Mike



I must admit that for 20 years as a MN Radio Officer, I often wondered about whether I was working in a short-wave oven. Most radio rooms were fairly well RF screened - one even had copper wiping strips on the doors, other than the glass windows.  Every ship had the aerial fed from the top of the transmitter via copper tube to an aerial switch, then copper tube to the lead out insulator. Transmitters varied, but for 12 years on the City of Durban/GXIC there was a nice Marconi 1.5 kW transmitter: 410 - 512 kHz, 2, 3, 4, 6, 8, 12, 16, 22 & 25 MHz.  Aerial current could be anything up to 12 amps depending on frequency. The main aerial on that ship being a proprietary unloaded vertical, a Dieckmann & Klapper MAS aerial.     https://www.radiomuseum.org/r/dieck_klap_mastsendeantenne_mas140ma.html

"The description is a vertical tapering fibreglass mast, about 400mm in diameter at the base tapering to the top. At the top of this mast, besides a fibreglass whip aerial was a tubular structure with hexagonal form. From this structure were six aerial wires connected to a ring which was about a metre in diameter. This ring then being tensioned with plastic insulators and bottle-screws to ring-bolts into the base of the fibreglass mast. The overall height being 14 metres." "the rated frequency range was 0.2 - 25 MHz"

Other ships used wire aerials either end or centre/off-centre fed and simple unloaded verticals.


I did also have a 750 watt transceiver primarily for fsk radio-telex - fully synthesised, which I also used for RT calls as it was so easy to use. Key in the channel number, say 1602 (an ITU duplex frequency pair on 16 MHz) and press the talk switch and the ATU on the monkey island would tune the 10 metre whip in less than a second.


So what soft of field those open feeders in the radio room produced I hate to think!


73's

Clive

Mike



I must admit that for 20 years as a MN Radio Officer, I often wondered about whether I was working in a short-wave oven. Most radio rooms were fairly well RF screened - one even had copper wiping strips on the doors, other than the glass windows.  Every ship had the aerial fed from the top of the transmitter via copper tube to an aerial switch, then copper tube to the lead out insulator. Transmitters varied, but for 12 years on the City of Durban/GXIC there was a nice Marconi 1.5 kW transmitter: 410 - 512 kHz, 2, 3, 4, 6, 8, 12, 16, 22 & 25 MHz.  Aerial current could be anything up to 12 amps depending on frequency. The main aerial on that ship being a proprietary unloaded vertical, a Dieckmann & Klapper MAS aerial.     https://www.radiomuseum.org/r/dieck_klap_mastsendeantenne_mas140ma.html

"The description is a vertical tapering fibreglass mast, about 400mm in diameter at the base tapering to the top. At the top of this mast, besides a fibreglass whip aerial was a tubular structure with hexagonal form. From this structure were six aerial wires connected to a ring which was about a metre in diameter. This ring then being tensioned with plastic insulators and bottle-screws to ring-bolts into the base of the fibreglass mast. The overall height being 14 metres." "the rated frequency range was 0.2 - 25 MHz"

Other ships used wire aerials either end or centre/off-centre fed and simple unloaded verticals.


I did also have a 750 watt transceiver primarily for fsk radio-telex - fully synthesised, which I also used for RT calls as it was so easy to use. Key in the channel number, say 1602 (an ITU duplex frequency pair on 16 MHz) and press the talk switch and the ATU on the monkey island would tune the 10 metre whip in less than a second.


So what soft of field those open feeders in the radio room produced I hate to think!


73's

Clive