The ITU definition actually says it's the power delivered to the antenna transmission line. Be that as it may, whoever wrote the Amateur LCD has chosen to define it as "pX means peak envelope power." so, in that context, pX EIRP does make sense. Maybe they should have said that maximum permitted PX is 37dbm less the antenna gain (i.e. plus the loss for any practical antenna).
73
Iain
So can anyone come up with a sensible reason that our ACMA apparently chooses to use a slightly different definition than the ITU for such an important specification? Harmonization on technical standards is a key part of developing standards and you need a sound and clearly articulated reason to diverge
My guess is that the outcome sought was 5W EIRP as given the likely losses that is a realistic limit. Compliance would require some discretion by field staff & justification by the licensee in terms of the input power and likely "real" antenna losses. That is how I think the system should work. However I suspect someone in ACMA's compliance area saw that and said "but how do we easily measure that?". So off it went back to the engineers and they threw in the term "pX" just so the compliance guys can plug a power meter in to make sure that the needle doesn't move past 5... In which case they should just have deleted any reference to EIRP...
Buried somewhere in the LCD and variations, we have a similar situation with the 2200m band, with "1W EIRP".
Tried to find it the other day, and got lost. I forget if there was an irrelevant reference to pX.
On these bands, antenna (in)efficiency is the major consideration. I calculate I can get about 10% efficiency on my toploaded 160m vertical antenna on 630m, so Drew's 50W tx should fit into the role nicely.
Now if the Dept sends a monkey over to measure 5W pX on my 630m station, I will tell him to piss off and send someone competent.
I'd better start to get the bits and pieces back in the one place and start building the thing! I reckon mid-winter 2013 may be a good time to start experimenting.
73,
Luke VK3HJ