15 Watt EIRP - What does that mean?

Hoping to go to ireland in July via a famous radio show on the way :slight_smile: Seeing VK does not have 5Mhz approved yet, I guess there goes my CEPT chance of getting on the band as EI/VK6NU

Guess I’ll have to get myself a new EI callsign, I knew I should have kept my old one. I presume this will allow me to use the Band while in EI.

73

John VK6NU/ ex EI4GY

Under CEPT rules and with a full license, you are allowed to operate on any band the hosting country permits. If not in EI, come to DL (or even better PA -> 100 kHz / 100 W)! :slight_smile:

Ahoy!

Ok, that sounds interesting, I must admit I haven’t looked into the finer details.

Thanks for the tip. I’ll check that out.

73

John VK6NU

Years ago, they dropped the ridiculous rule of complying with your home country’s and the host country’s laws when operating under T/R 61-01. Current recommendation: http://www.erodocdb.dk/docs/doc98/official/Pdf/TR6101.pdf

Ahoy,
Pom

Indeed I am, in fact a dual limit and a bit of a head scratcher - 100 watts but not to exceed 200 watts EIRP, with a maximum antenna height of twenty feet. I won’t ask if all our activators limit themselves to a 6 metre roach pole! In my case I use a 20 metre long wire fed by a 9:1 unun so not only did I have to measure my antenna height (in a garden that is not level so I had to take into account sag against ground level!) but I had to estimate antenna efficiency and losses in a long run of coax - no wonder I do most of my chasing on the band with an FT817!:grinning:

My point in the above post is that the power limits in region 1 are a bit of a hodge-podge, to put it mildly. I mean, whilst a number of the newcomers to the band follow the WRC-15 rules, we have Denmark and the Faroes with 1 kW ERP but with 100W ERP for the B license. Bulgaria, Hungary, Iceland, Norway, Netherlands, Slovakia and Macedonia with 100 watts but some output and others ERP, Luxembourg 15 Watts ERP, Ireland 15 watts PEP at the output (unless that has changed recently) and Belarus 50 Watts. I for one would be much happier with the USA limit of 100 Watts ERP referred to a half wave dipole. At least that makes sense!

Brian

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And your point is caller?

You are required to know the rules for where you operate. If you move about the world operating here there and everywhere and don’t know the rules for where you are then it’s not the rules fault or the rule makers. You just have to know these things. And, to be honest, it’s not hard.

I don’t know what point you are trying to make, Andy. You seem to have lost sight of or misread what I was originally commenting on three hours ago!

According to section (g)(iii) in the Notes to Schedule 1 of the UK licence

The antenna height shall not exceed 20 metres above ground level;

Unless I have missed some exciting new regulations in recent months?

73, John M0VCM

No, that rule for 60m has been there for a few years.

20m at the centre is technically quite challenging to achieve even at home, tower territory really.

Rules, rules, rules… Why is everyone on here so obsessed with them. Live your life and be happy, there are enough of these things about without having to go look for them :wink:

Jonathan

Thanks for pointing that out, John, it comes from a simple mistranscription - but they do say that “he who never made a mistake never made anything!”:grinning:

You’re welcome Brian. I just wanted to save anyone else the trouble of checking, since I saw your post and was immediately compelled to read my licence again to ensure my own 60m activations had been valid. For some of us happiness comes from obeying the rules, although not necessarily from dictating them to other people :slight_smile: Jonathan makes a very good point… I do really need to get out more…

73, John M0VCM

Gentlemen, (and possibly ladies) I think you all will think we have beaten this discussion to death, but I will ask for your patience a little longer and ask you where my calcualtions are going wrong.

Equipment - TX running 12w output, antenna halwave dipole - gain expected to be 2.15dBi.

Target is 15w EIRP -
Converting watts to DbM using the online calculator at https://www.everythingrf.com/rf-calculators/dbm-to-watts

I get that the desire 15w EIRP is near as makes any matter 41.75 dBm.

Now using the EIRP calculator at: https://www.everythingrf.com/rf-calculators/eirp-effective-isotropic-radiated-power
and trying to get close to te 41.75 dBm value with my 2.1 dBi gain antenna and 1.5 dBi cable and connector losses, I get:

This suggests that 12 watts RF out of the transmitter NOT 2.5 watts to 5 watts that our discussions have been suggesting would create 15w EIRP.

(there’s also a rather nice diagram and explanation on the same site as regrads where antenna EiRP gain comes from):

So… from these calculations, I would say with a half wave dipole on a SOTA summit, I should be able to run 12 watts from the transmitter and still be under 15w EIRP.

Since all are agreed above that the value is somewhere between 2.5 and 5 watts - what have I (or these calculators) missed?

Ed.

What is the gain of your antenna? i.e. the real in-situ gain.

I’m using 2.15 dBi - as stated earlier in this thread and online as a “standard” value for a half wave dipole.

That’s not the in-situ value for a summit though is it? What’s the gain on a summit?

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Hello Ed,

HNY…

Just stuff 5w into a dipole and you should be OK. Don’t fret too much about this.

All the ‘clever’ people asking questions could not answer their own questions. :wink:

At home here on 60M the max I can run is 20w into a 1/4 wave dipole that one half droops over the vegetable patch and the other half sags over a garden shed. It works quite well including DX.

I agree with Jonathan @GW2HFR - in essence just get on and try.

Good luck.
Cheers
Mike

Ed, I understand your quest for a simple answer to this question but unfortuntely there isn’t one.

I already explained, the 2.15dBi gain of a dipole happens in free space and ideal conditions; you probably realise the same antenna can have very different performance depending on where it’s installed.

If you really want to get closer to an answer by yourself, I would suggest to start experimenting with antenna simulation software. EZNEC for example is a powerful package and has free versions available:

https://www.eznec.com/

Cheers,
Razvan.

Just setting our rigs to an output power of 10 watts should be OK.
In case those 10 watts are too much power (LOL), we might be putting just a few EIRP watts above the limit. . How many? 2, 4, 5 EIRP watts?
No one is going to ever tell us off for something like that.
Problems might come when someone puts 100 watts or even 1Kw, as I have already heard on the band to hams from a European country recently adhered to WRC-15.

73,

Guru

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In all seriousness the main issue with ignorance surrounding power control levels in amateur radio today is not at the fundamental frequency power, but all the other garbage that some of these Japanese / Chinese radios and “linears” emit with it. No more evident is this the case then on the VHF bands.

The way the propagation is at the moment, you will be lucky to be herd with 100W let alone 10 on 60m.

That will vary not only with the summit but with your position on the summit vis. slopes in the direction of the contact. Better to treat it as an uncontrollable variable and ignore it.