[BC] Two-tower array designed for 990 running on 1030

[PeterH5322@aol.com]

>The average spacing for
>arrays that produce simular patterns must be around 80 degrees, and most of
>those are decades more recent than NARBA. My assumption is that DA designers
>like the fact that the shorter spcing produces a bit more gain in front of
>the pattern and a slighlty narrower pattern without sacrificing much in the
>depth of the minima behind the pattern.

90 degrees would be the logical choice, as engineers tend to be logical, 
and like "round" numbers.

However, under normal circumstances 120 degrees produces the best pattern 
for a Class A as it has the widest aperture without sacrificing much in 
the forward direction. See KFAB and WBT .

160 to 170, or perhaps even 180 degrees works best for cases where the 
COL is way off-axis. See KFBK or KYW or WRVA [ * ] .

If WTOP were to move its Tx somewhat to the north of DC, in Maryland, 
thereby placing DC and Baltimore more or less equally way off-axis, and 
equidistant from the putative Tx site, and also adopt a rather 
widely-spaced array along the lines of a three-tower version of KFBK's, 
and install Franklins as well, thereby getting about 100 kW, equivalent, 
out of 50 kW, equivalent, input, good service from Philadelphia to 
Richmond, with excellent service to Baltimore and DC, should be possible.

As it is, WTOP elected to change remain in-place, with its short-spaced 
array [ ** ] , change the phasing of the middle tower in order to fill 
the null towards KSTP (and WLQV) to about 1 kW, equivalent, and started 
the entire chain of events with WLQV which ultimately resulted in the 
Detroit station moving from 50/5 kW with 9/12 towers to 50/10 kW with 9 
towers, all of this at WTOP's and KSTP's expense.

Oh, what a difference that kilowatt made!

[ * ] Note WRVA's 184.9 degree spacing and recall 1140 was a forced move 
from 1110. It is not a coincidence that 184.9 * (1110 / 1140) is 180.0 
degrees. Similar comment with respect to WRVA's radiator height (180 vs 
185 degrees).

[ ** ] Similarly, WTOP's spacing, when on 1460, was 85 degrees, not its 
present 87.3 degrees. Similar comment with respect to WTOP's radiator 
height (180 vs 185 degrees).