Arizona repeaters

Official Frequency Coordinator lists

Here are the latest repeater listings for Arizona from Arizona's frequency coordinator, with band-by-band listings updated as changes are made by each band's respective coordinator.  Please also familiarize yourself with information provided on the frequency coordinator's home page:  Arizona's frequency coordinator 

The band-by-band listings come in PDF format, for which I personally prefer the faster, smaller Foxit Reader, which does not load 20 megabytes onto your hard drive the way Adobe Reader does.  (Adobe crashed some years ago after an automatic upgrade, and I started looking for alternatives.)

One last note:  If any of these files is for some reason not on the azfreqcoord server, you may see a "blue screen of death" titled, " General Protection Fault."  DISREGARD and do not restart your computer!  A check on January 5, 2008 reveals that the BSOD has been replaced with a more appropriate "Not Found" page.

1. 6 meter listings
2. 2 meter listings
3. 222 MHz listings
4. 440 MHz listings
5. 902 MHz listings
6. 1.2 GHz listings

Unofficial repeater lists

The frequency coordinators try to verify the existence of coordinated repeaters, but there may be some on the books that no longer exist, especially in remote areas.  Some coordinators poll their repeater owners of record and gather other information in order to ensure the accuracy of the lists.

There is another site that lists repeaters throughout Arizona, with a report card on which repeaters are active and which are not.  Check it out.  The information is presented in an easy-to-use layout.

• www.azrepeaters.net - Home
• www.azrepeaters.net - Repeater Maps and Listings

Please keep in mind that repeaters should be coordinated, and therefore will appear in the official lists above -- unless of course it's a brand new addition -- and that a coordinated repeater has FCC Rules in its favor in an interference issue with an uncoordinated repeater.

Repeaters of the Superstition ARC

Just a slight update ...

The club maintains two repeaters, both co-located in northeast Mesa, with antenna at 60 feet above the ground at its base.  They are linked together, on 147.12 MHz and 449.60 MHz.  A 902.7125 MHz receiver is also linked to the system, with a tone access of 156.7 Hz.

Access information:

Set your transceiver to these parameters in order to access the club repeaters:

• 147.12 MHz:  Set the tone encoder to transmit a 162.2 Hz tone and use a "+" shift.  This shifts your transmit frequency up from the receive frequency of 147.12, so that you may transmit on the repeater's uplink frequency of 147.72 MHz.
• 449.60 MHz:  Set the tone encoder to transmit a 100.0 Hz tone and use a "-" shift.  This shifts your transmit frequency down from the receive frequency of 449.60, so that you may transmit on the repeater's uplink frequency of 444.60 MHz.

All communications through the repeater usually require a vertical antenna for best results.  Vertical polarization is standard for FM communications.

Repeater's Coverage

Our repeater system has a fair reach for its being at ground level.  A repeater, as with any radio station, can hear as far as the eye can see, or in other words, over a line-of-sight distance.  The higher the antenna is above the ground, the farther it will reach, to a more distant horizon.

The 440 MHz repeater tends to peek around corners and fill in some dead spots encountered on 147.12, as I have heard it told, from a mobile perspective.  The shorter-wavelength signals tend to reflect off of large surfaces like downtown tall buildings, thereby filling otherwise shadowed areas.  Once we get it running with the commercial-grade "Big Boy" repeater, which will run about 50 watts, and putting it on an equipment par with the 147.12, it should really be heard.

For best user performance

Repeater performance varies, depending on the type and location of the user's antenna and surrounding terrain, factors which become more critical as distance from the repeater site increases.

If one is within a mile to two miles from the repeater, one can enjoy the benefits of a handheld transceiver, its small size, low power consumption, and portability, and still put a good signal into the repeater, possibly even from inside of a lath-faced stucco house.  Other users can enjoy listening to clean audio and a lack of noise and drop-outs during this user's transmissions.

The greater the distance from the repeater site, the more challenging it becomes to put a good signal into the repeater and avoid noisy and intermittent reception for other users.  The positioning of the handheld transceiver, with its built-in antenna, becomes more critical, requiring the user to stay in one location once the "sweet spot" is found.  At greater distances, this sweet spot may be so small that just moving the radio from where you can see the S-meter's bars on the display to where you can speak into it has put its antenna into a dead zone.

The antenna is the most important part of a successful amateur radio communications station. Therefore, if one uses a handheld radio at greater distances than maybe three miles from the repeater, one should invest in an aftermarket rubberized antenna that was designed with more gain than a stock antenna.

Estimated coverage range

Handheld

This is not my recommended choice for the one-and-only radio equipment a new ham is going to start out with.  Why, you ask?  It has a built-in antenna, which does not offer the best in antenna height or antenna gain, the most important ingredients to success.  A handheld is a good second radio, but please, if you can swing it, get at least a mobile transceiver and a power supply for home use.

Having said that, a handheld transceiver will give access to a ground-level repeater while out in the open, for a range of 5 miles or more.  Many factors enter into this picture to reduce the effective range.  A location inside a car, or inside a house may shorten the range that you can achieve, especially a mobile home or stucco house or one with aluminum siding.  The cab of a pickup truck may work out better than the cab of a passenger car, in part because the truck is higher-built and is surrounded on all sides with windows.  Terrain between your location and the repeater may limit your range, as well as the seasons and the weather.

It has been observed that summertime signal path loss is generally greater than wintertime path loss.  This means that the signal from your radio will arrive at the repeater with less strength in the summertime and stronger in the wintertime, without you doing anything different.  Some natural factors include the following:  More green foliage in the summertime will tend to absorb RF energy, creating loss, and wintertime temperature inversions and cloud cover may help to hold signals in closer to the ground, boosting signals, I have personally observed this phenomenon with regard to the five-mile distance between my home and the repeater site.

Seasonal noise floor changes have also been observed.  During hot dry weather of summer, overhead power lines tend to give off more noise, whereas these same lines are less noisy after a washdown from rain.  The noise floor at a repeater site governs what minimum signal strength is required to be heard and repeated.  A noisy frequency is going to require greater signal strength from the user to quiet the noise.heard.

Because the terrain falls away toward the southwest from the repeater site in northeast Mesa, people may well hit the repeater with a handheld as far away as 20 miles, but coverage is very spotty except if the operator is out in the open.  With the repeater at 200 to 300 feet higher elevation, areas downslope from the repeater will see some improved coverage.

Improving a handheld

I have touched upon this topic already, but it bears repeating:  The antenna is the name of the game.  To improve your range with a handheld, an aftermarket longer flexible antenna will increase your signal penetration and widen your sweet spots.  Or use of a 5/8 wave mag-mount mobile whip on a cookie sheet will greatly improve your chances to be heard.  Use of an antenna extension cable that lets you suction-cup-mount your rubber duck on the outside of your vehicle will even go a long way to improving your range -- I don't know what the product is called, as I was once given one without the packaging, but positioning it at the roof line of the cab of my truck gave me a good ground plane for the rubber duck!  (That's what these rubberized flexible antennas are called, by the way.)

If you are parked somewhere, and you have nothing but a handheld with its rubber duck, set the radio on the roof of your car and speak into it.  Positioning six to twelve inches may go a long way to finding a stronger signal in reception from the repeater, which generally translates to stronger transmission to the repeater.

Another trick is to hang a 19-inch wire for 2 meters or 6½ inch wire for 440 MHz, from the outer shell of your antenna connector.  Antennas West sells one they call the Tiger Tail, which was nothing more than a piece of insulated wire, with a washer on one end that fits over your antenna connector, and then your duck screws on to lock it in place.  The antenna may be a snug fit now with that washer under there.  The far end of the wire had a plastic end cap on it to cover the bare end of the wire.  You can make one yourself, just tying bared wire around the connector shell before placing the antenna.  The hot pin in the antenna connector is inside the shell, and your wire addition will not come close to that.

One last thing you can do is to connect a home station antenna to your handheld.  If you live in a downtown area, or near a broadcast center like South Mountain, a large base antenna will possibly swamp your receiver front-end with out-of-band RF energy from many radio services.  This would cause you to hear police, taxicab and mobile phone services or ham repeaters that are not on this frequency.  The physical size of the radio does not allow for the necessarily large components of a good band-reject filter to be included.

Mobile or Home Station gear

Home stations will typically reach our repeater from a distance of 40 to 60 miles, Antenna-challenged stations should be able to reach the station from at least 20 miles with less than 5 watts, and with a boost in power to maybe 30 watts, that should increase the readability of signals received by the repeater to a distance of 40 miles.  Antenna-gifted stations may reach to more than 90 miles.

There are people in Phoenix who have access to Flagstaff mountaintop repeaters and TV channel 2, whereas the terrain blocks that direction from the Mesa area.  Our repeater can be hit by a mobile stopped at just the right spot along the highway going west out of Payson along the Mogollon Rim, but that type of coverage rarely serves any useful purpose.

With a decent antenna in the clear, 15 to 25 watts will cover perhaps 50 to 90 miles, depending on terrain.  Fifty watts will do just about all you will ever need for repeater voice communications from the home or car.

There are power restrictions on the 440 MHz band of 50 watts in Arizona due to military radars, but 50 watts from a good mobile antenna will work the repeater as far as you can hear it.

Having said all of this, don't sell yourself short on the capabilities of one or two watts of power!  With a good antenna, and a decent location, you can work the Metro Phoenix area with just that much power.  keep power levels to a minimum, because the more people there are on the band running 40 or 50 watts when one or five will do, the higher the noise floor is for someone else trying to hear something.  It all comes back to that swamped receiver front-end, and less enjoyment by many if too many are running more than the minimum necessary power, which is addressed in the FCC Rules.  I will one more time re-iterate:  A good antenna trumps high power.  You can do more with less if you have a good station antenna, and do less harm along the way.

First rig:  Mobile or handheld?

The only difference between mobile and home station transceivers is that a 12 volt power supply has to be added to a mobile rig to run it at home.  The home station usually has a built-in 120 volt AC power supply included.

These radios have the physical size required to contain the circuit components necessary to reject out-of-band signals that hamper the use of the handheld radio on a big antenna.  The handheld may also have a hotter receiver, in order to perform reasonably well using that stock rubberzied antenna, which is designed more for portability than performance.

Use of any kind of outside antenna will get you around the VHF and UHF repeaters, with an easier signal to be heard.  There really is no need to have 50 watts if you have any decent antenna.  All that extra power will do is cause your neighborhood hams more interference potential to what they want to listen to on the same band.  And 50 watts into an indoor antenna can cause significant interference to other electronics in the home or next door.

Power versus antenna

With 65 watts of power into a 20-foot high antenna versus 15 watts into one at 70 feet, the fifteen watts is going to outperform.  That was demonstrated by a station in Deer Valley, who recently accessed our repeater.  With that said, it doesn't require a 70-foot antenna structure nor more than 30 watts to be solid into several area repeaters.  The antenna is the ace in the hole that trumps power every time.

A good signal can be had into our repeater with as little as one watt into an antenna with good gain over a distance of 30 miles if your location is out in the open.  A tenfold increase in power, to ten watts will fill in the gaps and achieve more reliable access from greater distances out, and result in a 10dB signal increase.

By selecting an antenna with 3dB more gain, your power has suddenly been effectively doubled.  A higher gain antenna makes more efficient use of the power your transmitter has, by concentrating the signal in all directions toward the distant horizon rather than being wasted skyward.  A directional beam can further concentrate power in a single direction.

Locating an antenna as high as possible and in the clear as possible, whatever you choose to use, will give you maximum range from your location.  If you cannot locate in the clear, you may benefit from positioning, six inches to a foot one way or another.

Mobile stations with a good antenna, best located in the center of the roof, but can be on the hood or rear deck, will reach the repeater over a range of 20 to 40 miles depending on power, antenna and location factors.  There are high places where the mobile can reach from 70 miles away or more.  See the story on our front page about the 180 mile round trip through the 147.12, between central Tucson and Wickenburg.  The Tucson station just happens to be in the right place with a beam and an above average power capability, and the Wickenburg station was a movile sitting in a high, clear place 90 miles away.

Use of the home rig on an indoor antenna can present some challenges.  Typically, if you are running any kind of power into an antenna stationed next to the radio equipment, the power supply may shut down, or there could be undesirable audio distortion because of RF energy swamping the radio's circuitry.  Other problems may cause out-of-band transmission of spurious signals.

The solution is for the antenna to be placed as far away from radio equipment and people as is feasible, or for radio and people to be placed as far away from the antenna as is feasible while in use, and with the antenna near a window.  A mobile whip on a mag mount must be placed on the roof of the car, or something similar, such as a cookie sheet, a filing cabinet, a refrigerator.  Not just for the magnet to stick, but for the counterpoise the sheet of metal provides.  Even aluminum foil will work, except that the magnet won't stick.

What makes a station loud?

As you listen to our repeater you will hear soft voices with no noise, LOUD voices, also without noise, and noisy signals where a LOUD voice may be too loud to achieve clear copy, and a soft voice may be lost in the noise.

Transmitter power

Transmitter power increases do not make the voice louder.  Transmitter power increases will only quiet the static and noise associated with a weak or distant signal.  Once the signal is being received at the repeater with full quieting, further power increases do nothing.

Audio power

Effects

A station with a LOUD signal, especially one that is louder than the voice-identifier messages emitted by the repeater (147.12), will not sound their best, as they will cause people's squelch circuits to clip voice peaks if they are in an area where the repeater signal is relatively weak.  Some radios have a tighter bandwidth filter than others, and LOUD voices will cause these radios to emit a distorted sound of the voice.

Soft voices, on the other hand, though fully quieted into the repeater, present challenges with mobiles traveling through noisy neighborhoods or areas of weak signal from the repeater.  As the motoring ham passes the power substation on his right, that softly-spoken voice suddenly gets buried in a bunch of power line noise.  A normal-level voice, approximately the same level with the identifier, will still be readable if the repeater can be heard at all.

Adjustments

Most FM rigs have no external microphone gain adjustment.  Some older rigs tended to be set a little louder than average, and the single adjustment if you are told that you are too loud, that you can make is to increase the distance between the microphone and your mouth.  Also, make sure that you are not talking loudly to compensate for noise around you.

If you have a soft voice on the air, you need to position the microphone closer to your face. 

Optimum microphone positioning

The optimum microphone position is with the microphone resting against your cheek, angled so that you speak across the face of the microphone, not into it.

Then if that is too loud, back away from the microphone with the guidance of another operator on the air.

Internal adjustments

Starting with your microphone resting against your cheek as described above, adjust the internal mic gain potentiometer for optimum voice volume.  If you are not ready to mess inside your rig, have a friend adjust it as you speak while someone is giving you critiques along the way.

The best adjustment you can make is to adjust the internal potentiometers on the printed circuit board inside your radio to ensure that microphone gain and deviation are not set too high, if you are comfortable with working inside your rig.  Or let a more-experienced ham tackle the job.

The radio check

If one is looking for a signal report on an FM repeater, there are a few things to consider when offering one.  Your S-meter, which reads incoming signal strength, is reading the strength of the repeater, not the user requesting the check.  It will usually be a constant full-scale, no matter what kind of signal the repeater is hearing, because the repeater is transmitting a strong signal to you.

If you are not receiving a full-scale signal from the repeater, there is the possibility that you will hear noise on the repeater signal.  You will hear this noise while the other user is transmitting, and while the repeater is still transmitting a carrier after the user quits transmitting.  You will hear this noise when no one is transmitting into the repeater, when the repeater identifies.  You will hear silence when the repeater is off, unless your squelch is standing open, in which case you will hear a loud roar.

If the user is not strong enough to hit the repeater with full quieting, you will hear noise on his signal in addition to any noise you have on the repeater signal at your location.

If the other user is running enough signal strength into the repeater to reach full quieting, any further increase in his power will not make any difference in audio quality.  It will have no influence on your meter, as, remember, you are listening to the repeater.

No change in your transmitted power is going to make any improvement in your reception of the other user.  Sometimes an outboard amplifier brick will contain a pre-amp that may improve your reception if the repeater signal is weak to you.  You may be able to switch in the pre-amp independent of whether you use or bypass the output power boost.  A pre-amp will increase the chance of receiver overload and reception of out-of-band signals, but can greatly improve a weak front-end's noise figure.  Experience will determine which is best.

The user on the repeater will not boost his audio level with more transmitter power, or reduce his loud audio level by reducing transmitter power.  This is controlled by his placement of the microphone relative to his mouth.

A loud user with a weak signal into the repeater may clip out of the repeater.  What you will hear is a noisier signal with him present than without, and his voice goes silent, taking his noise with it on the peaks of his speech.  You may even hear the courtesy tone or the repeater begin a voice ident and switch to Morse code.  Other users will hear the same thing.  Ask him to back off of the microphone.  If he backs too far off, his voice may be lost in the noise while the repeater is being held open.

A loud user may cause the repeater to clip your squelch if you don't have a strong signal from the repeater.  Other users may hear everything, and still others may hear the same as you.  Try setting your squelch toward where the squelch opens with no signal to see if that resolves the problem.  Then ask him to back off from the microphone.

Double distance, cut power density to ¼

The strength of an RF field around an antenna, the strength of sound waves into a microphone and the strength of the magnetic field around a power supply transformer are all affected by this rule of thumb:  Double the distance and cut the power density by a factor of four.  (Power density can be equated to volume, or loudness of sound, or intensity of light or other energy.)

Applied to setting your rig and power supply on the table, if you stack the two units together, you may experience hum in your transmitted audio.  Place them twice as far apart, and experience ¼ the hum.  Double the distance again and see a 16-fold decrease from the original problem.  The power transformer's magnetic lines of force were inducing hum into your audio cabling.

Applied to speaking into your microphone, if you move your microphone to half the distance from your mouth, you quadruple the volume of your speech on the diaphragm of the microphone.

Applied to the placement of your antenna relative to your sensitive electronics, doubling its distance from an object will cut its signal field by a factor of four at the object's location.  You may wish to raise the antenna to twice as high to distance it from surrounding rooftops, or you may wish to place it horizontally further away from something to reduce its impact.

Going one step further with the antenna, a vertical antenna is going to radiate most of its power toward the horizon.  The higher the antenna's gain, the less power it will send skyward and it will concentrate it more toward the horizon, in all directions, unless you use a beam, which is then more efficient with its power by sending it all in one direction toward the horizon.

Considering that a high-gain antenna is sending its power toward the horizon, raising the antenna above objects is going to greatly reduce its impact on those objects moreso than on other objects on the same plane with the antenna.  The power density rule still applies to objects on the same plane, as you move the antenna further away from them you see the four-fold benefit for every two times the distance that you locate it.

Objects directly below the antenna see far less energy from the antenna than objects at greater distance from, but on the same plane as, the antenna.  But this is the result of the antenna pattern, which is focusing on the horizon.  This is why an antenna place high in the sky will actually cause less interference potential than one placed low.