KWPZ’s Backup Transmitter Site Comes in Handy

KWPZ’s transmitter site was moved to an island mountain 21 years ago and has had few causes to be off the air — which is good, because in the winter, the ferries only serve the island four times per day
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Puget Sound, in Washington state, is home to the biggest fleet of ferries in the world, or so I�ve been told. One of their destinations is Orcas Island (part of the San Juan Islands), which is dominated by a 2,500-foot mountain called Mt. Constitution. Most of the mountain is a state park, but one square mile on the broad top of the mountain is home to three TV stations and three FM stations, one of which is KWPZ, Praise 1065, owned for 35 years by Crista Ministries out of Seattle.

A Washington State Ferry plies its way through the San Juan Islands. KWPZ�s transmitter site was moved to this island mountain 21 years ago and has had few causes to be off the air � which is good, because in the winter, the ferries only serve the island four times per day. If there is a failure of some kind that takes the site down it can take 12 or more hours to get up to the transmitter site.

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There have been a few times when the island�s local site engineer has reset a high-voltage plate breaker on a Continental transmitter or powered up the pump for the site generator�s day tank to get us back on the air. (What on Earth are we going to do when he retires?)

You do what you can to have backups for everything, but there�s nothing like having a completely separate transmitter site to bring up when that coax switch melts down (which has never happened to us) or when that UPS feeding the main rack dies (which has happened).

An alternate site was built for KVOS (channel 12) on Mt. Constitution, when the station went digital. They put up a 500-foot self-supporting tower for their own antenna, and there was plenty of room for a backup FM antenna along with space in the building for a backup transmitter. Well, not a lot of space � more like space for one deep rack. There is a fairly high ceiling, so it seemed logical to make the whole installation fit into one rack space, including bandpass filter. Keeping it to one rack also keeps the rent down.

GATESAIR FLEXIVA TO THE RESCUE

I had looked over a number of manufacturers� small-footprint transmitters, most of which, at 10 kW would fit into a rack without leaving much room for anything else.

Bob Ricker rigged the filter, lifted it with ropes and pullies, and set it atop the KWPZ rack.Doug Tharp from SCMS suggested looking at the GatesAir Flexiva, capable of 10 kW of analog power and close to 7 kW FM and HD Radio (which we might add in the future). The transmitter only takes 14 rack spaces.

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We had previously purchased the GatesAir Flexiva Exciter in order to upgrade the former main transmitter, a Continental HD25. When the HD25 was relegated to backup service at the main site, we returned the original exciter to it, freeing up the Flexiva Exciter for the new Flexiva 10 kW transmitter.

The whole transmitter and exciter would only take 21 RU of space. That amazes me. There is plenty of room in the rack for the Burk remote control, an Orban 8400, a UPS, the Moseley Lanlink and an old Dolby digital STL.

With an FCC monitoring facility not far away, it seemed fitting to install a 10 kW, HD-capable bandpass filter. Jampro provided a three-cavity filter capable of handling the power and it almost fit on top of the 42-inch deep rack. The bandpass filter hangs off the front and back of the rack a few inches.

An electrician friend, Bob Ricker, not only did my electrical for the site, but because he also does search and rescue, he�s become quite adept when it comes to rigging with ropes and pulleys. With a bit of effort, we lifted the 210-lb filter to the top of the rack. Using a number of lengths of unistrut from floor to ceiling, we were able to keep the whole structure fairly earthquake-ready. Kudos to site manager, Erling Manley, for letting me put this �science project� in his transmitter building.

Seacomm Erectors, out of Sultan, Wash., has done a number of projects for me over the years, so they were my first call for the installation of the two-bay ERI rototiller antenna, 300 feet of 1 5/8-inch coax and 7/8-inch coax for the 6-foot STL dish. They arrived at the site, having transported not only the FM antenna, STL dish and coax, but the new Jampro bandpass filter and the GatesAir transmitter as well. Seacomm, having erected the tower 9 years before, was quite familiar with the site. Even so, it took two days to rig the tower, mount the antenna and dish and install the coax.

PUTTING IT ALL TOGETHER

Radio and TV antennas high atop Mt. Constitution In the transmitter building, I placed the 42-inch-deep rack at the end of a row of other racks belonging to a power utility, an internet provider and a couple other wireless users, each having their own method of grounding. Each has varying levels of success.

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For lightning protection, my preference is to have the tower and the electric utility feeds on the same side of the building. I have leased space on few facilities that have it set up that way so we did our best to ground our coax at the base of the tower and again at the coax entrance panel, with supplemental grounding to the building and electrical grounding on the far end of the building. The rack, transmitter and bandpass grounding are all tied into the supplemental grounding.

For the remote control, I bought a used Burk ARC-16 system and linked them through a serial port on the Moseley LanLink. This fall, we plan to upgrade the whole remote control system for our three radio stations�� at five transmitter sites and two studio locations. I think it�s time to retire the old Burks, even though they have been amazingly reliable over the years.

A few years back, we started experiencing dropouts on our Mt. Constitution STL and had to revert to our old Dolby digital STL units. They are not negatively affected by the interference that plagued the other units. Fortunately, I was able to acquire a retired Dolby STL from another station for use at our new backup site. The Dolby feeds a veteran Orban 8400, which in turn feeds the input to the Flexiva exciter.

We plumbed the 1 5/8-inch coax to the output of the Jampro bandpass filter and from the output of the transmitter to the input of the bandpass filter. After the single phase electrical was plumbed to the rack, my assistant, Tim, installed the RF and power supply modules into the transmitter, made the interconnections to the exciter, and set up the IP. He did the preliminary checkout of the transmitter and fired up the site. The forward and reflected power looked very good with hardly any reflected power.

THE SITE CONTINUES TO EVOLVE

This tower features the main antennas on top of Mt. Constitution. If you look carefully, you can see KWPZ�s main antenna, a Kathrein six-bay panel. Since I put the site together, I�ve swapped out the tank of nitrogen that was used for pressurizing the coax with a new RFS/Cablewave dehydrator/pressurizer.

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This newly designed unit has different alarms that can be wired into a remote control, along with a USB port for downloading logs of run time and usage. It�s pretty handy for checking the integrity of the coax system. The unit is smaller than other units I�ve used and sits nicely in the bottom of the rack. It can be ordered with different high and low pressure settings as well as different alarm settings.

The construction of the backup site paid off immediately. We developed some problems with our new main transmitter (about 12,000 feet from the auxiliary site) and had to shut it down several times to test its bandpass filter, and to install new bullets in the 3-inch line. Clearly, it�s great having an entirely separate backup transmitter site.

STUDIO MOVE REVEALS QUALITY OF STL GEAR

The crew from Seacomm Erectors assembles the ERI antenna. Six months after building the site and putting it online, we moved our studios from the second story above a carpet store in the small town of Lynden, Wash., to an urban village in Bellingham, about 14 miles away.

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A tower crew was hired for the day during the studio move to re-aim the backup site STL dish as well as to raise the STL dish at the main transmitter site in order to clear trees on the top of the mountain that were blocking the view in the direction of the new studios.

It was a bit troubling when, after several months at the new studios, we made the trek to the transmitter site and discovered the old Dolby STL has be operating with only 5 microvolts of receive signal. The tower crew had raised the STL and TSL antennas 50 feet up the tower, but left them aimed at the old location. The difference in bearing is about 30 degrees. We could hardly believe the STL receiver was working. Naturally we repointed the dish and ended up with 80 microvolts of signal, plenty for those Dolbys.

With both the new studios online, and the backup transmitter site online, I can now look forward to rebuilding the six studios at our main campus in Seattle this winter. We never seem to find any down time, do we?

Bryan Hubert is the former chief engineer for Crista Media, KCMS, KCIS, and KWPZ. After 24 years, on Aug 1, 2016, he became the assistant engineer and is hoping to slow down just a tad.

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