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Six Essentials for Field Day
It's really easy to
enter field day, why not give it a go? CW field day is
on the first weekend of June, VHF field day on the first weekend of
July,
and SSB field day on the first weekend of September. Field days are a
fun
way to involve club members in contest operation, and can be combined
with a
social event such as a barbeque. Here are the six essential components
which
make up a field day entry.
FIELD
The idea of field day operation is that you can
set up an effective radio
station under emergency or 'field' conditions, with no more than 24
hours'
notice. You will not be reliant on an existing antenna, nor have a
permanent building from
which to operate, and you must not use mains power.
Field day operation also gives a chance to operate from a well-sited
location, which may be on top of a hill and which will be away from
sources
of interference and TVI hassles.
You may be lucky enough to have a team
member who has a spare field in a good location, but if not try
approaching
a local farmer. They often have pasture, or set-aside land and usually
respond favourably to a polite approach. Even a 6 metre wide 'headland'
at
the side of an arable field may be sufficient to establish a small
field day
station.
There is merit in choosing a location which is
quite close to the club's
centre of population, as you want as many members as possible to help
put up
the station and operate, or to attend to give their support. Make sure
to
give clear instructions on how to find the site, and guidance on where
to
park and instructions ensuring gates are left shut.
At the conclusion of operations, when all the
gear has been packed away,
make sure to do a 'sweep' of the field and pick up all rubbish:
discarded
cable ties, PVC tape, food wrappers, cigarette butts. Be especially
careful
to ensure all guy stakes have been removed - the farmer will not
welcome you
back if his plough should happen to come across a piece of angle iron
still
driven into the ground.
No more than a week after the operation, visit
the farmer to thank him for
use of the field. A bottle of whisky makes a good token of appreciation
and
normally ensures that a request to use the field in following years is
received favourably.
OPERATORS
Although mention has been made of clubs entering
field day, the rules only
say that all operators must be RSGB members so while it is usual for
field
day stations to represent a local club, this is not a requirement. Any
group
of like-minded amateurs may get together, think up a name, and enter as
a
field day group. For CW field day, some clubs have difficulty rustling
up
enough CW operators, and it is perfectly acceptable for two or more
groups
to pool resources in order to enter.
Don't be daunted if you are not a 'hot shot'
contest operator. There is room
in field day for all levels of operating ability. Plenty of groups
enter
knowing they have little chance of winning outright, but enjoy the fun
of
competing from a quiet location, often with much better equipment and
antennas than are available at home. Field day is also an excellent
opportunity to give training to those who are unfamiliar with
contesting,
and many of today's top competitors started their contest careers in
field
day.
How many operators should be on the team? For the
QRP section of NFD, which
is limited to 12 hours, one operator might be sufficient but this is
hardly
in keeping with the spirit of field day as a group or club event. Three
operators is really the minimum, especially if use is made of the
second
receiver in a rig such as the FT1000 series. Choice of section may also
be
influenced by the number of people available, and the Open sections are
only
really for the larger and better-equipped groups.
In the larger clubs, not everyone will want to
take part in the operating
activities but there are many other important roles to be fulfilled,
such as
helping to put up the antennas, filling the generator, keeping the
operators
fed, and finally helping with the tear-down so that everyone can get
off
site as quickly as possible.
GENERATOR
Of all the equipment making up the field day
station, the generator is most
often the one that gives trouble. Field day rules state that mains
power may
not be used, but a generator is not the only solution. For the QRP
section
of NFD you may well be able to get away with one or two gell cells, and
it
is also possible to run a 100w station for 24 hours from a lorry
battery
which can be kept topped up by a small 12v generator, a set of solar
panels
or even a wind turbine. Remember if you go down the 12v-only route that
all
items including keyers, computers, lighting must run from 12v.
If the generator is stored by one of the members
of the group, then it
should be brought out a while before the event, oil level checked, and
run
up and operated under load for at least 30 minutes. An 800w petrol
generator
can be used to power a 100w station, though 1.5 or 2.5kVA would give
more
margin.
Traditionally, the generator has been obtained
from a hire shop and this is
frequently where the problems start. Hire shop generators see most of
their
service on building sites and the voltage output and regulation must be
checked to ensure that the generator will power a radio station without
problem. Collect the generator from the hire yard on Friday, and run it
for
at least an hour under test conditions. Use an electric fire or similar
load
of at least 1kW, and check that the voltage does not rise above 250v
when
the load comes off. The reason for getting the generator on Friday is
so
that if any problems arise it can be taken back to the hire company
with
some chance of being able to obtain a replacement in time for the
weekend. Whatever generator is used, it is worth applying
a constant minimum load of
at least 100w, and this can be done by mounting a 100w bulb on a post
by the
generator.
Generator hire for a weekend should be under
£50, but the cost of buying a
generator has come down significantly in recent times and it is now
possible
to buy generators which use an inverter, and give a true sine wave
output.
Buying a generator is still a significant outlay for use only once or
twice
a year, and one of the members of the group will have to undertake to
store
it safely and securely.
Site the generator as far from the operating
position as possible, to keep
noise levels down. A car can be placed between generator and station
for
this purpose, but even better is to borrow straw bales from the farmer
to
provide sound insulation. Just don't place them so close to the
generator
that the hot exhaust sets fire to the straw. An awning can be suspended
above the generator to keep the rain off, especially important while
refuelling.
RADIO
Pay regard to the rules for the particular field
day and section that you
wish to enter. For CW field day, it is highly desirable that the radio
include a CW filter.
As mentioned above, a 12v radio can be run from a
well-charged car or lorry
battery, which can then be float charged. So long as all critical parts
of
the station are also powered from 12v, this will also enable the
generator
to be powered down before refuelling.
The question of which radio to use ofen comes
down to which group member is
prepared to let their rig be used by different people in a field day
situation, but modern rigs are so much more reliable than they were
even 20
years ago, and this should not be a major concern. The groups which are
going all-out to win have no qualms about using whatever
top-of-the-line rig
it takes, FT1000MP, Orion or whatever. Take a standby rig: Murphy's Law
ensures that the rig will only develop a fault if no standby is
available.
Make sure everyone who is going to operate has a basic 'driving lesson'
before the contest starts so they know the main controls of the
rig.
If different club members are bringing different
items of kit, it is a good
idea to try them out together beforehand. Especially if the field day
site
is some way from home, you need to make sure all necessary connecting
cables, interfaces, adapters and leads have been checked. Always make
sure
to have a soldering iron and set of tools to hand.
The operators will be wearing headphones, so in
order that other members of
the group or visitors can hear what is going on it is a good idea to
rig up
a simple audio amplifier and loudspeaker. Many rigs have an audio line
output, and this can be connected to a powered PC speaker for a simple
audio
solution. Make sure all visitors to the site are greeted, and it may be
a
good idea to prepare a short briefing note about the field day, the
club and
amateur radio in general - you may find some new recruits to the hobby
this
way.
ANTENNA
Choice of antenna again depends on which section
is to be entered, but for
the group trying field day for the first time, on HF it will be the QRP
or
Restricted section. In this section, the antenna height on CW field day
is
limited to 36ft, and to 50ft on phone. No more than two elevated
supports
may be used.
A 36ft support is easy to achieve, using scaffold poles and can be put
up
single-handedly with use of a gin pole.
Ensure the guy ropes are firmly
secured to guy stakes driven into the ground, and check the stakes if
there
is heavy rain or a strong wind blows up during the contest. It is
always a
good idea to mark the position of the stakes with a post and reflective
tape, to avoid visitors driving into them especially if the grass is
long. Rather than attach a wire antenna directly to the mast,
always use a pulley
and halyard so that the mast only has to be raised once, no matter how
many
times the antenna may need to be raised and lowered for
adjustment.
In practice, the antenna of choice for almost all
entrants in the restricted
and QRP sections is the centre-fed doublet. CW field day includes
topband,
so a common length is around 270ft whereas for SSB which is only on
80-10m,
135ft is a better choice. The simplest configuration is to have a 36ft
mast
close to the operating position, and run the doublet legs out on long
lines
so that the wire ends are at least 10ft above ground. 450 ohm lead or,
even
better, home-made 600 ohm open wire feeder is run to the ATU(s) at the
operating position.
The line of the doublet should run approximately
east-west. If this is not possible take care, since the 20m lobes tend
to be
in the wrong place if a doublet runs north-south.
The doublet is not the only possible antenna, but remembering that the
Restricted and QRP sections only allow a single antenna, it is usually
the
best choice. Loop antennas, trap dipoles and even longwires have also
been
used with success. The second elevated support may be used to raise the
height of one leg of the antenna, or both masts may be used to support
the
centre part of the doublet and ensure it is horizontal, while the end
legs
are suspended on lines down to ground. If this configuration is chosen,
make
sure the weight of feeder doesn't lower the centre of the antenna too
much.
Once the antenna is brought to the operating
position, an efficient ATU must
be employed. If a multiband ATU is to be used for all six bands, it is
as
well to check the configuration well in advance of field day and
confirm
that a match can be obtained on all bands. The feeder length may need
to be
changed, or lumped components added, to get a match on some bands. Most
multiband ATUs are of the T-match type and the 4:1 balun on the output
is
not always a good performer. On some bands where the feed impedance is
low,
an external 1:1 balun may be better, and it has been found that a 1:1
balun
when used with the internal ATU in the Elecraft K2 transceiver gave a
good
match on all bands. The internal ATUs on most transceivers are nowhere
near
as good as the Elecraft design, but another option is to use an Auto
ATU
together with a balun. Greatest ATU efficiency comes from use of a
balanced
link-coupled ATU with adjustable taps. Several may be needed to cover
all
six bands.
TENT
Some entrants in the 12-hour QRP section might
trust the weather forecast
and brave the elements, but in practice all stations need to have some
sort
of shelter. While the lucky ones may have a caravan from which to
operate,
it must be brought onto site: a caravan which is not moved from its
storage
position would be a violation of the field day rules. It is possible to
operate from a large car or van, though a van in particular can get
very hot
during the day.
Most groups use a tent from which to operate, and
someone in
the group can usually get access to a frame tent large enough to
accommodate
two operators and a rig. The larger the tent the better, though it is
best to discourage visitors and
club members from talking in the operating tent and distracting the
operators, so a second 'social' tent, if one can be found, is a very
good
idea.
Make sure the operating tent is equipped with
lighting - in the past, groups
have set up during daylight and happily operated until it got dark,
when
they realised no provision had been made for lighting and further
operation
was only possible because of the dial lights on the rig. Also make sure
one
or more torches are to hand, in case of sudden generator failure. Bear
in
mind that even in June or July, it can get very cold at night so ensure
the
tent flaps can be closed and that there is some provision for heating.
Only
if a really large generator is available will electric heating be an
option,
but calor gas heaters of various sorts are available and can be
effective
while the tent flaps remain closed. Care may be needed in routing
open-wire
feeder into the tent, or it will be found to be impossible to close the
tent
up completely at night.
There are many more detailed aspects of field day
operation that could be
discussed - provision of food and drink, operating rota, logging method
(paper & pen or software), but no group in its first foray into
field day is
going to get it 100% right - that's part of the fun. Make it a club or
group
event, involve as many people as possible, and learn together. There
probably won't be any fog and it's very unlikely there will be any rats
but
remember the six essentials - FOGRAT - and enjoy your first field day.
For further information and guidance on how to
enter field day, contacts the RSGB Contests Committee or ask the
community on the UK contest reflector. Links are at the top of this
page.
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