Yes, the metre-amps calculation.  It was carried at each annual radio survey by an appointed Radio Surveyor, the same bloke who in those days could carry out the 12-wpm Morse Test for an amateur licence. In fact I took my 12-wpm test  at Riversdale College of Technology when the Liverpool Radio Surveyor attended to examine those who were obtaining either a Radio Telephone Certificate of Competency or were revalidating their Morse at either 20 or 25 wpm. 


I digress. I will have to dig our a copy of a Radio Survey form that I have. I copied it because the Radio Surveyor's comments on it were full of praise for me!  The metre-amps related to 500 kHz and were the product of the aerial current at the transmitter output and the height of the aerial in Metres above a "certain point". This "certain point" escapes me, it was related to the load line of the ship, but I cannot remember which one. There was also a correction applied due to the fact that this particular ship - I was on her for 12 years - had a Dieckmann & Klapper MAS aerial. So could not be treated like an end fed or T aerial.


Often felt hot in the Radio Room, but that due to the location of the ship, the effectiveness of the air conditioning and whether the Captain or Chief Engineer felt hot....  On one ship which had a Reddifon Main Transmitter, I was warned on joining to expect shocks when transmitting on 22 MHz  Not nice if you were wearing headphones... It was caused by a break in the earthing copper sheet bonding between the transmitter rack and the steel structure. The transmitter being mounted on shock absorbers both below and at the rear, Once repaired was OK.


My real worry about radiation, was when I was using my mobile phone from inside my cabin, another virtually RF tight box. I had to sit on my bed and get as close to the rectangular window as I could and when passing Cape Town could always get a good signal. However, during the call I could always feel a buzzing adjacent to my ear which I put down to my phone going to full power due the constraints of the shielding.  Solved that with a magnetic base case antenna plugged in to the external antenna socket.


You can see a D&K Antenna on the starboard side of City of Durban/GXIC here https://photos.marinetraffic.com/ais/showphoto.aspx?shipid=924471


Plus a INMARSAT Std-A on the port side. Pity that the funnel was not made out of fibreglass.......


Clive

Yes, the metre-amps calculation.  It was carried at each annual radio survey by an appointed Radio Surveyor, the same bloke who in those days could carry out the 12-wpm Morse Test for an amateur licence. In fact I took my 12-wpm test  at Riversdale College of Technology when the Liverpool Radio Surveyor attended to examine those who were obtaining either a Radio Telephone Certificate of Competency or were revalidating their Morse at either 20 or 25 wpm. 


I digress. I will have to dig our a copy of a Radio Survey form that I have. I copied it because the Radio Surveyor's comments on it were full of praise for me!  The metre-amps related to 500 kHz and were the product of the aerial current at the transmitter output and the height of the aerial in Metres above a "certain point". This "certain point" escapes me, it was related to the load line of the ship, but I cannot remember which one. There was also a correction applied due to the fact that this particular ship - I was on her for 12 years - had a Dieckmann & Klapper MAS aerial. So could not be treated like an end fed or T aerial.


Often felt hot in the Radio Room, but that due to the location of the ship, the effectiveness of the air conditioning and whether the Captain or Chief Engineer felt hot....  On one ship which had a Reddifon Main Transmitter, I was warned on joining to expect shocks when transmitting on 22 MHz  Not nice if you were wearing headphones... It was caused by a break in the earthing copper sheet bonding between the transmitter rack and the steel structure. The transmitter being mounted on shock absorbers both below and at the rear, Once repaired was OK.


My real worry about radiation, was when I was using my mobile phone from inside my cabin, another virtually RF tight box. I had to sit on my bed and get as close to the rectangular window as I could and when passing Cape Town could always get a good signal. However, during the call I could always feel a buzzing adjacent to my ear which I put down to my phone going to full power due the constraints of the shielding.  Solved that with a magnetic base case antenna plugged in to the external antenna socket.


You can see a D&K Antenna on the starboard side of City of Durban/GXIC here https://photos.marinetraffic.com/ais/showphoto.aspx?shipid=924471


Plus a INMARSAT Std-A on the port side. Pity that the funnel was not made out of fibreglass.......


Clive