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This is John G3NCN outside the camping trailer which formed our home for the NFD
contest. This is the result of two months planning, and was the first time we
had put on a totally battery powered station in an amateur radio contest.
This page details what the contest is all about, and how we set out to achieve
our goal. And for those of you who are not familiar with amateur radio and
contests, an insight into what makes us sit out in a field all the night!
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So what is NFD??
NFD, National Field Day, is an amateur radio contest organised
by the Radio Society of Great Britain, the
national amateur radio society in the UK. The contest is arranged to coincide with a
similar contest in other European countries, though the UK scoring system is slightly
different. The objective is to contact as many other stations as possible, with extra
points for working portable stations and stations outside the UK. In practice most of the
contacts are with UK and European contest stations.
In NFD operation has to be portable, with the station power derived
from a generator or batteries, not from the mains. There are three sections - Open, with
no restrictions on the number of aerials - Restricted where a single aerial at 11m is
used - and Low Power where the power is also restricted to less than 10 Watts. This is a
CW (morse) contest - there is a SSB event in September. Operation is on all the amateur
hf bands between 160m and 10m, with the exception of the 30m, 17m and 12m bands where
contest operation is not permitted.
NFD is one of many amateur radio contests - the rules, operating
modes and frequencies differ, but the objective is the same - to work as many other
stations as possible, and hopefully to win! More details of NFD and other RSGB hf
contests can be found here.
NFD is a 24 hour contest, from 1500z June 1st to 1500z June 2nd
2002. For the Low Power section which we entered, operation is limited to 12 hours, but
can be in several sections over the period.
Initial planning
The Bracknell club has entered NFD many times in the past. We
are always looking for something different, and as we are not a big club in terms of hf cw
operators we are not in a position to do well in the open section, where we would be
competing against much better equipped stations. Two years ago for instance we operated a
single band station on 160m, and were the band leaders (though way down in the overall
entries).
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Initial ideas started when I bought an Elecraft K2 transceiver. This is a
very compact hf transceiver with, in its basic form, up to 12W output and running
off a 12V supply. With the options I have currently fitted, ie the 160m option and
the KAT2 automatic ATU, it looked attractive to use in the low power section with
its 10W limit. Normally we have powered all the station equipment from a 3kVA
petrol generator. What would be the possibility of instead powering the complete
station with all its accessories, from batteries, and hence saving the noise and
significant running expense of the generator?
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copyright Elecraft
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The K2 takes around 240mA from 12V in receive, and around 1.5A key
down in transmit. If necessary the receive current can be reduced to around 150mA by
turning off the LCD backlight and other measures. Rough calculations indicated that a 4AH
solid lead acid battery, readily available for alarm backups, might last for 12 hours of
operation, but a second one should be kept in reserve. I ran my K2 in the shack from
such a battery one day as a check, and was impressed with how long it lasted. Just
before Field Day John G3NCN produced a couple of 7AH units - we had enough power for
several days!! Oh, and the K2 has an internal keyer, which works very well. No problems
with incompatible keyer interfaces and rf feedback into them. And excellent full QSK - no
clattering transmit relays.
But what about the rest of the station, in particular power for a
logging computer (essential in today's contests), lighting and home comforts. The latter
were solved when John offered us the use of his camping trailer as our operating position
- towed as a large trailer behind his car onto site, and then magically transformed by
unclipping and reclipping a few bits into a spacious caravan, complete with all the
lighting, cooking and heating mod cons you expect from a camping enthusiast. And it had
a copious 12V supply of its own - 65AH in fact - enough to power the rest of our gear.
To maintain our aims, the K2 would still be powered separately from the gel cells.
Most modern laptops do not have enough charge in their batteries to
run for 12 hours without charging, and also require unusual voltages such as 18V so
cannot be run from 12V direct. By luck we still have a number of ancient Zenith laptops
- no hard disks, 720k floppies, and incredibly slow - but they run off 12V at around
0.5A! We checked these out on bench supplies and found they worked OK right down to
about 10V input. Software was EI5DIs Super
Duper - the later versions will not run on 8086 processors, but the copy we purchased
a few years ago did (take note, Paul!).
The Site
Field Day is a portable contest and a suitable site must be
identified in advance, preferably one with plenty of open space for antennas and away from
residential areas, permission obtained from the owners, and the site registered in advance
with the contest organisers. There are several suitable sites available to the Bracknell
Club, two of these are local. Our site in Dorset used for VHF NFD (and incidentally to be
used by some of our club members for the 50MHz contest that weekend) was not suitable in
this instance as two of us had commitments locally on the Sunday. One of our sites suffers
from waterlogging in wet weather, but was kept in reserve as a possibility.
Longhill Park where we operated is a former landfill waste disposal
site, which was converted into public parkland in the mid 1960s. We have operated NFD
and other contests there over the years, and it is an excellent location for amateur
radio - large, open, well away from housing developments, and with a low electrical noise
level. It is open to the public, and a favourite place for 'taking the dog for a walk',
but in general is quite peaceful. Most significantly, it is conveniently located for all
our members, and is only ten minutes walk from my QTH! Longhill is owned and maintained
by the local council, and permission was obtained from them to use it for the weekend.
Registration details were submitted to the contest committee in early May to allow their
'inspector' to visit us if necessary to check we were operating within the spirit of the
contest.
The Antenna
Stations in the Open section of NFD have no limit on the number of antennas they can
use, apart from a 20m height limit. In the Restricted and Low Power sections however only
a single antenna is allowed, to cover all the operating bands, with a height of 11m
maximum, and no more than two elevated supports. If operation on all bands is required,
the options for antennas are somewhat limited, and we decided to use what has become a
standard for Field Day stations - an inverted vee doublet with the centre supported by a
single mast and fed with open wire feeder. To give good performance on the 160m band a
total top length of 204 ft was decided on - there is nothing significant in this length,
but it is in fact a double size G5RV and so can be expected to give a sensible impedance
match on all bands. The feeder was 40 ft long, sufficient to reach the operating position
with some spare.
The internal antenna tuner of the K2 can match most antennas but for feeding balanced
line a balun is required. Using the designs in the ARRL antenna book I constructed a
suitable balun and arranged it to be switchable between 1:1 and 4:1 impedance ratio via a
toggle switch - in fact it was used just in the 1:1 position and a match better than
1.6:1 was obtained on all bands. The K2 remembers the ATU settings for each band so
instant band change was possible and it was not necessary to change the settings after
the start of the contest.
In order to identify any problems with the impedance of the antenna, I downloaded a copy
of the program dipole3.exe from Reg G4FGQ's site. This program is specifically written to calculate
the matching impedance of dipoles fed with balanced line. Although this was an
interesting exercise, the results of the simulation bore no resemblance to the
performance of the antenna when erected!
Any antenna requires a support mast or tower. Initially we had planned to use the same
mast as we had used two years ago - a light weight aluminium mast designed by John
G3NCN. Just ten days prior to field day we heard that a former member of the club had
kindly donated us an ex-army 30 ft sectional mast, brand new, for club use, and an
initial check indicated this would be ideal. To check out however we needed to do a
trial erection, and this was done a few days before the contest. The whole antenna and
mast was erected, checked with the K2, disassembled and repacked within an hour or two.
With just two of us on site it was remarkably easy to erect the mast, though we were
hoping more would be available on the Saturday! We had a quick QSO on 40m just to prove
it worked. Of course, to keep within the Field Day rules, everything was then taken off
site again.
Tactics
When operating all bands, it is important to choose what time to operate on each band
in order to maximise the scoring rate. In NFD double points are given for all contacts on
160m and 10m. The operating time for 160m is from late evening until the middle of the
night (by which time there will be few new stations to work). 10m is only open during
daylight, and is unpredictable as it depends largely on sporadic E propagation, which may
only occur for relatively short periods. It is important not to miss these openings on
10m!
In the Low Power section we are also limited to a maximum of 12 hours operating time in
total. We had another problem - both myself and John have church commitments on the
Sunday. On that basis an operating time of 5pm to 5am local (1600z-0400z) seemed
sensible. We would have a fair chance of catching any sporadic E opening on 10m on the
Saturday, and we would be able to use the whole of the night period for 160m, 80m and
40m. And by 5am it would be light, and the station could be dismantled easily allowing
us hopefully be rested in time for church (or that was the theory...).
Saturday Afternoon
Knowing now how long it would take to erect the antenna, we aimed to get on site
around 3pm which would allow us plenty of time to achieve our starting time - in fact we
were there a little earlier, as John's son-in-law was keen to witness the transformation of
the camping trailer! Our third operator was to be Ian G3TLH, a QRP die-hard, who cycled to
the site. We were joined in due course by Steve G4AUC (our 'cameraman' who supplied the
photos on this site).
The first task was to convert the camper trailer into the operating tent, which was done
by John with a little assistance. We were all amazed at how large and roomy it was after
assembly. Having stored all unwanted items (and Ian's bike) underneath the trailer we
paused before unpacking and erecting the mast. With four on site this was erected fairly
quickly, and the antenna with its open wire feeder uncoiled, pulled to the top of the
mast with its halyard, and the remote ends secured in the correct places. The balun was
attached, and the feeder fed through a convenient hole in the trailer to the operating
position.
We then encountered our only hiccup during the weekend. When we came to check the
trailer electrics we found the voltage collapsed when we turned on any load such as the
lighting. Dreading a flat battery which would have seriously limited our activities (but
certainly not stopped us) we investigated. We found the master fuse was not making proper
contact in its holder - a small piece of aluminium foil was placed in the holder to make
it firmer (no, we didn't short the fuse out...). The other problem was we were unable to
light the pilot light on our propane powered fridge - so the milk had to do without.
Setting up the station itself was done relatively quickly - it was just a matter of
connecting up and go. Each band was then tuned with the K2s atu, a simple case of
pressing the tune button and letting it do its work (loads of clicking relays as it runs
through all possibilities). In fact on most bands the tuning had not changed since the
trial run, quite surprising as the antenna had been in a completely different place in
the field. The logging computer was then powered up and we waited while it booted and
loaded the software. A quick check and break, and we were now all set for the fray!
The station in action
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Here I am operating the rig, with Ian G3TLH doing the logging on the Zenith
laptop. Since neither of us had used the SD program for some time, we had a few
problems during those first QSOs. In particular, we had forgotten that the '-' key
is used to totally delete an unwanted entry. I took a 'tea break' trip back home
and returned with the SD instructions - we had no further problems with that one!
This photo shows how compact our station was - absolutely everything apart from
the balun and antenna is in the picture. The gel cell is behind the K2,
partially hidden by the laptop.
No, that is not a road you see out of the window - it was the newly mown grass
the council had obligingly cut to allow us easier access.
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As if by cue, we found the 10m band open right at the start of the contest, so we spent
the first two hours down there taking advantage of the double points available. These
sporadic E contacts were largely with European portables, though it was nice to work
5B4/GM3YTS/P in Cyprus who was doing very well indeed in the contest. We stayed on 10m
until the band started to fade, followed by a short spell on 15m. Most of the time we
kept the K2 output at 5W to maximise battery life, and we had no problem making contacts.
After some successful sessions on 40m and 80m it was time to start on 160m at 2200z. I
had been sceptical as to how the 5W from the K2 would perform on that band, especially
since I had only had two QSOs on the band from home. I needn't have worried, we could
work virtually everything we heard - time and time again John suggested we would be
wasting our time calling a weak eastern European station and he was proved wrong every
time when we made it on the first call! It seemed our antenna worked like a dream on
that band.
It was a pleasant night. Fortunately there were no problems with thunder static which can
wreck havoc on the LF bands, and even worse damage equipment if there is an actual
storm. For a while we needed to use our propane gas heater, but it was by no means cold,
and as always it is a thrill to see the sun slowly appearing out of the dark. All too
soon it was 0400z and time to pull the plug and take down the station.
The results
And as we drove off site early that Sunday morning, it was time now to analyse the
results and work out the strategy for next year. These days preparing the logs and sending
them off is a very straightforward process - the SD logging software takes care of marking
all duplicates, scoring etc. and producing an electronic log file suitable for sending the
the adjudicators. In fact the log was submitted by e-mail on the Monday morning. Gone are
the days of laboriously copying all the contacts from paper onto the official log forms by
hand, checking for duplicates with check log sheets, and adding up the scores manually - in
those days this took several days, and there were always problems reading individual
operator's handwriting and sorting out conflicts and errors. This is one aspect where
computers score - and it also makes the adjudicator's job much easier (but doesn't mean
they announce the results any earlier..).
These are our results as submitted:
Band 160m 80m 40m 20m 15m 10m Total
Valid QSOs 95 90 67 4 28 51 335
QSO Points 756 331 252 14 98 364 1815 (including band
bonuses)
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When the results were finally announced in October we found we were placed second
in our low power section. It seems a little more time on 160m or use of 10W
instead of 5W would have made those extra few points to achieve our goal. In first
place were the Echelford club, operating as G3UES/P, who rather interestingly were
also using a K2!
However we received a nice certificate for our efforts!
The full results of the contest can be found in the November 2002 issue of the
RSGB magazine RadCom
Analysis
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Did our entry meet our expectations? Undoubtedly! Could we have done better?
Probably!!
I have no reservations in saying that the Elecraft K2 is an ideal rig for the Low Power
section of NFD. Of course now that they have introduced their 100W version, it would
also make an excellent rig for the Open and Restricted sections as well. But I shall not
be buying that version myself! Although we could have run the full 10W allowed, we were
very pleased with its performance at 5W - certainly we had no problem making QSOs, and
whether we would have worked many more with 10W is questionable. Time and time again Ian
G3TLH commented on how much he liked the feel and operation of the K2, it certainly is a
nice rig to use and less daunting than many of the other rigs on the market today. And
the performance of its receiver is the real bonus - excellent strong signal performance
and very nice CW filters. I suspect we had an advantage in hearing stations,
particularly on the lower bands, which others couldn't.
And what about the antenna? I think the length we chose, 204 feet, is a good
compromise. It gave excellent performance on Top Band and still gave reasonable results
on the higher bands. By using the K2 internal tuner we did not need to worry at all about
matching during the contest - instant band change, and a knowledge that it was always
matched and working as it should be.
The advantage of powering the whole station from batteries was also well received. In
the past the major expense in NFD has been the cost of petrol for the generator. We own
our own generators by the way, so never had the additional expense of hiring one. There
was also an absence of the generator humming away close to the tent, no worries about
electrical noise from it which can make reception difficult, and there was no need to
worry about keeping the fuel tank topped up (a potentially dangerous process at night).
We now know that we have more than adequate capacity in our batteries, both the gel cells
and the trailer batteries, though this was something of an uncertainty this year. Yes,
this is the way to do it.
Conditions on the bands were reasonable as far as NFD is concerned. Not much DX about,
but good propagation into Europe, a nice sporadic E opening on 10m, and no QRN (static)
on the lower bands. Our choice of operating times was optimum as it happened, though we
would have lost out if the 10m opening occurred on the Sunday. We missed out though on
working much on 20m. When we finally went on that band around 0130z we found propagation
to Europe had faded and most of the activity was from the USA who were only interested in
ragchewing. But the bonus points on the other bands made up for lack of QSOs on that
band.
Will we do the same next year? Maybe, but that is a decision to be made nearer the
time. But those taking part in this year's event agreed that it was a most enjoyable
weekend and would recommend a set up similar to ours as an excellent way of putting on a
station in the Low Power section of NFD with the minimum of effort - and achieve an
excellent position in the results.
Watch these pages for next year's attempt!
73s Dave G3YMC