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Lots Of Power With Just One Nighttime Tower-Class B Regionals

S

Schroedingers Cat

For simplicity purposes, we'll limit it to the 48 Contiguous States.

560

KSFO 5
WQAM 5/1

570

KVI 5

590

WOW/KXSP 5
KQNT 5

610

KEAR 5
WDAF/WCSP 5

910

KPOF 5/1
WALT 5/1
WGBI/WBZU 1/0.5

920

KVEC 1/0.5
KXLY 20/5

980

KFWB 5

A separate post will be used for stations from 1000-1600. Expanded Band stations will be excluded for now.
 
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This is taking longer than I expected. There are a lot of complex things that have happened to the higher power nondirectional stations. Some used SLRs with tall towers and/or changed tower location or tower design and have fallen below the magical 500 watt level that loosely constituted a "lot of night power" in the early days of radio. Keep in mind that those stations could often be regularly heard for 1000 or more miles with just 500 watts on the Regional Channels. Some were shared time and that further complicates the analysis. At least one of the shared time facilities became separate fulltime cochannel stations. It actually looks like one was considered to be 5000 watts fulltime, but actually used 5000 watts with just 2500 watts input to a 5/8 wavelength tower at night using an SLR and the full 5000 watts input to the 5/8 wavelength tower without an SLR in the daytime. It is complicated by a shared time arrangement with another station which is now separate. Over the years, you might have seen this referred to as different efficiencies, and now you see stations that use different input powers with the same licensed powers referrred to as having different constants day and night. Besides the Regional Channels, these were also common with those close 1230/1240 adjacent channel situations discussed in another thread, and other Regional and Clear Channel stations close to first adjacent Local Channels. When Class IVs went from 250 watts to 1000 watts daytime around 1960, and many Regional Channels went from 1000 watts to 5000 watts daytime in the 1950s and 1960s, these situations also arose.
 
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KOY 550 5/1
KLAC 570 5/1 (did it go to 5-U)

Also wasn't KSFO 560 5/1 for much of its history?
 
Schroedingers Cat said:
This is taking longer than I expected. There are a lot of complex things that have happened to the higher power nondirectional stations.
Click to expand...

While you indulge in the complexity, here is a brain teaser about the opposite situation:

What two adjacent Western Hemisphere nations, one with about 200 AM stations and another with around 500 AMs, had only one directional station each and in both cases the directional antenna was built because the owner preferred it to being non-directional?

These were not little stations, either... one 50 kw at 820 and the other 10 kw on 660.
 
Even before NARBA, stations like WWJ had already started to upgrade from 1000 watts to 5000 watts at night. KLAC has a pattern that has 1000 watt nulls like WWJ. Not sure when KLAC went to 5000 directional at night. Many of the other previously nondirectional night facilities also match the IDF of the previous power level. For example, WBCM...WMAX, which went from 1/0.5 U1 to 5/2.5 U4, the nulls in the DA pattern are on the order of the 1000 and 500 watt nondirectional IDFs. That didn't happen until the late 1970s, and I have found several others like that.

The earliest DAs that were already substantially built for the old frequencies, the FCC let modify as best they could with the existing physical authorization or facility. Phases and field ratios were adjusted as best as possible to maintain the pattern as close as possible to that authorized at the old frequency. WWJ's towers were already built spaced 30 degrees apart, and the tall tower was 180 degrees tall at 920 kHz. This became 31 degrees and 186 degrees at 950 kHz. Also in Michigan WXYZ(T), WOOD, and WFDF were originally designed for pre NARBA frequencies 1240, 1270, and 880 respectively. All have been completely replaced and relocated. They are all among the ten highest night power Class Bs authorized on Regional Channels. Both NARBA and World War II substantially slowed the licensing of many of the early US arrays, which were already built or in the process of being built when the US entered WWII. Things then ground to halt until 1946. Some of this information is available on the history cards.
 
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SC, the development of the class B regionals in the 30s is a fascinating study. Efficiencies, angles of departure, etc. are beyond me. But in those day AM consulting engineers couldn't have come cheap, which might explain why some of the oldest licensed class Cs like KFJB Marshalltown IA which dates back to the early 20s, never bothered moving to a regional channel. (Plus weren't DAs required to have First Phone licensed operators on duty all the time?)

Station consolidation came into play in the claiming of my hometown's 2nd radio station, WIAS Ottumwa IA in 1934. It operated on the-then local channel of 1310 with 100 watts, but interests with the Des Moines Register were busy trying to develop what became 1320 (or current -day 1350) KRNT Des Moines. WIAS was in the way, the Des Moines Register interests also owned WIAS, so WIAS was deleted. It was more complex than that, but I wanted to keep it short.

These studies have sure been helped by the FCC History Cards, plus having AmericanRadioHistory.com available has also been a big help, thanks DE.
 
Thanks for the further analyisis, Joe. I wish they had Technical History Cards with the DA data. Some of us should email Dale Bickel and ask if that information is available. It used to be that oldtimer engineers and radio geeks, and even a few nontechnical townies, would remember things about the early days. "There used to be a tower there. It wasn't there very long." "There used to be two towers with a thing that looked like a hammock in between them", "in that park over there" or "on that building". Unfortunately, most of those oldtimers have passed away. Too bad there isn't a "Find-An-Old-Transmitter Location" online.
 
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I bet a lot of those stations that were Class IVs and moved to another frequency, particularly first or second adjacents to Local Channels, are kicking themselves now. Some of the Class Bs have taken down DAs and have gone to Class Ds. Some are struggling to find the funds to maintain their aging directional antennas and even nondirectional facilities. Then the managers and sales staff ask the engineers, "do we really need to power down, I can't hear the station at my house three miles from here at night". And of course, few contract, part time, spread thin, corporate cluster engineers are at the TL anymore often enough to see what's going on. So the effective NIF from the stations who stay on day power equal or exceed the 20-25 mV/m NIF of a typical CONUS Class IV/Class C. It's hard to leave a Class C on day power and pattern. If anything, the power increases at night.
 
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Over on the converse thread, stations like 1170 KBOB (former KSTT, KJOC) Davenport had a hot-shot night pattern if you were in the lobe. But, KBOB is some 12 miles south of Davenport in Illinois. 250 watts of night power ND somewhere in the middle of the Quads would be a lot simpler. I'm guessing reduced protection to the As would be needed to make that happen, with 1170 at Davenport sandwiched between As at Wheeling,WV and Tulsa.
 
WAKE 1500 in Valparaiso, IN got 25 watts directional at night doing that KSTT suggestion, but only after WLQV, WTOP/WFED, and KSTP reached an agreement increasing interference to the other 1500 stations.
 
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That's a lot of jaw-boning for a measly 25 watts! Must have been worth it for them at Valparaiso.

Meanwhile another single tower class B power: KGHL 790 Billings MT 1.8 kW Night (5 kW - D)
 
Wow! I may have missed a few. Now I have to review the below 1000 kHz list. I think KGHL used to be 5000 watts directional at night. Looks like they lost the lease on their land. I was going through the 1969 and 2006 WRTH to spot the "U1" designation. There are so many 5/0.015 type U1s now that I went back to look at the old WRTH. Didn't think there would be many new ones with more than 500 watts night. I'll should write some code to spot all the ones in the database with one tower and >= 500 watts night. It would be good to dust off the code writing skills though. 1800 watts nondirectional with a central location is decent though. if you could end up that good, it would be OK. I don't like the Class D nondirectional downgrades though.

WAKE in "Valpo", as the "LCMS" University parents call it, is in the protection umbrella of WFED, KSTP, and WLQV. The NIF is about 8 mV/m, pretty good for a Class D, and unlikely to increase much.
 
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DavidEduardo said:


While you indulge in the complexity, here is a brain teaser about the opposite situation:

What two adjacent Western Hemisphere nations, one with about 200 AM stations and another with around 500 AMs, had only one directional station each and in both cases the directional antenna was built because the owner preferred it to being non-directional?

These were not little stations, either... one 50 kw at 820 and the other 10 kw on 660.
Click to expand...
Just guessing off the top of my head -- I'd venture Argentina and Brazil? Couldn't be the US, Canada, or Mexico (too many directional AMs). No other countries in the hemisphere I can think of (off the top of my head) that would have AM stations amounting in the hundreds.
 
1280

KFRN 1 U5
KIT 5/1 U1

1290

KCUB 1 U1

1300

KROP 1/0.5 U1
KCSF 5/1 U1
WOAD 5/1 U1

KFRN directionalized daytime with a taller tower to not increase overlap in some directions and/or to increase the signal inland as much as possible.

It's amazing just how many call letter changes some of these stations have gone through. It's also amazing how many of these nondirectional at night stations with substantial power there still are.

Away from keyboard. There is a severe thunderstorm and I should unplug things. More later.
 
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Schroedingers Cat said:
1250

KWSU 5/2.5

1260

KYA/KOIT/KSFB 5/1
KTRC 5/1

1270

KTFI 5/1

More later. Keeps changing call letters to lower case.
Click to expand...

KWSU used to share time with the Seattle 1250, which we'll call KTW. Both stations were 5KW non-directional. KWSU broadcast from sunrise to 10:15 PM and KTW, from 10:15 PM to sunset the following day. This went on until KTW put in a directional system giving them 24 hour authority. I have no idea what KWSU did after that.
 
1470

KKTY 1/0.5

They had been a daytimer on 1050, but were able to inherit the channel when KTWO moved from 1470 to 1030.

Did WWJ Really ever have "1000 watt nulls"?
The Oak Park two-tower array (still posted at an engineering firm's website) shows nulls at roughly 120 and 220 degrees with the voltage just under one fifth of the voltage in the peak of the lobe (less than 1/25th of the power?)
I was living near Cadieux and Harper in their COL, only 12.3 miles from the TL. While they could be heard (with a little noise) at night on a good radio, they would drop dead at sundown on my crystal set.

The nulls from the Newport site are even deeper. In many parts of Monroe County, their signal gets hampered by carrier suppression.

Curious question about arrays with two towers very close to each other and almost out of phase with each other: WWJ's old night pattern and WEXL's current day pattern (yes, they're a Class C running DA-D "U5"). while the old WWJ coverage maps showed their night GW coverage (NIF 2.56 mV/m!) Went a few miles further North than it did with 5kw ND day, WEXL's daytime DA shows significantly less field in all directions, compared to their ND at night. What's the difference? (Yes WEXL covers more during the day as the interference level is lower by orders of magnitude).
 
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Those WWJ nulls were very shallow, around 200 mV/m IDF. Remember that the maximum IDF was around 825 mV/m, and that AM arrays have gain over the power to the antenna. The tall tower was 186 degrees at 950. The short tower was 139 degrees. So you had quite a bit of gain over a quarter wave. Plus the spacing and phase squeezed more power into the horizontal. So yes, the nulls were on the order of 1000 watts into a quarter wave antenna. Reradiation from other vertical structures, and the aging phasor may have negatively affected the IDF in the nulls.

With a 120 foot antenna, I would lose signals below 5 mV/m to the detection limits of the Germanium Diode in my Rocket Radio. Hooked up to a metal lamp ground, it lost things below around 25 mV/m.

Carl Smith's Chapter on AM DAs in the NAB Handbooks from 1947 and 1949, and 1960, explain the spacing and phase gain factors. David has them on his wonderful website, except that 1949 is available but not 1947, but I think they reprinted it exactly, given the importance of the information with all the new DAs being built at that time. As a Southern Michiganian/Ohioan, you will probably like the WHKC/WTVN 610 array analysis. I always wondered why almost every tower of the six was a different height and/or top loading arrangement.
 
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The WWJ IDF refers to the old system at ONE MILE. I still think it's better than 1 km, because in many areas of the country, major roads at one mile apart. WWJ was on 8 Mile, so if you were at 16 mile, it was 8 miles away North South. Inverse field at 8 miles would be 200/8=25 mV/m. So if you are down by Joy Rd. by the pre 1959 WXYZ towers, the most it could be is 33 mV/m. It's just easier to get an idea what it would be with error cancelling.
 
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