2m digital EME and VK power permits?

[VK2GOM]

It has already been suggested in another thread that I 'need more power!' to be heard. I quite agree.

However, My IC910H puts out around 110W (pZ) carrier already.

Since 120W (pY) is the 2m digital modes legal power limit for VK, how difficult is it to obtain the necessary ACMA permit to allow running up to 400W 'for the purposes of reflecting radio signals off a celestial body'? The reason I ask is there are some nice 300W 2m amplifier pallets out there that would certainly help my Tx side of things

Can anyone who has successfully applied for the ACMA permit to run more than 120W (pY) digital modes on 2m advise on the process and any hurdles?

Without any room for more or larger antennas, increasing power is my only real option.

73 - Rob VK2GOM / GW0MOH

[VK4CDI]

GD Rob, first off, congrats on the first QSO........
When I applied, I submitted an EMR audit, based on the pattern of the relevant antenna's, and the proximity of the nearest neighbours etc.....
I used a spreadsheet from Joe VK7JG, (originally done by Rex I believe). and Google earth piccies......
I had a call from the ACMA tech section with some questions about my dish, but other than that it was OK.
500Watts on CW/JT for 144 and 432, and 400Watts CW/JT on 23cm.......

GL with it all...
Vy 73

Phil VK4CDI

[VK3HZ]

Hi Rob,

You've probably Googled and found the information here:
http://www.acma.gov.au/Industry/Spectru ... tion-paper

For a start, you need to comply with the EMR limits and I suspect that even your current setup would not get through, even with only 100W.
You might want to download the VK3UM EMR Calculator and have a play.

Several problems can be seen from your photos. For a start, your antenna appears to be readily accessible at ground level ("a public place"). In fact, looks like you could poke an eye out
Secondly, in some directions you are pointing into the house. Depending on distance, I'd suspect the levels to be too high even for 300W. My understanding is that, unless you physically can't point your antenna in a particular direction, EMR limits need to be assessed in all directions, not just where the moon might be.

I think in a built-up area with a small backyard, you'll be seriously pushing uphill to get a High Power Permit.

Regards,
Dave
VK3HZ

[VK2GOM]

Thanks for the links.

I downloaded and ran my details through the VK3UM EMR Calc, and it determines that for my current Yagi, feeder, and radio setup, for JT65, 1min Tx intervals, (drum roll please) ACMA Level 2 compliance is not required. Huge sigh of theoretical relief Interestingly, it seems the result is the same regardless of whether the antenna is ticked as 'accessible' (I guess meaning if I was out /P and someone can walk up to it to lick the driven element) or 'inaccessible' eg. in my garden, where they would either have to walk past me to go through my back door to get to it, or scale a 6ft colourbond fence which is actually more like 7ft from the other side since the ground drops away. Interestingly, I had to climb over it once to break into our back door when I'd forgotten my house keys. It was quite a struggle getting over it and I'm already 6ft 2". Also, the safe elevation angle is 14.03° which works out nicely since the moon is behind trees until then anyway. At a 3.7m safe tower height (easily achieved with another mast section dropped in) the on-axis exclusion zone is 6.99m (let's call it 7m - the errant 1cm could be accounted for in stretch in my XYL's fabric tape measure) which again works out fine pointing at the moon at a minimum elevation of 14.03° (since not even Robert Pershing Wadlow was that tall 7m away) through to transit at which time I would stop any EME activity anyway, to avoid pointing at the non populated (I hope - I really should check) roofspace of own house which physically blocks the view of the moon anyway, defeating the technique of EME.

It's looking like I might as well concentrate on improving my Rx performance for now as Owen suggests with a better LNA, and stick with my compliant 100W, and try to work the bigger EME stations until such time we either win the lottery or I find employment to move somewhere with an actual garden

73 - Rob VK2GOM / GW0MOH

[VK3ZAZ]

Its not about how easy or hard it is to get the high power tick , that's not the issue

The old days of rubber stamping eme permits where guys then go off and crank up on terrestrial are gone..
eme permits used to be too easy to obtain, but in 2014 a person must demonstrate an awareness and knowledge of how to protect the public (who require zero exposure).
And the templates fell well short of that as we found out..and now high power on HF is banned UFN.

I have held an eme 6m permit since 1993 never had any issues, but I measured as well as did the maths..
I bought and own a rad monitor because I don't take anyone elses word for it.
Neither should you.
People are full of advice but wont back you up if you get it wrong.
The conditions will be on your licence not theirs.
I suggest your first attempts were good but you can never run a setup like that so close to the ground where you can touch the antenna system without restricting access.
And its not enough just to do the emr calculations.
Beg borrow or steal an emr rad monitor and check it out.
Would you drive a car without a speedo using just a rev counter?

Heavy comments maybe, but emr is no longer some joke nudge nudge wink wink its a serious issue
(see herald sun 2 days ago)
A full new emr survey on smartmeters despite all the assurances they are safe.

good luck hope you succeed and are happy with the priviledges.

[VK2OMD]

...
I downloaded and ran my details through the VK3UM EMR Calc, and it determines that for my current Yagi, feeder, and radio setup, for JT65, 1min Tx intervals, (drum roll please) ACMA Level 2 compliance is not required....

That is quite an achievement for that antenna.

Possibly because you had the antenna height at or above 10m... but your pics didn't look like that to me.

That is the condition that cause so much grief in the high power trial.


Owen

[VK2GOM]

That is with antenna/tower height at the lowest possible setting in the program; namely Safe Head Height ticked, Tower Height 2.5m.

There is one shortcoming I can see in the program straight away though... as soon at the antenna elevates, the front goes up and the back comes down (assuming the user has mounted it the right way round), and thus becomes closer to those on the ground waiting to lick the driven element. It doesn't seem to take into account elevation changes change the spacing from the antenna licker to the driven part of the antenna? Or am I missing a user input somewhere?

73 - Rob VK2GOM / GW0MOH

[ZL2ADU]

Move to ZL.. We are allowed a KW..

[VK2GOM]

You can also inherit the phrase 'She'll be right'. We don't use it any more here!

73 - Rob VK2GOM / GW0MOH

[VK2OMD]

That is with antenna/tower height at the lowest possible setting in the program; namely Safe Head Height ticked, Tower Height 2.5m.

There is a box with no label immediately above the "accessible" red text... is that 10m or more... try making it 2.5m.

Owen

[VK2OMD]

EMRCalc cites AS227.2 for its methods.

That standard has expired (3 years ago).

It probably depends mainly on Appendix E which does not give a method for calculating off-axis near field... which is particularly relevant for your Yagi pointing upwards.

Under a previous regime (prior to AS2272.2), off-axis fields were calculated as for a point source radiator with 0dBi gain.

The safe distance for an average power of 50W under that regime would be 1.4m at 144MHz, and add head height to that, the requirement under that earlier regime would be that no part of the antenna was within 3.2m of ground where a person could walk.

That was then... and I don't know if the current standard gives a method for calculation.

As to what EMRCalc does exactly, I can't work it out from the documentation.

Owen

[VK2GOM]

There is a box with no label immediately above the "accessible" red text... is that 10m or more... try making it 2.5m.

Owen

Aha Done. Still compliant.



73 - Rob VK2GOM / GW0MOH

[VK2OMD]

Aha Done. Still compliant.

The ACMA took a view that a residential property is accessible to the public. I don't want to get into an argument, but again it is this matter that caused so many non-compliances in the high power trial.

Owen

[VK2GOM]

In which case tonight after my sked with W5UN will be the last night of EME operation here after which I will disassemble the antenna.

I might go trespassing on private property sometime and see if the 'But ACMA says your garden is a public place!' statement will hold up in court? It either is a public space or it isn't. You can't have legal entities with different interpretations.

Who even comes up with this stuff?! Another case of people educated beyond their level of intelligence!

73 - Rob VK2GOM / GW0MOH

[VK3DXE]

Rob, don't give up. Crunch the numbers and see what you can come up with for, say, 50w. I've almost completed on 2m with 50w and 6el = 9.5dB gain. Plenty of big guns out there that'll relish the challenge of working you QRPp EME.

[VK4WDM]

Some of the interpretations re "public accessible" are quite odd. I was told that I need a fence around my ground-mounted vertical in my back yard to stop a member of the public e.g a meter reader or some such person getting into the EMF danger zone (41cm from the antenna when running 100w according to the EMR calculator) when the antenna is transmitting. Given the actual amount of time that it is actually transmitting and the low frequency of such incursions into my backyard, this seems a bit excessive

With regard to Steve's suggestion about purchasing a radiation meter. I was told by a professional radiation surveyor that the meters that are likely to be affordable by individual hams are unlikely to be sensitive and/or accurate enough to satisfy the regulators. Perhaps it is something that a radio club could look at buying to lend or hire to their members.

73

Wayne VK4WDM

[VK2FAK]

Hi all.....


As far as the Public space issue is concerned, there are laws in place that stop you making a man trap in your yard, and public person could quite possibly be a burglar , yes you do have to protect them also even though they are trespassing ......its a damn crazy world we live in.

What I want to know is, where is the law that prohibits you from placing a mobile phone next to your head, hand, in your pocket or anywhere else on your body...freq's are way higher than your 2m setup there..

John

[VK2GOM]

The definitions 'inaccessible' and 'in a public space' would appear to be not mutually exclusive. The antenna could be up on your two storey house roof. What's to stop a burglar/member of the public taking a ladder along with him, and climbing up to the antenna? Or them hiring a cherry picker to get to it? Is the antenna still really 'inaccessible'?

And in my case, anyone would really struggle to get into my yard, unassisted without a ladder or at least someone to 'shin them up' to help them over the fence. So is it still an accessible public space? Even though common sense says it's 'inaccessible'?

I predict in this current over-regulated climate anyone using a soldering iron at home to build electronic kits etc. will be mandated to install fume extraction equipment and breathing apparatus next... or need a license. Welcome to the world - or at least Australia.

73 - Rob VK2GOM / GW0MOH

[VK2FAK]

Hi all....

Rob, see now there is your first mistake, you mention 'common sense'.....no such thing in Australia Laws...hihi

But don't let this get ya down....work on the RX side and see what you come up with

John

[VK5PJ]

Hello Rob,
about a year ago I applied for a 1KW permit for EME on 50 - 1296MHz to cover current and future operations from home. The ACMA want a export file from Google Earth (.KMZ file) showing the location of your antenna, your residence and each neighbour, including relative heights of the neighbours houses compared to the tower. Now for me that is easy as I live in a rural setting but none the less it was a sobering process to go through and plot this out.

I included screen shots of the VK3UM software for each band and intended antenna. The also wanted photos of any current antennas. While they made no comment about the information from the VK3UM software, that information did include each antennas height above ground and gain which was not included any where else so I would conclude they did look at those plots for information.

After the initial application I had a phone call to confirm that it was an EME permit I was after, other than that I received an updated station license in a few weeks and just paid the request variation to license costs.

Do not let it slide past, it can be done with less power but I suspect a permit for 500W should be achievable if you can find a little extra height for the yagi. I was amazed at how low the tower height needed to be to comply when I ran through the numbers.

Regards,
Peter, vk5pj