrap on each end, fed with about 30ft. of twin-lead and a short piece of coax. He says that he is about 90% effective getting into the net on 80M. He says he's worked both coasts during the Route 66 Contest where folks were trying to make contact with him as a Route 66 station. So it may not be all that good of a test, coast to coast.

ae5mn, Hank, mentioned that this might be an HF solution to his problem of finding something that would fit in with his neighborhood covenants.

kk5edd, Ed, said that he's in the process of building an NVIS antenna, from plans of Dr. Carl Gellenik, n6vng, with two 38ft. elements and then at 90 degrees from them, two 25 ft. elements. The design calls for a threaded center conductor on a SO-239 plug, which Ed is having trouble finding/fabricating. Ed would appreciate hearing back from anyone who might have information on how to find a threaded SO-239 center connector such as this.

ae5ft, Gene, mentioned also that in NVIS applications, we have to look at the maximum usable frequency. That is the maximum frequency that will bounce of (versus penetrating) the ionosphere. That "maximum frequency" can depend a lot on conditions, sunspot activity, and etc. Gene mentioned that 40 M is "iffy" on NVIS, which may explain na5dw's, problem making a 90 mile trip in Colorado. The other thing Gene mentioned, is that when you're looking at 80M NVIS, that's what most dipole installations are, to at least some degree. Few of us can afford to construct 120 ft towers for your dipole!

ke5und, Travis, checked in and mentioned that he's used NVIS technology inadvertently. He understands the principle but now knows what to call it. Travis asked if NVIS relates more to angle of take off. ae5ft, Gene, answered that yes, angle of take off is one of the parameters that NVIS defines. Travis mentioned also that this is probably why he can make it in to Albuquerque, NM but can't quite make the trip into Arizona.

NVIS (Near-Vertical Incident Skywave)

What is NVIS?

Near-Vertical (meaning somewhere around straight up) Incident (an event, something that happens) Skywave (the reflecting of a signal, usually RF, off the ionosphere). Think of it as pointing your antenna straight up and having the signal "shower" down all around you.

NVIS - compared to what?

Think of the two modes of antenna orientation with which we are most familiar: vertical and horizontal.

Vertical - line of sight, groundwave propagation

Horizontal - long-distance, skip

'Splain yourself!

If you can talk about 50 miles on a vertical antenna predictably, and on the horizontal plane you can pretty much count on shooting over most stations that are closer than 500 miles away, NVIS is a method that you can use to fill the gap (skip zone). NVIS allows you to have more reliable communications with stations within a 100-200 mile range.

Great! How do I do it?

You do this by directing your signal straight up. Rather than pointing your beam directly overhead, you can do it the easy way. Cut a dipole to the desired frequency, and install it less than 1/4 wave above ground. Last September at the Route 66 event in Chandler Park, N5FEM, Steve, installed one at about 5 feet and did very well with it. By installing it closer to the ground, you are using the ground as a reflector. In a sense, it becomes an upward pointed beam.


Putting One On Top of a Hill

Well...yes you can...but...with valleys generally containing more moisture than hilltops, often-times you get a better reflection in a valley. And, after all, you're directing your signal upward, so a valley may be more advantageous, especially if you're trying to avoid detection (military applications).


What Bands?

Generally speaking, 160M, 80/75M, 60M, & 40M is where you can use this system most effectively. As we have learned, the higher frequencies will tend to penetrate the ionosphere more, and reflect off the ionosphere less.


Why bother?

In an emergency or if you have friends within the dreaded skip zone (200 miles), this allows us to have fairly predictable communications. Skipping on the horizontal plane is not that predictable, and where it is predictable, may not be that useful. On the vertical plane, line-of-sight may not cut it. You often need more. NVIS fills the gap between the two.

You can read more about this at: athensarc.org/nvis.asp

Tech Net Notes May 13, 2009

Without much of a topic, the net began with a string of check-ins from Ron's, kb5vdb, group. There were storms looming around Oklahoma and Ron kept an eye on things for us with regular updates.

ke5yoo, Mike, started off with a question regarding a problem he was having with RFI. On 10 meters, Mike has been getting into his (and worse yet, his neighbors') wireless phones. Mike wanted to know if that was a common problem (on 10 meters) and if anyone had experience with fixes for that kind of problem. ke5omv, Don, stated that he had a similar problem on 10 meters, on with his computer, when he keyed up the computer locked up.

w2csl, Bob, asked what frequency the phones were on and mentioned that (older) 50 Mhz phones are near a harmonic of 10 meters. ke5yoo, Mike, responded that the phones were in the 2 Ghz range.

kb5vdb, Ron, suggested that K-COM makes a line of telephone filters that are sold through AES and can probably be found in AES's online catalog. In addition, the higher he could get his 10 meter antenna, the better for reducing chances of nearby RFI.

ae5mn, Hank, checked in and mentioned that his Fong Dual-Band Twin-Lead J-poles are doing well. He mentioned that he was surprised at how well his smaller Fong antenna was doing mounted in the attic. He said he enclosed it in a protective sleeve normally used around fluorescent tubes. It's a thin, clear tube of plastic with caps. Hank has it installed near a gable in the attic. Though he normally has problems getting into the 910 repeater, with that set-up, he seems to be doing fine.

ke5wga, Ray, checked in and gave a report on his GP9 look-alike, the Tram WP 1481. Ray just installed it last week and has it about 25 ft. in the air. Ray mentioned that he felt he did fairly well moderating the Saturday Night Simplex Net with it. He said he was able to talk to all that he heard.

ke5yoo, Mike, was asked what kind of antenna he was using that caused the RFI with wireless phones. Mike responded that it's a G5RV junior.

wb5uuw, Earl, cautioned to make sure that the coax, where you hook up to the balun is 35 ft. long. The ladder line should be about 17 ft. long with a 4:1 balun.

ke5uiu, James, said that he has a G5RV (full size) with 45 ft. of ladder line, a 1:1 balun, a 100 ft. of coax and can talk well on it. He would like to be more directional and is planning on a rotating dipole for sometime in the future. Being in Porum, he can hit the 910 repeater with his 4-element beam on low power. To get to Bartlesville on 2-meter he has to bump the power up to 25 watts.

kk5edd, Ed, questioned if anyone had built an NVIS, 4 radial, antenna. ae5pb, Paul, came back and mentioned some positive experience he had with it, through the military and that two legs are cut for 80 (moderator: I think!) and the other two are cut for 60 meters.

ke5icx, Tom, checked in from a Broken Arrow motel room. He is visiting the area and heard the net.

End of Tech Net

(Note: If you have any corrections or additions to these notes please leave them in the comments section. I did not take as good of notes as I would have liked, so if there are other cogent points that were made (or that you would like to now make)that I missed, please let me know.

Another contest station - these guys are serious!

http://www.qth.com/w0aih/

Tech Net Notes April 24, 2009

We opened up the net at around 9:00 p.m. and were immediately plagued with problems, kf5rd, Pete, had trouble linking things up through his HT and had to tap ae5ft, Gene, for some help. Then as we began talking and asking for check-ins, the QRM went crazy. It sounded to me, at first, like the squelch tail was incredibly long on the VHF machine and that someone was trying to get into a linked UHF machine and wasn't making it. So it would take several seconds (maybe 10-20, it seemed) for things to settle down.

But we pushed on.

The topic was logging software. I had posted several logging programs on this blog with their web address and cost just a few days ago. (It is two down from this one.) So most of the programs that came up were mentioned on the blog already. That being said, the big question was, "What experience have you had?" My experience was limited, but there were several folks who had good info to share.

It went like this:

kc5eqj, Scott, mentioned that the University station in Fayetteville uses N3FJP logging software. He had used it but was interested in hearing about any software that might be better suited for personal use. ke5lnn, Dave, said that he had recently been looking at G8PUT, which was recently reviewed in QST. ae5ft, Gene, added that the N3FJP software is excellent logging software, especially for contesting, and the cost is reasonable $50 for all the options. He agreed with ke5lnn, Dave, that G8PUT looks like it has some great features. He added that XMLOG is free, and the one he uses, MicroLog is only $10 and includes an up-to-date logbook.

ke5lnn, Dave, added that he just downloaded G8PUT, and has started using it. He said that he's been contacted by the company that an update is already in the works. One feature he likes is that you can push a button and see if you've ever made contact with the folks you just logged in.

ke5zcz, Mike, liked the sound of the G8PUT mentioned in QST, but thought he might need something simpler to start out with.

ae5ft, Gene, further mentioned that if simple is what you want, try eQSL. It is an on-line logging system and offers a whole set of electronic awards. It allows you to make and send electronic QSL cards as well. But if you want a program that you download into your machine and can use, independent of the internet, MicroLog is simple and has the added feature of the callbook data.

wa5vxi, Manuel, mentioned just using a Microsoft Excel spreadsheet. He also said he was aware of Ham Radio Deluse having a logging function along with it's radio control software package.

kc5zqm,Doug, said that he didn't have a lot of logging experience, but when he did log, he used a form that he designed with AutoCad. He also suggested a future Tech Net Topic of "Mobile Installations and Operations". (Note from moderator: That sounds like a great topic to me!)

ae5ln, Paul, had a question, "How does logging software track a frequency?" ae5ft, Gene, clarified with an explanation that new radios sometimes have a feature that allows a plug in the back of the radio to cable up to a plug to your computer, with the radio supplying the usable data to the computer. Older radios often lack that feature.

kc5ert, Jeff, mention that he bought a copy of MicroLog at Green County Hamfest this year and is looking forward to trying it out on Field Day. He likes it because it works, "stand alone" without the need to be hooked up to the internet. He said he had heard that if you have an old copy of MicroLog, you can download the current call book information. ae5ft, Gene, mentioned that Jerry (the owner of the software company) mentioned that he does not have that available for downloading and that you must buy a new CD to get the callbook (only $10 at hamfest, $12 over the net).

End of Tech Net