[BC] XETRA

[PeterH5322]

>I don't recall exactly but I believe the GE was at another site before Glen 
>Callison moved the 5 tower array to Rosarita Beach.  It was my recollection, 
>that it was moved to gain the ground conductivity similiar to XERB on 1090 
>already on the beach.

It was moved to vacate the site for, reportedly, housing construction.

The move to near 1090 was a natural one.

Both share the explicit requirement for an eastward null, towards 
Montreal (Canadian I-A) in 690's case and towards Baltimore (U.S. I-B) in 
1090's case, and the implicit requirement for a westward null, towards 
the Pacific Ocean.

This gives both a decidedly north-northwest/south-southeast pattern, with 
690, now, using five in-line conventionally-spaced short towers in an 
end-fire array giving preference to coverage of Baja California, and with 
1090, as always, using three in-line widely-spaced tall towers in a 
side-fire array giving equal coverage to Western North America and to 
Baja California.

"Rio" changed the rules for Class As, allowing certain signatories to 
increase the day power of their Class As to 100 kW, while maintaining 
those station's night power at what it was before.

So, we now have 690 with 77 kW days and 50 kW nights, the 77 kW gives 
service to Los Angeles about what it was before the move, with the old 
pattern.

Mexico has three Class As which are grandfathered at less than 50 kW 
nights (two at 10 kW and one at 20 kW), but these stations are operating 
with 100 kW days.

Under U.S. and Canadian national rules, a Class A must operate at 50 kW, 
and there is only one U.S. Class A which is grandfathered (at 25 kW days 
and 10 kW nights), while Canada has three which are grandfathered (at 10 
kW day and night).