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L.A. AM Gets a New Mountaintop Home, Part 2

A site built to last

Photosimulations were created to show neighborhood groups what the site would look like after construction.The author is director of engineering for Crawford Broadcasting Co. and a longtime Radio World contributor.

In the first part of this project profile, I provided a description of some of the difficulties our company had in locating and purchasing a suitable site for KBRT(AM), and then detailed some of the hoops we had to jump through to get through the regulatory process. We’ll pick up the account where we left off in this, the conclusion.

One of the key elements of the construction process was identifying and heading off potential opposition to our project at the neighborhood level.

Before the first shovel entered the ground, we found and contacted the homeowner groups in the canyons just below our site and set meetings with them. I prepared a PowerPoint slideshow that introduced neighbors to our radio station, described the project, talked about the environmental issues and even showed some “photosimulations” we had made showing sight lines from various points around the area.

Amazingly, we were well received, even warmly, by the neighborhood groups. They were pleased that we came to them first rather than them reading about our proposal in the public notices section of the Orange County Register. We showed them that there would be zero sight lines from their neighborhoods to our towers, how we would employ LED tower light technology to minimize light pollution in the canyons and even how we would take great care to protect migratory birds and other wildlife.

Our team, which included a local environmental consultant from Michael Brandman Associates, fielded a lot of questions, but by the end of the meetings, all the questions had been answered to the groups’ satisfaction. We had not only their non-opposition but their support as well, and we made some friends in the process.

The general contractor confers with the building inspector as he checks progress on the foundations for the security/screening walls around the towers.

We also made a good friend of a neighboring property owner. This particular gentleman vigorously opposed the 830 kHz facility back in the early 1990s and was responsible in large part for a number of very tough restrictions on the radio station’s use of the site. By getting this neighbor involved early, cooperating with him in some local, mutually-beneficial improvement projects and always keeping our word to him, we made a very good friend, not just in business, but personally as well. We continue to enjoy that friendship and partnership as stewards of the land.

The next months were spent working with planning commission staff, compromising, adjusting and eventually arriving at an arrangement that the staff was happy with. We went into the planning commission meeting with a positive staff recommendation. We also had a number of KBRT listeners, advertisers and friends — including our good neighbor and friend that I mentioned above — that spoke in support of the project. There was no opposition. A vote was taken and the use permit and waiver of the 30-foot height cap were approved unanimously! Before I left that day in October 2011, I got the declaration, took and recorded it with the county registrar.

With the use permit in hand, it was time to get down to brass tacks and complete a final design for the facility.

The towers were fairly straightforward, but we had to design a grading/drainage plan, a transmitter building and some serious security measures. The site had a long history of vandalism, including shooting at anything and everything (the ground was littered with shell casings and everything in sight was shot up), so I knew we would have to take extraordinary measures to protect our equipment.

A pier with rebar cage in place and inspected, ready for concrete. Each pier rests on bedrock, which is a must-do in earthquake country. The most vulnerable components were, in my view, the base insulators and the antenna tuning units. Not only were they likely to be damaged by gunfire, but unless we implemented extraordinary security measures, copper thieves would likely clean us out. With that in mind, I opted to install one-foot-thick, 15-foot-high concrete block walls close around each tower base area and the transmitter building. Each of the tower base walls would also have a chain-link fence at the proper radius for RFR protection.

That kind of wall requires some hefty foundations, especially in earthquake country. It was those foundations that gave the plan checker heartburn — for several months. We and our structural engineer went around and around with him and finally got a design approved. By June 2012, we had pulled all our permits: grading, towers, building, security/screening walls and solar (the state of California requires that at least one solar panel be used in each new commercial construction project).

With a final design and permits in hand, we solicited bids, selected a general contractor and got to work. That started with a biological survey to make certain that there were no nests of certain migratory bird species on the property, and there weren’t. Then we had to mow the tall grass that covered the site, which was fun given the slope and the fact that there was a lot of debris (mostly left over from Dr. Roaney’s ham radio antennas) down in the grass. We also demolished the old hamshack and poles, and removed all the debris from the site.

With the special site preparations done, most of the construction was fairly straightforward. We used drilled piers for all the tower bases and guy anchors for several reasons, including and especially that we would disturb a smaller volume of dirt and would thus be less likely to unearth an artifact or bone. A drilled pier (sometimes called a “caisson”) is essentially a column of reinforced concrete resting on bedrock or some other stable subsurface material. Its advantage is a much smaller footprint, and the foundation employing piers does not rely on the stability of the soil for vertical support.

Workers put the finishing touches on the silt dam. Holes were later bored into the standpipe at the elevation specified by the civil engineer to allow water but not silt to enter the pipe for discharge behind the dam. We were required to have an archaeologist and paleontologist on site during excavation, and so we did. Thankfully, nothing of any interest was unearthed, owing at least partly to the fact that much of the site was farmed back in the 1950s and anything of archaeological significance was probably long since dug up.

Tower base and anchor piers, a pad for the transmitter building and foundations for the security/screening walls were poured. A silt dam was constructed to prevent sediment in stormwater from our site from flowing downstream into the neighbor’s pond and the watershed below. Towers were stacked. Trenches were dug from the building to the tower bases, conduits (four per tower) were installed and concrete pads were poured for the antenna tuning units.

The transmitter building, a 12-by-30-foot prefab from Thermobond Buildings, was trucked to the bottom of the mountain on a flatbed, transferred in two pieces to a pair of flatbed bobtail trucks and then transported up the mountain (that was exciting!).We split the building into two parts so that we could get it around the tight switchbacks and hairpin turns on the road up the mountain.

At the site, a crane was used to set one half of the building in place, then set the other half on the slab but with a six-foot gap to the other half. The crane was then used to unload the Kintronics phasor cabinets, Nautel NX50 transmitter and other large items and set them into the building. The halves were then moved together and joined. A crew from Thermobond made fast work of that.

Next, the security/screening walls went up, and stucco was applied followed by an anti-graffiti coating. Kevlar-filled bulletproof doors were then installed, and after that came the 10-foot chain-link fence. We used PVC-coated fence fabric to eliminate the RF contact burn hazard.

With the east half of the building in place, the west half is craned into place, leaving a six-foot gap through which we would move the transmitter, phasor and other large equipment. Once the equipment was in place, the crane moved the two halves together. Transmission and sample lines were pulled into the tower conduits. We also pulled in 240-volt electric (3 x AWG #6 with ground), control (16-gauge multi-conductor), multimode fiber, video cable and alarm wire. Transmission line runs inside the building were all made with rigid line.

Next came the ground system. Because the security/screening wall foundations were so large and deep, we installed 4-inch ground strap stubs through sleeved ground-level slits in the walls, tying together a perimeter ground strap on the inside and outside of the walls; 3/4-inch rock was laid inside the walls and copper mesh was installed on top followed by fabric and another layer of 3/4-inch rock.

Outside the walls, copper mesh was installed to a total dimension of 24-feet square. Ground radials were then plowed in out to 321 feet with the usual terminations onto transverse straps. We put the wires in deep to make them difficult to steal — if someone does manage to find an end and pull, he will get only a foot or two before the wire breaks.

The construction was capped off with a sophisticated video surveillance and alarm system. Most of the property is covered by an array of dual-mode cameras, and key areas are lit with infrared floodlights that turn night into day for the infrared mode of the cameras, but are invisible to the naked eye. The building is fully alarmed, as is each security/screening wall area, and all the approaches are covered with long-range Doppler motion sensors.

The alarm is monitored locally, and an armed security service makes regular patrols and alarm responses. If the alarm is tripped, monitoring personnel see the camera array and can then look at anything specific with the steerable camera. If they decide the alarm is real, they notify the security company, which then makes an armed response.

CBC President Don Crawford ‘throws the switch,’ in this case a touchscreen virtual button, bringing the new site on line.MAKE OUTSIDE CONNECTIONS

With no phone lines or any other communications infrastructure servicing the site, we had to provide our own connectivity. We did this with a licensed 11 GHz fixed microwave link. We were able to get a clear path from our studio/office roof in Costa Mesa to the top of tower #1 in the KBRT directional array.

Operating a microwave link from a “hot” AM tower is always a challenge, and this was no exception. In other installations, I have employed unlicensed short-range 802.11 devices to get across the base insulator, but here I wanted something better, something that would not require an on-tower Ethernet switch. The solution: multimode fiber.

I ordered the Dragonwave Horizon Compact Plus microwave radio, which mounts directly on the back of a four-foot radomed dish at the 275-foot level of the tower, with a multimode fiber connection. We installed a weatherproof NEMA box on the tower face opposite the dish location and fed it with a 15-amp 120-volt circuit right off the Austin transformer. Inside this box is the 48-volt power supply that powers the microwave transceiver.

In the same conduit with the 120-volt circuit is a piece of dual multimode fiber, and that loops out and connects directly to the radio. At the tower base is a PVC junction box. From there, one piece of seal-tight conduit goes to the tower light control box for the 120-volt connection. Another piece of seal-tight, this one 100 percent PVC (non-metallic), goes over to the ATU cabinet and carries the multimode fiber cable. There, it plugs into the fiber cable coming from the transmitter building.

This link provides us with 110 Mbps of Ethernet bandwidth back to our studio network. We use it to for program audio (using APT Horizon NextGen codecs), remote control, Internet and telephone service.

For backup, we have a complete spare system, including transceivers, power supplies and cables, on the shelf, and we have a hot-standby Ku-band satellite system that connects to the uplink at the studio.

Tower workers and engineer Derek Jackson install and connect the Dragonwave 11 GHz antenna and transceiver at the top of tower #2.TUNE UP

With construction done, tune-up of the directional antenna was somewhat anticlimactic. The sample system had already been calibrated with a network analyzer at the time of installation, so all was ready.

In one day, base impedance matrix measurements were made and antenna models were calibrated and run. Operating parameters were determined from the models, and low power was applied to the array to see where we were.

Three of the towers were in the ballpark, but one, the low-power tower (which has a very low driving point impedance) was totally parasitic. It took a full day of adjusting before the “sweet spot” was found for that tower. By the end of day two, we had the pattern parameters dialed in on the antenna monitor and were able to bring the site up at full power.

The following day, we trimmed the ATU input impedances to 50 j0 ohms and once again finessed the pattern parameters back to the target numbers. With the facility operating at a full 52.65 kW input power, we sent out two crews with FIMs to make reference field measurements (three points on each null and lobe radial).

After that, we took a full day to drive the signal, stopping periodically to check the field intensity with a FIM. Coverage and signal levels were just about exactly what we expected; down somewhat from the 10 kW island coverage, but nonetheless excellent by any measure. Close to 8,000 square miles and 18.5 million people are within the 2 mV/m contour.


An array of eight dual-mode (IR night) security cameras, one of which is a steerable pan-tilt-zoom (PTZ), covers the site. The PTZ constantly scans the property. Live video is viewable online and high-resolution images are recorded for later examination and retrieval.” Looking back over the project, President Don Crawford offered, “When it became clear KBRT would have to move off the island, we immediately began the search for land for another site. Such a site obviously had to be on the mainland and to find any land that could be zoned for four towers and a transmitter site in Southern California was a task next to impossible.

“Our Director of Corporate Engineering Cris Alexander not only found the site, but strategized the gameplan and implemented that gameplan over a three-year period, which allowed us to produce one of the finest AM transmitter sites in this country, thoroughly modern, state-of-the-art, even increasing our transmitting power from 10,000 watts to 50,000 watts. No matter the hard work or expertise of so many individuals including and especially Cris Alexander, we do firmly believe that the end result was a miracle and no one could be prouder than I when the new KBRT(AM) begins broadcasting from this incredible site Thursday, Feb. 28, 2013.

“I as the owner of this great station will have the pleasure and the privilege of throwing the first switch when this new era begins!”

Mr. Crawford did so on that date.

This project was, without a doubt, the most difficult and long-running of my 36-year broadcast engineering career. From the outset we faced a near-impossible objective — to replicate, to the degree possible, the coverage of KBRT’s Catalina Island transmitter facility from a mainland site. Arrayed against us were the topography; geography; environmental regulations; neighbors; federal, state and local government regulations; bureaucrats and much more.

And yet somehow, by God’s grace, we got through it, clearing every hurdle and finally pressing our way through to completion. Today, KBRT enjoys for the first time in its 61-year history a transmitter/tower site of its very own that doesn’t require a boat to get to, one with state-of-the art equipment, a fully-optimized antenna pattern and the best security available. From this new site, KBRT can serve its loyal Southern California audience for many, many years to come.

Cris Alexander is a past recipient of SBE’s Broadcast Engineer of the Year award.

Read part 1 of this story.