I'm looking for antennas to attach to my CB radio. This one is a "rubber ducky" antenna.

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I'm not sure what the connector is, can anyone identify it for me? [edit] Here are some other pictures enter image description here

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  • 3
    $\begingroup$ Could you include a photo of the end, not just the thread, and a ruler up against it for scale? $\endgroup$
    – Kevin Reid AG6YO
    Jul 29, 2017 at 2:43
  • $\begingroup$ After careful consideration, I'd like to see this question being closed as unclear, because although there are three potentially correct answers (do have doubts with 2 of them), all is idle speculation until OP shows front of the connector and something to judge scale, as @KevinReidAG6YO asked for over 12 hours ago :( $\endgroup$ Jul 29, 2017 at 15:03
  • 2
    $\begingroup$ Sorry about that, I asked this question before I went to bed. I have included more images. $\endgroup$
    – ToastHouse
    Jul 29, 2017 at 16:18
  • 2
    $\begingroup$ and thus, I retract my close vote :) Also: Kevin's answer is the right one! $\endgroup$ Jul 29, 2017 at 16:31
  • $\begingroup$ I think I remember this was an old Radio Shack handheld CB radio antenna. $\endgroup$
    – SDsolar
    Jul 30, 2017 at 4:47

3 Answers 3


I can't tell for sure without better pictures, but that looks like, not an RF connector per se, but a 3/8"-24 stud. This is very common for CB antennas.

The reason I say it is not an RF connector is because it only makes one electrical contact. This means it can only be used for “monopole” antennas, not for feed lines or other types of antennas.

To confirm, first check that the end of the antenna is solid metal and not anything more complex than that. Then take the antenna down to your local hardware/home improvement store — or your garage, if you're well equipped — and try it against a 3/8"-24 nut.

(3/8" refers to the outside diameter, and 24 refers to the thread pitch in threads per inch. The other common size is 3/8"-16.)

You should not have any trouble finding CB antennas with a 3/8"-24 thread at the base, now that you know what it is called.


It is definitely not a 3/8" connector. 3/8" in in metric units is 9.525 mm. The image at the bottom seems to indicate that is about 6.25 mm which is 1/4". I believe this to be a mobile TV antenna element used by truckers. They usually come in pairs and mounted on the mirrors. The threading is 1/4-20.

A 9.5" in length definitely not CB probably used to receive in the VHF/UHF range.

  • 1
    $\begingroup$ I noticed that too. If you look closely, you'll see that the threads are to the left of the 0 mark. I actually opened the pic in PhotoShop and moved the ruler to overlay the threads exactly and then it did measure closer to 9mm. Based on that, I believe the answer that it's a 3/8" stud is correct. $\endgroup$
    – Lance
    Jul 30, 2017 at 18:31
  • $\begingroup$ @Lance It is close to 9mm. Can you move the scale 90 degrees and measure the thread pitch? (I had an older US-made commercial VHF HT that had the same design.) $\endgroup$ Jul 30, 2017 at 19:49
  • $\begingroup$ 9 mm is one mark to the left of the 1 cm and 3/8" is 9.525 mm which would be half the way between those 2 marks. I scaled on screen that is compared the image of the scale on screen versus the actual dimension. I stand corrected it is actually 5/16" -My apologies gentlemen. $\endgroup$
    – Old_Fossil
    Jul 30, 2017 at 22:33
  • $\begingroup$ Also it is a trucker TV antenna and they sell at Flying J truck stop.... :) $\endgroup$
    – Old_Fossil
    Jul 30, 2017 at 22:35
  • 1
    $\begingroup$ @Lance 3/8-32 is a UNEF thread. The standard pitches for 3/8" threads are 16, 24, and 32. $\endgroup$ Jul 31, 2017 at 2:11

I am guessing an N-type female connector. Already commented to that but I am using an answer to include a photo image:


  • 4
    $\begingroup$ from the thread structure of the carpet (?) beneath the connector, I'd argue it's too small for N. $\endgroup$ Jul 29, 2017 at 8:15
  • 2
    $\begingroup$ It also doesn't have a center conductor or the ground ring. This is not an N connector. $\endgroup$
    – kronenpj
    Jul 29, 2017 at 20:47
  • $\begingroup$ The only photo I saw showed only the threads end not much of anything else. Also, nothing to gauge size. The photos posted later clearly show the stub instead of an inner conductor. $\endgroup$
    – K7PEH
    Jul 30, 2017 at 1:18

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