FM02 SMA connector broken?

**imbluenote** · 03-15-2012, 09:52 AM

So i got my FM02 yesterday from Chris (thanks Chris!) and i did send him and e-mail but i know he is busy so i figured I'd post here for feedback. Anyhow...I hooked it up to my Dipole Antenna that i made and I was tightening the connector by hand (no tools) and I noticed it wasn't stopping. I looked at it and the male end was spinning inside the "block" portion that is connected to the board. I tugged on it slightly and it (the male threaded part) came out. I pushed it back in and everything works but I have a feeling it isn't supposed to come apart like that. Also looking at the end of the barrel/male threaded part and inside the "block" that is soldered to the board it doesn't look like it broke off either.
I don't think this supposed to happen but just wanted to make sure. Plus I would assume and easy fix would be a few solder points where the barell and the block meet if this is something I did by over tightening.
002.jpg

**g2ktcf** · 03-15-2012, 10:06 AM

Yes, I got the email...just have not had a chance to answer.

We will never know what caused it...that's beside the point. We can fix it one way or another. I do not have a connector but I can swap the board out for you. I do need that one back so I can repair it though.

Now, there is always a cost just to return the board. If you think you can repair it, I will see about the supplier sending me a few connectors.....

We have lots of options and time now...we just need to make sure you are ready to go and happy with the result.

**imbluenote** · 03-15-2012, 10:26 AM

Thanks Chris...I wasn't thinking that you weren't going to reply I was just going to socialize here to see if this was or wasn't abnormal to possibly save you a little time. I wasn't thinking it was, but i didn't know.

If you think you can get a few connectors I'd like to try the connector, since i'd rather not spend 12 bucks shipping back and forth for something i can fix.

**g2ktcf** · 03-15-2012, 10:36 AM

Originally Posted by imbluenote

Thanks Chris...I wasn't thinking that you weren't going to reply I was just going to socialize here to see if this was or wasn't abnormal to possibly save you a little time. I wasn't thinking it was, but i didn't know.

If you think you can get a few connectors I'd like to try the connector, since i'd rather not spend 12 bucks shipping back and forth for something i can fix.

Let me make a few calls...ROFL

**ukewarrior** · 03-15-2012, 10:54 PM

Yes, I would say you overtightened it.
It appears this is a press fit part.
Is the part still loose?
Did you have to hold it in order to screw an antenna or a cable on it?
If not, I would think you are a-okay.
Can you give another update with some more details?

Originally Posted by imbluenote

So i got my FM02 yesterday from Chris (thanks Chris!) and i did send him and e-mail but i know he is busy so i figured I'd post here for feedback. Anyhow...I hooked it up to my Dipole Antenna that i made and I was tightening the connector by hand (no tools) and I noticed it wasn't stopping. I looked at it and the male end was spinning inside the "block" portion that is connected to the board. I tugged on it slightly and it (the male threaded part) came out. I pushed it back in and everything works but I have a feeling it isn't supposed to come apart like that. Also looking at the end of the barrel/male threaded part and inside the "block" that is soldered to the board it doesn't look like it broke off either.
I don't think this supposed to happen but just wanted to make sure. Plus I would assume and easy fix would be a few solder points where the barell and the block meet if this is something I did by over tightening.
002.jpg

**glaforce** · 03-16-2012, 07:28 AM

I work with thousands of RF connectors each year and my take on this would be that it wasn't an over tight issue but instead poor construction of the SMA connector. An SMA connection is commonly tighted with a small wrench. I personal would look for either a replacement as stated above or use this as a way to move to a BNC connector you can get them with the same foot print to attach them too the PCB or you can just solder the barrell back into the body of the connector. This option should work just fine but will take a LOT of HEAT to do it right and I would remove from the PCB to do this type of repair. Good luck and happy DIYC

Gary

Sent from my Inspire 4G using Tapatalk

**Blackbeard** · 03-16-2012, 07:28 AM

Originally Posted by ukewarrior

Yes, I would say you overtightened it.
It appears this is a press fit part.
Is the part still loose?
Did you have to hold it in order to screw an antenna or a cable on it?
If not, I would think you are a-okay.
Can you give another update with some more details?

I had the same problem. I can almost guarantee that I didn't over tighten it. It seems to be a press fit part, as ukewarrior stated.

It was suggested to me to scrape a little of the outside on both parts and place a drop of solder on the scraped area. This appears to be the "ground" part of the connector, so as long as you don't get too much on it, the solder won't weep into the "hot" part of the connector.

I've never had to do that scrapy-soldery part since I've pressed it back together and stabilized my cable running from it. I only discovered it was slipping apart due to the limited range and scratchy sound I was first getting from my system. Upon moving the entire unit to see if a better location would fix it, it fixed itself due to the connector "grounding" itself and the radio started producing clear, long-range music. You could probably try the solder trick and save yourself a lot of trouble and efforts instead of trying to replace the part You might do more damage when you try to unmount the bad connector and remount a new one. Using a small-wire pigtail (with the proper ohms) and making it stationary to something like your enclosure so that it doesn't wiggle would help as well, allowing you to connect your heavier antenna wire to the pigtail instead of directly to the connector.

steve

**Mactayl** · 03-16-2012, 07:44 AM

Brass SMA connectors should only be tightened to about 3-5 inch-lbf or they can break loose from the press fit on the base of the SMA connector.
http://en.wikipedia.org/wiki/SMA_connector

**ukewarrior** · 03-16-2012, 09:31 AM

I've updated the wiki with this valuable info.

I too would recommend that IF you removed the connector from the board, that you replace it with a pigtail BNC connector.

**imbluenote** · 03-16-2012, 09:51 AM

Originally Posted by Mactayl

Brass SMA connectors should only be tightened to about 3-5 inch-lbf or they can break loose from the press fit on the base of the SMA connector.
http://en.wikipedia.org/wiki/SMA_connector

In my job (operations manager), my tech's work with SMA connectors daily, and i acutally have access to a SMA torque wrench, they are easy to overtighten, but I have never seen one fall apart like this. I didn't use the torque wrench becasue it was at work (or any wrench) when i was trying to initally connect it.

I had a coax already connectorized with a Female SMA which is why i went with that. I might beable to scrounge up something with a BNC connector.

However with the male threaded barrel screwed in the coax connetor, if i push it in the block it seems to perform pretty well. I did a quick test the night i was playing with it and with the antenna in the garage and not oriented any special way/tweaking. I was able to get out about a block or so way, which it farther than i needed since i live on a short cul-de-sac and i can only be see from about 3 houses away and it was very clear.