It’s always a good thing when your practice can be put to the test in the real world. It’s even better when you can pass that test with flying colors.
On Wednesday, I received an email from the Bremer County Emergency Manager, Kip. He stated that they were having some interference on the county fire frequency and it had already impacted communications on one fire scene. He had already done some looking around to try and find the source, but wasn’t able to find the source. He stated that he wanted to have my help with tracking down the source since he was familiar that we could do that sort of things as amateur radio operators.
The signal had been present for a few days and then stopped for a while and then started up again. It was present on Wednesday morning and then stopped until Wednesday night.
It was decided that we needed to find the source as soon as possible since it had already affected one fire response. On Thursday, with the help of fellow ham K0CQH, Dave, we met up with Kip and started our hunt. We were in a hurry to try and find the source before the transmissions stopped. We figured it was something temperature related and the temperature was warming up as each minute passed.
The signal was sending a DTMF string for about 1-2 seconds at a random period. By driving and watching the signal strength, we were able to get to a generally close area within Waverly before getting out the RDF equipment. There as a river near where we started, so we first checked the signal on one side of the river and found that it was weaker and pointing us back to the other side of the river. Once on the correct side of the river, we were able to take a few more readings which pointed us right at one of the city’s outdoor warning sirens.
When I got to the siren pole, I was able to take out my frequency counter and got a reading on the counter when there was a transmission. This confirmed that it indeed was coming from the warning siren. Kip called Waverly Light and Power to have someone come out to the siren with access so we could see what the issue was. It was determined that the batteries that run the system had failed due to the cold weather and the siren was sending an alert about the battery failure. The antenna for the system was broken, which is probably why the master system wasn’t receiving the alert. The tech turned off the siren and the transmissions stopped.
We found the source in about 40 minutes. There were several happy people within the county once they found out that we had found the source of the transmissions. Plus it was a good way to show off what we can do as amateur radio operators.