PTP600 failure, appears to be corrosion inside

[RF_Burns]

Hi All,
Just had a PTP49600 (connectorised) fail after about 3 years, replaced with spare now all is good again.

However looking at the connector inside it appears corroded. I tried to remove the caps over the unused inputs and found them to be seized. Finally got one off and found the threads and inside of the cap corroded.

Unit was mounted by professional crew with the connectors pointing down. It would seem the case seal is leaking.

I had the same issue last month with a RAD AirMux400 which was only up for less than 3 months.

Anyone else seeing such issues?

Thanks

[Bill_G]

I had a connectorized 49600 fail in the last year or so, and factory repair said warranty was nil because of water damage. This unit's housing did have several places the paint had flaked off with pitting and oxide formation spreading out from the revealed areas. But, there was no external indication that water had crept inside. We used the water tight seals they provided. So, we were not entirely sure how the damage occurred.

[RF_Burns]

Since it was out of warranty and the water damage was very evident at the ports, we took it apart. Its very evident that the case seal leaked in my opinion. Looking at the way the case is constructed, I'd say water trapped in the case seam, but still outside the seal, would freeze and thaw allowing water to work its way inside.

We had a similar failure with an RAD AirMux400 this summer after about 2 months in service. Water inside the unit and lots of corrosion. This was during summer so no freeze/thaw cycle there, just a poor case seal. Still have not heard back from RAD

We've had issues with AirMux200's but you could see the ODU cover was over-torqued so the cover was warped and allowed water to seep in. We used some wiring split loom along the edge of the case top and sides to prevent water from reaching the case seam.

I'm worried what I can do to prevent this on the other PTP49600 links I have.

In all cases the provided wire glands were used and connections sealed by a professional tower crew.

[jmfirefighter20]

I actually have a PTP49600 that just pretty much kick the bucket.

Has been running for about a year at 30-40 Mbps, about a 15 mile hop with no obstructions. All of a sudden she's running BPSK at 2.18 Mbps for no reason. Service company that installed them (they are not owned by us, but by a local FD that got them via grant, they just interface with our network) took a look and can't figure out the issue, they say everything is fine from a hardware point of view meaning the dish alignment is fine, and the software portion is configured correctly. They've since opened a case with Cambrium to determine the issue.

The unit having issues is the remote one mounted on the roof of a power plant near the ocean/salt water. I wonder if corrosion is a similar issue here. Both ends are uplinked from the little PTP to a parabolic dish (4 footers, I think), so it could be there as well.

[Bill_G]

I actually have a PTP49600 that just pretty much kick the bucket.

Has been running for about a year at 30-40 Mbps, about a 15 mile hop with no obstructions. All of a sudden she's running BPSK at 2.18 Mbps for no reason. Service company that installed them (they are not owned by us, but by a local FD that got them via grant, they just interface with our network) took a look and can't figure out the issue, they say everything is fine from a hardware point of view meaning the dish alignment is fine, and the software portion is configured correctly. They've since opened a case with Cambrium to determine the issue.

The unit having issues is the remote one mounted on the roof of a power plant near the ocean/salt water. I wonder if corrosion is a similar issue here. Both ends are uplinked from the little PTP to a parabolic dish (4 footers, I think), so it could be there as well.

I'm betting one of the antenna jumpers went bad causing the unit to clobber itself. That would be revealed in the diagnostic plot screens. High vector errors with V/H plot slammed top or bottom, and xmit at full power. The other possibility is someone else put in a link in the same band near the same azimuth. That can be seen in the spectrum screen.

[FMROB]

My suggestion would be a smearing of a silicone adhesive around the case prior to outdoor installation. May not be the best idea, but should help. You can even use a small 3/4 heater hose split down the middle to go over the seam and you can glue that down the case as well.

[jmfirefighter20]

Today the Link is completely down, no comms at all. The vendor is aware and now we're awaiting their answer. Yippeeeeeee.

[RF_Burns]

Silicon tends to have a short effective lifetime in my experience. A polyurethane sealant would likely work better, but you would never get the case apart again.

I'd run a split loom or split hose around the top and side edges, but at the center top there is a large hoisting eye. The casting of this eye can let water run into the seam around the case and sit in there. It would need about a 2"ID hose to cover that hoisting eye.

[jmfirefighter20]

I can now confirm today after speaking with the service company that this unit also failed due to water intrusion and corrosion. Unfortunately the unit was out of warranty by a month and Cambrium appears to be unwilling to bend on the warranty. I guess Cambrium also stated they can't confirm that it was manufacturing defect which caused the seals to fail.

[Jim202]

I can now confirm today after speaking with the service company that this unit also failed due to water intrusion and corrosion. Unfortunately the unit was out of warranty by a month and Cambrium appears to be unwilling to bend on the warranty. I guess Cambrium also stated they can't confirm that it was manufacturing defect which caused the seals to fail.

Now tell me if you were the company that built this device and were having failures all around the country, would you be willing to admit that you had a poor design on the weather seal?

My suggestion is to get some of the 3M high vacuum grease and put it on the sealing gasket. It won't migrate with the heat from the sun like the crap you get with most vehicle antenna roof mounts and the larger coax connectors. That stuff will just slim it's way all over the place. The high vacuum greese stays where you put it. Plus it will help you get coax connectors apart down the road if you put just a small dab on the threads.

Jim

[Jim202]

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[jmfirefighter20]

I can now confirm today after speaking with the service company that this unit also failed due to water intrusion and corrosion. Unfortunately the unit was out of warranty by a month and Cambrium appears to be unwilling to bend on the warranty. I guess Cambrium also stated they can't confirm that it was manufacturing defect which caused the seals to fail.

Now tell me if you were the company that built this device and were having failures all around the country, would you be willing to admit that you had a poor design on the weather seal?

My suggestion is to get some of the 3M high vacuum grease and put it on the sealing gasket. It won't migrate with the heat from the sun like the crap you get with most vehicle antenna roof mounts and the larger coax connectors. That stuff will just slim it's way all over the place. The high vacuum greese stays where you put it. Plus it will help you get coax connectors apart down the road if you put just a small dab on the threads.

Jim

As a customer of said company, yes, I would expect them to own up to their poor design. It shouldn't be up to the end user to reseal their product because they had poor manufacturing. But even if they bent a little, and covered it under the warranty, they're still not admitting they have an issue, it's called good customer service. When you pay XX number of dollars, and you know microwave radios aren't cheap, you expect a little more than normal. But I guess I shouldn't have expected much from a European company anyways.

[sladeltd]

I will be installing these exact models in the near future. I will be sure to keep my eye open for these issues. Thanks for the headsup!

[RF_Burns]

Here is some further observations on my PTP600's failing due to water damage. These units were new in 2011 with the first failure being in Dec 2013. We found water in both N connectors so we swapped out the faulty unit with the spare and installed new jumpers to the antenna. By mid February the spare was failing.

We had sent the faulty unit back to Cambium and paid to have it repaired. It was returned just in time to be re-installed in place of the now faulty spare.

The spare had a tiny bit of moisture in the connectors. Cambium claims the water is coming in the antenna cables and its a faulty installation. They did send me a set of replacement N female chassis connectors which we installed into the spare unit. The antenna connector assembly does read a couple of megaohms from center pin to shield when removed, but after a week they they dry out and read infinity.

Then over the weekend we had another link give issues, so on Monday we swapped out the remote end with the now fixed spare. This time there was water again in the Vertical only, but also a little curl of metal up inside the N Female causing the center pin to be shorted.

Observations:
-In all cases there was severe corrosion inside the case, top to bottom.
-A drop of water was found in one or both of the N Female chassis connectors
-The case screws were not very tight at all

I measured the amount of compression of the O ring case seal at 0.011"

My conclusion:
The case seal itself is leaking water into the housing. The compression of the rubber seal at 11/1000" is not enough to seal out the water. It was likely less than 0.011 since the screws were "finger tight" on all case screws.
Water then runs down the connector jumper cable and into the N-Female chassis connector where it collects. NOT the other way around as claimed by Motorola/Cambium.

Here is a couple of photos of the damage.

http://www.gmcmhphotos.com/photos/the-m ... -seal.html

http://www.gmcmhphotos.com/photos/the-m ... -seal.html

Anyone else had this problem?
Any ideas how to seal it and still be able to re-open it?

[escomm]

No need to start a new thread when your original thread is only halfway down the page...

[RF_Burns]

Sorry, I didn't want to upset the forum, I'm not part of the clique here, but knowing a few guys on here have these things I wanted my observations to get noticed.

These things are $7,000 an end and failing in under 3 years. Its obvious that the hollow rubber O ring seal is relaxing over time (case screws are now loose). Out of 8 transceivers in the system, I've had 3 fail in 3 months, all with internal water damage.

I'm going to be pro-active on getting these things sealed before more fail.

[celltech25]

Had this happen on several PTP300 units, we fixed the issue by taking the units apart and usign the black form a gasket stuff for cars gaskets to seal the units and so far so good after 9 months no more failures

cambium told us it was faulty install on the antenna cables as well but since the dish is mounted lower that the ODU to see if that helped unless water runs uphill it was the case gasket

[Bill_G]

Had this happen on several PTP300 units, we fixed the issue by taking the units apart and usign the black form a gasket stuff for cars gaskets to seal the units and so far so good after 9 months no more failures

cambium told us it was faulty install on the antenna cables as well but since the dish is mounted lower that the ODU to see if that helped unless water runs uphill it was the case gasket

Even if the ODU and antennas are at the same elevation, the natural cable drape on the ODU forms a drip loop. One would hope the factory would not try to convince us the water came in through the connector. I like the idea of using a window gasket. That stuff is pretty good at keeping water out for sure.

[RF_Burns]

Even if the ODU and antennas are at the same elevation, the natural cable drape on the ODU forms a drip loop. One would hope the factory would not try to convince us the water came in through the connector

This is exactly what Cambium is telling me. Take a look at the photo links in my message on March 13 and you can see the corrosion all the way to the top of the internal case. Maybe this is the reason Big M sold off that division.. dumping the liability.

We got a tube of Hylomar gasket goo stuff. Its not suppose to dry out, or run, not affected by heat (used on aircraft engines) or most chemicals. Have the spare now sealed using this stuff and we are going to do all our PTP units.

This morning a link that never gave issues before, slowly dropped 15db RX power. The H/V ration only slowly varied about 3db and the vector errors moved less than 2db. It started about 4am, then just before noon it returned to normal in about 5 minutes. I'm guessing that was weather related, but no other links had issues.

[RF_Burns]

Just an update to our PTP600 moisture issues.

We took down the balance of our PTP units and opened them up. They were all clean with no trace of moisture, only the three units were giving us issues. On closer examination the rest of the units had an obviously different "O" ring seals around the case. These seals were very firm and had not deformed into a "D" shape. The "O" ring seals on the three that leaked were soft and had a definite deformation from the flat case cover into a "D" shape. I would say these were hollow tube seals while the good seals were likely solid.
All but one were bought on one order and received at the same time, with the spare unit being ordered about 6-8 months later. From that I'm guessing Motorola changed the part number to the soft hollow "O" ring.

We've had lots of rain this summer, but no more issues after sealing them with Hylomar.

[JeffFireRadio]

Thank you for the update from all of us PTP600 users who were following this thread with interest. -Jeff

[RF_Burns]

Jeff,
I recall you had the same issues. Did you manage to get them resolved?

The initial 3 units have been good since I sealed them with this Hylomar sealant. The rest of the units which never gave problems, were perfect inside when we opened them.... but they have a much better O ring seal.

On the other hand, I had a couple RAD Airmux400's do the same thing. The one still under warranty we sent back and they returned it "Water damaged" not repairable. So we took both of them apart and you can see where the water comes in past the case O ring seal. One unit had a badly corroded RJ45 connector so we replaced that. The Airmux O ring seal is much thinner and the casting was never machined smooth so its very coarse where the O ring sits. We dried both units by just leaving them open for a week or so, then tried them on a temporary link... they worked fine. So we sealed them up and they have been back in service for about 3 months now.

Given the cost of a Airmux ODU vs the cost of riggers, we've decided to just open the ODUs and seal them before installing.

[JeffFireRadio]

No, my agency hasn't experienced any issues up to this point. We're watching carefully based upon your history. Our units are all Summer 2010 production units with a new pair coming from the factory in October for a new path. - Jeff

[RF_Burns]

Sorry Jeff, I got your handle mixed up jmfirefighter20.

My units all have dates of Nov.2011 inside the case, except for the spare which was purchased later. You should be OK with your 2010 units I'm thinking.