Re: Fwd: Re: Expanded band query...?

[dan.strassberg@att.net]

Believe me, I was _there_, being moved to a channel 
above 1500 was _not_ like winning the lottery! I did 
forget something when I wrote my summary of the 
extensions of the AM band: In 1936, the FCC established 
three so-called experimental high-fidelity channels 
1530, 1550, and 1570. So by March 1941 and NARBA, there 
were _some_ radios that could tune past 1500, but not 
many. Remember, this was the Depression. People were NOT 
making unnecessary purchases. So owning a radio station 
that was reassigned to a frequency above 1500--even if 
you were granted significantly improved facilities--was 
not calculated to put money in your pocket for quite a 
few years. And just eight months and seven days after 
NARBA, the US was at war. Consumer items, such as 
radios, were difficult or impossible to obtain. It 
wasn't until after the end of the War that large numbers 
of radios that could tune past 1500 became available.

WWRL in New York was an interesting case. The station 
ran 250W from a studio/TX site in the residential 
neighborhood of Woodside Queens, part of New York City 
and an area with notoriously bad soil conductivity. WWRL 
did not get out very far. Prior to NARBA, the station 
was a Class IV on 1500, which was the pre-NARBA 1490, 
and perhaps the only channel whose stations were moved 
en-masse to a lower frequency. Before NARBA, WWRL shared 
time with two other stations in the New York area. Don't 
ask me which; I don't know. NARBA made WWRL into a full-
timer, albeit still with 250W (one of a small number of 
Class IVs on Class III channels) but placed it up at 
1600, a frequency that even those radios that could tune 
the high-fidelity channels could not receive.

It was quite a few years later--quite a few years after 
the War--that WWRL moved its TX to the Jersey 
Meadowlands, increased to 5 kW-U DA-2, and became a full-
fledged Class III. By then WVOM, the predecessor of 
WUNR, was either on the air or under construction and 
WWRL had to protect WUNR. The result was a directional 
pattern that could not cover the Bronx or northern 
Manhattan very well at night, but the signal was still a 
lot better than 250W from Woodside.

As for ex-band stations with less than 1 kW at night, 
yes there is at least one--in the LA area. Turns out 
(and I did not know this until a week or so ago), the 
limitation on ex-band night power is more rigorous than 
just 1 kW; it's the lesser of 1 kW or the power that 
produces a groundwave signal equivalent to that which 
would be produced by putting 1 kW into a 90-degree 
antenna. The LA-area station (on 1650) is diplexed with 
a station that uses tall towers. The 1650 station is 
thus limited to something like 539W at night.

There is no such corresponding limitation on ex-band day 
power. So, unless it uses a shorter tower at night, an 
ex-band station that builds itself an optimum-height 
(200-degree) antenna to maximize daytime coverage, will 
be limited to about 500W at night. Even if the ex-band 
station builds a 195' tower, the tallest that requires 
no illumination, it has to run less than 1 kW at night.

As for WLAC protecting Boston, you've got that story 
exactly right, but the situation wasn't unique. KIRO is 
nulled to the south at night to protect the former KMPC. 
In both cases, a Class IB had to protect a pre-existing 
co-channel Class II. And on the same frequency, 710, WOR 
is nulled to the northwest (as it was with its old 
antenna system in Carteret) to protect CKVD. Curiuosly, 
though, it didn't always work that way. KFAB was not 
required to protect the pre-existing co-channel station 
in Pasadena, CA, and indeed, KFAB made life miserable 
for the Pasadena station for decades. That station (now 
KSPN) completely rebuilt its antenna system three times 
in futile attempts to protect KFAB. Only after the FCC 
reduced the protection requirements was the CA station 
able to arrive at a design that KFAB didn't protest.

And the technical/historical AM-radio trivia just keeps 
on coming!

> > The big thing NARBA did for this part of the band
> > was
> > that a bunch of stations that were just regional
> > stations with bad groundwave prospects in the high
> > 1400s moved up to what suddenly were not only newly
> > available channels, but U.S. Class I-B clear
> > channels
> > -- 1500, 1510, 1520, 1530, 1560. It was like WTOP,
> > WKBW, WLAC, etc., won the lottery. I believe this
> > sequence of events explains why WLAC has a null to
> > protect 1510 in Boston, even though WLAC is the
> > dominant station, which has been mentioned here
> > before. It was all done as part of the same moving
> > to
> > a new frequency.