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Transmitting from public transport

Picture of bus

Most articles and handbook chapters on mobile operation concentrate on operating from private cars and boats. They normally assume that it is possible to mount a fairly efficient antenna outside the vehicle. Users of public transport do not usually have this luxury. Nevertheless, it is possible to enjoy amateur radio while travelling in trains, trams, buses and ferries. This article tells you how. It's based on personal experience gained from operation on trains, trams and buses in three states.

Advantages and disadvantages

Operating from public transport has a number of disadvantages compared to transmitting from a car. These include the need to carry your own power source (instead of relying on the car battery), the lower transmit powers possible from hand-carried transceivers and the difficulty of erecting antennas outside the vehicle. All this means that a portable station in a bus or train carriage will have a lesser range than a mobile station.

However, this type of operation has advantages too. Not having to concentrate on the road and having both hands available means that using and adjusting equipment is easier. The greater height of coaches (compared to cars) means that in-coach antennas operate better than might be expected. The risk of being stopped by police for operating a mobile transceiver is eliminated and the novelty factor of working a train or bus mobile station increases the number of contacts obtained.

There are some differences between operating in urban and rural areas. In cities there will often be a choice of repeaters to use if the signals into one are marginal. In contrast, when travelling through the country, there will be times when no repeater at all is triggerable.

Repeaters may be located in a poor position relative to the railway or coach route, or be at some distance from the route taken. In such cases, there may be coverage for only a 10 or 15 km stretch of the road or track before the repeater becomes inaccessible. At other times, much longer distances are easily covered - for example with 2.5 watts and a dipole antenna, it was possible to access the 6950 Mt Ginini repeater from Cootamundra - some 120 kilometres away. Such distances are not common - ranges of 15 to 30 kilometres are more usual.

Provided that you can access a repeater, contacts are possible over the repeater's entire coverage area. The longest distance contact made from a train by the author was a South Australian station who was worked when the Melbourne-bound XPT train was approaching Wagga. The contact was possible due to a sporadic-E propagation opening.

 

Equipment

The author has taken some or all of the following on trips made:

* Yaesu FT290R two metre all mode transceiver (with batteries)
* Yaesu VX5R handheld 6/2/70cm transceiver
* Yaesu FT-817 HF/6/2/70 all mode transceiver
* Sony ICF7600D general coverage LW/MW/SW SSB/AM receiver
* 12v, 6.5 AH sealed lead acid battery
* Dipole antenna for 146 MHz
* Earphones
* Callbook or repeater list
* Map of area travelled, preferably showing repeater sites
* Logbook

Any two metre or two metre/seventy centimetre handheld would be a good choice for the transceiver. A rig with a wideband VHF/UHF receiver is best for tuning around in areas where no amateur repeater is within range. Buy the matching headset or plug in your own earphones to avoid disturbing other passengers.

Some hand-held transceivers come with a choice of several battery packs to provide for different transmit power settings. An RF output power level of 5 watts or so is desirable, particularly in rural areas, to maximise transmitting range. However, a trade off has to be made between talk time and power output. NiCad battery packs are usually adequate for short trips. A 12 volt sealed lead acid battery (3 to 7 AH) is better for longer journeys. See your transceiver's operating manual for advice on connecting your rig to an external 12 volt battery. When it's not convenient to carry such batteries and chargers, alkaline dry cells are highly recommended for low current receiving applications. These are expensive but can provide hours of reliable operation on long trips.

For best results, use an antenna better than the standard helical supplied with most hand-helds. A vertical dipole made from RG58 coaxial cable is compact, flexible, quick to make and delivers good performance from a coach or train carriage. Suction cups should be used to attach the antenna to the inside of the window, perhaps concealed behind a curtain. Construction details here.

The following items may be helpful for those planning to operate public transport mobile.

Disclosure: I receive a small commission from items purchased through links on this site.
Items were chosen for likely usefulness and a satisfaction rating of 4/5 or better.

 

Operating

Most contacts will be on FM. This is because of the greater activity on FM and the existence of repeaters. The vertical polarisation that FM operators use also helps because vertical antennas are easier to erect in a coach or train carriage than the horizontal antennas that SSB operators use. However, having said this, mobile SSB operation is always interesting and allows greater range than FM simplex. The ability to tune around for beacons (ranges of 60 - 120 km are typical) is another benefit of carrying SSB gear. If you do go SSB mobile, tell others about your trip and/or arrange times for local operators to listen for you to maximise the possibility of making contacts.

You should know the locations of repeaters along your route before setting off. A repeater list, such as in the WIA Callbook 99, and a good map (showing mountains) is useful here. Make a list of repeaters within 50 or 100 kilometres of your route and try accessing them as you travel along. Always use the actual location of the repeater (usually a mountain) rather than the nearest big town by which repeaters are often referred - the repeater may be some distance from the town and not be easily accessible from within the town itself. Information on the locations of repeaters is also important when deciding on which side of the train carriage or coach to sit - if there's a choice, get a window seat facing the direction of most repeaters that you wish to use.

Even quite large towns may have repeaters that are accessible with a 25 watt mobile station, but not with a 2 watt handheld in the town centre. The author has found that calling on 146.500 MHz is sometimes successful. Provided the other station has a good antenna, simplex contacts from a coach lasting 20 or more minutes are possible, especially if traffic congestion is reducing travel speed. Simplex operation is also practical in capital cities such as Melbourne, where the terrain is flat.

Receiving

When it is not possible to trigger repeaters or obtain simplex contacts, its interesting to see what can be received from inside a bus or train carriage. In such situations, a scanner and/or HF receiver is useful.

Receiving beacons on the low end of two metres has already been mentioned. Use an SSB receiver for best reception. Those without an SSB receiver could try tuning in to the Morse practice beacons that operate in some cities. Able to be received on a standard FM transceiver, their range can be considerable.

Below the AM broadcast band operate low frequency beacons for aircraft navigation. These transmit a Morse Code identification and, sometimes, weather bulletins. In most areas, several of these should be audible.

If you can extend the telescopic whip of your short wave receiver, it may be possible to pick up foreign broadcast stations, especially if travelling in a coach or bus. The time of day is important - around noon you may not hear anything, but signals improve by the early evening. Reception of stronger HF amateur signals may also be possible, depending on band conditions.

Many VHF/UHF amateur transceivers include extended coverage VHF/UHF facilities. This allows reception of commercial and other two-way radio traffic. Either program several known active frequencies into the memories or use the radio's scan feature.

The main problems encountered when trying to use a receiver in a train, tram or bus are noise and shielding caused by the vehicle's metal body. Both trains and coaches can generate noise, but this usually is not serious, at least on VHF. However, trams can be a noisier receiving environment. Shielding of signals is not usually a severe problem on a bus or coach, especially if it has large windows. Trains are significantly poorer RF environments than buses, and reception of LF, MF and HF signals is usually non-existent unless the signal is very local. Interestingly, VHF radio reception is usually quite good on a train. Whatever vehicle you are in, placing the receiver near the window usually improves signal strength.

Other Activities

This article has concentrated on voice repeater and simplex operation. However, other modes may be possible whilst bus or train mobile. Packet (in conjunction with a laptop computer) and CW offer the advantage of not requiring a microphone (thus drawing less attention to oneself). However, packet requires stronger signals than FM voice, and is prone to frequent disconnects. CW operation would allow longer transmitting ranges than SSB or FM simplex. However, the lack of activity means that you would need to arrange skeds with operators along your route beforehand. Weak signal digital modes are a possibility, but their slow transmission speeds may not accommodate mobile-type fading and more repetitions at a faster data rates may be better.

Contesting is another activity that should be practical from a bus or train. Those contests that have high local VHF activity combined with credit for repeat contacts (such as the Remembrance Day) would be well suited to this type of operation. Travel on the major rail lines or bus routes would place you within easy simplex range of most operators at some time during the contest period. Routes that produce the most contacts could be travelled along every few hours to maximise the number of repeat contacts. The purchase of a daily or smartcard ticket is suggested to keep the fares incurred by this amount of travel low.

You'll find more on public transport mobile on VK3JED's amateur radio on public transport website.

This article appeared in Amateur Radio December 1998 and was updated in 2012.

 

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