1. Introduction
Here are some tips for radio amateurs who are going to run a
VHF/UHF-Contest on a portable QTH. After three or four contests
and damaging a few antennas I was experienced to build up the hole
system (2m/70cm/23cm/13cm) you see on the photo by my own. I
want to share all my experiences with other single (or multi) operators
to activate the upper bands.
2. Reasons for running 23cm on a portable QTH
When I was building up my 23cm transverter I was thinking about running 23cm at home or only during VHF/UHF-Contests on a portable QTH.
There were three main reasons for my decision to run 23cm only on a portable QTH:
1. My home QTH was not good enough for running a contest
with low power and one small antenna on 23cm.
2. Building up 23cm at home would mean a big expense
for a student as I was. I would have needed a big antenna and a preamplifier
with at least one coaxial relay suitable for 23cm on top of the mast. Further
I would have lost about half of the TX power due to the coaxial cable RG213
(that time AIRCOM coaxial cable was not yet popular).
3. The main activity on 23cm appears during the VHF/UHF-Contests.
3. Where to install the transverter
It was clear for me that mounting the transverter system on the mast under the antenna by keeping the coaxial cable between antenna dipole and transverter input as short as possible will perform good results.
This will offer the following advantages:
1. There is no need for an additional preamplifier, because the
noise figure of a good transverter is usually about 1.5dB NF and this is
already good enough compared with expensive preamplifiers which offer a
noise figure of normally 0.8 to 1.0dB NF.
2. The attenuation of the TX power due to the short coaxial
cable will be minimized.
3. There is normally only one coaxial relay needed.
I want to mention here that also a lot of home stations are using there
transverter on top of the mast. The problem they are facing is that they
need to make a big effort in getting there system weather-proof. Of course
a portable station needs to follow the same way, but taking the transverter
down to repair it is not always easy for a home station.
4. How to prepare a portable VHF-/UHF-Contest
4.1. Fundamentals
Here I want to give some tips how to prepare a portable VHF-/UHF-Contest:
1. Make a list of all the things you need. An advice is given
in paragraph 4.2. Experienced contesters can also give you some advice.
After coming home from your first portable contest you will now which things
you forgot and should add these to your list.
2. Put the things you need already a few days before
the contest starts in some boxes. On the day of the contest it might
be to late. (You will be surprised how much time it needs to prepare a
coaxial cable with BNC-connectors a few hours before the contest starts.)
3. If you are going to use car batteries, charge them two or
three days before and check the voltage after charging. (Remember: If the
batteries have some problems you might be unable to run the contest.)
4. Built up your mast once to get some experience how this is
going to work and how long it takes. You don't need to built up the hole
system, but it makes sense to add some weight on top of the mast. With
this weight you will get a feeling whether you can build up the mast with
manpower or you need to use a tool. (If you have a big mast like I have,
this is the most difficult part in getting started for a contest.)
5. Study the map to find a good radio location. Go there to
take a look whether there are tall trees, good approach roads, nature reserves
or other circumstances which might make it impossible to go on the air.
(I was once driving around for 1 hour looking for an other location, because
the one I had chosen was not approachable due to a muddy country lanes.)
Think about an alternative location in case there is already a radio
amateur or any activity on that location. The experiences with my VHF-/UHF-Contest
locations are shown in paragraph 4.3.
6. Try to figure out how long all preparations like loading
your car, driving to your portable QTH and building up the whole station
will take. If you estimate it right you will be QRV in time for
the start of the contest.
4.2 List of the things you need for a portable VHF-/UHF-Contest
Following I want to show a list of the things you need. This list shall be a help, but there might still be some things missing.
- Transceiver(s): You need to have at least one transceiver for
one band with its coaxial cable and its antenna where you are absolutely
sure that it is working. For me this one was always 70cm. The most annoying
thing which might happen is driving to a distant location, building up
a system for two or more bands and none is working. It happened sometimes
to me that the equipment for one band was running unsatisfactorily or not
at all, but I was always sure that 70cm will work well and I could at least
be QRV on that band .
- Microphone and keyer: Don't forget to check the batteries,
if you use an electronic keyer.
- Computer: It will help you logging your QSOs and linking a
DX-Cluster (don't forget to bring your modem, an additional transceiver
and a vertical antenna). I for myself was running only two portable contests
with linking a DX-Cluster by computer. For the log I choose always the
old method writing it on paper.
- Antennas: One for each band should be enough. If they full
down and the connection to the dipole is still useable you can straighten
the elements by hand and still use them with good results.
- Power source and its connectors: My power source were always
two 12V/88Ah car batteries. One was usually enough and the second one was
for safety. The connection to the poles of the battery was done by big
battery clips. These clips where connected with leads which ended in a
case with three red and three black banana jacks (a very useful device).
- Coaxial cables: Think very clearly about the length they need
to have and take some more with you in case you need an extension.
- Coaxial adaptors: Take all you have with you.
- Wires: Think very clearly about the length of the power cord
for your transverter and of the wire to switch between RX and TX. Additionally
you should take about 10m two conductor speaker wire, some terminal blocks
and some test leads with clips on each end with you.
- Multimeter: Don't forget to check the batteries.
- Lamp: A small lamp for the night. The best thing is to use
a 12V type lamp which you can connect to your power supply. If you use
one with a different voltage and separate batteries (e.g. 3 times 1.5V)
you cannot connect it to your power source after the batteries have run
out.
- Mast and all parts for the mast: What you need depends on
your mast.
- Tools: You need at least a "+" and a "-" screwdriver (Phillip's
head tip and cabinet tip), a combination pliers and a hammer.
- Tapes: You need to have good tapes to fix your cables to the
mast. You might also fix them on your ropes which hold the mast to make
them more noticeable.
- Compass: Helpful if you are not yet experienced with the location.
- Locator map: Bring a small and simple locator map, which shows
only the squares like JN59, JN58, JN57 etc. A map like this is clearly
arranged and helps you to find your partners location within short time.
You can find these maps for USA in the ARRL Handbook (have look
in the index under headword map) or for Europe in the book with
the title "Amateurfunk im VHF/UHF-Bereich" available via the DARC
(Deutscher Amateur-Radio-Club e.V.) on page 10.
- Paper and pen: Bring some paper and pens (the best pens are
sharpened pencils). Prepare your logbook before the contest (click
here to get my log sheets).
- Watch: Change the time of this watch to UTC and make all logs
in UTC. If you don't do this you might get confused during or after the
contest.
- Beacon list: Beacons are always useful if you want to check
your system especially on the upper bands, where you might hear nobody
from time to time during the contest.
For your personal welfare:
- Food and drinks: Especially in the summer you will need to
drink a lot, because building up a system like mine will cost a lot of
energy. In the winter (or on cold spring or autumn days) you will be happy
if you have some warm drinks with you. Bring also some water which you
can drink or use for your personal hygiene. For the food it is the best
to ask your wife or mother to prepare something for you.
- Sleeping bag: It should be good enough for cold nights.
- Hygienic utensils: At least you should have a towel and some
toilet paper.
- Hat and sun cream: They protect you from getting sunburned,
if you need to build up your radio station in the sun.
4.3. Experiences with VHF-/UHF-contest locations
Everybody will ask now: What is a good radio location?
There will be much discussion and different opinions about a good radio location. I only want to mention my experiences with the two locations I was QRV during the contests:
- My first contest QTH was on top of a hill about 400m above
sea level. It could be reached by car and was about 150m higher than
the region direction southwest to north. Unfortunately there was an
other hill about 500m above sea level in a distance of about 1km direction
southeast to southwest. Therefore QSOs in that direction on 70cm and
the upper bands were nearly impossible. Another handicap you face mostly
on top of any hills are trees, which force you to build up very high towers
or even prevent you from building up any mast or antenna. Fortunately there
was a meadow on top of my contest hill with the size of a sports court
and only small trees around it. But trees are growing much faster than
you expect. Within three years these trees grew nearly two meters to a
height of about 6m. Therefore a small mast couldn't be used anymore. And
as already mentioned above there came the contest day after some rainy
days when it was impossible for me to drive up the hill because of muddy
country lanes. I think even tractors would have had there problem. This
was the day when I tried my second contest QTH the first time.
- My second contest QTH was no hill. It was only an elevation
about 300m above sea level and I could drive there by car on a concrete
road. The sight all around this QTH was free and the distance
to the nearest hills direction northeast to southeast with a height of
500m above sea level was about 10km. There were only fields around. The
photo on top of this page was made on that QTH. One handicap was
that there was no meadow where I could build up my portable station. The
only solution was building it up on a crossing. Fortunately I didn't hinder
anybody during my activities and there were nearly no farmers driving around
when I was QRV. One reason might be that the farmers don't work on Sunday
and not that late on Saturday.
Of course I could never compared both QTHs simultaneously, but in my
opinion the second QTH was better than the first one. It offered
me a lot of points in all directions and on all bands.
5. Contest results, QRP equipment and best DX
5.1. Contest results and QRP equipment of DH5NAH in 1994
Now I want to show you my contest equipment and my results in 1994, the year when I was placed 8th of 658 stations in the annual result.
My contest equipment in 1994:
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TR-851 |
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Transverter DB6NT (IF: 2m) |
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Transverter DB6NT (IF: 2m) |
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My results in 1994 on 70cm:
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My results in 1994 on 13cm:
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5.2. Best DX of DH5NAH during portable contests
Here are my s during contests:
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As you can see in the tables above I was a so called QRP station
on 70cm and the upper bands (maybe even on 2m), but my results were
pretty good. With these results I want to encourage all beginners
to get QRV on the higher bands. You don't need to have big antennas,
climb high mountains or spend a lot of money for power amplifiers and good
preamplifiers. No! You can have a lot of fun even as a QRP station. And
trust me: Working a station which is 721km away on 23cm with 10W output
and a 23-ele F9FT makes you more happy than working this station with 200W
output and 4 x 55-ele F9FT.
6. VHF-/UHF-Contest station of DH5NAH
6.1. Battery powered station
Further I want to mention that I was always operating battery powered.
Therefore I had always two 12V/88Ah batteries with me. I think only once
I needed to connect the second one on the end of the contest. All the other
times one 12V/88Ah car battery was enough to run all my above mentioned
equipment for 24 hours including a 12V/10W lamp for the night. This
was no problem due to the fact that I - as a QRP station - mostly listened.
When I was not working on 2m, 23cm (IF: 2m) and 13cm (IF: 2m) I switched
off the 2m-transceiver. The transverters were running all the time. If
you would switch them on when needed they would have a frequency drift
of a few hundred hertz within the first seconds of the QSO and you would
need to tune the frequency of your receiver again to understand your QSO
partner. In receive mode all the equipment I used needed a current of about
1.5A. In transmit mode I needed much more (peak current up to 20A on 2m),
but you always have to consider that we use SSB modulation and the average
output and also input power is usually not even half of the maximum output
power.
6.2 Details about 2m, 70cm, 23cm and 13cm equipment
Let us come to a description of my portable contest station:
As mentioned before the most important thing is to have one transceiver for one band with its coaxial cable and its antenna where you are absolutely sure that it is working. For me this was a TR-851, a 12m long RG-213 coaxial cable with both sides N-connectors and a 19-element F9FT for 70cm. Some OMs might think about the bad noise figure, but in this system I didn't want to add anything. If I would have added a preamplifier I would not have mounted it on top of the mast, because if it would have caused any problem I would need to get the whole mast down. That's why I would have placed it in the "shack" to be able to bridge it easily in case of a failure. Besides I want to mention that I didn't use any additional power amplifier for 70cm, because they are very expensive.
On 2m I used a very old TR 9000 (bought in 1980). This transceiver is according to my knowledge the only one which allows you to scan 10kHz-steps. Means: If you push the scan-button it will continuously scan for example from 144.290 to 144.300MHz. After turning the frequency tuning knob one step up it will continuously scan from 144.300 to 144.310MHz and so on. Therefore you can scan the band within short time. As an antenna I used small yagis with a length of about 3 to 4m like the 9-element F9FT. Only once I used a 16-element F9FT (as shown in the photo on top of this page), but it took me about 30 minutes to build it up and mount it on the mast. Also the handling with its length of nearly 7m makes it unfavourable for a portable single operator station. Further its gain is only 2dB better than the gain of 3 to 4m long yagis. As a power amplifier I used one with a preamplifier and a maximum output power equal to my legal output power (150 watts).
On 23cm I made very good experiences with the transverter designed by DB6NT and the Mitsubishi hybrid M57762, which offers an output power of 10W. My 23cm antenna was always a 23-element F9FT. This antenna will be delivered with a coaxial cable (RG213) fixed on its dipole. This cable is in most cases long enough to reach the transverter input on the mast. My coaxial relay between antenna and transverter was a CX 520 D. You should not save money using a cheaper coaxial relay with soldered connections for coaxial cable like RG58. These relays are in my opinion not suitable for DX on 23cm. The RX/TX switch over was done by a normal switch in the "shack", which supported the RX or TX parts of the transverter with power. The coaxial cable from the mast transverter to the transceiver was RG58. Due to its low shielding the nearby contest stations, which were on 2m could be heard in my 2m-transceiver when I was on 23cm. Let me explain the reason for this phenomenon briefly: Every coaxial cable acts like an antenna. You can disconnect the antenna of your home station when your 2m-transceiver is placed in the cellar and you will still hear radio stations. This is because of the radio stations emission through your coaxial cable to the antenna input of your transceiver. Of course these signals will be attenuated and it depends on the shielding of the coaxial cable whether they will be more or less attenuated (better or worse). If you are using a 1296/144MHz converter the converted signals of stations on 1296MHz and the signals of stations on 144MHz will come to the antenna input of your 2m-transceiver. To find out whether the heard stations were on 2m or on 23cm I turned my 23cm antenna slightly. If the signal was gone I knew that it was a 23cm signal, if it was still there it was a 2m signal. Nevertheless stations in an area with a lot of contest stations or with a contest station quite near to their location should consider to use RG213 for the IF signal. The transceiver on the 2m-IF was the above mentioned TR9000. As the frequency of the oscillators from the transverters of a lot of stations drift of about plus/minus 3kHz, you usually need to handle two variables to find the 23cm-signal: the frequency by tuning the transceiver always about 5kHz up and down and the antenna direction by turning the antenna. I only needed to take care of the second variable: the antenna direction. This was because I made skeds with DX stations on frequencies ending with 5 like 1296.245MHz and the 10kHz-scanner of the TR9000 scanned the frequency like from 1296.240MHz to 1296.250MHz continuously.
On 13cm I made very good experiences with the transverter designed by DB6NT which offers an output power of about 1W. My 13cm antenna was mostly a 25-director F9FT. This is an antenna with a horn including a N-plug and 25 directors. Once I only used half of this antenna. I did not use any coaxial cable between the horn and the coaxial relay of the transverter. There was only an adaptor N-male/N-male between the horn and the relay. My coaxial relay between antenna and transverter was a CX 520 D. Never use a cheaper coaxial relay on 13cm. The RX/TX switch over was done by a normal switch in the "shack", which supported the RX or TX parts of the transverter with power. The coaxial cable from the mast transverter to the transceiver was RG58.
Click here to see a photo of the 70cm, 23cm and 13cm equipment on
top of the mast.
6.3 The mast
A big advantage most of the portable VHF-/UHF-Contest stations have
compared to fixed stations is that they do not use a rotor. A rotor will
need about 60 seconds to turn 360 degrees. Turning the mast of a portable
station by hand will need about 10 seconds for 360 degrees. This is the
reason why a lot of the home stations will not turn the antenna when they
hear a weak signal from the back of there antenna. They know that it will
last 30 seconds to turn the antenna 180 degrees and they are afraid the
connection might get lost within this time. Therefore they will try to
work the station with the weak with the backside of the antenna, even if
it is an hard job. The portable station with hand-rotation is able to optimize
the direction of its antenna within a few seconds and will have no problems
to work this station.
In the beginning of running portable VHF-/UHF-Contests I used a mast which was just 6 meters high. That time I was mainly QRV on 70cm and 23cm. Even this mast was not easy to raise. Later when I was running four bands it came to the point where I needed a bigger mast. This was, because between each antenna should be an adequate distance and I did not want to mount my 2m antenna just 3 meter above ground. Therefore I used an aluminum mast with a height of nearly 9 meter. The guy collar was placed in a height of nearly 6 meters. The mast itself consisted of three valves which were 3 meters long. The lower and middle part had a diameter of 50mm with a strength of 5mm whereas the upper part had a diameter of 40mm with a strength of 5mm. The middle part was inserted in the lower part by using an intermediate valve (diameter: 40mm, strength: 5mm, length: 400mm) which was fixed in the lower valve. The upper valve was telescoped in the middle valve an fixed with one M6 screw. The connection between the lower and middle valve was also fixed with one screw. Without this screw the antennas would not turn when turning the lower valve. The guy collar was just a aluminum plate with a hole for the mast and four holes for the steel wires. To keep it slipping down the mast I used a ring clamp which was fixed with three screws on the mast. These two parts were strong enough to lift the mast with its four antennas. The four steel wires (three steel wires make it more difficult to lift the mast and are more unstable than four) had a diameter of 4mm. The pipe guy anchors where made of structural steel and about 50 cm long with a diameter of about 15mm. For lifting the mast a block and pulley fixed on the wrecking eye of the car was used.
I want to mention again that it not important to build up a mast
like mine to have a lot of fun. In Germany there is a contest called
BBT (Bavarian Mountain Day). The rules for this contest allows you
to use equipment with a weight of only 6kg (including the battery) and
a maximum output power of 6 watts on 23cm. Therefore you cannot
carry a big mast with you. Whenever I took part in this contest I used
one aluminum valve with a length of about 1.2 meters, a diameter of
about 25mm and a strength of 1mm to mount my antenna on its top. The antenna
was always only half of the 23 element F9FT (means a 12 element yagi)
and about 2 watts output power. With this conditions I usually worked
in two hours about 30 stations with a maximum distance of about
400km.
6.4. The car
In the beginning I used a tent as my shack, but this required
30 more minutes to become QRV. Later I used my car as my shack
to shorten this time (see the photo on top of this page). In my car I removed
the right front-seat (if you are in England you should better remove
the left front seat) and put a small table on its place. On this
table were the transceivers, the power amplifier, the log sheets etc. I
was sitting on the comfortable back-seat. Less comfortable was sleeping
on the front-seat, but it worked. (Click here to see a photo of my shack
in the car).
7. How to built up a mast
Building up the mast is the most difficult part if it is more than
5 meter high and you are one your own. I remember one contest very
clearly when I tried to built up a 8m high mast. Due to a mistake
when lifting the mast I needed to let it fall down with all its antennas
from a height of about 7m. That was really hard! All the antennas were
damaged. Fortunately they were still useable after straightening the
elements. But from that time on I thought very hard about a safe method
to lift the mast by myself.
Here is the procedure I followed to build up the mast:
1. Stick the parts of the mast together and fix them.
2. Mount the ring clamp which keeps the guy collar from
slipping down the mast and the guy collar on the mast. When
I used my 9m high mast these parts were fixed in a height of about 6m.
The steel wires were always fixed on the guy collar and rolled on a cylinder
when stored. After fixing the guy collar these wires were unrolled and
the ends were put on the points where I anchored them later.
3. Mount all the antennas and transverters on top of
the mast. (Click here to see a photo).
4. Connect the cables to the antennas and transverters.
Fix them with tape on the mast and make a loop where the pivot
is. If this loop is to short you cannot rotate the antennas within
360 degrees. Further you need to protect the connectors against getting
dirty what might happen when you lift the mast.
5. Dig a base pipe about 15cm deep in the ground. You
need it when you lift the mast. It prevents the mast base from sliding
away. A can on the bottom of the hole will reduce the friction when turning
the mast.
6. Lift the top of the mast a little bit with a strut. (Click
here to see a photo).
7. Connect the two side steel wires to their pipe guy anchors
and drive the anchors on the place where they should be when the
mast is lifted in the ground. The angle of all driven anchors should
have an angle of about 30 degrees to the mast to ensure a high stability
and to protect the steel wires from slipping out. Further there tip should
be at least 30cm deep in a solid ground. If the steel wires are to tight
it is possible that you can lift the mast only up to a few degrees. Then
you would need to take the time to loosen them. So better keep them slack
in the beginning.
8. Connect the steel wire for lifting the mast with the block and
pulley which is connected to the wrecking eye of your car and lift
the mast. I suggest you to make this wire that long that the antennas
cannot reach you if the mast falls in your direction. Further you should
avoid vibration when you lift the mast. (Click here to see a photo).
9. When your mast reaches an angle of about 60 degrees (and
your block and pulley has usually reached its end) you need to fix the
back wire in a distance to the base of the mast which allows the mast
to stand in an angle of 90 degrees.
10. Drive your car slowly away from the base until the mast
reaches its vertical end position.
11. Connect the last steel wire to its pipe guy anchor, drive
the anchor in the ground and align the four anchors for a correct vertical
position of the mast if necessary.