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Site Maintenance: Troubleshooting Example

Hey folks, it’s been a while! I’m happy to report that I’ve had a busy summer as things have ramped up to pre-Covid levels with respect to travel being taken, orders coming in, and transmitters getting out the door. Plus there’s yet more to come – better busy than bored I always say!

And that, in a nutshell, is the reason for this latest Tips n Tricks article. When it comes to site maintenance, I still see some horror stories out there, frequently after a failure or series of failures leads to comments about a substandard product and causes me to drop in when I happen to be in the area.

Here’s the deal, though – if you call me complaining about how the transmitter is terrible and it is a new site that is perfectly laid out, I reserve the right to use it as an example of situations that could be improved. Obviously, I will NOT be identifying the site or customer, that would be impolite, but if you had to replace the old transmitter because it finally failed to the point that it could no longer be repaired, odds are a new one in the same environment will see similar, if not worse, results. By the same token, if you put up a nice new building, but don’t include any grounding or surge protection, assume that things are going to go boom, especially if you put it on a tall hill connected to a giant lightning rod (tower) that also has marginal grounding at best.

So, let’s take a little walk through this site where the transmitter has been experiencing higher than normal failure rates (significantly higher). At first glance, I saw a transmitter – a bit dusty, sure, but that happens – and did notice a ferrite on the coax. Everybody knows I love ferrites, although I think the importance of them has been blown out of proportion. While they can make a difference, they are secondary to good grounding practices and properly installed surge protection when it comes to protecting equipment.

I did notice a PA failure on entry also – and there were indications on site that several PAs and combiners had failed over the life of this rig…

There have also been some instances of fan failures…

Notice that there is a significant buildup of dust and pollen on the fan housing and blades. Yet this is a well air-conditioned site – how is that possible? Well, it turns out that the mini split air conditioners were recently installed after the wall unit behind the transmitter failed – but the site has always been air conditioned. However, it did appear a bit more attention could be paid to sealing and weather stripping, especially around the entry door as shown in above photo.

So, what else did I notice at the initial cursory glance? Well, the dehydrator was unplugged, and line pressure was at zero, not ideal. Plugging in the dehydrator got line pressure up quickly… in fact, it just kept rising. Turns out the compressor was not shutting off – not relevant to my specific mission today, but something needing repair. Today’s solution was to unplug it and note the line pressure, which will allow the local engineer to see how well the line holds that pressure until he gets back to make repairs.

Next, we wander behind the transmitter to look at the surge protector. Oh, there is no surge protector. At all. That could be significant. While surge protection was frequently treated as optional in the days of big iron and hollow state technology (tubes), with more and more equipment using wall warts and switching power supplies, it should no longer be considered an option – in fact, some manufacturers will void warranty if there is no surge protection installed.

Finally, grounding – although I left it for last, it is arguably the most important part. Several things came to my attention here. First, although the tower is almost 200 feet tall, there is not a single grounding kit installed on the coax going up the tower. Tower base grounding consists of a small gauge wire in a clamp connector.

Moving into the building, we see the coax is not grounded anywhere, until we get to the transmitter output flange. The transmitter does have a ground lead – a small gauge copper wire, going through the same wall the AC is on, but on the opposite end. AC, transmitter, and tower all appear to be connected to ground rods… but there is no indication that the rods are tied together in any way.

Here’s a sketch of the site bird’s eye view.

So, how do we fix it? Surprisingly, it’s not all that difficult, nor incredibly expensive – certainly much less expensive than having an engineer come in to rebuild or replace PAs and hybrid combiners on an annoyingly regular basis!

First, let’s put a ground kit where the coax comes into the transmitter room. We’ll ignore the lack of ground kits on the coax coming down the tower – while they’d be helpful, a kit right at the building entry point will be key. Move the ferrite back toward the transmitter a bit (it can be anywhere between the transmitter output and the ground kit). Run a strap from this ground kit over to the AC ground point. Install a surge protector at the electrical panel and connect its ground to that ground point also. Finally, replace the transmitter ground wire with strap and run it to the AC ground point as well. At this point, we’ve got a well-established single point ground and a surge protector, which will conduct the bulk of any surge energy between the reference ground and the AC lines. The ferrite adds a bit of additional insurance – but the single point ground and the surge protector are key.

As sites get built or evolve, it’s easy to lose track of where things are connected and what has (or has not) been done. Having even a basic sketch of the layout, such as the one above, goes a long way toward providing a guide regarding what can be done. As a rule, if a new site has a higher-than-expected failure rate, reach out to the manufacturer of the gear that’s failing – but also take a careful look to see what may need improvement. For an existing site that didn’t have failures and suddenly does, the first question should be, “what has changed?” Perhaps copper thieves made off with the ground system, or a clamp connection has oxidized and is not making good contact anymore. Certainly, electronic devices can and do fail, but as a rule, most boxes are built to fairly exact standards, so if a company does not have a reputation for building failure prone systems, it is a safe bet that there is something else that needs to be addressed.

I will emphasize here, I did not show this particular site to call anyone out for their layout or install skills – we all know that budgets, owner decisions, local labour, time and various other factors can impact the build of a site or the installation of any piece of equipment. However, this site visit did serve as a great example of how to troubleshoot and document a troublesome situation, with an eye toward trying to improve the outcome in the future. I hope it was useful – please feel free to reach out with any questions or comments at all.

On that note, folks, let’s all take care out there and I’ll see you next time – until then, be safe and happy engineering!

Jeff

Jeff Welton, has worked with Nautel for 30+ years. He is currently the Nautel Sales Manager for U.S. Central Region but previously he spent 16.5 years as a Nautel Customer Service Technician. A regular speaker and contributor on broadcast engineering, Jeff was elected to the Board of Directors for the Society of Broadcast Engineers in August 2023, and has been recognized with the following awards: 2020 NAB Radio Engineering Achievement Award; 2019 APRE Engineering Achievement Award; and 2018 SBE Educator of the Year Award.

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