by Peter Parker VK3YE - first appeared in Amateur Radio, April 2000
What you need to pass the exam and the
practical skills required to be a successful amateur are two quite different
things. This month we outline six vital skills for radio amateurs. Mastering
them will assist you to fully enjoy amateur radio and further your electronics
knowledge. In many cases, possession of these skills is what distinguishes
newcomers from experienced hams.
If anyone asked me what was the number one
skill required for someone in electronics, I'd reply the ability to solder.
Despite the availability of solderless connectors, people who can't solder are
severely handicapped. Even if you use all store-bought equipment and antennas,
sooner or later you'll need to re-solder a loose microphone or antenna
connection.
The main alternative to soldering when
making connections is crimping. Crimping has its advantages, but the decision
to use crimped connectors should be made on a sounder basis than an inability
to solder. Antenna and earth connections should always be well-soldered to
reduce the risk of interference due to oxidised connections which can radiate
harmonics even when the transmitter is clean.
A soldering iron of around 20 watts is
satisfactory for most electronic work. The main exception to this is when
soldering PL259 plugs onto coaxial cable, where a larger iron, variable
temperature soldering station or butane torch will be found handy. Larger irons
are also useful when soldering onto large metal surfaces, as would be required
for some antenna work.
Successful soldering requires you to apply
heat to the joint and then let the joint melt the solder. Soldered connections
should be made quickly with a clean, hot tip to reduce the risk of overheating
components. Putting solder onto the iron's tip, and then trying to let this
solder drip onto the connection is not the right way to do it. Trying to
economise by recycling solder from old valve TVs is also a no-no! Applying too
much solder is also undesirable as it causes unwanted bridges to form between
adjacent circuit board tracks or plug connections.
Further information on soldering is provided
in the beginner's electronic books sold by the major components stockists.
All amateurs should be able to use a
multimeter and an RF power/SWR meter. An ability to use and interpret readings
from dip oscillators, impedance bridges, switched attenuators and noise bridges
is essential to the antenna experimenter. Constructors of transmitters and
receivers should be able to use RF signal generators, crystal calibrators,
frequency counters, inductance and capacitance meters and (ideally)
oscilloscopes.
With few exceptions, the above items can
either be bought cheaply (eg multimeter) or constructed in a day or two (eg
attenuators, dip oscillators, RF signal generators, noise bridges). Ample
constructional information on test equipment will be found in back issues of Amateur
Radio, the standard handbooks and the World Wide Web.
Studying for the exam teaches one how to
identify components from a schematic diagram. Students should also have learned
about the basic functions of each component, and the purpose of each component
in common stages found in transmitters and receivers.
When it comes to making projects, many
beginners are unconfident about tackling a project for which a printed circuit
board layout is not provided. Yet, many of the most interesting projects
(whether appearing in amateur magazines or on people's websites) lack a printed
circuit board layout. This is generally because the builder uses alternative
forms of construction (eg matrix board, 'ugly construction' and 'paddy board')
that are cheaper, quicker and more easily modified than specially-etched
printed circuit boards. Also, developing a reproducible circuit board layout
requires time that in many cases experimenters would rather spend on developing
the next project.
Being able to construct a project directly
from the schematic diagram is one of the most important skills that the
homebrewer can possess. This ability greatly the range of projects that can be
built and makes it much easier to customise circuits to suit one's needs.
A good plan for most projects is to try to
base circuit layout as much as possible on the schematic diagram. Have the
low-level or input stages on the left-hand side of the board, and the
high-level or output stages on the right part of the board. Build and test
large projects in modular sections to assist fault-finding, modifications and
upgrading.
Before cutting the circuit board to size,
draw a plan showing the proposed mounting of components on the board. There is
nothing more frustrating than cutting a board, and finding that it's 2cm too
short! More experienced constructors will have an idea of the size of board
needed from a cursory glance at the schematic diagram, and may wish to proceed
straight from gathering the parts to cutting the board without drawing a
diagram.
Also very important is the ability to make
intelligent substitutions, especially when building projects developed
overseas. This is often not feasible with circuits using rare, special-function
integrated circuits such as the MC3362 VHF FM receiver chip. However,
substitutions are easier when circuits use discrete components. Constructors
should have some idea of the function of each stage and the type of components
that are used in it so that they have some idea of suitable substitutes.
As an example, let's take the keying stage
in a low power CW transmitter. It may require an esoteric PNP transistor that
is unavailable locally. Inspection of the circuit reveals that the stage is a
transistor switch that applies voltage to the collector of the final output
transistor when the key is held down. Depending on the current drawn by the
final, a low to medium power PNP transistor is called for. As the keying stage
is not handling RF, an audio transistor such as the BC640 or BD140 would be a
workable substitute. Try the BC640 first, and if it gets too hot, substitute
the higher power BD140.
Computers now occupy an important place in
most amateur shacks. Whether used as a terminal for digital modes, logging,
designing antennas, morse practice, e-mail or running circuit simulation
software, a computer will be found indispensable for many amateur activities.
However, a computer will only be useful if
you're able to drive it. As a minimum, amateurs should possess the following
computer skills:
These general skills will serve well for
most people. However, many specialist facets of amateur radio require
additional computing abilities. Examples include:
Notwithstanding the proposed regulatory
changes that will make Morse proficiency less important for amateur HF
privileges, Morse remains a desirable skill. This is because it can be handy
for identifying repeaters and beacons on VHF and its utility as an additional
mode, especially when signals are weak. Also, Morse transmitters are much
simpler and cheaper to build than transmitters for any other digital or voice
mode.
Learners should aim to be competent in the
following:
Almost all active Morse operators have the
above mentioned skills. However, you will notice that the 5 and 10 words per
minute Morse exams test none of these essential abilities. This means that
these skills must be learned on air after the exam.
There is thus a large difference between the
Morse taught to prepare people for the exam and the mode as used on the air by
experienced operators. It is unfortunate that people frequently obtain a
jaundiced view of the latter based on their experiences of the former. Morse at
5 wpm is indeed a slow, clumsy and tortuous mode. However, 20 wpm sent and
received in one's head, with appropriate use of abbreviations, is many times
faster and a fully practical mode for communications purposes.
Passing the regulations exam is a good
start, but is not sufficient on its own. There are many skills that are best
learned by listening to good operators on the air and reading the operating
section of the ARRL Handbook. These topics have already been covered previously
(October 1995, June 1996, August 1996), so won't be repeated here.
Have at least a vague idea of what's
happening on the bands. This way you won't be caught unawares when asked to
give a number for a contest that you didn't know about. Reading Amateur
Radio each month and listening to your weekly divisional or club news
transmission is usually sufficient.
Gain a broad knowledge of bandplans and the
frequencies allocated to each licence class. This is so that you do not cause
interference to other modes by operating in the wrong part of the band, or
worse, breach your licence conditions by transmitting outside your allocations.
All required information on these topics appears in the WIA 2000 Yearbook.
You may be asked questions on amateur activity
and clubs in your area. Make it your business to familiarise yourself with
local groups, on-air nets, coming hamfests and examiners near you. Most of the
required information is provided in this magazine, the WIA Yearbook, on-air
WIA/club news bulletins and what you yourself hear on the air.
These days most repeaters channels are
referred to by the last four digits of their output frequency. Thus a 2 metre
repeater transmitting on 146.700 MHz is 6700 and a seventy centimetre repeater
transmitting on 438.525 MHz is 8525. In the early days of channelised two metre
FM operation, Australian amateurs used several different channel numbering
conventions. You still hear old timers refer to frequencies by their old
channel number. Possibly the most common is 'Channel 50' - 146.500 MHz - the
national simplex calling frequency. As to repeater frequencies, 146.650 MHz was
known as Channel 1, progressing upwards until Channel 15 on 147.350 MHz.
Also worth knowing is your grid locater
square. Knowing your square to four characters is acceptable to give out in
contests, but if there is a need to calculate distances, knowing all six
characters will be necessary. Grid squares are seldom used on HF SSB or VHF FM,
but are commonly used by VHF and UHF SSB operators.
Passing the amateur exam is a great start, but is only the beginning. Learning several of the practical skills mentioned above will assist you to become an experienced amateur better equipped to enjoy what amateur radio has to offer.
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Licensed Page
This page was produced by Peter Parker VK3YE parkerp@NOSPAMalphalink.com.au. Material may be copied for personal or non-profit use only.