NI4CE regional linked repeater system

Articles

By The Numbers

Your First Radio (Part 1)

Your First Radio (Part 2)

Your First Radio (Part 3)

Your First Radio (Part 4)

Your First Radio (Part 5)

Why SKYWARN Is Important

BY THE NUMBERS
Paul Toth-NB9X

Even though Ham Radio is all about “wireless communications”, getting the RF signal from the radio to the antenna efficiently and effectively requires using the right cable. That sounds easy and it is. But it requires a bit of education and some calculation to come up with the numbers and the right cable selection.

First, let’s shine a little light on your cable options. There are many different kinds of coaxial cable on the market. Two-way radio for Ham and commercial use is designed to use fifty ohm cable. That will provide your radio with the best impedance match, lowest power loss and lowest reflected power.

There are lots of different fifty ohm cables to choose from. Let’s focus on some of the more popular cables. They include RG-58U, RG-8X, RG8U, RG-213, LMR-400, Belden 9913 and LMR-600.

Most mobile installations require a cable that is relatively thin, flexibility and something that will not break easily. RG-58U and RG-8X are most often used because they use a stranded center conducted. These two cable types work because the length of cable required is usually short, less than twenty feet. Even at that length, the loss you can expect from RG-58 is typically 2 dB. Using RG-8X nets a loss of 1.6 dB. If you are using a quarter wave antenna with a gain of 3 dBi or 0 dBd, you will experience a NET LOSS.

RG-58 and RG-8X are not the most efficient cables to use for a Base Station application. Here, you want something beefier. A fifty foot run of RG-8 will net you a loss of 1.2 db at 146 MHz, 2.2 db at 446 MHz. RG-213 has similar loss numbers. Time Mirror LMR-400 lowers the loss at 146 MHz to 0.8 db, at 446 MHz to 1.3 db. Belden 9913’s numbers are similar. If you are looking for even lower loss, LMR-600 reduces the loss at 146 MH to 0.6 db and at 446 MHz to 0.9 db.

What makes one cable type better than another? The most dramatic feature is the gauge of the center conductor. RG-58 is a stranded, 20 AWG (0.033”) wire. By comparison, LMR-400 and Belden 9913 uses a solid core center conductor that is 0.108” in diameter, 10 AWG or what is used for most 20A electrical circuits in your home.

Times Mirror has an easy to use Cable Performance Calculator on their website that makes it easy to determine which cable type is best for your application. Go to: http://www.timesmicrowave.com/calculator/?productId=121&frequency=445&runLength=100&mode=calculate

Go to facebook.com/NI4CE now and tell us what you think. Or send an email to info@NI4CE.org.

YOUR FIRST RADIO (Part 1)
By Paul Toth – NB9X

When I was first licensed over twenty years ago, I was faced with the same daunting challenge that every new Amateur Radio operator faces: “What should new FIRST Amateur Radio purchase be?” Should my first radio be a Portable I can take everywhere? Should it be a Mobile radio that I can use as a Base Station (with a power supply) or in the car? Decisions, decisions, decisions. Well, here is what I decided.

My first radio was (wait for it) a MOBILE radio. A curious choice you are thinking. But in retrospect, if I had to do it again, I would make the same choice. Here’s why.

Portable radios, no matter the brand or model, are limited in their power output. Now, if the repeater you are trying to talk through has an output of fifty watts and the portable radio you have chosen transmits at five watts, you will be operating at a distinct disadvantage. That difference in power output is 10 dB. That may not sound like a big difference. But believe me, it is. Now, let’s compare Antenna Gain. The repeater is probably using a high gain antenna to boost the Effective Radiated Power by 6 dBd to 10 dBd, maybe even more. But comparison, most portable radios are outfitted with antennas that have a negative gain maybe as much as -4.0 dBd. Now, add up the differential and, as you can see, that portable radio you are trying to use has a -20 dBd or more disadvantage. And just got good measure, let’s say you are trying to use your portable radio inside a vehicle or a well built structure. You can tack on -15 dBd to the RF hole you are in.

By comparison, most VHF mobile radios transmit at up to 50 watts. UHF radios can transmit at up to 45 watts maximum output. Most mobile antennas will offer a gain factor that will offset any losses introduced by the coax cable needed to connect the antenna to the radio. And because your mobile antenna is located on the exterior of your vehicle and the radio is powered by the vehicle’s alternator, you will not be added to the losses described above with a portable radio. Base Station antennas may actually offer you enough gain to increase your Effective Radio Power (ERP) by a factor of two or more. And a Base Station antenna will likely be mounted at some elevation that will allow you to eliminate losses from trees, buildings and other vertical obstructions.

Why is all this important for a new Ham? You have heard the saying “Success begets success!” A successful first radio experience will encourage and motivate a new Ham (and, for that matter, any Ham) to want to do more. Ham Radio is not a spectator hobby. You learn by doing. And the more you do, the better you will be.

More on your First Radio in my next post.

YOUR FIRST RADIO (Part 2)
By Paul toth-NB9X

In my first post on this subject, I discussed my rationale for selecting a MOBILE radio as my first Ham Radio. When I added up the numbers including Transmit Power Output and Antennas Gain and factored in other losses I could expect using a Portable radio, it just made more sense to make that first radio a MOBILE radio.

But there were other important criteria I took into consideration for that first purchase. Many new Hams will purchase a VHF, single band radio. It is less expensive than many VHF+UHF dual band models. And, in many parts of the country, there is more activity on the VHF (Two Meter) band or so many people believe. But even though a dual band, VHF-UHF radio was going to cost more, I thought going that direction was worth the every investment. And that decision turned out to be a good one.

Another factor was audio quality. Once again, the MOBILE radios I had been exposed to before making that first purchase just sounded cleaner and more full bodied than their Portable Radio counterparts. That still holds true today for most ANALOG radios. Digital Mobiles and Portables (e.g. NXDN, DMR, P25, Fusion, etc.) tend to have virtually identical audio quality. There are other factors, including the Speaker/Mic you may be using and the digital format itself, that make once format better than another. More on this topic in another post.

Perhaps the most important item I factored into my first radio purchase was how I wanted to use the radio. Did I want to talk with other Hams going to and from work? YES! Did I want to participate in Nets? YES! Did I want to get involved with emergency/public service activities, like SKYWARN and ARES? YES! How about Club activities? YES! With those criteria in mind, a MOBILE radio made the most sense.

Now, in all fairness and in full disclosure, it became pretty clear within three months that a VHF-UHF dual band Portable radio was going to be in my immediate future. Ultimately, an active, energized, engaged Ham is going to have at least one MOBILE and one PORTABLE radio.

More on DIGITAL Ham Radio in my next post.

YOUR FIRST RADIO (Part 3)
By Paul Toth-NB9X

A new Ham in the 1990s had some important choices to make when selecting his/her first radio. Was it going to be an ICOM, Kenwood, Yaseu, Alinco or one from a handful of lesser known brands, like Standard or Azden. Or maybe, you knew someone who could convert an old Motorola or GE mobile or portable that had been used by a commercial user.

Twenty years later, the choices are a lot more numerous. Yes, the Big Four in Ham Radio are still around and still innovating with radios that include color LCD screens, PL+CTCSS+DTCS tone control, voice compression and more. Many of the lesser known brands have been replaced by radios from Chinese manufacturers who have flooded the market with low cost (and, in some cases, dubious quality product).

While most ANALOG Amateur Radio repeaters still operate Wide Band FM, that is with a 25 KHz channel bandwidth, the Narrowband Mandate (12.5 KHz bandwidth) imposed on commercial and government users in 2013 has dried up the availability of commercial radios capable of 25 KHz operation. We are also seeing older WBFM repeaters now being replaced by new models that must operate at 12.5 KHz NBFM.

The FCC mandate for commercial radio has also brought with it new DIGITAL operating modes that some Hams are experimenting with. P25, NXDN, DMR, Fusion, TERTA and D-Star are just some of the DIGITAL modes out there. All but D-Star and Fusion (which are Ham Radio only) are gaining prominence in commercial and government use. All of these DIGITAL modes are feature rich. Some allow multiple VHF and UHF repeaters to be connected via IP. Interoperability, one mode to another and one manufacturer to another, is still a problem (just as computer networking was twenty years ago). And each mode has its strengths and weaknesses. No two modes are created equally.

I personally like NXDN, created by ICOM and Kenwood jointly in 2005. Each manufacturer’s radios are interoperable. The repeaters can be networked easily. And equipment is readily available from dealers and on the Internet. I also happen to like the range and clarity of NXDN radios, which rivals WBFM despite the fact they use one quarter the bandwidth of WBFM.

DMR offers two talk paths per RF carrier, a feature some Hams find desirable and fascinating, although you can only talk on one at a time. DMR repeaters tend not to cover the same amount of real estate as NXDN repeater do. And there have been some interoperability issues between Type 2 and Type 3 formats. Yet, DMR is popular in many areas, in part because of the availability of product.

P25 has two versions, the older Phase 1 mode and the newer Phase 2 mode. Both are designed for the Public Safety market and, as a result, P25 radios are a lot more expensive than most other Digital radios.

More on the Ham Radio only DIGITAL modes in my next post…..

Go to facebook.com/NI4CE now and tell us what you think. Or send an email to info@NI4CE.org.

YOUR FIRST RADIO (Part 4)
By Paul Toth-NB9X

In my last post, we started talking about DIGITAL two-way radio, why it exists and why you should seriously consider a DIGITAL radio.  Let’s expand on that with a look at the several DIGITAL radio protocols and radios that are available.

First, no two digital modes are created alike.  Each of the several CAI (Common Air Interface) has their strengths and weaknesses.  NXDN is the only mode that meets all of the FCC’s 2004 engineering mandates for Ultra Narrow Band Digital.  In a Report and Order issued in December, 2004, the FCC told the radio manufacturers they wanted to see radios that used 6.25 KHz bandwidth, FDMA modulation and a data rate of 4800 baud.  That is what NXDN, jointly created by ICOM and Kenwood, is.

In that same R&O, however, the FCC gave manufacturers like Motorola some wiggle room allowing their two channel TDMA mode to operate.  DMR radios, the generic term for TDMA, uses 12.5 KHz bandwidth with two simultaneous voice paths.  Some early DMR offerings are not compatible with the newer Type 3 radios that include products from Hytera, Tait and others.

P25, the modes (there are two) adopted by APCO for Public Safety are also 12.5 KHz.  P25 Phase 1 uses a FDMA modulation schema while the new P25 Phase 2 mode is a two voice path TDMA offering that uses one modulation type for the uplink (radio to the repeater) and a different modulation schema for the downlink (repeater to radio).

Radios using all these operating modes have been created primarily for commercial and government use.  But they are also is use on Amateur Radio bands.  Why?  What are the benefits of DIGITAL?

ANALOG transmissions are subject to all kinds of noise and disruption.  Weak signal analog voice transmissions are often difficult to copy because of the inherent noise that is part of the signal.  Then, add to that “snap, crackle pop” from atmospherics in the area, disruptions caused by multipath, trees and other vertical obstacles.  In short, analog transmissions have drawbacks that can make communications difficult.

DIGITAL transmissions are usually much cleaner, clearer and easier to comprehend.  That’s because the transmitting radio turns your voice into a stream of “zeroes and ones”, sends them over the air to the receiving radio that decodes the stream and re-creates the voice communications.  With some exceptions, digital voice is far more stable than analog voice.  Digital voice transmissions are generally usable at RF signal strengths up to 20 dBm weaker than analog signals.  Most digital radios also feature ambient noise reduction to eliminate or substantially reduce road noise.

One drawback with most of the commercially available digital radios:  they are single band only. 

More on DIGITAL radio in our next post….

YOUR FIRST RADIO (Part 5)
By Paul Toth-NB9X

Some of you have heard me state that “Amateur Radio was the FIRST Social Media”.  That is a rather bold statement given all the other Social Media offerings that now grace the digital landscape.  The fact that Ham Radio, in Analog or Digital mode, is still a relevant Social Media, is pretty remarkable.
 
Let’s close the loop on DIGITAL radio before we get too far off topic.  Here are some thoughts on the several DIGITAL modes available to all Hams.
 
I personally like NXDN, created by ICOM and Kenwood jointly in 2005.  The radios from both manufacturers are interoperable.  The repeaters can be networked over IP easily.  And equipment is readily available from commercial dealers and on the Internet.  I also happen to like the range and clarity of NXDN radios, which rivals WBFM despite the fact they use one-quarter the bandwidth of WBFM.   NXDN radios also support Text Messaging and GPS.
 
DMR offers two talk paths per RF carrier, a feature some Hams find desirable and fascinating, although you can only talk on one at a time.  DMR repeaters tend to come up short on coverage compared to NXDN and P25 Phase 1, a product of their modulation schema.  And there have been some interoperability issues between Type 2 and Type 3 formats.  Yet, DMR is popular in many areas, in part because of product availability and local dealer support.  There is also the Motorola name recognition that has helped popularize DMR.
 
P25 has two versions, the older Phase 1 mode and the newer Phase 2 mode.  Both are designed for the Public Safety market and, as a result, P25 radios are a lot more expensive than most other Digital radios.
 
There are two digital products that are “Ham Only”:  ICOM’s D-Star and Yaesu’s Fusion.  D-Star remains ICOM’s prominent Ham Radio offering, even though its GMSK modulation schema is hardly state of the art.  The end user D-Star radios will do both analog and digital modes. D-Star repeaters are digital only.  D-Star has become less of a “proprietary” mode thanks to the proliferation of D-Star dongles that turn your computer into a virtual radio.  Still, if you want to operate wirelessly, ICOM is your radio source.
 
Fusion, from Yaesu, is a ‘proprietary’ created only for Ham Radio product.  Its C4FM modulation schema has some P25 Phase 1 characteristics.  Fusion radios support both analog and digital mode operations.  And Fusion repeaters can be programmed to automatically convert analog to digital and vice versa.  Fusion has gained a foothold with some Ham Radio Clubs, in part, because of an early marketing campaign that made Fusion repeaters available at Fire Sale prices.  Yaesu’s success with Fusion may also be based on a belief that the majority of Hams will only buy Ham-class radios.
 
The West Central Florida Group, Inc. currently has two NXDN repeaters in operation at our Riverview and Verna repeater sites.  Like our analog repeaters, the NXDN repeaters are linked full time to create a large coverage footprint along Florida’s West Coast.
 

WHY SKYWARN IS IMPORTANT
By Paul Toth-NB9X

When the NI4CE Repeater was first conceived sixteen years ago, it had two primary objectives:  Provide a VHF-UHF platform that ALL Hams in West Central Florida could communicate through.  This included support for the several Nets the ARRL West Central Florida Section conducts each week.  The second objective was to provide a VHF-UHF communications platform to support the National Weather Service’s SKYWARN severe weather spotter program.
 
Ham Radio has played an integral and vital role since the SKYWARN program first started in the late 1950’s in “Tornado Alley”.  Trained Ham operators were the eye and ears of the NWS during severe weather outbreaks in Kansas, Oklahoma and Texas using their radio communications privileges to report severe weather directly to NWS meteorologist.  It wasn’t until the 1970s when the program was rolled out nationwide.  In the 1990s, when the Weather Service was downsized and re-organized into the 118 offices it now operates from, SKYWARN took on an even more important role.
 
The technology used by the National Weather Service has changed dramatically since the early days of the SKYWARN program.  Forecasters now have geo-synchronous satellites and 3D Doppler radar to help predict severe weather and issue warnings to keep all of us safe.  Spotters who were limited to telephone and Ham Radio now have a plethora of social media and email to send in reports, including still images and video.
 
So, why is Ham Radio still relevant to the SKYWARN program and to the general public?  The answer is simple.  Ham radio does not require the Internet, a working telephone or any other technology (other than a portable or mobile radio) to get severe weather reports from spotters to the NWS forecasters.  Moreover, that same Ham Radio link can also be used by the forecasters to push out severe weather warnings and other guidance to all the SKYWARN Hams as needed in a timely manner.
 
Let’s turn the question around.  Is SKYWARN still relevant to Ham Radio?  Absolutely!!!  SKYWARN is a year-round opportunity for Ham Radio operators to demonstrate our importance at a time when society is cell phone and Internet centric, so much so that many people think Ham Radio, the original “social media”, is a thing of the past.  And SKYWARN participation is a great opportunity to fulfill one of the prime justifications for the Amateur Radio Service’s existence.
 
2017 has the potential to be a very active Hurricane and Severe Weather year, maybe the most active since the 2004 and 2005 seasons.  Now is the time to get ready.  Attend an upcoming SKYWARN Training session scheduled for your area or take the online SKYWARN training offered by the National Weather Service.  Participate in the SKYWARN Information Net every Tuesday night at 9:00 PM on NI4CE.  Be ready to be part of the solution when severe weather threatens your county, your neighborhood.  And when you finish reading this article and feel so motivated, find the PayPal “Contribute” buttons on our main NI4CE.org webpage to help keep NI4CE on the air and ready for whatever Mother Nature will throw at us this year.
 
A correction to my comment about ICOM being the sole source for D-Star radios in my last column.  Kenwood’s TH-D74 portable now provides Hams with a second source for operating in D-Star mode wirelessly.