Exploring The HF Bands - Cfarc-edu

Exploring the HF BandsBy Frank Tomkins, W8EZTCuyahoga Falls Amateur Radio ClubWhat You Need to Get There,What To Do Once You Are There,andSome Useful Operating Tips1

The HF Bands As Technicians you learned the Radiofrequency spectrum was divided into“bands”, based on theircharacteristics.You’ve probably operated on the VHF(Very High Frequency) and the UHF(Ultra HF) bands (2 meters and 70cm), and perhaps the Techniciansection of the 10 meter band.2

The HF Bands Generally, the bands from 160 meters (1.8to 2 MHz) through 10 meters (28 to 29.7MHz) are collectively referred to as the HF(High Frequency) bands.There are two other bands that will soonbecome available to US Hams, the 600meter band (472 to 479 KHz) – just belowthe AM broadcast band, andThe 2200 meter band (135.7 to 137.8KHz).3

Getting on HF Basically, you will need three thingsto operate on HF: The privileges (which hopefully you willhave at the end of this class), An HF antenna, And an HF rig (transceiver). However, there are some other itemsthat you’ll find useful:4

Getting on HF A suitable length of coax to connectyour antenna to your radio.5

Getting on HF A grounding system and lightening arrester.6

Getting on HF An SWR meter – to help protect your radioand to alert you when something hashappened to your antenna.7

Getting on HF An easier to use SWR meter.8

Getting on HF A log – either paper or electronic.9

Getting on HF A place to put your station that issomewhat secluded. You want to avoidbackground noise and interruptions.10

Getting on HF Some hams have portable stations.11

Getting on HF Of course, some hams do get a bit carried away.12

Getting on HF And some of them go completely over the edge!13

A Bit of History As radio development evolved, individualexperimenters were forced to give way tocommercial users.The powers that be (the Government andBusiness interests) had realized the value of theradio spectrum.The need for more spectrum (and higher power)pushed the development away from widebandinefficient spark gap transmitters to narrow bandhigh power AM transmitters.It was commonly believed that the lowerfrequencies were best for long distancetransmissions.Ham radio operators got pushed higher andhigher in frequency, and by 1920, were notpermitted below 200 meters (about 1.5 MHz).14

A Bit of History As always, Hams started experimenting inthis vast RF waste land they wereconsigned to and strange things startedhappening.The radio waves were not behaving asanticipated.In fact, as they generated higher andhigher frequency signals, they beingreceived further away than physicsdeemed possible.It just didn’t make sense . . .15

A Bit of History Until in 1924 a British researcher namedEdward Appleton confirmed a predictionmade in 1902 by researchers ArthurKennelly and Oliver Heaviside.Kennelly and Heaviside predicted reflectivelayer of charged particles up in theatmosphere that very efficiently reflectcertain radio frequencies.Today the general term for these reflectivelayers (yes, there are several of them) arecalled the ionosphere.16

A Bit of History This meant that under the rightconditions, certain radio signals couldbounce off the ionosphere and the earthmultiple times, enabling communicationsaround the world.17

HF Today As this potential was recognized, thepowers that be took most of this “vastwasteland” of RF spectrum away fromhams, leaving them with small windows orbands throughout the HF spectrum(roughly 1 to 50 MHz).These windows are the HF bands called160, 80/75, 60, 40, 30, 17, 15, 12, and10 meters.You will want to get an Amateur RadioBand Chart and post it near your radio.18

HF Today19

HF Today Make sure it’s current, and use it to keepfrom go into areas you are not permitted.20

HF Today However, beyond the Band Chart is asubdivision of most bands called aband plan.Each band has a band plan.It includes not only FCC rules, but italso . . .Reflects a “gentleman's agreement”on what types of signals should beseen in what part of each band.21

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HF Antennas The standing joke goes: “Look up antennain a dictionary and it will say “see:compromise””Antennas are compromises betweenalmost 25 separate factors including:Cost, ease of installation, covenants anddeed restrictions, efficiency, radiationpattern, polarization, take off angle,available space, single or multiple bandcapabilities, and even your S.A.F. (SpousalAcceptance Factor).28

HF Antennas If you’ve got the room, (and neighbors and yourspouse will tolerate it), wire antennas are a goodstart.They are easy to put up using a sling shot, aweight, and some fishing line.Simple wire antennas can be made with wire,insulators (PVC works), rope (use weatherresistant paracord) and trees for support.You will probably want a multiband antenna, solook into G5RV, OCF, and Fan Dipoles.If you have only one attachment point (besidesyour house) consider an end fed antenna.29

HF Antennas Vertical antennas can be wires hung fromtrees, any conductor works, even freeHarbor Freight tape measures have beenused.Most vertical antennas need groundradials to work efficiently. Minimum is 4,not much improvement beyond 32.While most vertical antennas need groundradials, there are several that do not,including: Gap-Titan Cushcraft R7, R8, and R9 series30

HF Antennas Depending on constraints, antennas mayneed to be installed in an attic or crawlspace.Antennas can be disguised as a flag poleor downspout, or made with very thin wirethat is virtually invisible, or temporary innature (set it up, operate, take it down).Antennas can even be installed on vehiclesand used with a base station.An antenna I have been experimentingwith is the Magnetic Loop Antenna.31

HF Antennas If funds permit, buy a reasonably currentversion of the ARRL Antenna Book.The Internet is full of antennas and plans,but not all perform as well as the authormay claim.32

HF Radios This will be your big expense.New vs. used decision. New has warranty. Used – let the buyer beware. Watch out for online sales (Craigslist, E-bay),local hamfests may be a better place to look. Depending upon ratings and life cycle, usedgear may save you 50% over new. Ask Ham friends for advice andsuggestions.Do your homework – don’t just look at thescore, read the E-ham reviews.33

HF Radios E-Ham Review pages:34

HF Radios A specific review:35

Tips Watch out near band edges!Your buddy (an Extra) asks you (aGeneral) to meet him at 7.175 MHz on fora sideband QSO. 7.175 MHz is the bottomedge of the General portion of 40 meters.If you key up, you are out of band!Your side band (lower side band on 40)extends down to about 7.172 MHz.The same applies near the top of bandswhen using USB.36

Tips Keep a band chart posted by your radio.Know the band plans and be politeWhen getting ready to transmit, ask: “Isthis band in use?”Use the minimum power needed tocommunicate clearly.Join a club. There is a lot of experienceand wisdom there, and most are willing toshare.Sometimes when a special tool is needed,someone in the Club will loan it to you orhelp you with the task.37

Tips Offer to help other Hams. It’samazing how much you learnworking with others.Look for and participate in HF nets.If you can afford it, join the ARRL.When someone is annoying you,remember, that’s why you have afrequency dial. And in the worstcase, and on & off switch.38

A Quick Review of the BandsSo what affects HF Ham band propagation? Day or night or grey line. Time of year. Solar activity (and where we are in the 11year cycle). Storms (creates electrical noise on lowerbands). Antenna type (NVIS vs. others) See the handout for a brief description ofband (and user) characteristics.39

The HF Bands Generally, the bands from 160 meters (1.8 to 2 MHz) through 10 meters (28 to 29.7 MHz) are collectively referred to as the HF (High Frequency) bands. There are two other bands that will soon become available to US Hams, the 600