RSGB EMF compliance

Hi All,


For those that don't know, the RSGB have updated, (yet again), their calculator for EMF compliance.

However this time there is a useful web based app which is helpful for those that didn't get on with the spreadsheet version. (Problems with passwords, not loading etc. Or even not fluent in spreadsheeting. )

This can all be found at :-

https://rsgb.org/main/technical/emc/emf-exposure/


A direct link for the new web based app here :-

https://rsgb.services/public/software/emccalculator/



Have to admit I did find the new web based version pretty slick, so much so that I reworked my own compliance calculations.  


Posted in the spirit that it might come in useful for at least somebody.

All the best,
Victor

Interesting and I appear to be compliant, .pdf's stored for future inspection - which will never happen :p

I was compliant on most bands.
On one band/mode i wasn't so i changed the height but still the same even at 40m in the air.
Back to the drawing board me thinks.
Will have a go again tomorrow as all was ok with the old calculator got them all saved.

Hi Roger (TrunkY),

I'm sure most ran through EMF compliance then filed it away which is all Ofcom is pretty much after anyway. Some would have had to take further action but it's all about raising awareness more than anything else. Of course there'll be others who won't bother, take the chance of never being 'inspected' and carry on their merry little way....but it does give Ofcom another tool if they ever need to close down a poorly run station or flippant operator.

All the best,
Victor

Hi Alan,

I too was pretty much compliant using the old calculators but I've also had some changes to my own operations which would've changed things. One such example is even though limited to 10W on Foundation my utilisation of 'beam' antennas for VHF/UHF brought up a flag. All I did was add notes because unless someone breaks into the house, gains access to the loft where my antennas are and I never notice so carry on transmitting...it won't be a problem! 

One thing I had never calculated for was 10m FM use, fully compliant on SSB & FT8 but turns out not so with FM. Again, antennas in the loft so just added notes to the records.

Makes me want to stay at QRP though, all becomes a bit of a headache on higher power output!


I do think the web based app is a great addition though as I've seen that it runs on any of my devices so not having a computer is no longer an excuse.

All the best,
Victor

Victor
Just gone through it again but in the house not the shack.
Doesn't make sense at all this but i am now compliant lol.
Must have been a glitch as where i am won't make any difference at all.
Well there is something different my fingers are warmer in here lol.

You keep yourself nice and warm Alan mate. Mild hyperthermia and performing tasks don't mix well!

I always realise despite certain things that I ain't half lucky having an indoor shack.  

I have a good heater in there Victor but still get cold fingers.
Station commander wants to buy me some fingerless gloves but my hands are warm i keep saying lol.

Thanks for posting this Victor. That calculator is one of the simplest ones to use that I have seen.

Low power compliant on everything I use, even on 10m FM as you highlighted that one, as long as the % transmit does not get too high.. have to keep those overs short. Only had one 10m FM QSO so far since getting my licence, so not too worried about that for now.

Alan, I know what you mean....we get to a certain age where fingerless gloves conjure up images of old Fagin from Oliver Twist!!

Hi Neal,

I really do like the web based calculator so had to share details to the CT forum.   

Yep, I think I may have over optimised my 10m percentile but I am known to gas on my overs.
Like you I haven't used 10m FM much but as it's there you just have to give it a go!

Am I just being thick or is there no option for an end fed wire? I have a Tri bander for 10, 20 & 40 meters fed from a UN UN with a coil for resonance on 40m.

I can't see an option me. Any ideas?

73's Gary.

GaryWilson wrote:

Am I just being thick or is there no option for an end fed wire? I have a Tri bander for 10, 20 & 40 meters fed from a UN UN with a coil for resonance on 40m.

I can't see an option me. Any ideas?

73's Gary.

I'd have thought it would be described as a trapped or longwire vertical.

I'm assuming here you have a vertical tri-bander (not certain whether you're describing a horizontal antenna), and that the coil is acting as a trap, but normally multi-band end fed wire has a 49:1 Balun.

I'll be getting round this with a random vertical+horizontal dipole (~2.96 MHz resonance) fed with an Auto ATU (SGC-235).  Although it might not manage Top Band as the minimum antenna wire length maybe too short at ~24 metres per leg.

I may have to invest in a different SGC and think about selling the 235, since the lower power versions appear to manage with shorter antenna wires overall.

Mind you as we're limited to 32 Watts on Top Band this may not be a real issue, and the thing may match anyway with the vertical section of each leg affecting the dipole.  Its a case of suck it and see.

I plan to operate the FT-847 with just 5 Watts SSB anyway, as the antenna is designed for NVIS rather than DX.

You'd have to look at each of the example antennas and work out how closely this fits your set up, or use Custom Settings indicated in the application.

I have 2 end-fed 1 with a 49:1 and 1 with a 9:1 Balun.
Both horizontal.(1 is not in use coiled up inside the shack.
Not sure what they come under i only did the sums for the cobweb.

Wireless wrote:

GaryWilson wrote:

Am I just being thick or is there no option for an end fed wire? I have a Tri bander for 10, 20 & 40 meters fed from a UN UN with a coil for resonance on 40m.

I can't see an option me. Any ideas?

73's Gary.

I'd have thought it would be described as a trapped or longwire vertical.

I'm assuming here you have a vertical tri-bander (not certain whether you're describing a horizontal antenna), and that the coil is acting as a trap, but normally multi-band end fed wire has a 49:1 Balun.

I'll be getting round this with a random vertical+horizontal dipole (~2.96 MHz resonance) fed with an Auto ATU (SGC-235).  Although it might not manage Top Band as the minimum antenna wire length maybe too short at ~24 metres per leg.

I may have to invest in a different SGC and think about selling the 235, since the lower power versions appear to manage with shorter antenna wires overall.

Mind you as we're limited to 32 Watts on Top Band this may not be a real issue, and the thing may match anyway with the vertical section of each leg affecting the dipole.  Its a case of suck it and see.

I plan to operate the FT-847 with just 5 Watts SSB anyway, as the antenna is designed for NVIS rather than DX.

You'd have to look at each of the example antennas and work out how closely this fits your set up, or use Custom Settings indicated in the application.

Hi Wayne, 

Sorry I didn't describe it very well, it's a horizontal end fed and the coil is indeed a trap. It's resonant on 10, 20 & 40 meters, no need for ATU.

I was looking at the tool on my phone so may we'll have missed something. I'll have a look on the PC later. One thing is for sure there doesn't seem to be an obvious choice for end fed options though.

I think anything under 10 watts ERP is exempt from the regulations so you should be fine with the FT-847.

73's Gary.

That's a good point raised there Gary as the swathe of calculators already given has included or dropped many antenna types over their development.


I suppose I was just lucky in that all the antennas I have built and use are within the web based app drop down list so it was relatively easy for me. I think Oli MM0YOS has done a great job with the web based calculator it being much easier to use than all the spreadsheet faff that has gone on so far.

Do remember that the HF frequency EMF calculations still haven't been finalised until May 2022 and below 10MHz by November 2022, so currently only the VHF up are the compliance checks we actually have to make at this time.

There is a handy 'Custom' option on the web calculator and you can see instant results as you scroll through the custom 'gain' of the antenna in use. Along with the options for feeders, horizontal or vertical orientation etc. we can get a very good idea of the compliance required.



I think up to now many have been preoccupied with the calculations and results rather than the intention of this all....

The actual intention is to make sure that as far as we know we aren't exposing other individuals to potential effects of the RF emanations we actively make pursuing our hobby. Even if not conclusively proven to our own personal satisfaction I would rather take on the responsibility of such concerns raised by others with well meaning intent.

We wouldn't, (or rather shouldn't!), run mains voltage carrying cables loosely strung along the neighbours fence knowing the consequences of our actions should anything untoward happen. It's simply no good shrugging off our responsibility to such actions should the neighbour inadvertently cut through, nail to, or otherwise come into contact with such a cable. This should be quite obvious really....

So the same should be true with our lengths of cables strung around that we call 'antennas' knowing that we are transmitting RF currents, voltages and maybe potentially hazardous fields.

Most of the calculations simply provide what is believed to be a safe distance for innocent members of the public to be away from our radio 'experimentation'. I think that is a fair thing to be doing and we should accept our responsibilities for such by being aware and acting accordingly.


Of course, we could get the neighbour to hold the end of our transmitting antennas whilst prodding them with a cattle prod thereby jumping higher and helping us achieve that elusive DX.....

Not really as funny as that first seems.


It's a good tool which was why I shared details for it. The rest, is pretty much up to us.  

All the best,
Victor

Looking at the calculator, mostly anything under 60 watts ERP seems to be exempt at any HF Frequency for a dipole.

Anything above 10 watts for NVIS HF is overkill, if the FoF2 is below your band of choice, then using even 400 watts is not going to help.

NVIS HF Base Stations should really operate at 10 watts max and have the best reception antennas, since they are either Permanent or Portable.  Mobile (vehicle) NVIS HF Stations might again opt for a max of 10 watts and employ Magnetic Loops, paired horizontally mounted HF whips as dipoles, or use of a single HF whip tilt adaptor at between 73 to 90 degrees from the vertical, reception won't be as good as a Portable or Base Wire Antenna.

If you're on foot, then power requirements depend on what you can physically carry, and your antenna might be a hand held Magnetic Loop, or more likely a Mobile HF Whip which again you'll tilt beyond 73 degrees to the vertical for best results.  Likely you'll use a small gel pack and QRP HF Transceiver, and use the lowest transmit power, and may even only switch the set on for regular contacts at timed intervals if you're many hours from re-supply or a road network.  In such situations you need to be able to rely on Base and vehicle based Mobile Stations always monitoring your operating frequencies/bands in case you have an emergency and need assistance.

Obviously either 4x4 and/or Helicopter Support might need to be available.

I'm looking at returning to RAYNET HF Operations, and providing a resilience option for digital communications using either ALE or JS8Call on all HF Frequencies and SSB on 6m, 2m.  In addition, I also plan to become active again as a part of the RAYNET HF Team for the regular skeds four times a month, to aid experimentation on Voice and Data Nets, utilising my Home QTH, and also re-establish Portable and Mobile (vehicle) Participation where appropriate using an FT-100D, ATAS-120, Horizontal Paired HF Mobile Whips, and a trapped Inverted-V (portable).

Anyway, that's the plan.

'bull'?  Please explain.

Wireless wrote:

'bull'?  Please explain.

My apologies, I should have deleted the comment earlier. 

We don’t want to see Threads become slanging matches folks.

My apologies too.
I meant when the powers that be keep changing things.
The first calculator did for me.
Bye.

Paddy wrote:

Wireless wrote:

'bull'?  Please explain.

My apologies, I should have deleted the comment earlier. 

We don’t want to see Threads become slanging matches folks.

I think we were at cross purposes Paddy, and whilst I did waffle slightly off topic, I couldn't see what I'd done wrong, water under the bridge, I have sent a PM to Alan hoping we haven't had a falling out, and waffled on a bit more I think, but also apologised if I'd in some way offended.

Just cross purposes, no harm no foul.

Nice one Lads.  


I've said before that the written word with forums can be perplexing at best. "You say tomato and I say tomato" simply doesn't work without contextual input.


All the very best,
Victor

Many thanks Wayne and Alan, like Victor says it is sometimes difficult with the written word. The amount of times I’ve upset my sister when sending her Nice texts is ridiculous.

Noticed that there’s now a note that for FT4/FT8 and other WSJT modes you have to use 100% as the transmit time in 6 minutes - there’s no derating for receive time.

Many an argument to be found on the net about ft4/8 100% or50%.
After all it is 50/50 tx/rx.