AM Stations that broadcast from the top of tall buildings

[radiorob2.0]

WKRC 550 had a 2 tower directional array on the Hotel Alms until the summer of 1975 when the current site at Cold Spring,KY was commissioned

I've never been to Cincinnati, but I am sekptical that what you believe was a rooftop DA on 550 was a rooftop DA. Given the wavelength at 550 (more than 1/3 mile!), the building would have had to occupy a huge area to get the towers far enough apart for the DA to function even half decently. I know that a few DAs have towers spaced only 45 degrees apart but, spacings of less than 60 degrees are not very common. And the ground system would have required still more real estate. Moreover, 60-degree towers at 550 are ~300' high. Did the towers REALLY add the equivalent of 30 stories to the height of the hotel?

It is much more likely that the towers supported a nondirectional horizontal long-wire stretched between them, with the feed wire dropped from the center of the long-wire, to form a T configuration. A few such AM transmitting antennas remained in use into the 70s. Indeed, I'm told that one of this general type (it's and L rather than a T) is still in use at KYPA in Los Angeles, even though the station has built (and I thought had been granted a license to cover) a conventional vertical antenna comprising (and diplexed from) two of the six towers of a co-owned station. When and if this diplex goes into operation on 1230, it will be the first nighttime DA on a US Class C AM.

Among the stations where long-wires survived until after World War II was KNBR (I guess it was still KPO at that time). At the other end of the power spectrum, there was one until just a few years ago at a Class C AM in western PA, north of Pittsburgh. I've forgotten the CoL and the call sign. I think the station was on 1340.

I understand your skepticism and while I didn't actually see this in operation, I was on the engineering staff when the shut it down & we activated the new site. I can only go by what I recall. A Google Search for WKRC Hotel Alms did bring this site up, which contains a picture that depicts the 2 self supporting towers. It was decommissioned 34 years ago this summer...hopefully someone who remembers it first hand can fill us in on the particulars. I agree...it seems most unlikely, but I honestly do believe it existed. It had to be directional to minimize the signal toward co-owned WTVN/Columbus and to protect St Louis on 550. There we probably other protections as well. I wonder if there's any archive of past AM facilities on line?

http://www.cincinnativiews.net/alms_hotel.htm

Here's a quote from a recent post on another topic:

Title: Re: Best signal in Cincinnati
Post by: Cincinnati Kid on April 17, 2009, 03:18:59 pm
I think WKRC 550-AM is probably not thought of as a powerful station in connection with some of the others in Cincinnati. However, during the day, it really seems to get out well. I remember being in south-central Kentucky in the early 1960's and with a regular plug-in table model AM radio, I listened to the University of Cincinnati football and basketball games on WKRC. In doing that, it was important to get away from florescent lighting and other interference such as the the whine put out by TV sets. Back then, WKRC had its towers on top of the Hotel Alms in the Walnut Hills section of the city.

I doubt WTVN was a protection issues since it was down the dial a bit. However, co-owned and co-channel WGR would be protected.

 

[BobOnTheJob]

WKRC 550 had a 2 tower directional array on the Hotel Alms until the summer of 1975 when the current site at Cold Spring,KY was commissioned

I've never been to Cincinnati, but I am sekptical that what you believe was a rooftop DA on 550 was a rooftop DA. Given the wavelength at 550 (more than 1/3 mile!), the building would have had to occupy a huge area to get the towers far enough apart for the DA to function even half decently. I know that a few DAs have towers spaced only 45 degrees apart but, spacings of less than 60 degrees are not very common. And the ground system would have required still more real estate. Moreover, 60-degree towers at 550 are ~300' high. Did the towers REALLY add the equivalent of 30 stories to the height of the hotel?

It is much more likely that the towers supported a nondirectional horizontal long-wire stretched between them, with the feed wire dropped from the center of the long-wire, to form a T configuration. A few such AM transmitting antennas remained in use into the 70s. Indeed, I'm told that one of this general type (it's and L rather than a T) is still in use at KYPA in Los Angeles, even though the station has built (and I thought had been granted a license to cover) a conventional vertical antenna comprising (and diplexed from) two of the six towers of a co-owned station. When and if this diplex goes into operation on 1230, it will be the first nighttime DA on a US Class C AM.

Among the stations where long-wires survived until after World War II was KNBR (I guess it was still KPO at that time). At the other end of the power spectrum, there was one until just a few years ago at a Class C AM in western PA, north of Pittsburgh. I've forgotten the CoL and the call sign. I think the station was on 1340.

I understand your skepticism and while I didn't actually see this in operation, I was on the engineering staff when the shut it down & we activated the new site. I can only go by what I recall. A Google Search for WKRC Hotel Alms did bring this site up, which contains a picture that depicts the 2 self supporting towers. It was decommissioned 34 years ago this summer...hopefully someone who remembers it first hand can fill us in on the particulars. I agree...it seems most unlikely, but I honestly do believe it existed. It had to be directional to minimize the signal toward co-owned WTVN/Columbus and to protect St Louis on 550. There we probably other protections as well. I wonder if there's any archive of past AM facilities on line?

http://www.cincinnativiews.net/alms_hotel.htm

Here's a quote from a recent post on another topic:

Title: Re: Best signal in Cincinnati
Post by: Cincinnati Kid on April 17, 2009, 03:18:59 pm
I think WKRC 550-AM is probably not thought of as a powerful station in connection with some of the others in Cincinnati. However, during the day, it really seems to get out well. I remember being in south-central Kentucky in the early 1960's and with a regular plug-in table model AM radio, I listened to the University of Cincinnati football and basketball games on WKRC. In doing that, it was important to get away from florescent lighting and other interference such as the the whine put out by TV sets. Back then, WKRC had its towers on top of the Hotel Alms in the Walnut Hills section of the city.

I doubt WTVN was a protection issues since it was down the dial a bit. However, co-owned and co-channel WGR would be protected.

Interestingly, the azimuth to Buffalo and WTVN were within just a few degrees of each other. It's possible that even at 400 miles some WGR protection was required. Back in those days, common ownership was prohibited and even though Columbus was a totally different market, WTVN's blockbuster signal made for some overlap (or so the elder engineers at WKRC told us). Even with the null toward Columbus/Buffalo, WKRC was still audible in Columbus, but it wasn't what you'd call a great signal. I suspect that the potential overlap was in the area between Cincy & Columbus, rather than in either city. Had to protect those cows from too much media concentration. A little more research indicated that WKRC built new studios at the Hotel Alms in 1937, but "what didn't change was the towers"...that hints that the towers went up before 1937.

 

[Nostalgia]

WKRC 550 had a 2 tower directional array on the Hotel Alms until the summer of 1975 when the current site at Cold Spring,KY was commissioned

I've never been to Cincinnati, but I am sekptical that what you believe was a rooftop DA on 550 was a rooftop DA. Given the wavelength at 550 (more than 1/3 mile!), the building would have had to occupy a huge area to get the towers far enough apart for the DA to function even half decently. I know that a few DAs have towers spaced only 45 degrees apart but, spacings of less than 60 degrees are not very common. And the ground system would have required still more real estate. Moreover, 60-degree towers at 550 are ~300' high. Did the towers REALLY add the equivalent of 30 stories to the height of the hotel?

It is much more likely that the towers supported a nondirectional horizontal long-wire stretched between them, with the feed wire dropped from the center of the long-wire, to form a T configuration. A few such AM transmitting antennas remained in use into the 70s. Indeed, I'm told that one of this general type (it's and L rather than a T) is still in use at KYPA in Los Angeles, even though the station has built (and I thought had been granted a license to cover) a conventional vertical antenna comprising (and diplexed from) two of the six towers of a co-owned station. When and if this diplex goes into operation on 1230, it will be the first nighttime DA on a US Class C AM.

The proof is in the pictures. http://www.cincinnativiews.net/alms_hotel.htm Several drawings clearly show a flattop/cage antenna stretched between the two supports. Not a dipole by any means since 468/.550= 851' long!! BOTJ is probably correct, more likely an old style T antenna. The vertical wire is the actual radiating element and the horizontal elements acting as a capacitive top hat. The cage is needed to increase capacitance since this appears to be a short radiator, assuming it terminates on the roof and does not to all the way to the ground. The antenna functions as an omnidirectional vertical. Here is an article I found on the subject. http://www.smeter.net/antennas/simple-t-antenna.php

 

[BobOnTheJob]

The proof is in the pictures. http://www.cincinnativiews.net/alms_hotel.htm Several drawings clearly show a flattop/cage antenna stretched between the two supports. Not a dipole by any means since 468/.550= 851' long!! BOTJ is probably correct, more likely an old style T antenna. The vertical wire is the actual radiating element and the horizontal elements acting as a capacitive top hat. The cage is needed to increase capacitance since this appears to be a short radiator, assuming it terminates on the roof and does not to all the way to the ground. The antenna functions as an omnidirectional vertical. Here is an article I found on the subject. http://www.smeter.net/antennas/simple-t-antenna.php

I only looked at one picture & indeed you are correct. Another picture clearly shows a wire antenna being supported by the two towers. Another google search dug this piece of evidence up :

I agree with you Bill in BC. My first logging of them
was in 1975 when I lived in Lansing Michigan. I sent
them a reception report and they responded that mine
was they received since recently changing their
antenna pattern. I believe this predated the WKRP TV
Program by a year or two.

I also have a post card from the late 1920's picturing
WKRC in a hotel building with two towers and a
horizontal dipole antenna with their call sign letters
hanging from the antenna wire. Now you that's old, hi.

VY73, Joe Miller, AB8YP, Troy, MI

That report must have been received shortly after the new site came on in '75. The 1937 article I ran across indicated they operated with 5000 watts day & 1000 watts night at that time and that was an increase during the day. Yet the new site is directional with a pretty deep null toward St Louis. I suppose one possibility is that the new antenna system with vertical towers produced more field intensity than the dipole or T did and therefore the need for the directional antenna? The new site was built well before the "ratchet rule" that requires new or changed AM facilities to ratchet down interference by 10%. It would be fascinating to read the history of this station.

 

[DanStrassberg]

It had to be directional to minimize the signal toward co-owned WTVN/Columbus

WTVN 610??? No need for 550 in Cincinnati to protect a station 60 kHz away.

BTW, the current 550 two-tower array produces a three-leaf-clover pattern. Such patterns require wide spacing and the towers are 260 degrees apart--almost 1/4 mile!!! Assuming that the hotel-top setup did not have to protect WGR (seems unlikely, though, that WGR isn't at least as old as the Cincinnati 550) and only KSD had to be protected, the towers on the hotel roof could have been as little as 250' apart. That's getting short enough that I might be willing to believe that it was a DA. Rooftop DAs are quite uncommon, however. The only one I am aware of in the US (if you don't count KTNQ/KTLK, which I think should be excluded because a) the towers stand on the ground and b) the towers predate the surrounding building) is KPIG 1510 licensed to Piedmont CA and located atop a warehouse in Oakland. There are four physical towers plus a drop wire, which is due to be eliminated when the station increases its night power. The night upgrade is either a CP or is still an app; it's tied in with the downgrade of KGA.

 

[BobOnTheJob]

It had to be directional to minimize the signal toward co-owned WTVN/Columbus

WTVN 610??? No need for 550 in Cincinnati to protect a station 60 kHz away.

Maybe protection was the wrong term. In 1975, there was a limit of 1 AM station per owner in any given area. The definition of area was not set by market, but by signal overlap. I don't recall what the actual signal level was, but WKRC and WTVN (both owned by Taft Broadcasting at the time) and both having 5000 watts at the low end of the dial exceeded that threshold. It's my understanding that WKRC had to provide less signal toward WTVN to prevent that overlap. Maybe "prohibited overlap" would be a more correct term.

 

[fybush]

I checked with Someone Who Should Know, and he confirmed my suspicions: the towers atop the Hotel Alms were built as a conventional (for the era) flat-top T in 1923 - but were converted into a most unconventional two-tower DA in the 1930s when the station was owned by CBS. Vir James did the work, which involved jacking up the towers and installing base insulators.

My source tells me: "The towers were very short electrically. The south tower carried most of the juice, and the base current was 34 amps. Vir told me that the burned up two 50 amp base current meters tuning it up.

The pattern was an oval NW/SE, but not all that directional. Overlap with KSD and WIND was significant."

So the DA significantly predated the Taft co-ownership with WTVN.

 

[BobOnTheJob]

I checked with Someone Who Should Know, and he confirmed my suspicions: the towers atop the Hotel Alms were built as a conventional (for the era) flat-top T in 1923 - but were converted into a most unconventional two-tower DA in the 1930s when the station was owned by CBS. Vir James did the work, which involved jacking up the towers and installing base insulators.

My source tells me: "The towers were very short electrically. The south tower carried most of the juice, and the base current was 34 amps. Vir told me that the burned up two 50 amp base current meters tuning it up.

The pattern was an oval NW/SE, but not all that directional. Overlap with KSD and WIND was significant."

So the DA significantly predated the Taft co-ownership with WTVN.

I was hoping you'd weigh in Scott. So it was an actual DA at the low end of the dial on a rooftop! The new (current) site is the one that dealt with the Taft overlap from what I was told in my days there.

 

[Nostalgia]

Last night I re-read Scott;s "Columbus, Ohio Part 2" tower adventure because I remember it saying something about the Taft/WTVN/WKRC situation. However it referred to the two TV stations, not the radio stations so I didnt post the link. Glad to see the author himself clearing this up.

Scott, I used to drive by that Obetz Road tower farm on my way to the 1230 studios downtown. I wish you had mentioned that the 1230 tower (then WCOL-AM with the WCOL-FM antenna top mounted on it) was a half wave tower with only 1230 on it initially. Big tower, big building, little Gates Vanguard transmitter sitting up against the wall that could be heard as far south as Chillicothe and beyond during the day with no problem.

 

[LA_Guy]

In Los Angeles, two 50-kW stations, KTNQ 1020 and KTLK 1150, have their ground systems on the roof of a massive warehouse that was literally built around the five half-wave towers of what was originally the KTNQ array but later became the diplexed array. The warehouse is cut out for each tower base. Actually, the warehouse is two buildings with a wide driveway between them and a large number of the ground radials of one of the towers run across the tops of both buildings. I've seen a photo taken from the driveway at ground level with the radials overhead crossing the driveway. It's quite a site.

There is a little more to it...

The ground system is underground covering the entire piece of property. When the warehouses were built, it was decided that the buildings would potentially reduce the effectiveness of the ground system, so the sytem was duplicated at roof level... covering the parking lot between the buildings, too... across the roofs, and down the far sides of the warehouses and connecting to the radials there with strap. The area over the parking lot, several acres in size, is mesh made of copper wires, which are silver soldered. The mesh also surrounds the tower "cut outs" and to get to the bases, you to to the roof, and then down a ladder to the base. The ATUs are on the roof, though, for ease in servicing them. I have a number of burnt out ATU components decorating my office (along wihth an 892 tube), proof of the fact that 5 500" towers attract lightening!

Did you finally interlock 1020 so the transmitter cuts off carrier during pattern change? The last time I was there, it stayed on and a spark could be seen coming from the phasor. Thank goodness the DX-50 has foldback!

 

[Charlie Gee]

This should be a web page devoted to the KTNQ and KTLK transmitters and antenna system. I can't remember where or when I was led to the pages.

http://www.hottips.org/kxtapage.html

There's some great pictures of everything.

 

[BillP]

I remember that back in the '40s & '50s, WFOX (860 AM if I remember correctly) had it's antenna on top of what was then a tall building in downtown Milwaukee.

I think the station is now WNOV, but I don't know if they still use the same tower.

Anyone?

----------------- Bill

 

[DanStrassberg]

I think the station is now WNOV, but I don't know if they still use the same tower.

As far as I know, WNOV still uses the rooftop stick, but I thought I had read that the nighttime flea-power (5W) operation used a different tower. Seems that info was wrong (or I misremembered). As far as I can tell, there is only one stick: 90 degrees (~300' at 860) with a sub-standard ground system. The efficiency just meets the Class D minimum, whereas a 90-degree stick with 120 1/4-wave ground radials would have an inverse-distance field roughly 10% higher than the minimum.

 

[w9wi]

I think the station is now WNOV, but I don't know if they still use the same tower.

As far as I know, WNOV still uses the rooftop stick, but I thought I had read that the nighttime flea-power (5W) operation used a different tower. Seems that info was wrong (or I misremembered). As far as I can tell, there is only one stick: 90 degrees (~300' at 860) with a sub-standard ground system. The efficiency just meets the Class D minimum, whereas a 90-degree stick with 120 1/4-wave ground radials would have an inverse-distance field roughly 10% higher than the minimum.

The current transmitter site isn't downtown -- it seems to be on 29th St. just north of Locust Ave.. (or 30th St.?, fcc.gov and Google Maps disagree... 30th is probably right as it appears to abut a railroad line.) Very roughly 2 miles northwest of downtown. FCC says same site day & night. (though strangely enough, right now AM Query also says the day and night powers are both zero!)

At least in the mid-60s the station's address was listed as 208 E. Wisconsin which is indeed downtown.