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Dealing With Repack — Moving an FM Cluster to a Temporary Site

Scouting for a temporary home involves a lot of legwork

The incentive auction that ended in 2017 was bound to have consequences for the FM stations on Los Angeles’ Mt. Wilson. TV and radio share tower space there, often in close quarters. It soon became clear that this would be especially true in the vicinity of the “Post Office” site, where iHeartMedia has three of its four FMs, with the fourth next door. Historically, collocated users coped with the occasional work in the neighborhood by participating in group power reductions — but the anticipated changes would probably require days upon days of work.

In a series of articles, we’ll discuss the ways and means by which iHeartMedia decided to operate its four Mt. Wilson FMs while the TV antenna changes are being made.

Not long after the incentive auction came to a close, it started to become obvious that we would be adversely affected by changes occurring in our immediate area on Video Road (on Mt. Wilson). We have three stations in the Post Office building, making use of three towers that surround the building. These include:

• The KIIS-FM main, aux, and an aux used by our HD transmitter
• The KRRL main and its aux (also used for HD)
• The KOST main antenna, and its aux antenna

Additionally, immediately next door to the west, at the Poole building (now owned and operated by Insite), we have KBIG’s main and aux, and our aux site for KYSR. In the immediate neighborhood to our four stations on Mt. Wilson are various FM stations, including Entercom’s 97.1 (Amp) and KRTH at 101.1. Cumulus’ KLOS (95.5) is also close by.

The TV stations directly affected by the incentive auction results are:

• KDOC, which is moving down the road to Deer Park, to the new DTV site on the tall tower
• KOCE, which is going off-air
• KJLA, which is going off-air
• KXLA, which is staying
• KCBS-TV, which is moving from RF channel 43 to channel 31, and thus changing antennas
• KTLA, which is going from RF channel 31 to channel 35, and likely changing antennas (full plan not known at the time of writing, at least by me)

As time went by late last year, we asked the TV station engineers for more details on their plans but for the most part they were not forthcoming. The reality is that not all of the plans were in place yet, so clearly, they couldn’t tell us what they were. During this period, we knew something was going to happen, we just didn’t know exactly what or when.


The group of stations that I’ve discussed has been very cooperative, among the ad-hoc group, with power reductions when the need arises. Many times, one of the stations needed scheduled maintenance, which was usually preceded by an announcement one or two weeks in advance. Everyone prepared for it ahead of time.

Occasionally, some sort of failure would necessitate an immediate repair, again accommodated well by the group, with everyone in the neighborhood going down in power by 50 percent. (Radio stations insisted that power reductions not occur prior to 10 a.m., and if at all possible, end by 3 p.m.)

Our corporate engineering asked about the possibility of power reductions, or worse, in the near future, to satisfy the needs of TV stations making substantial changes. I responded that the 50 percent power reduction had, up to that point, been good enough, and “likely” would continue to be. After all, everyone had an ox to be gored — so everyone is incentivized not to change the way we’ve been doing things. Clearly, I couldn’t guarantee the same process would always work though.

Eventually, in the fall of last year (and especially after an infamous trade publication article about the repack that specifically mentioned KIIS-FM and KOST), the corporation decided that we needed to take a far more proactive approach, and to build an entirely different site, in order to minimize the impact of the upcoming work. I was tasked with finding the site.


Every year (almost without fail) the Southern California Frequency coordinating Committee (SCFCC) puts on their Christmas party at Mt. Wilson during July. Yes, a bit early, but it’s a real tradition. Naturally, the weather is great (as opposed to Christmas-time) and in 2017, representatives from American Tower Corp (ATC) were onsite to update the Mt. Wilson crowd on what was coming up with respect to the repack. At the same time, a couple of their guys were going to show us two sites, either of which they thought would work for our repack site: Mt. Harvard and Deer Park. Having not been to either, I very much looked forward to the opportunity.


Mt. Harvard is about two miles southeast of the Mt. Wilson, at about 5,000 feet of elevation, so it covers the greater Los Angeles and Orange county area similarly. It’s not a popular site for FM though. The major tenant is KUSC radio.

In my “discovery trip” email, I wrote the following: “This tower and antenna belong to KUSC radio, even though KUSC’s transmitter is up in the ATC building. It’s a curious arrangement. The building directly below this tower (which we believe belongs to ION media) has the space I mentioned above. As you can see, there’s an old transmission line running up the tower; some station removed a TV antenna evidently.”

It’s a great-looking tower (Fig. 1), and there is physical space directly below that of KUSC; however, being that low to the ground could present a problem with NIER levels.

Another tower (Fig. 2) at Mt. Harvard looked good, but had little to no space. At that time, I wrote: “This is the tower currently with the ION antenna. Below that you can see a four-bay Dielectric, the KLOS aux. Below that, a Channel 6 basket; and below that, the old FLO antenna, which could be removed. Unfortunately, this space isn’t that large or high AGL. The tower is triangular, and the most favorable leg is the one that the FLO antenna is on. So, for us, the best aperture is unfortunately adjacent to the ION antenna.” The tower looks great but there’s no space on it.

There’s also a very large candelabra type of tower on Mt. Harvard (Fig. 3). In my “discovery” email, I wrote: “This picture shows the structure for all the various TV antennas. Some of these are going, but it’s pretty clear that using any available space on this tower would subject us to repack work at this site.”

So, while Mt. Harvard had some potential, the reality is that antenna space was at a premium (at the time) and, just like our situation on Video Road, the TV stations didn’t have their plans in place.


The ATC guys were interested in showing us what ATC had available at Deer Park, which is a site they bought from CBS TV. Formerly known as “123 CBS Lane,” Deer Park at that time was really only hosting KCBS-FM as its main tenant. It’s about 0.6 miles west of the main grouping of antennas on Mt. Wilson; there’s an 800-foot tower there, along with a shorter one, which at one point was used by KCBS-TV for their aux antenna on channel 2 and was still in place (see Fig. 4).

At the time, I wrote: “The short tower is ASR 1229046… It’s 245 feet to the very top. The last section of the tower is a pylon which is currently holding an old Channel 2 batwing, obviously abandoned. What we’re thinking is that the batwing would come down, and we’d re-use the space for at least one of our antennas. Now, notice the two-bay Jampro; that belongs to KCBS-FM.

“There’s a virtually empty building near the base of this tower — so space is abundant. The building doesn’t look great but evidently isn’t suffering too much for leaks. The roof actually looks new. There’s a generator available as well, but it appears to be only a 50 KVA set.

“If I had to pick between Deer Park and Mt. Harvard, I would definitely pick Deer Park. Coverage considerations aside (since I can’t study them), I would say it would be easier, cheaper and faster to make use of this (relatively) small tower. I would also gauge that the ATC guys would prefer this solution as well, for what that’s worth.”

Next time: I design our new site

Doug Irwin, CPBE AMD DRB, is vice president of engineering at iHeartMedia in Los Angeles and a technical advisor to Radio World.

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