Branching Out
Ten Metres for the Newcomer
by Peter Parker VK3YE - first appeared in Amateur
Radio, October 1998
Ten metres (28.000 - 29.700 MHz) is one of
the most interesting bands available to the radio amateur. No band supports a
greater variety of amateur activity than ten metres - you will hear SSB, AM,
CW, FM, repeaters, satellites, DX, award-chasing, contesting and local nets at
various times. Local, interstate, and international contacts are all possible
on 28 MHz. Portions of ten metres may be used by all licence grades (except
Novice-Limited). The band's wide open spaces and spectacular openings win it
many adherents during the peak years of the sunspot cycle.
Ten metres is the HF band most prone to
variations due to the eleven year sunspot cycle. During the bottom years, it is
possible to go for months without hearing any overseas stations on ten, but
long-distance contacts are an everyday occurrence when sunspot activity is
high.
We are currently in the early years of
sunspot cycle 23. This is good news to ten metre operators, as openings will
become more frequent and produce stronger signals as we approach the sunspot
peak, expected for early 2000.
A propagation mode known as sporadic-E
provides contacts on ten metres during all phases of the sunspot cycle.
Sporadic-E can occur at any time but is most prevalent in summer. Distances
covered typically range between 500 and 1500 kilometres, making sporadic-E a
useful (but not reliable) propagation mode for contacts within Australia.
Signals are often very strong. Mobile stations can do as well as home stations during
a good opening.
When there is no long-distance propagation,
ten metres is a good band for local operating. Noise levels are lower than on
80 or 160 metres, and antenna requirements are less (particularly for mobile
stations). The lack of crowding makes also makes operating easier. The range
and variety of contacts possible is enhanced if your area is lucky enough to be
within range of a ten metre FM repeater or simplex gateway linked to VHF or
UHF.
Beacons and Repeaters
Because ten metres is 1.7 MHz wide, there is
room for modes and activities that would cause interference if carried out on
the lower HF bands.
One such activity is beacons. Local clubs
have installed beacons to let overseas stations know when ten metres is open to
their area. These beacons transmit continuously and send their callsign in
Morse. Beacons can normally be found between 28.200 and 28.300 MHz. The WIA website and callbook lists Australian ten metre beacons.
A special worldwide network of beacons
operates on 28.200 MHz as part of the International Beacon Project (IBP). All
beacons share the one frequency and are timed so that only one transmits at a
time. Australia's IBP beacon is VK6RBP in Perth. IBP beacons also operate on
20, 17, 15 and 12 metres.
Ten metres is most similar to the VHF/UHF
amateur bands when it comes to FM and repeater activity. However, ten metres
has the added advantage of providing international FM contacts via repeaters
during high sunspot years. To use the repeaters, you need a 10 metre FM
transceiver that can be set up to transmit and receive on different frequencies
to accommodate the repeater's 100 kHz frequency offset.
Repeaters permit contacts that would not
ordinarily be possible. For example, a station in Sydney may not be able to
hear a station in Canberra, but both may be able to communicate via a repeater
in Brisbane. Repeater operation gets more interesting if the repeater is also
able to retransmit signals from other bands. The four standard ten metre
repeater channels in use around the world are listed below.
Input 29.540, Output 29.640 MHz
Input 29.560, Output 29.660 MHz
Input 29.580, Output 29.680 MHz
Commercial equipment
All current-model HF transceivers cover the
entire ten metre amateur band. However, before buying, check that FM is offered (as some transceivers do not include it).
Those whose budget does not extend to the
four-figure price tag of a new multiband transceiver may wish to consider
buying a 28 MHz-only set (sometimes available secondhand). Transceivers like these would be particularly
suitable for mobile/portable operation or as a second rig for the 10
metre enthusiast. However, their cost is not much less than a basic used multiband SSB
transceiver on the second-hand market, which makes them poor value. The newcomer to amateur radio should
consider the extent to which they will want the other HF bands before buying a 10 metre-only set.
Be careful when buying secondhand gear. Some
very old valve transceivers did not cover ten metres at all. Other models did
include ten metres, but had deaf receivers and/or put out reduced power on 28
MHz.
Some older (1970s) sets covered only a single 500
kHz segment of ten metres. A 28.000 - 28.500 MHz range is not a great
limitation as it includes coverage of CW, digital, beacon and popular SSB
frequencies. However, the owner of a set that tunes 28.500 - 29.000 MHz only is
severely disadvantaged. Either avoid buying the set or talk the seller down
thirty or forty dollars so you can afford to get a crystal cut for the bottom
500 kHz segment of the band.
Converted equipment
If you have sufficient technical knowledge
and the required information (Reference One), it is possible to convert some
models of 27 MHz SSB CB transceivers to operate on 28 MHz. If the modification
is done properly, the results obtained are well worth the small cost involved.
Some of the older AM-only sets can also be converted to ten metres, but this is
not usually worthwhile unless you want local contacts only or have a special
interest in AM operating.
It is also possible to convert sets to
operate on 29 MHz FM. Either some types of AM-only 27 MHz CB radios or 30-50
MHz FM two-way radios can be converted. The need for coverage of the correct
frequency range and inclusion of a 100 kHz repeater offset are complicating
factors here.
You probably shouldn't attempt any but the
very simplest modifications if you are a newcomer - it is very easy to
mistakenly 'butcher' the set and render it permanently inoperative. If you
still need a small cheap ten metre set, get someone else to do the modification
for you, look for a used, already-converted CB (price range $10 - 100).
Homebrew equipment
For some reason, there are few homebrew
designs around for 10 metre amateur equipment. However, constructing one's own
equipment on ten metres is certainly possible for the technically-inclined
operator. VHF/UHF operators who wish to use 29 MHz FM but see no point in
buying an HF rig should consider building a
transverter to use in conjunction with a six or two metre FM transceiver.
Building an entire transceiver for ten
metres is also practical. However, circuits for 28 MHz are usually more
complicated than those for lower frequencies. This is because: (a) the gain of
power amplifier transistors falls as frequency is increased, so more stages are
needed to achieve a given output power+ADs- (b) 28 MHz variable frequency
oscillators are not as stable as lower frequency VFOs, hence the need for a PLL
frequency synthesiser or premix VFO+ADs- (c) Because fundamental crystals are not
common on 28 MHz, and overtone crystal oscillators are difficult to pull over a
worthwhile frequency range, frequency multipliers are needed to obtain output
from a lower frequency VXO+ADs- and (d) receiver gain needs to be higher on 10
metres than on other HF bands because noise levels are lower. Nevertheless, for
the constructor curious about what ten metres has to offer, a five to ten watt
VXO-controlled double sideband transmitter or transceiver should not be
too hard to put together.
Antennas
Devoted ten metre enthusiasts often use a
three to six element monoband yagi or quad. This type of installation allows
you to work stations that cannot be heard on a simple dipole or vertical.
However, this does not mean that if you lack
high power and big beams, you should give up on ten metres. It's quite the
reverse - ten metres is often better than the lower bands if output power or
antenna gain is restricted. With 10-30 watts SSB and a small vertical (eg a
mobile whip), it is possible to have dozens of satisfying contacts. During
years of low solar activity, these contacts will be mainly within Australia and
New Zealand, but the proportion of international contacts will rise with the
sunspot count. The stations with the big beams generally have excellent receive
capabilities, and can often hear the operator using a converted CB and a
cut-down mobile whip.
A mobile whip mounted on a metal railing or
balcony is ideal for omnidirectional coverage. Use a whip reasonably close to a
full quarter wavelength (2.5 m) for best results. For the last three years, the
author has successfully used a 1.8 metre 27 MHz CB whip cut down to resonate on
10 metres. A 90 cm whip has also been tried but its performance was well down
on the larger whip.
Operating frequencies
All amateur licencees can use all frequencies on ten metres. However band plans should be observed to lessen interference to those using other modes.
In particular, never transmit between 28.198 - 28.300 and
29.300 - 29.500 MHz. The reason for this is that these segments are reserved
for beacons and amateur satellites respectively. Following the 10 metre
bandplan (see WIA website or callbook) maximises the chances of getting contacts and reduces
the risk of causing interference.
Operating on ten metres
There are many times that ten metres is
open, but you would not know about it by just tuning across the band. Beacons
can help in monitoring propagation, but have their limitations - the band can
be wide open to places where there are no beacons. If you suspect the band may
be open, but no beacons can be heard, tune across the 27 MHz CB band
(particularly 27.355 LSB) and the 29 MHz FM segment to get a better picture of
propagation patterns.
If 27 MHz is busy, but there is nothing on
10 metres, it's up to you to create some activity. Several CQ calls in a
popular part of the band (28.400 - 28.500 MHz) will often yield results, even
when no beacons can be heard. If no results, change frequency and resume
calling - your original frequency may have been in use by people who you can't
hear, but could be interfering with your transmission in some parts of the
world.
As noted before, the stations with the best
antennas are those best placed to receive weak DX signals. When conditions are
marginal, you will still have contacts, but it will be only with the stations
using the bigger antennas. As propagation improves, you will start to hear more
stations using dipoles and verticals in addition to the 'big-gun' operators
with the big beams and high towers.
Possessing a powerful transmitter and large
antenna array may give you a big signal on ten metres, but does not in itself
make you a successful operator. Operator persistence and 'being there' are the
main determinants of success on ten metres. If you are listening and are not
calling, everyone will think the band is dead and switch off. If you are keeping
the band alive by calling CQ, the activity will come to you, and you will work DX, no matter how modest your station is.
Of course, all this calling requires both
time and patience. However, technology can be used to automatically call CQ,
leaving time for the operator to attend to other tasks while waiting for calls.
In its simplest form, an automatic CQ caller can be a tape recorder with a 30
second endless loop cassette placed in front of the rig's microphone
(transceiver set to voice-operated transmit (VOX) mode). Other options include
the use of a 20 second digital message recorder set up with a special timing
circuit or even a suitable computer with sound capabilities. Whatever method is
used, the switching between transmit and receive should be automatic - having
manual switching detracts from the labour-saving benefits of an automatic CQ
caller.
Of course, all this calling requires both
time and patience. However, technology can be used to automatically call CQ,
leaving time for the operator to attend to other tasks while waiting for calls.
In its simplest form, an automatic CQ caller can be a tape recorder with a 30
second endless loop cassette placed in front of the rig's microphone
(transceiver set to voice-operated transmit (VOX) mode). Other options include
the use of a 20 second digital message recorder set up with a special timing
circuit or even a suitable computer with sound capabilities. Whatever method is
used, the switching between transmit and receive should be automatic - having
manual switching detracts from the labour-saving benefits of an automatic CQ
caller.
Conclusion
This article has given the reader a brief
tour of ten metres, to many people HF's most interesting band. The band is set
to explode with activity in the next few years. Will you be a part of it?
Acknowledgments
I would like to thank Mark Bussanich VK6AR
for his assistance in the preparation of this article.
Note
This article was amended in September 2010 to remove out of date information
This page was produced by Peter Parker VK3YE . Material may be copied for personal or non-profit use only.