Nautel V5 Module D Failure

[TVJunkie12]

Just thought I'd see if anyone else has had this problem. It's in a 2.5 year old V5 with a good ground system (deep, steel cased well with strap from the TX line and tower) and it's also attached to utility ground. It doesn't happen during every storm but it has happened enough times to cause concern since the warranty is up in a few months. The failure is always in Q4 of module D. Nothing else is affected in either the TX or any other equipment at the site. Nautel support has sent us a new combiner and new RF cabling to install and neither fixed the problem. Any ideas? I've talked to another engineer with an older FM5 that has never lost a module through the years and another friend with a V10 who has gone through numerous modules (though his contractor didn't record whether it was a repeated failure of the same module or not) that have been replaced under warranty.

Anyone else have this happen? If Nautel has any answers they haven't given them to us.

 

[Lazy J]

I am currently going head-to-head with Nautel over a similar issue. I take care of a V10 that is about 3 years old. It's on the same power lines, same antenna, same grounding system with 2 BE solid states. The building is very clean and well cooled. But that dang V10 has wiped out 14... yep 14 modules. Nautel blamed the first 8 on a software issue. They sent me an entire set of new modules and we did the software upgrade. Since then, we have lost another 6 modules, and two different power supplies. It has been pretty random which modules fail and when. I do think module A has failed more than the others though. We sort of have a running joke (sadly) that it has never run more than 3 months at full power. The last repair lasted 6 weeks.

I'm not just trying to bash Nautel. I think they make some of the best transmitters out there. However, when you get a lemon, you REALLY get a lemon!

 

[ChiefEngineer]

1310 Indianapolis had a ton of problems with their 5kw Nautel. Replaced all modules. Found out way after the many failures the large obvious ground strap formerly on the RCA 5kw that was carefully connected to the Nautel and into the pit with all the other wires had been cut before it became true ground. Once this was corrected no more blown modules. The ground always acted okay as when it was checked another station ground through electric appeared and this grounded the station ground on a meter but not really.

The problem was only noted during a storm. Deep well grounds are great but follow the strap and see if it really is still there all the way. Lightning hits take out well pumps. They also break ground straps.

Have you checked the station ground, even though the big flat copper strap looks good at teh transmitter?

 

[Kmagrill]

There is a recent thread about lightning and grounding on this board at:
http://boards.radio-info.com/smf/index.php?topic=196097.0

There are several good ideas presented and links to other reference sites, however, if the problem is occuring when there is no lightning in the area, it may not be a grounding issue.

 

[TVJunkie12]

Have you checked the station ground, even though the big flat copper strap looks good at teh transmitter?

We have checked and double checked the well ground. There is no pump, the well was drilled some years ago to strictly be a ground after lightning beat the crap out of the old FM5K1. But what's strange to me is the fact that it is always Q4 on the same power module. Nothing else is damaged. Seems like if the ground wasn't good that other things would be taken out too.

 

[OlderRadioGuy]

1310 Indianapolis had a ton of problems with their 5kw Nautel. Replaced all modules. Found out way after the many failures the large obvious ground strap formerly on the RCA 5kw that was carefully connected to the Nautel and into the pit with all the other wires had been cut before it became true ground. Once this was corrected no more blown modules. The ground always acted okay as when it was checked another station ground through electric appeared and this grounded the station ground on a meter but not really.

The problem was only noted during a storm. Deep well grounds are great but follow the strap and see if it really is still there all the way. Lightning hits take out well pumps. They also break ground straps.

Have you checked the station ground, even though the big flat copper strap looks good at teh transmitter?

Ha! Reminds me of a few years ago (OK, many), that I followed a nice 6" wide ground strap, transmitter to transmitter to rack to rack to hole in the wall. You guessed it ... just stuck in the wall and didn't come out the other side.