[BC] the end of radio ...

[PeterH]

On Feb 2, 2010, at 4:57 PM, <steve at theengineeringbureau.com> wrote:

> In the later 70's I was able to pick up 10Q in southeastern  
> Arizona. I've
> run across the present-day 10Q pattern and it would have been  
> impossible to
> receive in Arizona.
>
> When the towers were relocated, did the pattern change significantly?

The pattern(s) has not/have not changed.

The basic pattern is provided by the two widely-spaced towers. This
would otherwise be a figure-8 with major lobes towards WSW,  the
desired one, and ENE, the undesired one.

The final pattern is provided by the two narrowly-spaced towers. this
would otherwise be a cardioid with two deep nulls and a deep local
maxima towards KDKA.

Multiply the two patterns together and you get the very same nulls
towards KDKA, but, additionally, you get two deep minima towards the
NNW and the SSW.

The SSW null protects a Mexican on 1010 in Baja California.

The NNW null protects a then-new Class I-N, now a Class A, in Alaska
on 1020.

The sole function of the fifth tower is to detune those nulls for
marginally better coverage of the metro, to the East of the site,  
during days, only.

The fifth tower is not used at night.

Now, in order for Storer to pull-off this miracle, two things had to
happen, at Storer's sole expense ...

First, Storer had to pay for the engineering and installation of a 50
kW night pattern at what was then KSWS, in Roswell, which was then 10
kW at night, but was sending its entire pattern towards L.A.,
something like 50 kW, effective, thereby making 1020 unusable at
night in L.A.

The six-tower multiplication method array preserved the complete null
from KSWS towards KDKA, yet it also provided a minimum towards L.A.,
to about 10 kW, effective, thereby making 1020 usable in L.A. at
night. This six-tower pattern also had the effect of improving
coverage of the two most populated cities within NM, Albuquerque and
Las Cruces, in addition to its own COL, Roswell, of course.

Second, Storer had to pay for the ongoing operational expenses of KSWS
operating at 50 kW at night, rather than its initially licensed 10 kW
at night. These expenses amounted to substantial electric power,
additional tubes for the 50 kW transmitter, and other provable expenses.

Storer didn't have to pay for KSWS's 50 kW daytime operations as that
was already a sunk cost.

The original 10Q array, just off of the Long Beach Freeway, and still
seen on some topo maps of today, was two towers.

This protected KDKA, only, and the station was then operating as
KGBS, licensed for 50 kW U, DA-1, L-KDKA.

It was customary for the station to operate from 9 pm on Sundays until 2
am on Mondays with the licensed day array.

Originally, this station was on 1000, and was licensed to Culver City.

When it was forced, by NARBA, to move, it moved not to its customary
reassigned frequecy, 1030, but to 1020.

The reason for this is somewhat strange, as either 1030 or 1030 would
do, and 1030 would have been better in the long run.

But, pre-NARBA the same-community minimum spacing was 50 kHz, and
there were stations on 900, KHJ, 950, KFWB, 1000, KSVD and 1050, KNX,
whereas post-NARBA, the same-community minimum spacing was 40 kHz,
and this meant KHJ on 930, KWFB on 980, KSVD on either 1020 or 1030,
and KNX on 1070.

KHJ and KFWB preserved the 50 kHz spacing. 1020 preserved the 50 kHz
spacing from KNX, reassigned to 1070, but asserted the 40 kHz spacing
from KFWB, whereas 1030 would have preserved the 50 kHz spacing from
KFWB, but would have asserted the 40 kHz spacing from KNX.

The odd-duck in all this circle-jerk of AM frequencies was KNX, which
had to move to accommodate the new Mexican on 1050, but which should
have been moved to 1080, not to 1070.

Remember, State makes the treaties, and Commerce simply implements
and enforces them.

Were it up to Commerce, KNX would have been moved to 1080 and KRLD
and WTIC would have had to go elsewhere.

In this case, KSVD most probably would have wound up on 1030.