BCD436HP/BCD536HP: How durable is the SMA Connector on the BCD436HP?

[MTScannerNut]

Recently got a new BCD436HP and have been experimenting with various different antennas to see which works best for my area. All previous scanners I've owned have had BNC connectors and never had any connector issues. It got me to thinking, just how durable is the SMA connector, specifically on the BCD436HP? Aside from abuse and accidentally dropping the radio, can the SMA take repeated antenna swaps/re-connections etc. without issue like the BNC? It seems more delicate to me, but maybe it is just as durable with proper care and common sense?

 

[Drumbum]

I have tried various antennas on mine without problem., its had a lot of screwing and unscrewing, everything from short to the diamond 77 to using my mag mount no problems over almost 3 years now,,, I have never dropped mine

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[MTScannerNut]

I have tried various antennas on mine without problem., its had a lot of screwing and unscrewing, everything from short to the diamond 77 to using my mag mount no problems over almost 3 years now,,, I have never dropped mine

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Thanks, that is good to know. I too have the diamond 77 sma version, but worry that it might be too long and heavy for the radio. Maybe I'm worried unnecessarily.

 

[DCHarris]

You could use a SMA to BNC adapter if you have some BNC antennae around; I think one came with mine. That way, only have to screw it on once, and if the BNC side goes bad, toss it out and get another. Last year I had my 436 hooked to my belt when I had a substantial bicycle wreck. The rear case and control knob had to be replaced and I had to replace the antennae itself, but the connecter was undamaged, as was the guts of the unit.

 

[jonwienke]

I installed the BNC adapter that came with the radio, and use only BNC antennas like the Diamond RH77CA for handheld use. The BNC adapter takes all of the wear from switching antennas when I go from base to mobile to portable use, and when the adapter wears out, it can be replaced with minimal wear on the SMA connector.

 

[K2KOH]

On one of my 436's I had the locknut loosen up. Just check that every so often by seeing if the SMA connect rocks. I noticed it when I was putting a single band antenna on, felt funny when I was putting the antenna on

 

[KE5MC]

Thanks, that is good to know. I too have the diamond 77 sma version, but worry that it might be too long and heavy for the radio. Maybe I'm worried unnecessarily.

The adaptor that came with the radio is the first thing I had attached to any of my Uniden scanners. My ham HTs have been treated the same allowing me to swap antennas around as needed.

While the Diamond77 was one of my first 3rd part antenna purchases I don't use it now for its stiffness and weight. Very good antenna other than that.

Mike

 

[jonwienke]

If you use a SMA-BNC adapter, it eliminates the need for a lock nut. It is in effect a second lock nut if the adapter is tightened properly.

 

[MTScannerNut]

If I didn't already have the native SMA antennas, I would consider using the adapter the radio came with, sounds like a good idea.

Is it common for the connector to loosen up with frequent antenna changes? Is there a specific tool needed to tighten it?

 

[KE5MC]

If I didn't already have the native SMA antennas, I would consider using the adapter the radio came with, sounds like a good idea.

Is it common for the connector to loosen up with frequent antenna changes? Is there a specific tool needed to tighten it?

I would say its not common, but can happen depending on specific of carry and antenna stiffness.

Spanner wrench correctly sized or if you are feeling lucky needle nose pliers with fine tip. Pliers put the nut at risk if they slip to be dinged up including the barrel of the sma connector the nut is threaded on or damaging the tips on the pliers.

Mike

 

[majoco]

I don't like hanging adapters and maybe heavy cable onto SMA connectors - often the socket is just soldered into a PC board so doesn't have a great deal of mechanical strength. I much prefer to use an adapter that has a short length of coax cable so that you can secure the lead to the back of the radio with a cable clip or something similar. No good of course for handhelds. If you order one of these things, make sure you specify which style of SMA plug you need - male/female screw thread and male/female centre connector. Same with the RTL style SDR's.

12.8" RF Pigtail Cable SMA Male to BNC Male Adapter Connector LW | eBay

 

[jonwienke]

The 436 SMA connecter is screwed to a metal support bracket, which is attached to the rear circuit board with several screws. There is a short jumper soldered between the connector and the circuit board. It's a pretty robust setup.

 

[Rred]

I can't speak to how strong this radio is, but the SMA connector itself was intended to allow two subassemblies (i.e. in the same cabinet) to be connected "once" when a product was built, and then left alone except for maintenance and repairs.

It was never intended to be physically robust, or for repeated use, and while you can put a lot of wear on it, eventually something will get cross-threaded and ruin it. If you are careful and lucky, that may never be a problem.

Otherwise, adding a bayonet connector (direct or pigtail) and letting that perform as it is intended, can be a better way to go. Or an SMA "extension" pigtail of any kind, just to get past the experiments.

 

[DeDawg]

I can't speak to how strong this radio is, but the SMA connector itself was intended to allow two subassemblies (i.e. in the same cabinet) to be connected "once" when a product was built, and then left alone except for maintenance and repairs.

It was never intended to be physically robust, or for repeated use, and while you can put a lot of wear on it, eventually something will get cross-threaded and ruin it. If you are careful and lucky, that may never be a problem.

Otherwise, adding a bayonet connector (direct or pigtail) and letting that perform as it is intended, can be a better way to go. Or an SMA "extension" pigtail of any kind, just to get past the experiments.

This is an accurate assessment. I worked with SMA, SSMA, MCX, and all of the very small connectors for decades.

Something that can degrade the SMA after repeated connection cycles is the spinning of the center pin in the mating female pin. This may act like a miniature lathe and wear away the finish. Industrial connectors and many adapters have an external nut that may be turned to tighten while holding the body still, avoiding the lathe action. Most antennas appear to have the nut embedded so spinning of the center contact is unavoidable.

Forced threading while pins are misaligned is another problem, with the center pin going into the teflon next to the mating contact, ruining the connector.

The SMA shell is not strong nor was it intended to be. The BNC adapter is a good idea if many connection cycles are happening. Only problem is the increased leverage on the SMA if something hits the antenna.

 

[jonwienke]

The factory BNC adapter has a fairly large outer diameter that minimizes tensile stress on the SMA if bending force is applied to the antenna. Using it reduces the probability of damaging the SMA connector if the scanner is dropped.

 

[pb_lonny]

I don't use the standard aerial at all so have left the SMA -> BNC adaptor on mine all the time and just use BNC aerials.

 

[kr19]

I highly recommend this antenna:

https://www.ebay.com/itm/162443576355

Signal improved quite a bit from when I used the BNC version of the exact same antenna with the included adapter. Best $30 I have spent so far for scanner stuff, and best of all, since it’s already made for SMA, you won’t have to guess whether an adapter is causing your signal woes.


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[DeDawg]

Picked up a Uniden brand SMA-BNC adapter from scannermaster. Not a shock, but it is not dimensionally very accurate. Outer BNC shell is too large by almost .010", and a very tight fit into the mating connector. I selected an old BNC antenna that was not a ridiculous fit for now.

That said, it does have a nice wide base that should help spread side loads if the antenna it hit. Most professional grade adapters are just a SMA male nut and offer no added support. Why should they?