EMF

[Gary Fox]

The whole business is surreaI and laughable.
I thought Ofcom were meant to be skint.
How will they train and employ the thousands of uniformed jobsworths needed to enforce these draconian new guidelines, rules, recommendations, laws or whatever they are?
The jobsworths will need training and cerificates to work at height, using equipment to measure the exact power of radio transmissions.
The results of their investigations may be used as evidence in court, so all the test gear will have to be certified (like police car speedometers).
Many yachts do not have a suitable way for a jobsworth to go aloft with all his test gear, in which case he will need to hire a cherry-picker or erect scaffolding, which might be tricky if the vessel is afloat, in a mud berth, on a pontoon, or in a boatyard, or anywhere in fact.

If Ofcom want to do something useful, they can regularise the legal status of DSC handheld VHF's in other countries.

 

[jdjp]

Calm down.... no one is going to be climbing up your mast with a power meter. If it ever comes to it (which it won't) you can show you pass regulations by just quoting the specifications of your VHF unit, and doing a quick calculation as others have done further up the thread.

These rules are a very sensible minor update to address the general concerns in the population about the biological effects of radio transmissions, and they are mainly aimed at people installing mobile phone masts and high power transmitters. OFcom is just doing it's job.

I do agree that tone of the email that we received was a bit alarming to a non-technical audience, but as yotties we are a tiny tiny group and shouldn't expect special treatment. As far as Ofcom are concerned we get lumped in with radio-hams, a group who are supposed to know what they are doing and who could cause damage and disruption if they get their setup wrong.

 

[tudorsailor]

Calm down.... no one is going to be climbing up your mast with a power meter. If it ever comes to it (which it won't) you can show you pass regulations by just quoting the specifications of your VHF unit, and doing a quick calculation as others have done further up the thread.

These rules are a very sensible minor update to address the general concerns in the population about the biological effects of radio transmissions, and they are mainly aimed at people installing mobile phone masts and high power transmitters. OFcom is just doing it's job.

I do agree that tone of the email that we received was a bit alarming to a non-technical audience, but as yotties we are a tiny tiny group and shouldn't expect special treatment. As far as Ofcom are concerned we get lumped in with radio-hams, a group who are supposed to know what they are doing and who could cause damage and disruption if they get their setup wrong.

Is my SSB a problem when transmitting

TudorDoc

 

[ithet]

Reading the Ofcom email it seems that the methodology for measuring radiation exposure and the limits are being updated. There were limits before. Why are we getting concerned about these new values when installations were never checked against the old figures?

 

[jdc]

Is my SSB a problem when transmitting

Less so than one might think because (i) there is a frequency element to the calculation of allowed exposure - in fact they don't even bother calculating below 10MHz on the Ofcom spreadsheet, and (ii) SSB modulation actually puts out rather low average power, typically 10% - 15% of peak.

To use some numbers, suppose 14.3MHz transmission (and often it's 7 MHz or lower), and a 100W peak power, so let's say 15W average, and transmitter with a 1/2 wave dipole (gain about 2dB, or a factor of 1.6). That gives EIRP = 24 Watts. Plug these numbers into the spreadsheet, and the safe distance is 3.34 metres.

Although the spreadsheet calls for EIRP, it's not quite clear that the radiation pattern of the antenna really counts as he safe distance limit is always in the near-field for HF (wavelength = 20m at 14MHz), so although the far-field pattern is a doughnut with the maximum normal to the antenna wire, you probably can't rely on this when standing just under the lower insulator (assuming you've an insulated backstay antenna).

But in conclusion, if you allow a safe distance of bit more than 3m that should be enough. In my case the antenna is right at the stern, and I'm sitting in the cabin when transmitting so it's 5 or 6m away, but it's a little more dubious if there is a helmsman's as he'd only be 1.5m or so away.

 

[mickywillis]

Time to bulk buy tinfoil and start creating relevant headgear for all on board or within a 5Mtr range I guess??
Aldi and Lidl is probably cheapest?

 

[James_Calvert]

Time to bulk buy tinfoil and start creating relevant headgear for all on board or within a 5Mtr range I guess??
Aldi and Lidl is probably cheapest?

And is a plastic or metal colander better for the hat base?

 

[jdc]

For those interested in where the guidance and health physics came from, here is the reference document and guidelines which the UK, and much of the world, has adopted. It's not an EU thing afaik, despite their headquarters being in Munich. The organisation is the "INTERNATIONAL COMMISSION ON NON-IONIZING RADIATION PROTECTION" with members and funding from all round the world.

 

[tony_lavelle]

Ofcom's motto is "making communications work for everyone". Ooops