SMA to BNC Adapter

[RadioDitch]

Does anyone have a specific brand or source of SMA-F to BNC adapter you use with your G-series pager? The two brands I tried both were so tight on the antenna center conductor pin it actually pulled it out of the radio when I unscrewed the adapter. Thankfully it's simple enough to reinsert and seat it.

 

[bob550]

I purchased this in June of 2019 and continue to use it with my G5 with no problem. The SMA connector on the adapter is recessed to the same depth as the Unication OEM antenna, and does not appear to place any stress on the center conductor.

 

[N6ML]

I purchased this in June of 2019 and continue to use it with my G5 with no problem. The SMA connector on the adapter is recessed to the same depth as the Unication OEM antenna, and does not appear to place any stress on the center conductor.

I use something very similar to that, but in order to get it to match the dimensions of the stock antenna, I had to "machine" down the skirt. I did that rather kludgily with a drill press and a file - BNC end of the adapter in the drill chuck. It works well.

The thing to really look out for is that the end of the "SMA" connector must be recessed like the stock antenna - otherwise it'll mash the pin.

 

[bob550]

No alterations were necessary with the adapter I referenced above. In fact, after I received it, I measured the depth of the SMA contact on the adapter (the part that connects to the pin on the G) and the antenna using a tire tread depth gauge. The OEM antenna is deeper, literally, by the width of a hair. The threaded shaft of the SMA contact on the adapter is slightly shallower than the reference shaft on the OEM. The bottom line is that it works without damaging the G pin and without any machining.

 

[RetiredVolunteer]

I also purchased and utilize the above mentioned adapter on my Unication G2.

 

[RadioDitch]

The thing to really look out for is that the end of the "SMA" connector must be recessed like the stock antenna - otherwise it'll mash the pin.

Yessir. I was using a genuine Motorola SMA-F test adapter out of my work supplies, then tried a Maximoral. Both had the same result. I'll give a shot to what everyone has linked.

 

[N6ML]

No alterations were necessary with the adapter I referenced above. In fact, after I received it, I measured the depth of the SMA contact on the adapter (the part that connects to the pin on the G) and the antenna using a tire tread depth gauge. The OEM antenna is deeper, literally, by the width of a hair. The threaded shaft of the SMA contact on the adapter is slightly shallower than the reference shaft on the OEM. The bottom line is that it works without damaging the G pin and without any machining.

By "skirt", I mean the part with the grip. Although the "SMA" part is very close to a match, it (mine, at least) wouldn't screw on all the way because of that skirt would hit the body of the radio first. Maybe it makes enough of a connection without, but I wanted mine such that it'd fully engage as the stock antenna would (but no further!)

 

[jonwienke]

By "skirt", I mean the part with the grip. Although the "SMA" part is very close to a match, it (mine, at least) wouldn't screw on all the way because of that skirt would hit the body of the radio first.

That's how the adapter is supposed to fit. The skirt should contact the body just before (like 0.1-0.2mm before) the threaded part bottoms out in the hole. The adapter will be far less likely to break if sideways forces on the antenna are transmitted to the body of the radio rather than the threaded part of the SMA connector. The threaded part of the SMA does NOT need to bottom out in the hole to make a good connection.

 

[N6ML]

That's how the adapter is supposed to fit. The skirt should contact the body just before (like 0.1-0.2mm before) the threaded part bottoms out in the hole. The adapter will be far less likely to break if sideways forces on the antenna are transmitted to the body of the radio rather than the threaded part of the SMA connector. The threaded part of the SMA does NOT need to bottom out in the hole to make a good connection.

I guess I'm not explaining it very well. I want the skirt to make contact with the body at exactly the point where the "SMA" connector is engaged fully (but not allowed to go any further). That provides both mechanical strength *and* a fully-engaged RF connector.

Edit: I don't remember exactly how much I took off the skirt, but it was over 1mm - certainly much more than 0.2mm.

 

[RadioDitch]

My issue wasn't the length of the thread collar, which was equal to Unication and Motorola stock spec, but that the diameter of the cavity on the SMA-F end was too small. The tolerances were too tight. Bad lots and poor QC I guess. But I'll give the one y'all recommended a shot.

 

[jonwienke]

I guess I'm not explaining it very well. I want the skirt to make contact with the body at exactly the point where the "SMA" connector is engaged fully (but not allowed to go any further). That provides both mechanical strength *and* a fully-engaged RF connector.

You don't want to do that. It's pointless. The center contact pin engages the mating female contact a couple of millimeters before before the threads bottom out, so getting that last 0.1mm of thread engagement has zero benefit re electrical connectivity, and transfers stress from the skirt to the threaded part of the SMA connector. You've compromised the mechanical/structural integrity of the adapter for zero benefit connection-wise.

 

[bob550]

By "skirt", I mean the part with the grip. Although the "SMA" part is very close to a match, it (mine, at least) wouldn't screw on all the way because of that skirt would hit the body of the radio first. Maybe it makes enough of a connection without, but I wanted mine such that it'd fully engage as the stock antenna would (but no further!)

This has been my experience as well. While I don't make constant use of this adapter, I've never had a loss of connection while in use.

 

[eorange]

How exactly does a tenth of a millimeter compromise the structural integrity?

 

[jonwienke]

When the adapter is bottoming out on the threaded part, and sideways stress on the antenna is applied directly to the threaded part of the SMA connector and can easily break it off. That's the flaw with the Uniden factory SMA adapter--all sideways stress is funneled to the SMA connector and breakage is fairly common. But if the adapter has a skirt that mechanically engages the body of the radio, a good deal of that sideways stress is routed through the skirt to the body of the radio, and not to the SMA connector, and the threaded part of the SMA connector is a lot less likely to break.

 

[bob550]

When the adapter is bottoming out on the threaded part, and sideways stress on the antenna is applied directly to the threaded part of the SMA connector and can easily break it off.

So I think this adapter should then mitigate that stress as it sits flush with the G5 body.

 

[jonwienke]

As long as the adapter skirt engages the radio case before the SMA bottoms out, and the center pin contacts correctly, yes.

 

[bob550]

As long as the adapter skirt engages the radio case before the SMA bottoms out, and the center pin contacts correctly, yes.

This adapter that I had first purchased does not contact the case, and so I don't use it.

 

[Prospect62]

I purchased this in June of 2019 and continue to use it with my G5 with no problem. The SMA connector on the adapter is recessed to the same depth as the Unication OEM antenna, and does not appear to place any stress on the center conductor.

Hey Bob550, the link to that adapter you posted is now dead. Any chance you could assist me in locating that same product?

 

[bob550]

Hey Bob550, the link to that adapter you posted is now dead. Any chance you could assist me in locating that same product?

The adapter I purchased from Amazon last year is an ExpertPower SMA female to BNC female pictured here:



Amazon no longer lists this but you can find something very similar here. The SMA adapter just needs to be compatible with the Baofeng radios.

 

[Prospect62]

Thank you!