Words cannot begin to express my gratitude to KOSU’s engineering team for the blood, sweat and tears that they poured into this fix. KOSU is very fortunate to benefit from the expertise and dedication of Ken Boyd, Dan Schroeder and Bob Buford. They are tireless champions for public who work behind the scenes to bring our audio broadcasts and digital streams to 100,000 weekly listeners. I’ve told both Dan and Bob that it's time to catch up on life, and hopefully KOSN will cooperate.
This represents the third major outage of 107.5 FM caused by lightning at the KOSN tower site near Nowata, OK since I became station director in 2007. Consultants have told us that we have adequate lightning suppression systems in place on the tower. However, we will revisit this issue to determine what else might be done to prevent future damage from lightning. Already, our parts bill for this fix stands at more than $9,700 and labor will top $35,000, and it is unclear at this time whether the total bill will be enough for the university’s insurance policy to kick in.
These unplanned expenses are particularly difficult for us as we juggle the demands of creating and curating the best that public radio has to offer with the needs of reliably delivering said content. This outage exposes a significant weakness in KOSU’s broadcast infrastructure. Our lack of redundancy at 107.5 FM can result in significant disruptions of broadcast services when a serious technical issue arises, and that is unacceptable. At the very least, we must purchase a back-up antenna and feed line system, and ultimately, a back-up transmitter that we can turn to when our primary system fails. Such a system will cost as much as $200,000 and we will pursue a strategy to begin building this redundancy as money allows.
Finally, I want to thank the dozens of listeners who have contributed specifically to KOSU so far to help offset the costs to repair the lightning damage at KOSN. All of us are moved by the response from this passionate group of public radio listeners. To each of you, we are so very grateful that you choose to spend part of your week with KOSU-KOSN and we will do everything we can to improve your listening experience with us.
- Kelly Burley, KOSU Director
If you would like to donate specifically for the more than $45,000 in tower repairs, you can do so here. Thank you.
Below is a retrospective from KOSU engineering consultant Dan Schroeder:
A radio broadcast is something that can easily be taken for granted until there is a major problem. Unfortunately, our northeastern Oklahoma listeners know all too well what can happen when lightning strikes. After a thunderstorm on Tuesday July 21, 2015, KOSU Chief Engineer Ken Boyd could not get the KOSN 107.5 transmitter to continue transmitting at about 2:30 p.m. that day. Staff engineering consultants Bob Buford and I checked the transmitter readings at the tower site near Nowata, Oklahoma that same evening and determined a severe antenna system fault had occurred and operation would not be possible until tower climbers could inspect for damage at the 1,000 foot level of the tower.
On Friday July 24, climbers with the PCI Tower Company inspected the antenna at the 900-1,000 foot levels and discovered that the 4” diameter feed line that connects the antenna to the transmitter suffered a lighting strike and subsequent burnout at about the 950 foot level. The internal fire produced smoke and soot that went up into the antenna. At that time we believed it went only a few feet.
Boyd was lucky to find a short 71+ foot long piece of replacement feed line and have it shipped across country to the site. Since the internal line fire damaged the $1500 connector just 12” above the lightning hit, a new connector was ordered. The old connector is obsolete and parts are not available. The replacement line with connector was hoisted up to the 900 foot level and installed on a low wind day.
The new line checked out and showed a perfect connection to the antenna. Unfortunately the climber’s technician saw the antenna via the new line on his instruments and it indicated the antenna itself had problems. The climbers disassembled a few parts of the antenna and found only some black soot from the fire. Tower climbers brought those parts down to the ground because it is impossible to properly disassemble and clean the antenna parts (with the soot damage shown below on the white insulator) with alcohol when working 1,000 feet in the air.
We discovered that trying to piecemeal clean the antenna parts was not an efficient use of our climbers’ time. We elected to take the entire antenna down to the ground for a thorough inspection and cleaning in a much more methodical manner in a controlled environment where KOSU staff and contract employees could properly supervise all aspects of the cleaning. This took two days.
After reassembly on the tower the antenna did not perform as well as it should have on the test gear. We ordered and shipped in overnight a $750 kit of tuning parts to make it more efficient on KOSN’s frequency. That took another day, but the antenna was working better than ever (on test gear). The climbing crew left.
About 1 p.m. on Friday August 14, we were ready to begin broadcasting again. We soon heard a crackling noise coming from the area of the $5,500 tube inside the transmitter. We immediately shut it down and inspected. We found that the antenna burnout caused an enormous amount of power reflected back into the tube area. Luckily, the tube was not damaged, but the 16 inch plate that holds it in place burned off part of the silver plated finger stock that must make a high power connection to the aluminum box it sits in.
Parts ($950) were delivered overnight and installed and we resumed broadcasting at 5 p.m. on Saturday, August 15, 2015.
- Dan Schroeder, KOSU Engineering Consultant
If you would like to donate specifically for the more than $45,000 in tower repairs, you can do so here. Thank you.
