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KCUR is replacing our transmitter antenna. Here's what that means and how it will affect your radio

A tall, skinny steel radio tower, painted red and white is seen from below against a cloudy, blue sky. Metal framework near the base is in the foreground.
Carlos Moreno
KCUR 89.3
The KCUR 89.3 transmitter antenna is located about 850 feet up this 1,100-foot radio tower in eastern Jackson County.

KCUR replaced our aging transmitter in December 2021 after a successful fundraising campaign. Thanks to that listener support, it's now time to replace the decades-old antenna, but that means the radio broadcast for 89.3 FM will be temporarily weaker than usual.

If you're a listener of KCUR 89.3, the broadcast you normally hear in your car or on your home radio may be temporarily weaker than normal — or not available at all — while crews replace the aging antenna on top of the tower.

That disruption is scheduled to begin at 10 a.m. on Wednesday, August 30, 2023, and, weather permitting, should conclude by Thursday evening, August 31. Thanks in advance for your patience, and we hope to be back, better than ever, in a flash!

Still, you might be asking: Why has KCUR needed so much maintenance work lately? And how exactly does its broadcast work in the first place?

With the help of KCUR's longtime chief of broadcast operations, Stephen Steigman, here are some answers to your questions about what it takes to get KCUR on the air.

How does KCUR make it from the studio to your radio?

As Kansas City's locally owned and operated NPR member station, KCURbroadcasts on the radio signal 89.3 FM.

All of KCUR's content — nationally produced shows like Morning Edition, All Things Considered, This American Life, etc. and locally produced programming like Up To Date, the Fish Fry, Night Tides and hourly newscasts — is managed from our studios at 4825 Troost Avenue in Kansas City.

KCUR sends audio from the equipment in our studios to a transmitter, located in eastern Jackson County, Missouri, through a studio-to-transmitter link. Equipment at our transmitter building prepares that audio for air, then sends the signal to the transmitter.

A tall, skinny steel radio tower, painted red and white is seen from below against a cloudy, blue sky. Metal framework near the base is in the foreground.
Carlos Moreno
KCUR 89.3
KCUR leases space for its antenna on a tower owned by Kansas City PBS.

The transmitter sends 28,000 watts of power through a 3-inch-wide copper transmission line up the tower to KCUR's antenna, 850 feet in the air. KCUR's eight-bay antenna finally sends out an electrified radio signal at a power level of 100,000 watts, beaming it out across the region — that's what you hear when you turn the dial to 89.3 FM.

This whole process happens incredibly fast: From the time a KCUR host speaks into the microphone to the time their voice reaches your ears, it takes less than 9 seconds.

Currently, we can reach radios up to 90 miles away, stretching farther east into Missouri and west past Lawrence, Kansas.

The tower itself is not owned by KCUR, but rather by our friends at Kansas City PBS. (No, that giant orange tower on 31st Street isn't theirs; that's a whole other story.) Their tower also houses antennas for Kansas City PBS's television signal and other broadcasters.

So there are several pieces of (pricey) technology that go into broadcasting to the radio: KCUR's studios, the transmitter, the tower and the antenna.

Didn't KCUR just ask for money to repair its transmitter?

In December 2021, KCUR replaced our old transmitter — which, remember, is what receives audio from our studio and turns it into a radio signal — following a really successful fundraising campaign. If you're a regular listener to KCUR, you might have heard a lot of messages about that effort, which ultimately raised $500,000 in donations from 1,725 audience members and the Sunderland Foundation.

That was a critically important change for KCUR, Steigman says. "The old transmitter was installed in 1992, had become increasingly unreliable, and was ready to be retired. It didn’t handle power outages — even short ones — very well."

That transmitter was already several years past its prime, and in a worst-case scenario, could have suddenly failed and taken KCUR's broadcast signal off the air entirely.

Steigman says the replacement transmitter, a Nautel GV40, has been "operating like a champ" for the last year and a half, including through multiple power blips.

A large gray metal cabinet with the lettering "GV40" sits on a concrete floor in a room with other electronic equipment. People can be seen in the reflection of a glass panel and one person is walking at the left of the box.
KCUR 89.3
KCUR 89.3
KCUR's new transmitter may not look like much, but it takes the audio signal from the station's studios and makes it ready for air.

Why did KCUR go off the air recently?

In July 2023, powerful thunderstorms hit the Kansas City metro and left nearly 200,000 people without power. KCUR's studios on the University of Missouri-Kansas City campus lost power and internet, so we had no way to broadcast or stream any local programming for almost two days.

In that case, the issue wasn't with the transmitter — it wasn't receiving any audio from KCUR in the first place.

Eventually, power was restored to KCUR's offices. But in the meantime, we were able to have NPR send programming directly to our transmitter so our radio listeners could hear something in our absence.

What about the other times that KCUR is not broadcasting at full power?

Even if KCUR doesn't go "off the air," there are a few reasons why your radio reception might be interrupted.

Whether it's for KCUR or Kansas City PBS or another broadcaster that leases space on the tower, occasionally maintenance requires everyone to band together to protect climbing workers.

Recently, technicians were required to climb more than 1,100 feet in the air to conduct repairs for the entire tower. When that happens, we need to lower power on our 100,000-watt antenna to a safe level — so the tower climbers don't get irradiated.

"When they spend time right in front of our antenna array, we have to turn it off, because prolonged radiation from our antenna can poison them," Steigman says.

While those devices are completely safe when they're hanging out by themselves, it's a different story up close.

Occasionally, KCUR switches off its main transmitter and shifts to our auxiliary backup transmitter and antenna, which are both located on the campus of UMKC.

That backup transmitter and antenna have a much lower output — just 500 watts compared to 100,000 — and is also on a much shorter tower (174 feet). That signal can only travel about 10-15 miles, and is affected more by the dips and curves of the landscape.

As a result, KCUR's broadcast can't reach parts of our normal listening area, and your radio might not pick up reception at those times. Your best bet is in your car, where walls don't block the signals. The HD1(KCUR) and HD2 (Classical KC) signals are also not available.

Sometimes we're on the backup transmitter and antenna for just an afternoon, depending on the type and amount of work needed. But rarely, like with the main transmitter antenna replacement, we're required to remain on the auxiliary site for a couple of days.

However, when we switch to that auxiliary transmitter and antenna, it does not affect streaming on KCUR.org, smart speakers or other platforms.

So what repairs are being done right now and why are they needed?

KCUR's main antenna on the top of its tower is 31 years old.

"It’s been sending out signal well," Steigman says, "but it’s been hanging out at 850 feet in the air, witness to countless thunderstorms, lightning strikes, and other weather and electrical events that have weakened its structure."

Thankfully, KCUR's recent transmitter fundraising campaign was successful enough that those funds will cover the cost of replacing the antenna, as well.

Once the transmitter is powered off and KCUR switches to its backup transmitter and antenna, crews will ascend the 850 feet, remove the old antenna array, lower it to the ground, and then bring up and install the new antenna array.

As long as the weather cooperates, the work begins Tuesday, August 29, when climbers will install the rigging on the tower. KCUR will switch to our auxiliary transmitter on Wednesday, August 30, and Thursday, August 31, when the disassembly and installation happen.

Our hope is that by Thursday evening, KCUR will be back in business at full power.

And just as a reminder, you can continue to stream KCUR 89.3 online — from your smart speaker, phone or computer.

You can stream KCUR news, podcasts, music and more, from your car, phone or smart speaker.

As KCUR’s Audience Editor, I ask the questions: What do people need from us, and how can we best deliver it? I work across departments and projects to ensure our entire community is represented in and best served by our journalism. I help lead KCUR’s digital efforts to make our station more responsive, more competitive and more engaging. Contact me at gabe@kcur.org
KCUR serves the Kansas City region with breaking news and award-winning podcasts.
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