It's extremely important to maintain all your equipment no matter what the application, especially the transmitter site. Year after year and contract job after contract job it still amazes me that some owners and staff just disregard their equipment until it's almost completely dead. The following example is by far one of the worse we've ever come across, but it shows exactly what can happen when you have an owner that thinks he can perform engineering till he's finally forced to hire someone in order to get his station back on the air.
This is how we found the connection from the AM transmitter to the heliax that heads out to the tower. Do you think that there was some RF loss? How about safety?
For those of you wondering how on earth this ever worked with minimum VSWR, it didn't. The ATU (Antenna Tuning Unit) located at the base of the tower, had recently been replaced by the owner, but left at the default input impedance of 50 ohms. Yup, never bothered to balance either the input or output impedance to match. They simply adjusted the tune and load controls on the transmitter to give them zero VSWR. Never mind the fact that the ATU hadn't been matched to the transmitter or the tower.
So for the most part, almost all of the 1000 watts from the new solid state transmitter was being absorbed by the ATU and nothing really ever made it to the stick. And they were wondering why they couldn't hear the station five miles away. Needless to say we replaced this mess with the proper connectors.
This is how we found the connection from the AM transmitter to the heliax that heads out to the tower. Do you think that there was some RF loss? How about safety?
For those of you wondering how on earth this ever worked with minimum VSWR, it didn't. The ATU (Antenna Tuning Unit) located at the base of the tower, had recently been replaced by the owner, but left at the default input impedance of 50 ohms. Yup, never bothered to balance either the input or output impedance to match. They simply adjusted the tune and load controls on the transmitter to give them zero VSWR. Never mind the fact that the ATU hadn't been matched to the transmitter or the tower.
So for the most part, almost all of the 1000 watts from the new solid state transmitter was being absorbed by the ATU and nothing really ever made it to the stick. And they were wondering why they couldn't hear the station five miles away. Needless to say we replaced this mess with the proper connectors.
As we looked further into the issues, we found this problem out at the ATU. If you'll look closely, see that tiny wire in front of the light bulbs with the crimp connection? That's what was connecting the heliax to the ATU! To make matters worse, the shield of the heliax wasn't connected to the ATU's ground either.
It took us almost a day just to get to the ATU and tower due to the neglect of the site. We had to bring in a brush hog to cut down the 7' of grass, weeds and small trees.
As I stated, the amount of over growth around the tower was pretty bad. We had to remove some pretty massive trees that had quite literally grown into the grid. Yes, that's a bulldozer pushing the first of many stumps out of the ground. The tree in the background had to be removed as well. It's stump was so massive that the dozer couldn't remove it. I wanted to dynamite the thing out, but the city had a bit of a problem with that.
Once we removed all the overgrowth and repaired all the problems between the transmitter to the ATU, we focused on matching the tower and transmitter to the ATU. This took nearly a day alone to get it right. It was an old tower and each section had to be re-strapped in order for all the sections to work correctly again. If I had my way, I would have knocked it down and started over. But we made it work. Before we started you couldn't hear this 1000 watt AM five miles out of town. After we were done it could be heard clearly 50 miles away.