WT8WV “Colossus” Air Cannon Antenna Launcher
These are the basic parts to make my “WT8WV Colossus” antenna launcher.
Folks, this has been a fun and hilarious winter project. Yesterday, when I built this air cannon antenna launcher it was -4 degrees outside and this was a perfect evening project to put together. For years, me and my two ham radio buddies (WR8S Bill Shultz and WV8TG Tom Graf), have enjoyed ARRL Field Day activities and usually used a slingshot and a 3/4 ounce fishing sinker weight and an old Zebco fishing reel (with 20 pound test line) to shoot and suspend our doublet dipole antennas high into the trees. Certainly, the slingshot worked pretty much flawlessly… but… boys will be boys, and the idea of an air cannon / spud launcher / potato gun type system seemed to be a new desire. (Most people, our wives included, wouldn’t trust our 3-man team with a slingshot, let alone a potato gun! But I digress.) Actually, our local ham radio club (Monongalia Wireless Association) had a version of a potato gun antenna launcher, so we decided we needed one of our own… and to make some design modifications in the interest of… “science”… plus our own sadistic pleasures. (Make sure you read below WV8TG’s initial “pressure test” experience.) The following pictures hopefully provide the basic concept and parts we used. Tom and I split the cost of the parts needed to make launchers and each built our own version, but they both are the same basic design with only length dimensions of the air chamber and barrel being the difference.
All parts where sourced from our local Lowes store in their plumbing department, except the Schrader valve which can be purchased at an automotive store. Total cost about $40 but you could make a couple of them as a joint project with a friend and reduce that cost per launcher a bit. I got a small rubber gasket for the outside nipple of the Schrade valve to act as another seal on the exterior of the air chamber. You will need to drill holes for Schrader valve, barrel slug stop and projectile slug caps to attach the screw eyes to attach the fishing line. I used 3 inch PVC for air chamber, 1.25 inch PVC for the barrel and short sections to mate the air chamber, trigger valve and threaded barrel. The projectile slugs were made from 3/4 inch PVC and caps and I filed off the nubs on the caps with a Dremel tool for a smooth fit into the barrel. I used PVC Prep on each joint before applying the glue. When gluing joints together, insert the sections together and twist a quarter turn for a solid adhesion. Let all glue set up for 24 hours before testing air pressure chamber. I will pressurize the chamber inside and let it sit overnight to see if it loses any pressure. It’s too cold right now to take outside in -4 degree temperatures to test, but I will use a bicycle pump with a pressure reading valve, and start at 40 psi… then 50 psi… and then 60 psi for test shots to see how it functions and check for any air pressure leaks. We use 60 psi for our club launcher.
WV8TG (Tom) charged his air chamber (barrel not attached) and let it set overnight to test for chamber air leakage. When he opened the trigger value… there was NO leakage… but there was a sudden LOUD release of 60 psi air gush out of a 30 inch long, 3 inch wide fully charged air chamber. He indicated the compressed air release was… impressive. However, his wife was not impressed… nor was she aware of the scientific test that was taking place. #surprise! #WHOOOOOOOSH #loudwifeexpressions I have no reason to doubt Tom will find his projectile slugs in the next county using his design. The club chamber was 12 inches long versus his 30 inch air chamber. #overkill? I designed my air chamber for 14 inches and will conduct all tests… outside. #potentialmeanwife
Try an HF Net… Rack up those States and Countries FAST!
I was rolling across the 40 Meter band one night and hit a nightly net called the OMISS NET (Old Man International Sideband Society) and there was a busy back and forth between stations making a call sign and signal report in a very orderly way on 7.185 MHz LSB. So, I tuned up (off frequency) and when they called for “check-ins” I threw my WT8WV call sign in and they called me back and the next thing I knew I racked up 14 new states in about an hour or so! The next night I added 10 more states! They have nets on most of the HF frequencies and can be found on their website.
OMISS 101
OMISS, or Old Man International Sideband Society, has been operating list-type awards nets on the General Amateur bands since 1981. Want to get your WAS quickly? This is a great place to get it done. Do you like to work lots of stations for unique awards? We have several challenging awards to work for, each with an attractive certificate to hang on your wall. Do you like contesting? We hold an annual QSO Party and invite the whole Amateur community.
The real cool thing is they use a free software program called NETLOGGER (see info on Netlogger below) that is an online logging server that shows in real time who has checked into the net and available to be contacted. When it’s your turn, you call who you need and make the exchange with them. Then as you listen someone might want to call YOU to get your state! Slick as a whistle! For a one time cost of $7 you can get your own OMISS Number (i.e. 10722 is assigned to me) and you log in with it each time for a speedy check-in process and it is also tied to numerous awards you can get.
Perfect CW / Morse Code Trainer
This program G4FON Koch CW Trainer has been a joy to play with and learn from. I am wanting to increase my Morse Code speed skills and this is a perfect way to do that! I am wanting to get back into CW but have gotten rusty from not practicing for years. I seem to be stuck at copying about 7 words per minute. My goal is 20+ words per minute so I can help rack up more points at Field Day events! The key, I have now found, is to HEAR letters at 25 words per minute… but at a longer spacing between them when received, and then begin shortening that spacing time over a period of practice sessions.
I have it set to send the individual letters at 25 words per minute (wpm). I am starting at the time between those letters at 10 wpm. I started with two letters and would copy just those two for a few minutes in one minute drills. Once I get to 90-100% copy, I add another letter! I practice about 15 minutes each night, if I can. I am halfway through the alphabet now and having a ball. It is easy to download and configure… you’ll be instantly surprised at how much fun it is!
You Need Your Own QSL CARD
I know, I know… we have QRZ and eQSL and LOTW (Logbook of the World) and Ham Radio Deluxe (HRD) and Netlogger and N1MM and… blah, blah, blah. An old fashioned paper QSL card is still sweet to hold in your hand and to enjoy the real memory of a fun contact. Especially if it’s a DX station from a far away land toward DXCC or the last state you needed for WAS.
They aren’t as expensive as you think. For simple black and white cards you can buy 100 cards for about $12… my color card above cost about $30 for 100 of them. I got mine from Cheap QSL’s on the internet and they sent the proofs the same day and shipped them out the same day! Most folks are migrating toward electronic QSL’s these days. I predominately use Ham Radio Deluxe (HRD) Logbook for my main logging software but also upload my logbook to eQSL, QRZ and LOTW every couple days of logging, however if someone requests a paper card I will oblige. Sooooooooo… if I do that once in a while I’ll have about 65 cents in the effort by the time I add postage. Below is a Special Events Station I worked and got this electronic QSL a few days later…
Merle Taylor: Maven of Morse Code
When this Manitoba farm girl joined the Royal Canadian Air Force, she proved to be such a whiz at Morse Code that she was assigned to instruct the air crews. Now almost ninety-three, Merle still practices her dots and dashes every day, claiming that Morse Code keeps her mind sharp.
Merle Taylor of Lochaber, Nova Scotia, wrote to me after reading my column in The Senior Paper, a newspaper widely distributed to seniors across Canada. (If you haven’t seen a copy yet, email me for more information).
We exchanged copies of our books – I sent her my wartime novel, Bird’s Eye View; and she sent me a copy of her memoirs, Until the Cows Come Home.
When my husband and I travelled to the Maritimes recently, I was determined to meet Merle in person. We found her still living on the farm she operated with her husband Fred since 1946, about thirty kilometres south of Antigonish.
After serving lunch to us, Merle took me on a farm tour in her electric golf cart. I loved hearing her stories of life in the air force, and in the decades since then.
Programming Your New Ham Radio… the Easy Way!
I recently took a deeper dive into digital ham radio and picked up a Yaesu FTM-100 mobile System Fusion rig. VHF and UHF… 500 Channels on each band! Holy Crap, Batman… I’ll wear my aged, stubby, fat fingers to the nubs tryin’ to poke all that individual channel info into those 1,000 spots using those little buttons! Plus, I have to look up all that info… somewhere… on EVERY channel I want to add to my line-up. Ain’t no-body gotz time for dat! (I also had to do that with my Baofeng UV-5RV2+ portable HT a couple years ago.)
What to do? Path of least resistance! Did a little research and found a computer program that does it all for me. (I actually used the free CHIRP software to program my HT a couple years ago.) RT Systems software makes the programming easy! You simply pick out your software version based upon what radio you want to program, download the software, (Hopefully your radio came with the right interface cable to hook your radio to your computer to make the download of freq’s to your rig.), grab the repeater frequencies from some site like RFinder World Wide Repeater Directory and in 20 minutes you can load up your rig with more frequencies than you will ever use. (While CHIRP is freeware, RT Systems and RFinder software platforms are paid versions. I can honestly say that the software is very reasonably priced for both and you might only need to use it once in a while but it saves you HOURS of manual poking and prodding your radio buttons.)
(Click link below to see the typical instructions)
Radio Programming Software for the Yaesu FTM-100
(See the videos below…)
You can easily marry RT Systems software to RFinder software and quickly create a sort routine that grabs the EXACT frequencies you want and transfer it to your radio. You can sort by town, state, zip code, ham bands, NOAA frequencies, etc.
It makes short work of all of it! You’ll spend more time convincing yourself to not pull in frequencies you will never use than the download takes!
Once you set up your channel database you want to use for your radio, you simply hook your radio to your computer with the cable… poke a couple drop-down menus… and then the magic happens! UPLOAD COMPLETE.
I programmed about 75 VHF and 75 UHF Channels into my radio, start sort to finish sort to upload compete in under 20 minutes. You might export your databases to your laptop or website to store for the future.
One thing I did that sort of brought sanity to my programming strategy and thinking was that I added the freq’s in sort of “banks” of channels so I could visually sense what channels I needed to tune to depending on my car’s location as I traveled. For the first 10-15 channels, I loaded repeater data for the local area repeaters within about 75 miles of my home QTH. I live just below the Mason-Dixon Line… and yes, I consider myself a southerner but I can be in Pennsylvania within 10 minutes; in fact, I can be at the Pittsburgh International Airport in under 90 minutes! So, since I travel a good bit for work, I can bounce to various repeaters as I drive in any direction!
In the next grouping of channels I might add just the Pittsburgh area repeaters. In another group of channels I added the Dayton, OH repeater freq’s since my daughter and son-in-law live and work next to Wright-Patterson AFB and I also usually attend the Dayton Hamvention each year. Another group of channels I include are the NOAA Weather Channels. Other groupings include various regions of West Virginia since I also hunt, fish, camp and hike all over the place.
Morse Code: Straight Key and Others
I enjoy a niche of ham radio called Continuous Wave (CW) / Morse Code sending and receiving. There are all sorts of hand keys out there to use. Lots of CW Contests occur every month for all levels of CW enthusiasts… you don’t have to send fast, if you don’t want to! It’s a very efficient system of communicating when traditional modes of messaging are out of service, too. Some say since the advent of the telephone and then the cellphone, it is a dying art… I say it’s a BLAST to do!
Every ham ought to try a little CW every once in a while. Find a key you like and use it periodically to stay proficient but also pick up a straight key and join the annual Straight Key Night Contest around New Years. (It’s not really a contest; it’s more of an opportunity to pull out a straight key and try sending Morse Code the old fashioned way.
I love to scour the hamfest flea markets looking at all the old time keys available to buy for a variety of prices. Some served in Post Offices, Telegraph Offices, military communications, in combat and in ham shacks! My favorite straight key is a 1950’s era South African Special Forces straight key… super compact… light weight… and darned cute… that I picked up at the Dayton Hamvention in 2015! It wasn’t cheap, but it’s unique and has a good story. See some of the key configurations below…
Bencher Paddles and Memory Keyer UNITE!
As soon as I get my Yaesu System Fusion FTM100-DR online, I want to mate my Bencher paddles to the new MFJ-490X Menu Driven Memory Keyer that I picked up at the 2016 Dayton Hamvention last week (May 21, 2016). I am itching to get these two toys working in some CW / More Code Contesting very soon! 5 programmable memories plus all sorts of keyer speed, weighting, side tone, hand key capability, serial number decrements, random code practice, iambic settings, etc.
(See video below!)
MFJ-490X Memory Keyer Instruction Manual
APRS… from the inventor, Bob Bruninga WB4APR
I would venture to say you can’t do better than hearing it from the inventor himself!
Automatic Packet Reporting System overview by its inventor, Bob WB4APR given at the HACDC Amateur Radio Club. For more information about APRS, go to http://www.aprs.org For more information about HACDC Amateur Radio Club go to http://www.w3hac.org
REVIEW: Yaesu Fusion FT2DR dual-band digital portable radio
This is a solid review by Don Trynor from VA3XPR from July 2015 of the Yaesu FT2DR dual-bander HT. (They have a very nice website!)
Our local ham radio club, Monongalia Wireless Association, recently bought 2 of the Yaesu Fusion repeaters and I am doing my own research into being able to enjoy a new type of technology. I am looking at my options and hope to find something to get my hands on at the 2016 Dayton Hamvention! I would think that prices would be moderating downward by now as others adopt the new radio and there may be some rebates floating around or “Specials” by some of the dealers. (Read Don’s full review here… Review: Yaesu Fusion FT2DR dual-band digitl portable radio )
The FT2DR is a good choice for anyone looking for a full-featured dual-band portable radio that is compatible with Yaesu’s Fusion line of digital radios. While this radio has some innovations, we think that they may not justify the $550 USD price point of this unit. In addition, we feel that Yaesu could improve upon future radios like this one, especially as it relates to the overall user experience. In this day and age when a good user experience for touch screen devices is the norm, such as with smartphones and computers, we think devices like this have room for improvement. All in all, if users can live without the touch screen display and louder audio, they might want to consider a cheaper alternative in the Yaesu FT1DR, which retails for $300 USD.
- View Original
- July 18th, 2015
Amateur Radio Go-Box and Go-Bags Examples
Ham Radio Operators need to be ready to roll out to a crisis quickly if it requires communication support. Are you ready to “grab and go”? How quickly could you have a functional ham radio station on-the-air ready to support an emergency situation? Could you support your local authorities efforts, and for how long? Can you personally sustain yourself with food and water for 3 days of support, without being a burden on the emergency relief efforts? Constructing your own version of a “Ham Radio Go-Box” and a “Go-Bag” might be a great addition to your preparedness efforts. Below are some pictures of potential Go-Boxes to stir your imagination and creativity. You might even have some of the items laying around that could be put into the effort to BE PREPARED.
GO-BOX IDEAS
GO-BAG IDEAS
How Does a Crystal Radio Set Actually Work?
Here is an excellent YouTube video from RimstarOrg that breaks down the concept of how crystal radios actually DO their magic! Yes, MAGIC. Radio signals are all around us 24 hours a day. Invisible! You can’t really touch them. You can’t smell them. You can’t hear them without assistance. We don’t really feel them bombarding us. We don’t sense those signals without some mechanical help… but they strike us with many different frequencies constantly… so let’s explore the range of frequencies we can decipher with a homemade crystal radio set!
Crystal Radios. A blast from the past!
Many of us have looked at, or even built a crystal radio set at some point in our lives. Maybe it was in our Scouting days, youth group, science class, science fair… or just to DO IT! The circuit itself is relatively simple to wire-up. A long piece of wire acts like an antenna. Some configuration of earphones or speaker will let you listen to signals. And believe it or not, the signals are all around you! The local AM radio station should be easy to hear. You can even build a simple pre-amp (pre-amplifier) circuit to boost the incoming signal to add extra volume and signal strength to the fun.
Let’s understand WHY a crystal radio set is sooooooo cool! SIMPLE CIRCUIT DESIGN. EVEN KIDS CAN DO IT! EASY TO GET PARTS. NO EXTERNAL POWER REQUIRED. INTERCEPTING INVISIBLE RADIO WAVES THAT ARE ALL AROUND US. Plus, it’s just a pile of fun!
Here is a YouTube video from WonderstruckHow who teaches us to build a very rudimentary crystal radio set with parts that are easy enough to scrounge up.
After you watch the video check out the picture gallery of all sorts of crystal radio sets that can be built in just a short time. They are great for kids working on a science fair project (and sure beats out a terrarium!) Some of us “Seasoned Citizens” might actually remember the paper towel tubes or Quaker Oat cardboard cans we wound the magnet wire around and even some of the commercial kits sitting under our Christmas tree!
Straight Key Night… FUN!
Every January 1st there is a fun filled evening of laid back, “no pressure” CW (Morse Code) operating using a simple “Straight Key” to key your transmitter without the aid of added electronics to perform the speed and spacing of your sent letters and numbers. This isn’t a contest! It is designed for fun sending CW the “old fashioned” way. The object is to simply enjoy sending and reading Morse Code. There are numerous configurations and sizes of straight keys and a jaunt down any ham radio flea market aisle will often give you quite a few options for a great purchase!
Here is a video example of the annual Straight Key Night experience. MIKROWAVE1 explains and actually makes CW contacts with other amateur radio operators enjoying the annual event. (Below the video, look for some pictures of several types of straight keys you might find as a bargain to add to your own ham radio station!
Here are some pictures of various CW (Morse Code) keyers. You can grab several to use for contesting or just simple rag-chewing. Some hams actually collect various types of keys!
Famous Ham Radio Operators and their Callsigns
I love learning who shared our favorite hobby… and the list is very long! It was so interesting to see not only WHO they were but also WHAT they did to be famous. Literally from every corner of the globe (try and find a corner on a globe).
I found this on the DX-QSL website and somehow the Bedworth Lions Club apparently had something to do with the creation of the list. I am quite fond of the good work The Lions do and I belong to a couple fraternal organizations (Masonic Lodge and Woodmen of the World) myself, so I am sure there is a story about The Lions being connected to this list. The list is long, so grab a refreshment and enjoy! Be prepared to be surprised!
Click the link below…
World Famous Ham Radio Operators
Amateur Radio, Radar, Lidar & Radio on Postage Stamps
I love collecting stamps and vintage baseball cards and have quite a collection of both… but I have NEVER seen this many RADIO STAMPS in one setting! Kirt Blattenberger, KB3UON, has a really cool website with lots of neat things to read. This caught my eyes INSTANTLY. Thank you, Kirt! His quote and stamp array begins below.
************ ************ *********** ********** ***********
Over the past many decades, my involvement in stamp collecting (philately) has waned and ebbed with the amount of time available to dedicate to it. Commemorative stamps – from all countries – have always been of the greatest interest to me. Even if you are not a philatelist, your interest in radio should be piqued by the large number of postage stamps that have been issued in radio’s honor. Although I do not own most of the stamps pictured here, there are some that are in my collection. This is a small cross-section of what is available. Over time, I have added to the list and will continue to do so. Please let me know if you have relevant stamps to add.
I was amazed to discover how many countries have postage stamps recognizing the important role that weather radar has played in history.
Note: Many of these images are uncredited because although I might have retrieved them from a particular website, they appear to be replicated in many places. Therefore, the true origin is not known. My policy is to always provide attribution as part of the “Fair Use” law when the source is certain. I will be glad to link back to the owner’s website if evidence of ownership is provided.
| Amateur Radio Postage Stamps | ||||
 Amateur Radio USA Postage Stamp |
 Amateur Radio Luxembourg Postage Stamp |
 Amateur Radio China Postage Stamp |
 Amateur Radio Germany Postage Stamp |
 Amateur Radio Bosnia Postage Stamp |
 Amateur Radio Japan Postage Stamp |
 Amateur Radio Canada Postage Stamp |
 Amateur Radio Viet Nam Postage Stamp |
 Amateur Radio Bulgaria Postage Stamp |
 Amateur Radio Bhutan Postage Stamp |
 Amateur Radio Bulgaria Postage Stamp |
 Amateur Radio Zazzle Postage Stamp |
 Amateur Radio Russia Postage Stamp |
 Amateur Radio Zazzle Postage Stamp |
 Amateur Radio Poland Postage Stamp |
 Amateur Radio Qatar Postage Stamp |
 Amateur Radio Tuvalu Postage Stamp |
 Amateur Radio Slovania Postage Stamp |
 Amateur Radio Austria Postage Stamp |
 Amateur Radio Sweden Postage Stamp |
| Radio Postage Stamps | ||||
 Radio USA Postage Stamp |
 Radio USA Postage Stamp |
 Radio USA Postage Stamp |
 Radio USA Postage Stamp |
 Radio USA Postage Stamp |
 Radio USA Postage Stamp |
 Radio East Germany Postage Stamp |
 Radio Slovenia Postage Stamp |
 Radio Russia Postage Stamp |
 Radio Canada Postage Stamp |
 Radio Germany Postage Stamp |
 Radio East Germany Postage Stamp |
 Radio Russia Postage Stamp |
 Radio Belgium Postage Stamp |
 Radio Russia Postage Stamp |
 Radio Pitcairn Island Postage Stamp |
 Radio Tuvalu Postage Stamp |
 Radio India Postage Stamp |
 Radio Moscow Postage Stamp |
 Radio Gremany Postage Stamp |
 Radio Republic of Transkei Postage Stamp |
 RadioRadio Republic of Transkei Postage Stamp |
 RadioRadio USSR Postage Stamp |
 Radio Monte Carlo Postage Stamp |
 RadioRadio Cuba Postage Stamp |
 RadioRadio Romania Postage Stamp |
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| Radar Postage Stamps | ||||
 Radar China Postage Stamp |
 Radar Antenna Barbados Postage Stamp |
 Sea Radar Solomon Islands Postage Stamp |
 Radar Altimeter Gilbert & Ellice Islands Postage Stamp |
 Meteor Tracking Radar Fiji Postage Stamp |
 HF Radar France Postage Stamp |
||||
| Weather Radar Postage Stamps | ||||
 Weather Radar Jamaica Postage Stamp |
 Weather Radar Belize Postage Stamp |
 Weather Radar North Korea Postage Stamp |
 Weather Radar Iran Postage Stamp |
 Weather Radar Iran Postage Stamp |
 Weather Radar Senegal Postage Stamp |
 Weather Radar Philippines Postage Stamp |
 Weather Radar Qatar Postage Stamp |
 Weather Radar Libya Postage Stamp |
 Weather Radar Malagasy Postage Stamp |
 Weather Radar United Nations Postage Stamp |
 Weather Radar Viet Nam Postage Stamp |
 Weather Radar Taiwan Postage Stamp |
 Weather Radar Spain Postage Stamp |
 Weather Radar Central African Republic Postage Stamp |
 Weather Radar Belgium Postage Stamp |
 Weather Radar Afghanistan Postage Stamp |
 Weather Radar Austria Postage Stamp |
 Weather Radar Bahamas Postage Stamp |
 Weather Radar Bahamas Postage Stamp |
 Weather Radar Afghanistan Postage Stamp |
 Weather Radar Bangladesh Postage Stamp |
 Weather Radar Canadian Postage Stamp |
||
| Lidar Postage Stamps | ||||
 Lidar France Postage Stamp |
 Lidar Australia Postage Stamp |
|||
| Electricity Postage Stamps | ||||
 Electricity British Postage Stamp |
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| Also of interest are Radio Reception Stamps that were used by commercial radio stations to officiate reception of signals. These were not official Postage Stamps | ||||
 KDKA Pittsburgh, PA Radio Reception Stamp |
 KFUM Colorado Springs, CO Radio Reception Stamp |
 KFSO San Francisco, CA Radio Reception Stamp |
 KFQZ St. Louis, MO Radio Reception Stamp |
 WTIC Hartford, CT Radio Reception Stamp |
 CNRO Ottawa, Ontario Radio Reception Stamp |
 WDAF Kansas City, KS Radio Reception Stamp |
 WBEN Buffalo, NY Radio Reception Stamp |
 WGBF Evansville, IN Radio Reception Stamp |
 WSYR Syracuse, NY Radio Reception Stamp |
A more comprehensive list can be found on the Ground-Based Remote Sensing in Meteorology (Radar, lidar, sodar, etc.) website from Cooperative Institute for Research in the Atmosphere (CIRA) at Colorado State University.
This website has a few other communications Postage Stamps.
Yet another source is Joseph Morris‘ Flickr collection.
Near Vertical Incidence Skywave (NVIS)
I love DX. I love chatting to interesting people all over the world and making new friends. For short range chatting I use our Monongalia Wireless Association W8MWA Repeater on the 144/440 frequencies. Sometimes it’s more difficult to talk short distances than it is to talk half way around the world. Let’s consider Near Vertical Incidence Skywave (NVIS) antennas with our HF radios.
NVIS is something every Ham needs to learn about. The antenna system is not difficult to construct and can serve an important function for shorter range communications, especially in time of an emergency when normal local / regional communication systems are down for some reason. (i.e. cell towers, cellphones, landlines, etc.) Hams may be called into service quickly.
Here is what Wikipedia says about NVIS communications…
Near vertical incidence skywave, or NVIS, is a skywave radio-wave propagation path that provides usable signals in the range between groundwave and conventional skywave distances—usually 30–400 miles (50–650 km). It is used for military and paramilitarycommunications, broadcasting,[1] especially in the tropics, and by radio amateurs. The radio waves travel near-vertically upwards into the ionosphere, where they are refracted back down and can be received within a circular region up to 650 km from the transmitter.[2] If the frequency is too high (that is, above the critical frequency of the ionospheric F layer), refraction fails to occur and if it is too low, absorption in the ionospheric D layer may reduce the signal strength.
The most reliable frequencies for NVIS communications are between 1.8 MHz and 8 MHz. Above 8 MHz, the probability of success begins to decrease, dropping to near zero at 30 MHz. Usable frequencies are dictated by local ionospheric conditions, which have a strong systematic dependence on geographical location. Common bands used in amateur radio at mid-latitudes are 3.5 MHz at night and 7 MHz during daylight, with experimental use of 5 MHz (60-meter) frequencies. Broadcasting uses the tropical broadcast bands between 2.3 and 5.06 MHz, and the international broadcast bands between 3.9 and 6.2 MHz, Military NVIS communications mostly take place on 2-4 MHz at night and on 5-7 MHz during daylight.
Optimum NVIS frequencies tend to be higher towards the tropics and lower towards the arctic regions. They are also higher during high sunspot activity years. The usable frequencies change from day to night, because sunlight causes the lowest layer of the ionosphere, called the D layer, to increase, causing attenuation of low frequencies during the day [3] while the maximum usable frequency (MUF) which is the critical frequency of the F layer rises with greater sunlight.
NVIS is most useful in mountainous areas where line-of-sight propagation at VHF or UHF frequencies is ineffective or when the communication distance is beyond the 50-mile (80 km) range of groundwave, and less than the 300–1500-mile (500–2500 km) range of lower angle sky-wave. Another interesting aspect of NVIS communication is, that direction finding of the sender is more difficult than for ground-wave communication (i.e. VHF or UHF). For broadcasters, NVIS allows coverage of an entire medium-sized country at much lower cost than with VHF (FM), and daytime coverage similar to MW (AM) nighttime coverage at lower cost and often with less interference. https://en.wikipedia.org/wiki/Near_vertical_incidence_skywave
Below are a few very good links to articles for the nuts & bolts of putting together a simple and good NVIS antenna.
http://www.tactical-link.com/field_deployed_nvis.htm
http://www.qsl.net/wb5ude/nvis/index.html
http://www.w0ipl.net/ECom/NVIS/K2GW-NVIS.htm
http://www.w0ipl.net/ECom/NVIS/cbp-nvis.htm
Here is a sample video by NG9D with an 80 Meter End Fed NVIS Field Antenna.
Multimeter Tutorial by AfroTechMods
THE BEST Multimeter Tutorial
The voltmeter… the Volt-Ohm Meter… the Multimeter… digital or analog… continuity… amperage, voltage and ohms… COME ON, MAN! What is it and how hard is it to use in the every day life of a ham radio enthusiast or just someone working in their workshop? Once again, Afrotechmods has an excellent tutorial on his YouTube channel for us to learn from!
CQ de WT8WV... GraHAM's Dits & Dah's 