(Originally published November 11, 2011)

WLW's auxiliary tower
...and at dusk
WLW's tower, late in the afternoon...

It wasn’t hard to decide which site should be the first to be featured here on the new version of Site of the Week: the mighty Blaw-Knox tower at Cincinnati’s WLW (700) was our front-page logo for 11 years at the previous incarnation of, it’s still featured on our business cards and pens, and – oh yeah – it’s probably the single most historically significant tower site in the nation.

What’s so special about this one?

It’s one of just two remaining tall Blaw-Knox “diamond” towers from the 1930s. It’s one of the oldest vertical AM radiators still standing. It’s one of the oldest AM sites in the country, period. It’s home to the oldest 50 kW transmitter still in existence, and to the largest collection of 50 kW transmitters at any site in the country. Oh yeah – it’s the only AM station in the country that was ever licensed to run 500 kilowatts of power. (And it’s featured as the “centerfold” spread in the 2012 Tower Site Calendar, too!)

WLW’s transmitter room, summer 2010

These pictures come from a summer 2010 visit to the site, which has been impressively cleaned up and updated since we first visited in the late 1990s. Today, visitors to the site in Mason, Ohio (some 20 miles north of downtown Cincinnati) are greeted by the sight seen above: no fewer than five 50,000-watt transmitters dating back as far as 1928.

The 1928 transmitter is the one seen at far left: a Western Electric model 7A. By the time it was put into use here on October 4, 1928, the Mason site had already been in service for several years. It was built in 1925 for another station, WSAI, which boasted of its own “super power” (a whopping 5,000 watts) when it constructed the original house-like building and flat-top antenna here.

WLW's transmitter building

Cooling pond at WLW
WLW's tower

Powel Crosley’s WLW had been operating from its own 5,000-watt “high power” facility in Harrison, Ohio, west of Cincinnati, when it settled on Mason as a superior transmitter location – and so Crosley bought WSAI and began building a new transmitter plant next to the existing WSAI facility.

The WLW plant expanded quickly, because Crosley had no intention of stopping at 50,000 watts.

By 1932, he’d applied for experimental 500,000-watt power, and construction crews were busy in the spring of 1933 erecting an addition on the back of the transmitter building, a cooling pond out front, two separate 33 kV power feeds from Cincinnati Gas & Electric – and over in the field to the east of the WSAI building, the mighty 831-foot Blaw-Knox tower, one of the first of its kind, boldly labeled with a giant “W L W” sign across its midsection on the side facing Tylersville Road.

In the tuning house at the base of the WLW tower

Base of WLW's tower
Looking up the WLW tower
WLW's antenna/transmitter controller

Let’s head out to the base of that massive tower, still perched (all 200 tons of it!) on its original 1933 insulators and fed by the original 1933-vintage aluminum 10″ transmission line. (72 amps at the base when it was running the full half-megawatt, if you’re curious…)

When we visited last summer, the tower was still supported by its original 1933 guy wires, too, but not for long – last fall, those guys were replaced for the first time in the tower’s history in a nail-biter of a project that had a successful conclusion, thankfully.

The tower is no longer at its original height: like its close cousin a few hundred miles to the south at WSM in Nashville, it proved to be just a little too long, electrically, for its intended frequency, resulting in skywave/groundwave cancellation that impaired nighttime reception of WLW in important communities such as Columbus, Dayton, Louisville, Lexington and Indianapolis.

So the tower’s top section was removed a few years after it was completed, reducing the height to 736 feet. (Much later on, an FM antenna was added to the top of the tower for a former sister station; it’s now Cumulus-owned WFTK 96.5, which operates from a small building of its own behind the WLW transmitter building.)

The Western Electric and Crosley transmitters

WLW's current transmitter

Heading back inside the WLW building, we find a veritable museum of AM broadcast transmission over more than eight decades. On the left side, as viewed from the front door, WLW’s oldest transmitters line a wall next to the stairwell that goes down to the ground floor: the 1928 Western Electric 7A at left, and next to it the homebrew Crosley “Cathenode” transmitter that once boasted spectacular high-fidelity performance (and a spectacular low-efficiency power bill to match) before being modified in the 1950s into a more conventional plate-modulated transmitter. To the right of the Crosley, along the rear wall, is a Harris DX50 that powered WLW in the 1990s and into the early part of this century before being replaced by a 3DX50 “Destiny” that sits to the far right of the room, in front of the Continental 317C1 that went into service in 1975.

WLW's 500 kW transmitter

The WFTK FM building

But the front room is only a warmup act for the back room. The double doors between the DX50 and the Continental open up into the big back room that’s filled, end to end, by the 500-kilowatt water-cooled monster that bears an RCA badge, though its innards include an RF section built by General Electric and a control system designed by Westinghouse, and its modulator section was the original 1928 Western Electric. (You can read more about the technical history of WLW at Jeff Miller’s excellent History of WLW page.)

To protect adjacent-channel CFRB in Toronto (then on 690), the FCC ordered WLW to directionalize at night; a passive tower was built in a farmer’s field to the northeast to provide some null toward the Canadian signal when Cincinnati was up and running at full bore.

This beast roared its way across the ether for only five years, from its first official sign-on (triggered by a remote control at the White House desk of President Roosevelt) on May 2, 1934 until the FCC declined to renew the superpower authority (under experimental callsign W8XO) at the end of February 1939.

And it remained usable, or so the stories go, well into the 1960s. There are tales – lots of them – of the big transmitter being fired up during World War II to aim propaganda at Europe (though that function was soon filled by another Crosley site just to the east; the “Bethany” shortwave facility that was initially WLW’s international voice quickly became part of the Voice of America, though it was decommissioned in the 1990s and is now a park and museum.)

The workroom in WLW's basement

Modulation transformer for the 500 kW monster

While the WLW site isn’t officially open as a museum (and, indeed, still contains a private residence – the old WSAI building next door to the WLW building has been converted into a home that’s been occupied by several generations of WLW engineers), it’s been cleaned up nicely in the last few years and often plays host to visiting engineers, ham radio operators and other interested folks.

The informal tour today includes not only the transmitter floor but also the basement of the building, which is a magnificent piece of history itself. At the bottom of the stairs, a well-equipped workshop allowed many of WLW’s 63 engineers (!) back in the day to fabricate a lot of their own parts. Behind it, a fallout shelter is being rebuilt as a last-ditch emergency studio, and back behind that is perhaps the most awe-inspiring room in the building (which is saying something, considering what’s upstairs): the 40-foot-long vault under the 500 kW transmitter that housed the gargantuan modulation transformers. One was removed (oddly, the one with a blocked path to the outside door!), but the other still sits here, bearing witness to a day when nobody yet knew just how much power would eventually be the maximum for AM broadcasting in the United States.

Thanks to current WLW chief engineer Ted Ryan, his predecessors Paul Jellison and Chris Zerafa, and to Clear Channel’s J.T. Anderton for their insight into the WLW site over the years!

The WLW tower site is one of many you’ll find featured in the Tower Site Calendar 2012, still available from the all new store!

Next week: More Cincinnati, Summer 2010


  1. Scott, the WFNX 101.3 subject has come up at least 50 times in the past couple of years and I answer it over and over again, I feel like
    I am talking into the ether and no one has a radio. Phoenix Media had no choice in keeping 101.3 The turn on of the One Financial was contingent upon turn off and surrender of the translator license in Boston. Our Washington Attorney Jim Winston worked out the only way for us to keep the translator was to move it more than 6 miles west or NW. I toyed with putting it on the small ATS tower under the 25/38/56 tower but with a test signl it was lost in the high power receiver overload and they did not want to spend money to persue it further. then the pirate moved in.
    After disclosing this over and over I fell like Debra talking to Marie on Everybody loves Raymond. Marie…when I talk…what do you hear? I hope this ends it once and for all but somehow I doubt it .As i wrote to NECRAT, It seems these days when people want something to be true they begin to believe its reality. This mis info is pissing me off so much that I may give Jim a call and see if he will release the paperwork, though It may be confidential client info.

    • I understand your frustration, Chris, and perhaps I didn’t phrase things as well as I should have. Given the way the translator rules were interpreted at the time of the WFNX move, your DC lawyer probably steered you in the best way he knew to be possible. But what’s interesting, at least to me, is the way in which the interpretation of the rules changed very dramatically and very quickly in the years right after the WFNX move. In 2006, nobody could see any compelling reason why an urban FM signal would need a fill-in translator right AT its own antenna location, and so nobody even thought to ask whether the rules might allow for such a setup.

      But it turns out that in 2002 (FCC 02-224, paragraph 12), the FCC noted that it would allow such operation, provided that the area in which the translator would interfere with the second- or third-adjacent full-power signal nearby did not encompass any population.

      Here’s a real-life example of how that works: translator W255AJ on 98.9 in Atlanta runs 250 watts from a site 5.3 km from a class C0 station on 98.5, WSB-FM. WSB-FM’s signal at the W255AJ site is calculated at 109.3 dBu, so the interfering contour of the translator would be 109.3 + 40dB = 149.3 dBu. The 149.3 dBu contour of the translator never touches the ground (it’s something like 300 meters up a tall tower), and so as far as the FCC is concerned, there is no second-adjacent interference. Here’s the application in question:

      In the case of 101.3, there are two stations at play, WFNX and WZLX. WZLX appears to put about 114 dBu at One Financial Center, so the interfering contour of the translator would have been its 154 dBu contour. WFNX, obviously, puts even more RF right at its transmitter site, so you’d probably need to consider the 150 dBu contour of the translator. Under today’s interpretation of the rules, it should be pretty simple to show that there’s no population within the 154 dBu contour of a hypothetical 101.3 translator on the roof of One Financial Center; the key in that case would be to show that the 154 dBu contour never touches an occupied floor of the building. Pages 2 and 3 of this application show how it’s commonly done these days:

      Again, this is all in hindsight. In 2006, nobody even thought about doing this, because there’d have been no reason – why put a translator where your originating signal is, by definition, strongest? It wasn’t until a year or two later that some very clever consulting engineer thought to ask the FCC staff, “hey – there’s nothing in the rules that explicitly says I can’t translate an HD2 or HD3 subchannel…is it OK?” The answer turned out to be “yeah, I guess that’s OK,” and the floodgates were open for this new use of the interference-ratio policy that had quietly been approved back in 2002.

      I don’t think your attorney was steering you wrong at the time, and I doubt I would have done anything differently had I been in your shoes back then. It’s more of an interesting – “if we knew then what we know now” sort of question…kind of akin to asking, “if Westinghouse knew what would happen with FM, would they have sold 106.7 as cheaply as they did in 1981?”

  2. Point well taken Scott, what really pains me is at the time I was trying
    to find a way to keep it from falling into the clutches of an illegal pirate operation. Once I decided that placing it at the antenna farm was useless as the 101.7 signal actually cut through far better than
    the 10 watts did. Before we turned it in I told Bob Bittner what was about to happen, it would have been an outstanding fit for WJIB
    transmitting from Belmont Hill or from the top of one of the very tall Bronx style apartment towers at Rindge Ave and Ailwife in Cambridge. Both these site would have probably just met the 6 mile required spacing by a hair. This would have been a win win situation for both stations and the industry but Bob never persued it.

  3. Hey Chris, I’ve toyed with the idea of suggesting that WZLY move to 101.3 for years, but their 100dBu would be about 1 or 2 miles inside the 101.7 60dBu, and thus technically not permitted under the Class D rules. But if the translator was still an option that close in…would you think it’s worth pursuing with CC taking over or is it too late?

    WZLY is really on a horrible frequency…first adjacent overlap from WDJM, co-channel problems from two major sources (WUML and WMLN) and more first adjacent issues from WUMT/WAVM, too. Their little 7 watt signal barely makes it off the campus on a good day…

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