[BC] X-Banders - Was: Can traditional AM and IBOC co-exist?

[PeterH5322@aol.com]

>Why is it that x-banders also tend to work with shorter towers? One would 
think
>that given the wavelength, they'd want to utilize the benefit of a shorter 
structure
>inherently. Call me naive- I'm very curious!

X-banders are Class Bs, and Class Bs are required as a minimum (and are 
permitted as a maximum) 281.63 mV/m/kW at 1 km.

This is about 80 degrees, give or take.

While the Commish seems to let X-banders operate 10/1 kW with radiators 
of a "reasonable" height, say, 80 to 110 degrees, with 90 degrees being 
customary, X-banders who install, or are diplexed with taller sticks, 
say, 180 or 200 or 225 degrees, all good heights for this service, are 
still bound by 281.63 mV/m/kW at 1 km.

Let's say I diplex with a station which gives me a super-tall stick, such 
as 225 degrees, which is about 440 mV/m/kW at 1 km.

281.63 mV/m/kW at 1 km is imposed as a limit at night (and could be 
imposed as a limit during days, I suppose, if there were adjacent channel 
issues), and such a station would be allowed about 0.4 kW, maximum, as 
400 watts into a 225 degree stick produces about the same horizontal 
field as does 1 kW into a minimum conforming radiator.

The maximum power permitted in such a situation is:

Pmax = 1000 watts * (281.63 / Actual Efficiency)^2

For a 225 degree, 440 mV/m/kW at 1 km stick,

Pmax = 1000 watts * (281.63 / 440)^2 = 407 watts

I can point to one X-bander which has a 220 degree stick, and operates 
with 490 watts.


One incredible fact is Class Cs sometimes get away with 225 degree 
towers, and yet are still allowed 1/1 kW.

The effective power from such a station is remarkable ... about 3,300 
watts day and night ... ND, too.

More than lots of ex-Class III Class Bs.

Of course, their NIF may suck :-) .