BNC to SMA adapter?

[ES13Raven]

Is there any signal loss when using an SMA to BNC adapter?

If a handheld scanner has an SMA connection, but you have a BNC antenna - should you get the SMA version of the antenna or just use the SMA to BNC adapter?

 

[Dubbin]

There will be a loss with any kind of connector.

 

[UPMan]

"Voyager" on the Yahoo! boards put the BNC-SMA adapter on the test bench and found that the signal loss was present but was virtually undetectable. As with all things RF, though YMMV.

 

[ES13Raven]

Are there any advantages to having an SMA connection? Or is it just different than BNC?

 

[zz0468]

On a scanner, the advantage is that it is physically smaller. Electrically, the sma is good to well over 20 GHz, much higher than the BNC is. But that advantage really doesn't show itself until you're operating well into the microwave region. I suspect it's all about size.

BTW, the loss of an adapter can vary wildly with the specific brand (spelled quality). A $20 adapter from some place like Pasternak is going to have less loss than a $3 adapter at Radio Shack, especially at the higher frequencies.

On the frequencies we're interested in here, expect average losses to be around 1/4 db or so.

 

[gcgrotz]

One thing has always bothered me about SMA connectors on scanners. The specs only require 300 insertions/removals for the life of the center pin, since SMA connectors were originally designed for use internally mostly in microwave equipment. I personally have SMAs on test cables that have been used many times more than 300, maybe as much as 2 or 3000 times, and they seem to be ok, at least at 2 Ghz. But it still bothers me.

I would not worry about loss at typical scanner freqs however.

 

[jonny290]

Yeah, it's a tradeoff for me between the increased physical security of the SMA and the quick connects/disconnects of BNC. I actually think I still like BNC more.

 

[zz0468]

Yeah, I have to agree... at least in this application, the bnc is a better connector. I suppose one could put an sma-bnc adapter on the radio, and let the bnc side take the abuse. But in that case, you've just thrown out all of the sma's advantages - better electrically and smaller size. How many of you do it up right and use a torque wrench on your sma connectors!?

*raises hand*

8 lb-in folks. Any more, and you'll damage those delicate little things.

 

[LordJ]

Before I had my 396 I had a pro 43 and a bc92xlt, both of which I removed and attached the antenna for different reasons. Almost daily on the 92xlt. The thing about the bnc connector I hate is after a year or so of this the 'ears' of the connector would be flattened out on the bottom and cause a loose fit. With the 396 I purchased a WSMA-889 and never have to remove it. I guess what I'm saying is that if you aren't going to change the antenna frequently, get the SMA and be done with it, if you are going to switch out alot, use the connector, and save wear and tear on the radio and replace the adapter when needed. The less you actuall disconnect it the longer it should last.

 

[mike_s104]

http://universal-radio.com/catalog/parts/bncadapt.html

part #0292

I bought this one and I like it better then the one that came with the 396T. I connect/disconnect the antenna a few times a day and wanted to save the SMA connector on the scanner. I also (yes, I know about loss) use a 90 degree connector so I can leave the scanner on it's back to lessen the chance of knocking it over and still have the antenna vertical.