Topic: Efield F connector concern

[DaleReid]

There have been a couple reports from early builders that the F connector that is needed to link the preamp board to the amplifier board has a possible flaw in those shipped with the kits.

I'm behind on my start, but wonder since the preamp board should go fast, if there is a source in US that is a quick shipper where a known substantial substitute can be obtained?

Or should I 'roughhouse' the ones I have a little bit to see if they, too, pop apart, or perhaps are from a more vigorous stock and would hold up?

To me replacing one is a lot more difficult that waiting for a good one to show up and be put in, doing it right the first time, so to speak.

and considering the size of the thermal mass of these things, heating up the boards to get the old ones off isn't what I have in mind for a careful, low stress construction.

Thoughts on the F connector scare?

Dale

[Cutty Sark Sailor]

Build your kit. If you have to remove it, use fine solder wick. I'd suggest no more torsion on the connector than needed... I'm pretty sure I may have simply over tightened the nut I used to secure it in the pvc cap,.. didn't seem like it took much, however...
anyway, mine's working with solid wire into a barrel connector. 

[DaleReid]

OK

[W3DRM]

Actually, there are two F-connectors. One on the main E-field Amplifier pcb and one on the Pre-amp pcb. I'm planning on using nothing more than a light finger-tightening. I may also think about using some kind of strain relief on the coax so any movement of the coax doesn't over stress the connector. If there is a problem with the fittings loosening, we may want to consider something like a tiny dab of locktite-blue to hold things in place.

Mouser has quite a few different pcb F-connectors. Here's a link to their f-connector listings:

• http://www.mouser.com/Connectors/RF-Interconnects/RF-Connectors-Coaxial-Connectors/_/N-89mcy?P=1yx6xqnZ1z0xbq0

I haven't been able to find build list for the E-field kits on the Blitzortung website so don't know what manufacturer they sourced from.

EDIT: I just took a very close lookat the f-connectors in my kit using my eye-loop. Neither of them have any manufacturer markings or name on them. The threaded portion of the connector appears to be press-fit into the portion that attaches to the pcb board. Guess we'll just have to be extra careful when connecting the coax on both of them.

[JonathanW]

I looked at the specs/drawings of the various pcb mount right-angle pin connectors available from Mouser, and there's a range of pin spacings (from about 7.6 mm to 8.6 mm).  The pin spacings for the jack on the PCB drawings in the project document, assuming they're to scale, are about 8.2 mm.  I don't think the size of the drill holes are large enough to allow a lot of flexibility in pin spacings, so you may need to modify the PCB slightly for a different part.

[Cutty Sark Sailor]

This is the connector supplied 
http://uk.mouser.com/ProductDetail/Emerson-Connectivity-Solutions/25-7652/?qs=%2fha2pyFaduhO%2fiW0nB8zRqDkFssUZXc5OsBYjVvccDI%3d
8.6mm housing
Just because I abused mine perhaps, or the other fellow struggled with his, does NOT mean the rest of you will be oafish. This is by no means the first F connector I've ruined in my 67 years. I must have made several dozen coax connections to this one while fabricating my housing design, testing, finding a bad solder joint on A channel amp, etc.
I say again, that whole preamp ckt board is part of the 50khz filtering. from whence depends the other two channels. Including the ckt bd structure and fabrication, wherein lies a good part of the cost.

Relax, use normal care, and get online. 

[92merc]

I'm still waiting for my parts to arrive from across the pond.  But looking at the above picture, it looks like this part is similar to the SMA GPS connector on the controller.

I had the joy last night of finding out how that is put together.  Long story short, I'm not getting an external GPS antenna detected.  In trying to find out if I had a bad connection, I broke that SMA connector.

After taking the controller into the house, I found out that the external threaded part is just press fitted onto the base.  A L shaped wire comes up from the base and into the middle.  Only the external barrel and white insulator are what comes off.

I desoldered my SMA connector from the controller.  Not an easy feat BTW.  But I then cranked up the heat on my soldering iron.  I was able to press fit the barrel back in.  I then soldered everything back together.  I'm fairly certain that part won't come apart again.

With that assumption, if the new E Field board connector looks the same, I'll probably stick some solder on it and make sure it doesn't come apart on me.  Easy prevention before the fact.

Now I just need my new GPS antenna to arrive so I can verify that is my issue...

[DaleReid]

Can we reinforce the connector before putting it on the board?

I'm concerned about too much heat doing bad things to the poly-whatever white insulation molded into the F connector, so applying a 'bead' of solder around the barrel/square part may not be the best to do this trick. 

I wonder if something like a very very strong epoxy applied to the junction, after using a bit of steel wool to rough up the surface and give the epoxy something to hang on to would be of benefit.

Your report on how tough it was to get the old one loose only intensifies my concern about having to do this on an already assembled board and the havoc it would do to the board structure and delicate traces etched therein.

I'm suspicious of these connectors.  Sorry, I am.

I have dealt with plenty of connectors on very cheap preamps and splitter/combiners, etc. for decades and I have NEVER, despite my or the owner's or some lackey's manhandling of them, ever had one come apart. 

[dfroula]

Make up a short length of terminated RG6 coax and use a barrel connector on one end, mounting the barrel connector with two nuts to the PVC end cap,

Or, use a couple of F-connector nuts from an old TV splitter or other device and mount the barrel portion on the board to the end cap. That will avoid twisting issues when attaching the F connector from your coax run.

Don
WD9DMP

[92merc]

I'm not sure if the poly is of the same make as the SMA connector.  But I was able to heat the gold plated connector up and get a good bead of solder around it.  No issues with that poly melting.  I just made sure I did about 1/4 of it at a time and let it cool between.

I'm willing to be the first tester of that theory, when I get my boards.

But I plan on stuffing the whole unit inside a pipe.  No F connector sticking outside.  Just a cable up through a hole.

[dfroula]

SMA connectors are normally made with a Teflon (high-temperature tolerant) insulator. F-connectors vary, but are usually cheap low-temperature tolerant polypropylene. The ones with a blue insulator are usually rated up to 3GHz. Not sure what those are made of.

Avoid the "tighten it until it strips, then back off 1/4 turn...." syndrome! 

Don
WD9DMP

[JonathanW]

This is the connector supplied 
http://uk.mouser.com/ProductDetail/Emerson-Connectivity-Solutions/25-7652/?qs=%2fha2pyFaduhO%2fiW0nB8zRqDkFssUZXc5OsBYjVvccDI%3d
8.6mm housing
Just because I abused mine perhaps, or the other fellow struggled with his, does NOT mean the rest of you will be oafish. This is by no means the first F connector I've ruined in my 67 years. I must have made several dozen coax connections to this one while fabricating my housing design, testing, finding a bad solder joint on A channel amp, etc.
I say again, that whole preamp ckt board is part of the 50khz filtering. from whence depends the other two channels. Including the ckt bd structure and fabrication, wherein lies a good part of the cost.

Relax, use normal care, and get online. 

Thanks, Mike!  Obviously, my copy-and-paste measurement technique was off a little bit.

Still there is a range of pin spacing for connectors, so care is needed if ordering a replacement.

[Cutty Sark Sailor]

Make up a short length of terminated RG6 coax and use a barrel connector on one end, mounting the barrel connector with two nuts to the PVC end cap,

Or, use a couple of F-connector nuts from an old TV splitter or other device and mount the barrel portion on the board to the end cap. That will avoid twisting issues when attaching the F connector from your coax run.

Don
WD9DMP

That is exactly what I did, in effect, after I manhandled the F connector.

Folks, out of all the testing the developers did, out of the several boards up and running elsewhere, it seems 2 of us jacklegs have managed to mangle an F-connector. I say again, I'm quite certain I over tightened mine the way if was attempting to mount. I suggest that you won't have an issue if you don't treat it like a lug nut on a wheel.  And the insulation packing will heat up and distort.... believe me I tried it.

[Cutty Sark Sailor]

This is the connector supplied 
http://uk.mouser.com/ProductDetail/Emerson-Connectivity-Solutions/25-7652/?qs=%2fha2pyFaduhO%2fiW0nB8zRqDkFssUZXc5OsBYjVvccDI%3d
8.6mm housing
Just because I abused mine perhaps, or the other fellow struggled with his, does NOT mean the rest of you will be oafish. This is by no means the first F connector I've ruined in my 67 years. I must have made several dozen coax connections to this one while fabricating my housing design, testing, finding a bad solder joint on A channel amp, etc.
I say again, that whole preamp ckt board is part of the 50khz filtering. from whence depends the other two channels. Including the ckt bd structure and fabrication, wherein lies a good part of the cost.

Relax, use normal care, and get online. 

Thanks, Mike!  Obviously, my copy-and-paste measurement technique was off a little bit.

Still there is a range of pin spacing for connectors, so care is needed if ordering a replacement.

This IS the exact connector supplied, the 25-7652.

[JonathanW]

This is the connector supplied 
http://uk.mouser.com/ProductDetail/Emerson-Connectivity-Solutions/25-7652/?qs=%2fha2pyFaduhO%2fiW0nB8zRqDkFssUZXc5OsBYjVvccDI%3d
8.6mm housing
Just because I abused mine perhaps, or the other fellow struggled with his, does NOT mean the rest of you will be oafish. This is by no means the first F connector I've ruined in my 67 years. I must have made several dozen coax connections to this one while fabricating my housing design, testing, finding a bad solder joint on A channel amp, etc.
I say again, that whole preamp ckt board is part of the 50khz filtering. from whence depends the other two channels. Including the ckt bd structure and fabrication, wherein lies a good part of the cost.

Relax, use normal care, and get online. 

Thanks, Mike!  Obviously, my copy-and-paste measurement technique was off a little bit.

Still there is a range of pin spacing for connectors, so care is needed if ordering a replacement.

This IS the exact connector supplied, the 25-7652.

Right.  I mean if one intends to use a different make/model.