[TowerTalk] Legal Power measurement Discussion

[jimlux]

On 9/26/16 6:50 AM, Joe Subich, W4TV wrote:
>
>> And they don't mention ERP except for the new VLF.
>
> Wrong. The criteria on 60 meters is expressed in ERP.  See 97.313(i):
>
>> (i) No station may transmit with an effective radiated power (ERP)
>> exceeding 100 W PEP on the 60 m band. For the purpose of computing
>> ERP, the transmitter PEP will be multiplied by the antenna gain
>> relative to a half-wave dipole antenna. A half-wave dipole antenna
>> will be presumed to have a gain of 1 (0 dBd). Licensees using other
>> antennas must maintain in their station records either the antenna
>> manufacturer's data on the antenna gain or calculations of the
>> antenna gain.
>
> 73,

And ERP (or EIRP) is probably factored into getting permission to 
operate high power on 70cm (where virtually all antennas where high 
power is used are mounted on a tower).

And, of course in the RF safety analysis as well.

I think the FCC has done a great job promulgating rules that are "easy 
to follow" - stick a power meter in the line after the amp is "easy". 
And the amateur service is unique among the radio services - it's the 
only one with a "don't do this" as opposed to "you shall do this" 
regulation set.

Safe harbor RF exposure calculations are similar.

If you want to do something else, you're going to have to justify it to 
the FCC, should they ask.  My contention is that ultimately, the FCC is 
going to care about ERP, not whether the feedline is cryogenically 
cooled superconductor or glowing red from the loss as your power meter 
disk spins off the bearings. The power limits were created to manage 
co-channel interference when ships and shore stations started to 
interfere with each other.