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Making the most of sunspot Cycle 24 (or 25, 26, 27 etc)

Graph of sunspot cycle

You've read about the sunspot cycle in the text books - how it peaks approximately eleven years, and how more sunspots mean more ionisation and better HF propagation. Well, according to the pundits, Solar Cycle 24 is around its peak. This article tells how you can maximise your enjoyment of the next few years of high solar activity and good HF conditions.

What to expect

More of HF will be open longer. In low sunspot years 20, 15 and 17 metres go dead at night. When sunspots are high these bands remain open well after dusk. 10 and 12 metres, which open only briefly in low sunspot years, will provide international (DX) contacts almost daily. In peak years, 20 metres becomes almost a 24-hour DX band. The skip zones on 30 and 40 metres shorten with higher sunspots, making them reliable for short and medium distance intra and inter-state communications.

Six metre buffs also get excited during the high part of the cycle. Whereas you almost need to make a phone call to get a contact on six in the low years, on high-sunspot days the band bustles with DX. On particularly good days, the best six metre stations have contacted Europe, while operators running as little as one watt CW into makeshift antennas have worked into Japan.

Propagation paths change when sunspot numbers rise. It is normal for north-south paths (eg between Australia and Japan) to be open longer and later than east-west paths (eg to Europe or Africa). In sunspot years, most contacts made on 10 and 15 metres tend to be with Asian stations. However as the bands improve, a wider variety of locations, such as Europe and North America become workable on these bands.

Sunspot cycles rise faster than they fall. In an eleven year cycle, it may take four years to reach the top from the trough of the previous cycle, and six or seven years to get to the bottom from the top. This is good news as it means that though this cycle is expected to peak soon, excellent HF conditions will remain for about the next three or four years. See the IPS webpage for updates on the progress of the cycle.

High solar activity is not all fun and games - conditions can be very volatile. When sunspot numbers are high, solar flares become more frequent. After a severe solar flare the bands may go dead, and you may wonder if your rig still has an antenna connected to it.

Preparing for the coming cycle

When conditions are good, and you're on the right frequency at the right time, almost anyone can work DX. However, the higher HF bands are more fickle than bands such as eighty, two metres and seventy centimetres. Follow the four steps below to maximise your success.

Step One - Obtain information about solar activity and DX propagation.

Many amateurs enjoy working anyone anywhere. They might be testing a new antenna, seeing how far their low-powered signal will go, or just enjoy chatting to people. For these people, planning their operating is often merely a matter of tuning around and finding a band that's open.

Others specialise in working a particular part of the world, perhaps to gain points for an award, for a DX contest or to practice a language. For these people, success requires a more rigorous approach.

The first step is to find out the right frequencies and times for contacts to a particular location. Such information is provided in the prediction charts elsewhere in this magazine. Propagation charts are only a guide as conditions vary from day to day - one day, signals might peak at 6pm, the next day they might reach their strongest at 7pm.

Updates on solar activity are given on the WWV time and signal station. These are broadcast at 18 minutes past the hour on 2.5, 5, 10, 15 and 20 MHz. Near real-time propagation information also provided on various websites, some of which provide maps showing maximum useable frequencies by region and the progress of the 'twilight zone' around the globe. A search on 'Cycle 24', 'sunspots' or 'radio propagation' should reveal plenty of sites on the topic.

Computers are powerful tools for radio propagation forecasting and analysis. Programs that provide details of likely propagation given a particular set of solar conditions are available. A good way of testing them is to make use of the worldwide network of International Beacon Project (IBP) beacons on the higher HF amateur bands. IBP beacons share a single frequency on each band and are time-sequenced so that only one is transmitting at any given time. They transmit on 14.100, 18.110, 21.150, 24.930 and 28.200 MHz. IBP beacons initially identify at 100 watts and then drop power to 10 watts, 1 watt and then 100 milliwatts - a useful feature that allows one to quickly check band conditions.

Picture of log of DX contacts - all made with 5 watts

Step Two - Erect antennas for the higher HF bands.

You'd be surprised how many amateurs own do-everything multiband transceivers, but miss out on many bands for the want of five dollars' worth of wire stuck up in the air. Dipoles, ground planes or half-wave verticals will get you started and can provide worldwide contacts at times.

If you like a particular band, erect a directive gain antenna, such as a yagi or quad. Such antennas can either be rotatable (usually made of telescoping aluminium tubing) or fixed direction, with wire elements slung between well-located poles or trees. Gain antennas have the following advantages compared to dipoles and verticals.

* Clearer reception. Gain antennas can usually be rotated to null out interfering stations coming from the rear or side.

* Stronger signals at the other end. A station using a three element yagi and a 100 watt transmitter should sound as strong as a 400 watt transmitter feeding a half-wave dipole.

* Longer operating periods possible. A low gain antenna will provide DX contacts in the middle of an opening. However, at the beginning or end of openings, people with dipoles often find it hard to make themselves heard. A gain antenna allows contacts during these marginal conditions, thus extending the period that stations can be worked.

* A greater variety of stations become workable. The author has found that when using low power and simple antennas the majority of DX stations worked had quite large antennas, such as five or six element yagis. As conditions improved, a more contacts were with people using smaller antennas, such as two or three element yagis. Improving your antennas makes reception easier and therefore aids contact with stations who may be mobile or running low power.

Not everyone can erect towers stacked with beams. Look at smaller beams such as the VK2ABQ or Moxon rectangle. But even if you're restricted to verticals or dipoles, there's plenty of things that you can do to improve your signal at the other end. These include:

* Raise the height of your dipole. Most radiation from low dipoles goes straight up, rather than towards the horizon. This is fine for local contacts on 80 and 40 metres, but poor for long distances. Greater antenna height allows more radiation at angles close to the horizon, permitting longer distances to be covered. Increasing you antenna's height from five to ten or (better still) fifteen metres is one of the most cost-effective improvements to your station that can be made.

* Use elevated verticals with above-ground radials. Vertical antennas with buried radials require many radials to perform efficiently, especially in areas of poor soil conductivity. Installing vertical antennas on a support pole several metres high and using above-ground radials allows good performance with only a few radials.

* Use verticals that are less dependent on ground systems. If installing radials is difficult, consider a half-wave vertical. Compared to quarter-wave ground plane antennas, half-wave vertical antennas (such as the famous CB Station Master antenna) can be highly efficient with a minimal ground system. The extra height will help too!

* Consider fixed-wire beams. If you're mainly interested in one direction, wire beams strung up in trees can provide low-profile antennas capable of top performance. A two-element wire yagi can be slung between four well-placed trees, while a two element quad for ten or fifteen metres can be concealed in the canopy of a single tree.

* When all else fails, operate portable. Most Australians have ready access to open spaces, whether in the hills or by the coast. A simple inverted-vee or vertical antenna can yield outstanding results, especially if installed in an over-water location, such as on a boat or pier.

Picture of inverted vee dipole antenna Picture of vertical dipole good for DX



Step Three - Know your station

Once you have some antennas and know the right times and frequencies to try, the next step is to assess if your station is capable of exploiting the propagation available. A full assessment is beyond the scope of this article, as it requires an advanced understanding of wave propagation, antenna gain, radiation angles and receiver noise. However, the following example should succeed in explaining the desirability of having reasonable expectations based on what propagation can provide.

After looking at propagation charts or a computer program you may conclude that 40 metres may currently be open to the US. Turning on your receiver may reveal strong signals from North America. However a full assessment (as mentioned above) is likely to disclose that expecting frequent North American contacts with five watts and a low dipole is unrealistic. You would get very disappointed very quickly if you were expecting regular contacts with North America using that dipole. On the other hand, if your ambition is simply to span the Pacific occasionally with low power and are using an efficient, low-angle antenna (such as a high dipole or vertical) there is no reason why you cannot achieve your aim with a little persistence. The lesson here is to set reasonable objectives, and design your station so it can meet them.

Step Four - Polish your operating technique

You may have a good station and antenna installation, but will not be able to use it to its full potential unless you can properly adjust and operate your equipment.

* Set your transceiver up correctly. Excessive microphone gain can cause over-modulation and interference to other band users. Poor earthing gives rise to RF feedback, microphones that zap your lips and rough-sounding audio. A quarter wavelength wire connected to the transceiver's metal case usually fixes these problems where a proper RF earth cannot be installed. Speech processing can raise the intelligibility of your transmission when signals are weak, but too much causes distortion and excessive pick-up of other noises in the shack. A power supply that is too small or poorly regulated causes 'FMing' on SSB and chirp on Morse.

People prefer to answer calls from stations with clean signals, and quality signals penetrate through interference better. See your transceiver's instruction manual for more detailed guidance on adjusting your particular rig.

* Tune around the bands for DX. You'll hear nothing if you're not listening. To learn which bands are open to which places, spend 20 or 30 minutes at various times of the day to tune across the various bands. Note the locations of stations heard on each band and correlate this to the time of day. You don't always have to wait for the station to give his exact location - listening for the callsign prefix and looking up the country in the WIA Yearbook is usually good enough.

After a while you will observe both certain consistent patterns of propagation (eg many strong European stations in the late afternoons on 20 metres) and significant day-to-day differences in conditions. Don't overlook the IBP beacon frequencies (given earlier) in case there is propagation but no activity.

* Use various means to gain contacts. There are several ways to get contacts. These include calling CQ, answering someone else's CQ, or calling one of the stations involved in a contact that has just finished ('tail-ending'). The latter is particularly effective as you know the band is open and there is a good probability that someone is still listening. When tail-ending, the main thing to watch is to ensure that all parties have properly signed before you call. This is not always easy - sometimes people take five minutes to say 73, may sign off several times and do not always end their contacts cleanly. Count to four or five, and if nothing heard, make your call.

One benefit of being in Australia is that when working DX (eg Europe, Japan, North America), there's many more of them than of us. This works to our advantage in several ways. Firstly, it makes overseas stations eager to work VK. Secondly, if you are calling DX stations (whether answering a CQ or tail-ending), the competition from other VKs/ZLs who may also be calling is relatively light.

* Know when to call people I have often heard people whose signals should have been heard, but have missed out on contacts because they timed their calls poorly. They may have been calling while a previous contact was still signing off, or called at the same time as several others. If dozens of stations are calling a particular station, it is likely that he is unable to pick out an individual callsign. It can sometimes be worthwhile to insert your call as soon as the melee dies down. With any luck the DX station will hear you, not because you were the strongest, but because you timed your call best. At other times, DX stations may be tuning up or testing. It sometimes pays to give them a quick call before they call CQ and the multitudes find them. Timing is very important. It can't be taught, but can be learned through regular on-air activity, and observing what works and what doesn't.

* Put out calls if the band appears dead. People will not know if the band is open if no one is using it. It's up to you to activate the band by putting out a call. These days this doesn't mean endlessly pounding the key or calling into a microphone. Cassette recorders, digital voice recorders and even computers can be set up to call CQ automatically, especially if your rig has VOX (voice operated transmit) facilities Always be in attendance to answer any calls - there's nothing worse than trying to answer someone's unattended CQ caller!

Picture of log of DX contacts - all made with 5 watts


More detail on propagation and operating is provided in these favourably reviewed books.


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Should I upgrade?

The short answer is yes, if your licence level permits less than 50 or 100 watts output power or does not allow all-mode operation on all higher HF bands. Particularly restrictive licence categories include the US Technician licence (no SSB and limited bands below 28 MHz), the UK Foundation licence (10w power limit) and the Australian Foundation licence (10w power limit and limited bands).

A further upgrade to your country's top level is sometimes desirable to take advantage of even more frequencies and power. This is however less important than the first upgrade from entry-level except in the US where the Extra gives access to desirable frequencies on 14 MHz and other bands. Upgrading is relatively more desirable during low sunspot years (such as now) than when 10 metres was open for much of the day.


Demonstrations of DX contacts on the higher HF bands



This article has, I hope, provided an introduction of what to expect from the solar cycle and how you can take advantage of it. Many amateurs' most memorable contacts are made in high sunspot years such as this one. Prepare your station and make sure you get a fair slice of the action in the years ahead.

This article appeared in Amateur Radio February 2000 and was updated in 2012 and 2017 to reflect licensing and other changes



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