[BC] Re: AM daytimers

[Phil Alexander]

On 22 Feb 2006 at 15:52, PeterH5322 wrote:


> I cannot remember a Class D which was authorized with more than 250 
> watts, nighttime, irrespective of its antenna system efficiency, but I 
> can point to Class Bs with less than, or significantly less than 250 
> watts, nights, but which do meet the Class B minimum of 140.82 mV/m at 1 
> km, RMS.


I have not researched it, but suspect there may be an 
international treaty involved. I was asked to review a 
denied application where the applicant sought 250 W DA 
nite with an 80% rule waiver. It appears the consultant 
who drafted the application misunderstood the waiver 
history because the waiver request was ill-advised 
(considering specific circumstances that I can't detail 
for obvious reasons). 

After kicking out the 250 W Class B application, FCC staff 
encouraged re-filing for the same facility at 240 W as a
Class D. Once I explained the difference between Class B
and Class D, the applicant recognized the investment cost
was not worth the potential return.

WRT the FCC's Rules, I believe the answer can be found in
73.21(a)(3):

"(3) Class D station. A Class D station operates either 
daytime, limited time or unlimited time with nighttime 
power less than 0.25 kW and an equivalent RMS antenna 
field of less than 141 mV/m at one km."

Notice that the f/s limit is a governing factor, but
the power limit appears absolute. Thus, it appears 
granting a power => 250 W with a field < 141 mv/m @ 1 km 
as a Class D would require waiver of this section. 

I may be wrong, but the presence of the power level as
an absolute tends to imply to me that this definition
is codification of treaty language.


Phil Alexander, CSRE, AMD
Broadcast Engineering Services and Technology 
(a Div. of Advanced Parts Corporation) 
Ph. (317) 335-2065   FAX (317) 335-9037





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