BCD436HP/BCD536HP: SMA Connect/Disconnect Longevity

Has anyone used their handheld in a mobile setup where they're removing, disconnecting external antenna and then reconnecting on a daily basis?

If so, how long have you been doing it and is there any sign of the SMA connector weakening?

I don't have any room for my BCD536HP as I have other gear already installed.

I use the BNC adapter for that same fear of the SMA connector being fragile. I have done several hundred connect and disconnects over that last few years no issues. BNC is so much easier to connect and disconnect too.

SMA connectors are not designed for many connect / disconnect cycles. BNC connectors are. The adapter can be replaced when it wears out, saving thousands of wear cycles on the radio itself. Some of the better scanner antennas (Diamond RH77CA) have BNC connectors anyway.

SMA and BNC connectors both spec 500 mating and unmating cycles. That being said, I've encountered BNC connectors that were worn out far sooner than 500 cycles, and I've yet to have any kind of issue with the SMA connectors on any of my gear. I think the fears of SMA connectors being frail/weak/fragile compared to other larger (and more lossy) connector types are unfounded and based in ignorance... not unlike when someone says a 1969 Chevroldsmobuicadillac is safer than a 2017 vehicle, and that seatbelts kill more people than they save.

500 cycles is the requirement to meet the military standard. You'll find that an SMA or BNC connector from a respectable manufacturer will likely exceed that.
There's a wide range of quality out there, and there are plenty of companies that will claim they meet standards that they don't.

Personally, I've never had an SMA connector break, but I have had BNC's break. However, I've worked with a lot more BNC's than I have SMA's, so that's understandable. Depends a lot on how they are treated, too. Identical components will have vastly different results depending on who the operator is.


Seems like the risk to the connector is one of the drawbacks of using a portable radio in a mobile environment. I understand the space limitations, though.

as the voice of experience, i feel compelled

ur20v said:

SMA and BNC connectors both spec 500 mating and unmating cycles. That being said, I've encountered BNC connectors that were worn out far sooner than 500 cycles, and I've yet to have any kind of issue with the SMA connectors on any of my gear. I think the fears of SMA connectors being frail/weak/fragile compared to other larger (and more lossy) connector types are unfounded and based in ignorance... not unlike when someone says a 1969 Chevroldsmobuicadillac is safer than a 2017 vehicle, and that seatbelts kill more people than they save.

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as the voice of experience, i feel compelled to add little to nothing on the SMA front, but would like to highly recommend the UNIDEN BNC jacks and the SMA to BNC adapters. i dunno how well the SMAs would hold up under my "care" but i know that the BNCs do just dandy. the amount of antenna switching i have done......well let's say most would call it excessive, i call it testing, but nonetheless, i figure has far exceeded the industry standard testing protocols for mating cycles for this type of purpose, and i have had basically no issues worth mentioning nor fixing. the beauty with the adapters being, quick switch, quick fix.

however....

the BNC jacks on PRO-668's are not to be regarded as, nor played with, as if it were an appendage one, as a young boy, discovered has more than one function. it...will...fall...off. so to speak.

as a side note, anybody know a way to get a new BNC jack on a pro668 without having to get it sent off somewhere for all eternity? like a BNC to BNC twist-on UNIDEN-type solution that doesn't end up being 5 inches taller than the housing?

Anyone???

mines.... about to fall off.... so to speak

If you use BNC antennas the SMA-BNC adapter can be used as a protector for the SMA connector. If the BNC connection wears out due to use it can be easily replaced. Having replaced the SMA connector on my 436 I can tell you from experience it is much easier to replace an adapter than a connector, sort of like a haze filter on a camera lens.

I'll join the chorus and say that the best approach is to use the BNC-SMA adapter. Those are cheap and easy to find, and any signal loss will be negligible at most.

As stated, SMA connectors are rated for about 500 cycles. That's for good one's tightened properly. How many of you have the required 8 in/lb torque wrench required for "proper" installation? Unless you have the torque wrench, use no tools and go finger tight. You'll probably get several thousand cycles out of it.

Clean the threads with an alcohol moistened Q-Tip periodically. Threading connectors causes wear, and the wear creates microscopic metal shavings. The merely shavings cause wear. It's a vicious cycle - the more the connectors wear out, the more the connectors wear out.

After cleaning, you'll notice how much smoother the connectors feel while threading them together.

One cautionary note regarding SMA to BNC adapters....

I was using an adapter to mate a BNC antenna to a handheld radio with an SMA connector.

One day I dropped the radio. It didn't fall far and It landed on a carpet so the case wasn't damaged, but the sideways force that was applied to the antenna as it hit caused the top few threads of the SMA to snap off. They won't handle much sideways force.

Just something to be aware of if you use this type of adapter.

I use a washer at the base of adaptor that helps to give it additional support.

The same thing can happen if you don't use an adapter. You just break the SMA connector a little further down.

Here is a way to look at it. For arguments sake, the radio is never dropped or the connector damaged in any way other than removing/installing antennas and the connectors wear out at 500 cycles (remove and replace the antenna equals 1 cycle). You have the radio in the house with an antenna attached, you go to the car, remove the portable antenna and connect the car antenna, that's one cycle. You get home, remove the car antenna and connect the portable antenna, that is 2 cycles in one day. 2 cycles per day would wear out the connector in 8 months 7 days. If you used a BNC adapter, with the same wear, you would replace the adapter at the same 8 months, 7 days but only have 1 cycle on the SMA adapter. This means that it would take 343 years to wear out the SMA adapter. Kind of a no brainer to me.

The other advantage of the BNC adapter - after you get the SMA connector lined up to start screwing it down, it's turn turn turn turn turn turn turn turn turn, etc. until it's snug. With the BNC connector it's tu and it's done. Yes, I realize I only typed tu, because tu is only half of turn, and a BNC is less than half a turn to connect/disconnect.

BTW - I have had a SMA to BNC connector on my BCD396T for over 8 years, yes, it's showing wear on the pins but, it still works just fine.


Tim
W6TGM

Lots off different opinions and practical suggestions. My external antenna connector in the vehicle is male SMA so I would have to get yet another adapter to mate with the BNC adapter on the handheld. I could always cut the connector and change it out but then I'd have to dig out tools which I haven't used in years.

I don't really use the scanner that much, except on longer drives and sits idle indoors. I may just keep going the SMA route.

Thanks