Fun with LMR600 crimp on connectors

[Bill_G]

Scenario - new 21 position dispatch center with two back up radios at each position.

42 strands of LMR600 running under the floor 150 to 190ft away to dbSpectra base station combiners in the equipment room. NF crimp on connectors at both ends (84 total!) so we could use pre-made jumpers at both ends. Over half the crimp on connectors were open at one end (or both in some cases). Real Times Microwave plenum LMR600 with real Times Microwave plenum crimp-on captivated center pin connectors. Real Times Microwave cable prep tools (drill jig) used. Real Times Microwave crimpers used. The Anritsu says the connector zero ft away is open. Cut it off, put on another, coin toss if it passes. Cut into a failed connector with a cutoff wheel so we can see inside. The center conductor fully inserts into the captive pin, but measures open with an ohmmeter meaning the conductor is perfectly centered and not making contact. Cut into another - same thing.

Are you effing kidding me??

Demonstrated the problem to our manager and to our customer. Not a workmanship issue, or a failure to use the right materials. We replaced ALL the connectors with clamp on solder center pin. 100% pass.

I'll let our legal dept handle the complaint. Cost us over three hours of labor each strand to open the floor, rework, and retest each cable.

And people wondered why I logged over 300 hours in August.

[Jim202]

I gave up on trying to crimp the center pins years ago. Even if they are crimp center pins, I always solder them. Never had a problem with an open center pin since I have been doing this. Do this on small cables all the way up through the large coax cables.

Like you found out, it takes time to go back and try to locate the problem and put a new connector on again. I can't afford the extra time going back over work I already have done.

Jim

[Bill_G]

I hear ya. OTOH, they are sold as cost cutting products. Certainly not living up to it.

[RFguy]

Were they the EZ type connectors? De-buring tool used?

We have used probably a thousand with the only issue being when they were not properly seated. They will be open. Improper installation.

[Bill_G]

These were just the captivated center pin type. About as easy as it gets, but I don't think they were EZ type. Do they make an EZ LMR connector?

As for deburing tool - that's what the cable prep tool does in one step - cut, strip, step, and bevel. Takes about 10 seconds. And like I said, we cut into a couple - the center pin was fully seated and completely open. Either the cable center conductor was too narrow or the connector center pin was too wide by thousandths.

[Bill_G]

I looked up EZ connectors for LMR600 and found this Times Microwave installation guide. It's showing male, and we were using female, but that's the type. They don't call it EZ in the catalog. It's described as captivated center pin. Looks like the same concept. Our cable prep tool does everything shown with the hand tool shown in the pdf. As far as I can tell, we did it correctly.

[wavetar]

I sympathize with your plight, but I think the biggest mistake was waiting for all 42 cable runs to be completed before testing. At a bare minimum, if an analyzer can't be had for whatever reason, we'd test each run as it's completed with a 50-ohm load at one end and measuring for it at the other.

[TBerry1966]

It's possible there was a "bad batch" from the factory. I had a similar problem with some N connectors for RG58, only in reverse. I had to debur to a larger opening to allow my center pin to fit. I made contact with the vendor, who made contact with the manufacturer, who said they'd had "multiple complaints" and it was narrowed to a single "batch".

Just a thought

[Bill_G]

I sympathize with your plight, but I think the biggest mistake was waiting for all 42 cable runs to be completed before testing. At a bare minimum, if an analyzer can't be had for whatever reason, we'd test each run as it's completed with a 50-ohm load at one end and measuring for it at the other.

It should have been a no-brainer. Run the cable, put on the connectors, sweep the lines. Budda bing budda boom. Times Microwave really hosed us. I let their rep know that they owed us big.

[Bill_G]

It's possible there was a "bad batch" from the factory. I had a similar problem with some N connectors for RG58, only in reverse. I had to debur to a larger opening to allow my center pin to fit. I made contact with the vendor, who made contact with the manufacturer, who said they'd had "multiple complaints" and it was narrowed to a single "batch".

Just a thought

Yeah. Maybe. It's not the first time LMR type connectors have bitten us in the butt. This is why I spent the additional money for Time Microwave product on everything. Still didn't save me any money or time. We've since determined the cable center diameter was too narrow by a few thousandths on the strands that failed. It came on several large reels all pulled at once. We don't know which reel it came off of to give them lot numbers so they can trace it.