Slide 12012
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PT0S - IDXC Visalia 2013
15 ilhotas – Uma “desembarcável”
Mais inóspito no Brasil
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530 Milhas Náuticas
Águas profundas
Convenção da ONU sobre direitos do Mar
Supervisão da Marinha
Ocupação por Cientístas
1966 : PY0XA Don Miller inválida
1967 : PY0SP-PY0DX by PY7s 1ª válida
1978 : PW0PP-PY0RO 1ª ativação 160m
1982 : PY0SP- PY0SJ 1ª ativação 6m
2001 : PW0S – Última ativação significativa
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“Balde de água fria”
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Estudo de impacto ambiental
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7 dias no Mar – 4 horas Rochedos
Checagem da Estação Científica
600kg Material comprado no Brasil
450kg of material enviado para o Brasil
8 X 50kg caixas de bagagem
Suprimentos, gasolina, etc... comprados em Natal
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We try to keep things simple. To be effective on 160 meters, there is a minimum amount of equipment that you need. You need at least 500 watts (more is better) and, of course, you need a good antenna. You really need a good antenna.
The antenna is key to a good signal. An amplifier can make a 10 dB difference. The difference between an good antenna and a bad one can be 20 dB (or more). In our case, the antenna had to work well on all bands too. The critical ingredient on an island DXpedtion is the salt water. It provides a near perfect ground and allows for very low angles of radiation. A vertical standing in salt water can be very efficient. The antenna, however, should stand in the water, or at least have water under it (under the sand). This is critical. The belief that a vertical will be as good if “it can see the water”, is simply false. Sure, having salt water a few wavelengths away will help, but signals will be down by many dB-s because of ground losses. To illustrate this point, let me pose a hypothetical question. If half of your yard happened to be covered with a continuous sheet of copper and the other half with sand, where would you put your vertical? Obviously, you would put it in the middle of the copper sheet. Not on the edge of it, and most certainly not in the sand. So we put out antennas in the water. There are serious challenges, however, when installing an antenna in the sea. Tides will vary its feed-point impedance, waves will batter its base, especially at high tide; and of course, everything must be water-proof and corrosion resistant. I know of DXpeditions that moved their antennas away from the water: they did not like them getting wet and salty. With us, it is the opposite: we put the antennas as far into the water as we can and deal with the problems caused by the water.
The key to our antenna system is a home built, water-proof, dual output automatic antenna couple (the coupler has two antenna ports with an internal ANT select relay). The coupler solves the problem of the tides changing the feed-point impedance (1.8 meter tides on Mellish). It allows operation on any band, and it gives us total freedom of antenna geometry. (In amateur practice, antenna geometry is often dictated by the desire for a given feed-point impedance, usually 50 ohms. A lot of sacrifices are made to obtain this impedance. The use of coupling devices is seen as undesirable because of losses and complexity (and cost). I believe that for multi-band antennas the situation is the opposite: a low loss coupler makes things simple and easy! Simple and easy are desirable on a two-man DXpedition.)
For Mellish we designed an antenna that had an array of wires suspended from two 18 meter SpiderPoles. The array, which essentially consisted two separate antennas – one for the low bands and one for 20 meters and up – also included a grounding relay at the base of the second pole. This array allowed us good performance on 160 to 10 meters with only a single structure. Because of the large tide, and because of the sloping beach we placed the antenna at the half-tide point: it had about 3 foot of water at its base at high tide and at low tide, while seemingly standing on the sand, the sand was saturated and had salt water under it. Based on the reports we were getting, the antenna seemed to have worked.
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PT0S - IDXC Visalia 2013
Antenas Set-up
Antennas Set-up
PT0S - IDXC Visalia 2013
Antenas Set-up
PT0S - IDXC Visalia 2013
3º Dia:
3 Estações no Ar trabalhando todas bandas de 160 to 6 m CW/SSB/RTTY
Pouco tempo para descanso
PT0S - IDXC Visalia 2013
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Estação 1: K3 + 2 x SG-500 (1 kW)
Estação 2: K3 + 1 x SG-500 (500 W)
Estação 3: K3 + 300 W PA for 6 m, 100 W on 10m
Power: Todos equipamentos em 12 V DC
9 x 12V Baterias de Carro 60A
6 x 10 A Carregadores
1 x 2.5 kW Gerador
PT0S - IDXC Visalia 2013
Acoplador automático
Sistema em 2 partes: Inv L 160, 80, 40 e 30, Wire Frame: 20 – 10 m
Guy
Rope
6
4
2
COAX
ATU
16
GND
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We try to keep things simple. To be effective on 160 meters, there is a minimum amount of equipment that you need. You need at least 500 watts (more is better) and, of course, you need a good antenna. You really need a good antenna.
The antenna is key to a good signal. An amplifier can make a 10 dB difference. The difference between an good antenna and a bad one can be 20 dB (or more). In our case, the antenna had to work well on all bands too. The critical ingredient on an island DXpedtion is the salt water. It provides a near perfect ground and allows for very low angles of radiation. A vertical standing in salt water can be very efficient. The antenna, however, should stand in the water, or at least have water under it (under the sand). This is critical. The belief that a vertical will be as good if “it can see the water”, is simply false. Sure, having salt water a few wavelengths away will help, but signals will be down by many dB-s because of ground losses. To illustrate this point, let me pose a hypothetical question. If half of your yard happened to be covered with a continuous sheet of copper and the other half with sand, where would you put your vertical? Obviously, you would put it in the middle of the copper sheet. Not on the edge of it, and most certainly not in the sand. So we put out antennas in the water. There are serious challenges, however, when installing an antenna in the sea. Tides will vary its feed-point impedance, waves will batter its base, especially at high tide; and of course, everything must be water-proof and corrosion resistant. I know of DXpeditions that moved their antennas away from the water: they did not like them getting wet and salty. With us, it is the opposite: we put the antennas as far into the water as we can and deal with the problems caused by the water.
The key to our antenna system is a home built, water-proof, dual output automatic antenna couple (the coupler has two antenna ports with an internal ANT select relay). The coupler solves the problem of the tides changing the feed-point impedance (1.8 meter tides on Mellish). It allows operation on any band, and it gives us total freedom of antenna geometry. (In amateur practice, antenna geometry is often dictated by the desire for a given feed-point impedance, usually 50 ohms. A lot of sacrifices are made to obtain this impedance. The use of coupling devices is seen as undesirable because of losses and complexity (and cost). I believe that for multi-band antennas the situation is the opposite: a low loss coupler makes things simple and easy! Simple and easy are desirable on a two-man DXpedition.)
For Mellish we designed an antenna that had an array of wires suspended from two 18 meter SpiderPoles. The array, which essentially consisted two separate antennas – one for the low bands and one for 20 meters and up – also included a grounding relay at the base of the second pole. This array allowed us good performance on 160 to 10 meters with only a single structure. Because of the large tide, and because of the sloping beach we placed the antenna at the half-tide point: it had about 3 foot of water at its base at high tide and at low tide, while seemingly standing on the sand, the sand was saturated and had salt water under it. Based on the reports we were getting, the antenna seemed to have worked.
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Remote Pre-Selector Low Noise Amplifier
Remote control RX Pre-Selector and Amps
SDR with CW Skimmer
PT0S - IDXC Visalia 2013
N4IS: Jose Carlos Silva A lot! Filters, RX Ant, Etc.
KD9SV: Gary Nichols RX pre-amps
K9YC: Jim Brown Noise filtering
HA5PT: Tamas Holman LoTW, SDR
HA5X: Chris Hildebrand Web page, OQRS
PS7RK: Mauricio Barreto Logistica em Natal
PS7AB : Ronaldo B Reis Logistica em Natal
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Marinha do Brasil