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10:49 am
Thu September 20, 2012

Stations Off-Air Due to Antenna Problem

Very early on Thursday morning the 20th, an unexpected problem developed with our antenna which transmits all six HD channels of Public Radio Tulsa on 88.7 and 89.5 FM. 

All eight antenna elements and interconnecting lines on the ground for repairs

Mon, 9/24 • 9:29 am: Over the weekend, all eight elements and interconnecting tubular transmission lines of the main antenna were lowered to the ground for repair. At least half of the antenna shows signs of damage from an internal electrical burnout. The factory will begin constructing replacement parts, which we hope will arrive in about a month to complete repairs. At that time, both stations will again periodically go off-air to allow the crew to safely remount the antenna on the tower. In the meantime, Public Radio 89.5 and Classical 88.7 are on-air from the emergency antenna.

Sun, 9/23 • 2:12 pm: The weather cleared and the winds calmed enough to resume work on the tower and the four remaining main antenna bays are being inspected for damage. Both stations should be back on the air this evening.

Sun, 9/23 • 8:17 am: Yesterday's forecast held out little chance for rain overnight, yet it came. The danger of working on a tower during storms is not the unpredictable gusts of wind or even the slippery steel, but the fact that one is standing on a superbly-grounded lightning rod poking 2000' into the sky. This antenna was attached to the tower in September of 2010 in what was imagined to be a long weekend job. That installation took over two weeks because of fickle September weather. The good news is that both stations may remain on-air most of today, unless the weather clears and the wind calms.

A burned-out connection on the inside of bay #5 of the main antenna

Sat, 9/22 • 4:21 pm: "Ooook-lahoma, where the wind comes sweepin' down the plain…" Rodgers & Hammerstein   probably weren't thinking of tower climbing when they penned that phrase, but it's certainly appropriate. Work on the tower stopped because of unsafe wind speeds at the antenna. We're back on-air with the emergency antenna until tomorrow morning when work will resume, winds permitting. Four antenna element bays were examined before work stopped. The first three bays appear to be undamaged, but bay #5 is burned out, which will necessitate lowering it to the ground for repairs. Examination of the remaining four antenna bays will continue tomorrow. To safely continue repairs, both stations will again be off-air most of Sunday.

Sat, 9/22 • 1:58 pm: The stations have been off-air much of the day to allow our tower crew to disassemble the main antenna, piece by piece, looking for damage. The wind has picked up today, with strong winds 1000' above ground, making it difficult for the crew to safely work on the tower. We'll resume broadcasting from our emergency antenna sometime early this evening and overnight.

Tower climber is next to the Public Radio Tulsa main and emergency antennas

Fri, 9/21 • 3:32 pm: Listeners report hearing completely different radio formats on 89.5 and 88.7. Rest assured that we've not switched from NPR news/information and classical music - when we're off-air, radios receive distant stations.

Fri, 9/21 • 3:16 pm: Public Radio 89.5 and Classical 88.7 are back on-air using the emergency antenna, while the tower is being rigged with lines and pulleys to lower damaged sections of the main antenna to the ground. Internal inspection of the main antenna shows burned sections caused by high-power electrical arcing. The stations will continue to go on and off during the day as repairs proceed.

Fri, 9/21 • 9:01 am: Both stations went off-air to continue repairs of the antenna and transmission system, located on our transmission tower in Coweta, Oklahoma. The wind has picked up today, making it harder to make repairs 1000' in the air. Windspeeds at that level can be 20-40 mph higher than on the ground. 

Thu, 9/20 • 8:46 pm: KWTU and KWGS are back on-the-air for the evening using the emergency antenna. The tower crew has gone home for the night, but will be back in the morning to take both stations off-air at 8:00 am. External repairs to the antenna were finished today, but the antenna doesn't tune properly. Portions of the antenna and transmission line, which connects the antenna on the tower to the transmitters on the ground, will need to be disassembled on Friday to look for internal damage. Unfortunately, we won't be able to continue broadcasting while this is being accomplished because the emergency antenna is too close to the main antenna and the safety of the tower crew would be in jeopardy. We may be off-air most of the day on Friday.

Thu, 9/20 • 3:59 pm: Stations are back on the air for the first two hours of All Things Considered. Both Public Radio 89.5 and Classical 88.7 will sign off at 6:00 pm to continue antenna repairs.

The KWGS & KWTU antenna, 1000' in the air in Coweta, looking toward Tulsa

Thu, 9/20 • 2:53 pm: Parts are now on-hand and four tower climbers are making repairs, assisting our two broadcast engineers. We're blessed by today's calm winds and clear skies: ideal conditions for working 1000' above ground on the tower. The stations will continue to go on and off the air as repairs are made and tested. If all goes well, work might be completed by late this evening.

Thu, 9/20 • 11:16 am: Both stations are temporarily back on-air while parts are being located for repairs. High winds over the past few weeks might have caused the antenna's multiple rigid copper straps to break, which ground the antenna to the tower, resulting in the antenna being unable to accept full transmission power. The stations will continue to go off and on today as repairs are made.

Thu, 9/20 • 9:19 am: Engineers and tower climbers are at the tower site troubleshooting the problem and making repairs. Both stations are off-air for the safety of the climbers, who are disassembling parts of the transmission system. No time estimate as to how long this will take.

Thu, 9/20 • 4:21 am: Switched to emergency antenna for most of Morning Edition.

Thu, 9/20 • 3:39 am: Transmitters detected an antenna problem and automatically lowered broadcast power to 50%.