How repairable is this BNC? - Page 1
Forum section: electronics / repair

author: aarons
author_rank: Regular Contributor
timestamp: July 29, 2025, 09:05:59 am
content: I got an FM signal generator that was damaged during shipping. Much to my disappointment, the BNC output that got crushed wasn't just solder cups or an SMA or something on the inside, but rigid coax. Is the panel mount connector something that can be replaced on its own, or does the whole bit of coax need to be replaced with it?

author: HighVoltage
author_rank: Super Contributor
timestamp: July 29, 2025, 10:15:36 am
content: You should be able to fix the BNC mechanically.I had a similar situation a long time ago and made a metallic insert on the lathe. Then I carefully wiggled the insert into the BNC until it fitted perfectly. After that I applied pressure from the outside with flat parallel pliers until the outside shape matched. It took some time but at the end it paid off and you could no see the damage anymore.

author: Dougmc
author_rank: Contributor
timestamp: July 29, 2025, 11:26:29 am
content: https://www.eevblog.com/forum/repair/how-to-remove-dent-in-bnc-connector-without-removing-it-from-transceiver/https://groups.io/g/TekScopes/topic/fixing_dented_bncs/99707099Is the other connectorsmall enough to go the the front panel when bnc connector is removed?Any brand and model of this unitHave a better dayDoug

author: jdragoset
author_rank: Frequent Contributor
timestamp: July 29, 2025, 11:37:46 am
content: Try JTS 1406-24140 parallel pliers round concave jaw and JTS 1406-23140 flat and half round.

author: inse
author_rank: Super Contributor
timestamp: July 29, 2025, 01:49:07 pm
content: Maybe a cheap flat nose plier and an angle grinder will deliver the required tool even easier

author: coromonadalix
author_rank: Super Contributor
timestamp: July 29, 2025, 02:15:57 pm
content: or wack something like this as written ?

author: Harry_22
author_rank: Frequent Contributor
timestamp: July 29, 2025, 03:03:22 pm
content: I would remove the connector with rigid cable.Then insert a cylindrical mandrel inside and tap it with a hammer. To make everything neat, it would be good to wrap the mandrel and hammer with safety tape.In any case, if the edge of BNC sleeve breaks off, do not be upset.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 29, 2025, 04:09:50 pm
content: i would avoid hammering you will thin the external plug side, and create deformations

author: David Hess
author_rank: Super Contributor
timestamp: July 29, 2025, 06:17:42 pm
content: That looks very repairable. I use the sockets out of my small socket set as mandrels to push the dents out from the inside, starting with smaller ones and finishing with a larger one.

author: Sorama
author_rank: Frequent Contributor
timestamp: July 29, 2025, 06:18:06 pm
content: why not 'just' solder a new connector onto that rigid thing?

author: Paceguy
author_rank: Regular Contributor
timestamp: July 30, 2025, 10:59:26 am
content: I had a similar problem with a Agilent counter. I used a pair of long nose pliers and pulled out the dents and re-formed the outer ring. Used a small jewelers' file to remove any burrs and raised mat'l. Turned out good and one could hardly noice that the connector had been damaged.

author: tszaboo
author_rank: Super Contributor
timestamp: July 30, 2025, 11:18:02 am
content: Quote from: HighVoltage on July 29, 2025, 10:15:36 amI don't think you should repair RF connectors. It might look OK, but every time you attach a cable, you risk ruining that cable.This is a bigger issue on SMA or other smaller connectors, probably smaller issue on BNC.But I would rather replace the entire cable assembly and use a semi-rigid cable rather than try to fix that connector.

author: Astralix
author_rank: Regular Contributor
timestamp: July 30, 2025, 12:14:56 pm
content: Sometimes some mechanical calibration boxes show up on eBay. They have all sizes of round hollow steel pieces to calibrate holes and diameters.These can be used to widen the BNC connectors and re-form them to original specifications.Good BNC connectors can easily be tapped to original shape without any negative effect. Cheap ones, especially those with shiny coatings, are probably useless afterwards as they loose the coating.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 30, 2025, 12:48:44 pm
content: Replace the connector. Same for damaged coax.https://www.eevblog.com/forum/rf-microwave/is-is-possible-to-repair-a-hairline-crack-in-semi-rigid-coax

author: coppercone2
author_rank: Super Contributor
timestamp: July 30, 2025, 01:09:18 pm
content: I would not want to work on that unless I could anneal it.IMO that destruction is too severe for a pry-bar repairyou will find that using those round nose pliers make it deform in such a way where it will have a 'divet' where the pliers gripped it. I was using them on fine wires for a while before I switched to a flat+round plier, when I looked under the microscope the wires were smushedthe JTS 1406-24140 look alot better for general re-formingtwo cylinders put MASSIVE pressure on a very small areaalso hard line may surprise you on how its mated tto the cable, some connectors are soldered others are like press fit. If it took a impact it might be in bad shape

author: coromonadalix
author_rank: Super Contributor
timestamp: July 30, 2025, 02:20:09 pm
content: yeah you're right, any pressure may or would deform it ...

author: u666sa
author_rank: Frequent Contributor
timestamp: July 30, 2025, 02:39:59 pm
content: The bent part could be grind away using rotary tool. It would look half bitten off, but won't interfere with bnc functionality.

author: Harry_22
author_rank: Frequent Contributor
timestamp: July 30, 2025, 03:04:46 pm
content: Yes, the probability of bushing breakage is high, since brass is a fragile material.The photo shows that the fastening nut is in the front, and there are flats for the key at the back.Most likely, the connector is detachable.Then you can simply replace the front part.

author: coppercone2
author_rank: Super Contributor
timestamp: July 30, 2025, 10:23:27 pm
content: cutting it away, soldering a patch in from another BNC connector is an option too. You need very precise cutting to do thisthen you would need to sand the solder joint and re-plate parts of it with brush plating (copper and then nickel)

author: Cyclotron
author_rank: Unknown
timestamp: July 31, 2025, 12:37:33 pm
content: I've straightened a few BNC jacks, but none that badly bent. Work hardening will happen, and it may fracture.The bulkhead connector could be replaced by desoldering and replacing it with something like this:https://www.amphenolrf.com/112714.htmlI'm not sure why they used the rigid coax. Are the frequencies involved that high, or is there a desire to eliminate any interference? The whole thing can be replaced with semi-rigid materials, which are easier to work with.

author: David Hess
author_rank: Super Contributor
timestamp: August 01, 2025, 06:00:36 am
content: Quote from: Cyclotron on July 31, 2025, 12:37:33 pmIf it is an RF signal generator, then there are two reasons. One is flatness for calibration purposes, however the more important reason is to prevent leakage around the output attenuator needed to produce microvolt signal levels. Externally to maintain this performance, double shielded cable is required and tight BNC connections.

author: sean0118
author_rank: Frequent Contributor
timestamp: August 01, 2025, 06:07:32 am
content: Quote from: Harry_22 on July 30, 2025, 03:04:46 pmI was thinking this as well, looks like it can be dissembled without soldering? You can then replace the front part of the connector if you can find a replacement.Something similar to this (but BNC rather than N type)?

author: Paceguy
author_rank: Regular Contributor
timestamp: August 01, 2025, 10:47:40 am
content: Quote from: tszaboo on July 30, 2025, 11:18:02 amI have a specific BNC male connector I use to make sure that no damage to connectors occur afterwards. No connectors on cables were damaged by the repaired female connector following the repair.