Licence revision from OFCOM.

[Malcolm T]

Citys and town are disappearing under a fug of unpleasant and non essential RF emitted from an amalgam of devices in houses and streets.
What I would call modern style spark transmitters totally broadband and unregulated affecting the HF spectrum 24/7.
In this day when HF comms is starting to look valuable again it's about time there was action taken to eradicate this pollution.

[Andrew2]

I've just been reading through that stuff. All about how we will be required to comply and keep records etc. Excuse me, do they mean the way THEY were so vigilant when they abysmally failed to stop the infestation of noise generating wall-warts, phone chargers, laptop supplies LED lighting and a million and one other unfiltered devices into our country with no effective market surveillance.
Their inaction caused the bands to be flooded with high levels of noise and they showed little interest in investigating complaints. I'll be as vigilant as they were and sod it. And if they come round for a 'chat' I'll give them my reasons. Do I sound angry?
Isn't it strange that due to pressure from amateur astronomers there are efforts to darken our skies by fitting special lighting all over the place, but when it comes to lowering the RF noise level they don't give a fig?
I'll just tick the boxes they want to see and carry on, it's not as if I run vast power anyway.

Sorry for the intemperate rant everyone, but hypocrisy and injustice *really* get my goat.

[GMB]

Reminder: the licence always had a requirement that you do not fry people with your RF power. All that has changed is that you are now required to prove you actually thought about it by documenting how you checked it would be OK.

I think they were concerned that some people had never bothered to check.
I think they were right.

[HamishBoxer]

I have to say, that calculator is very good and put my mind at rest on how to comply.

At least if you have made an effort, than I think they will be satisfied, should any checks be made.

I never had the GPO around back in the 70's but I was ready.

[G6Tanuki]

As far as I'm concerned, this is no big issue.

You need to consider and attempt to quantify the RF-exposure risks, if these are excessive you need to take steps to mitigate the risks of exposure [as you always should have been doing anyway], and document your assessment-process/any remediation undertaken..

For my VHF antennas this took me all of fifteen minutes; with the necessary Word text [preamble/postamble] to wrap around a cut-and-paste of the spreadsheet, I can now easily repeat the process for HF in a few minutes.

Biggest problem was remembering enough trigonometry from O-level days to estimate the height of the feed-point, and finding a protractor.

It takes less time than the old annual rigmarole of writing out a cheque, putting it in an envelope and taking it to the post-office to renew our licenses.

It's also motivated me to take a long hard look-at my 3.5/5/7MHz antenna system, see just how rickety it had become (frayed guys, a tree catching against the wire) in the last decade, and - despite already being compliant with the EMF calculations - make efforts to enhance it [once the rain stops....]

[kellymarie]

I'm glad I read this i was fretting over this issue since it was first mentioned on our local club net. I'm not good at maths and trigonometry and algebra are a mystery to to me isn't the second one that stuff that grows on your roof Lol. Sorry bit flippant but I 5hink im right in saying that my longwire at about 20 feet at its highest point being fed with just under 50 watts is going to be OK on all bands 3.5 to 28 Megacycles. Due to mobility issues I can't change it easily

[Jon_G4MDC]

That Email from Ofcom is absolutely full of web links.

One thing you are told never to do with Emails is to click on the web links.
I was almost fooled. It's probably OK but who knows?

Much prefer that they don't use links but just describe the page to find for yourself.

Don't they know better?

[HamishBoxer]

They (Ofcom) re sent the email due to faulty links and all is well. Re clicking links, they also said that about opening attachments but normally you can smell a rat and plenty of AV progs pop up and give warnings.

[Keith]

The .XLSX file won't run on my version of Excel and I'm blowed if I'm going to shell out a small fortune for a new version of MS Office just to prove that I'm compliant.


Instead I've downloaded IcnirpCalc.exe from DL9KCE via the DARC and plugged in appropriate numbers to that. It indicates a safety distance of 1.57m. As no part of my aerial is closer than 50m to any public access I consider that the attached printout is sufficient to show compliance. If not - tough!

[HamishBoxer]

I agree Keith, you should be fine. My version would not open that file either , nor would a freebee I downloaded but then I found something that did it in Cloud and let me download the zip and all is well.

Panic over! Though I guess there are a lot more comments to come yet, subject to moderation on this important topic.

PS Are you running 400 W of AM??

[Herald1360]

ISTR that 400W pep of AM is about what you get running 150W dc input to a 100% modulated class C valve final.

Of course SSB is just a particular form of AM......

[Graham G3ZVT]

Is there any proven danger to health from full legal RF below 30MHz other than getting burnt fingers touching the end of the antenna?

Apart from the possibility of interfering with cardiac pacemakers, syringe drivers, etc I'm not aware of any.

[Panrock]

The ICNIRP document talks of a 'nerve stimulation' effect brought on at frequencies below 10 MHz "typically reported as a "tingling" sensation for frequencies around 100 KHz."

As far as I can see, the 2 watts per square metre absorption power density limit they quote for the general public (30 - 400 MHz) has no more heating effect than standing in the beam of an old fashioned torch with a 6v 0.3A bulb, when its round beam is slightly more than a metre across. It wouldn't warm you up much. Although unlike RF heating, infra-red heating is of course surface-only.

Steve

[Radio Wrangler]

A key word there is "absorption" Of wave hitting a person, some will pass straight through, some will be reflected and some will be absorbed. There is a matter of a mismatch between the impedance of someone's body and that of the incident fields.

Perhaps it was incautious wording?

David

[Panrock]

Right. And could there also be the little matter of the human body 'resonating' due to its dimensions? Perhaps particularly relevant for the Band I television frequencies.

Steve

[Vintage Engr]

Originally Posted by HamishBoxer

Perhaps the perfect tool, if the bulb lights up , then you are out of order!

I've also got one of those! Very accurate I don't think!
Well my QTH is more than 3/4 of a mile from any road, & the only living creatures within about 20m are sheep...

Don't,- no cracks about roast lamb, I don't run that much power.
I guess it's up to us all to at least show compliance by risk assessment & some sort of documentation. But unless the RF police have a very good 4WD they'll not make it here.

David.

[HamishBoxer]

Hi David, Sorry, I could not resist putting that on and of course totally useless for complying with the regulation.

You will see my other posts stating I find the calculator first class and easy to use, which is what is needed by a lot of us.

We are going to have to do the calculations and have them ready at hand whether or not anyone does indeed turn up.

[Sparky67]

Well, I am certainly going to have to redesign my HF 5MHz long wire configuration, where the fed end is about 1m from my head. The neighbour's fence supports a counterpoise, which will also have to go. No rush until next November 2022 though, it can't be that unsafe if Ofcom are allowing me to spend another 17 months sitting in these RF fields until compliance becomes mandatory.

As an aside Birmingham University supports a National Register of RF Workers. Their work is 'dedicated to exploring the potential health effects of those potentially exposed to RF above the general public guideline values'. I have been registered with them for many years, but they don't appear to make the resuts of their studies available to third parties.

Martin
G4NCE

[dsergeant]

Distance from your own head Martin is irrelevant, the licencee is exempt. But do the sums, even at sensible power you may find the safe distance is less than that. That aside, end fed wires, which I use here, have not really been recognised in the Ofcom/RSGB spreadsheets.

You only need to worry about that counterpoise, also not very well modelled, if your neighbour is actually in his garden and near it.

I feel a lot of people have got far too worried about this and sadly in some cases will be giving up the hobby. I have already partly completed my own assessments and the files stored in my computer. I have no issues and am fully compliant, but there again use qrp which is mostly below the 10W EIRP level.

Whatever, don't just give up.

73 Dave G3YMC

[murphyv310]

Hi.
I had no problem with the spreadsheet even on Linux and openoffice so long as you change the password on the four boxes. I did my assessment and have printed out the relevant results.

Our club (KLARC) had a talk by an official from the RSGB and also our club secretary Len Paget has been very helpful on all points of this, there will only be very few amateurs that may need to change their antennas or reduce power, its amazing where 10 watts can go though!

Many are overly concerned that they may fall foul of this and are throwing in the towel, that is defeatist IMHO. Take time to go through it all and then make a decision what if anything needs to be done to be compliant.