Broken Connectors

[pacificrim]

I moved my 1.2m dish last weekend and in the process managed to break the F connector on my SG9120b at the output to the LNB. I was tightening the connector (not too tight I would say) when it made a crunching sound. Well, that was the end of that. I couldn't unscrew the connector, so I cut the cable just past the connector and sealed it and bypassed the motor by putting a splitter to the LNB. Luckily, it was the output and not the input or else the motor would be dead.

At about the same time, I also managed to break the connector at my LNB - I just didn't notice until today when I had sketchy reception on a sunny day. I was about to test signal at the LNB and I was removing the cable from the LNB when the F81 connector came with it. In both of these cases it was bound to happen. From pictures I found here, the connector on the motor is soldered to the board and it doesn't seem that anything stronger than the circuit board and solder is holding it in place. As for the LNB, it is only soldered and the F81 is threaded in but no nut or even glue is holding it to offer resistance. I bought both from WSI and their warranty specifically names connector breakage as outside of the warranty. Anyway, I have replaced the LNB and bypassed the motor, so I have "fixed" the problem. It is too bad that things aren't built or designed to withstand the same "stress" as a $2 splitter.

 

[dougruss]

That's why its advisable to ONLY "Finger Tighten" those connections, never use a Wrench.

 

[pacificrim]

I am a professional cable and satellite installer and I use wrenches all day. I know I don't need to "wrench" things tight but should be snug. In both cases I would have expected a nut on the F81 and not a floating connector. A pigtail on the motor board would make sense - connectors go bad and it would be stupid to throw away an otherwise good motor. Either way, it is unfortunate. I won't be buying WSI stuff anymore. To me it seems cheap.

 

[WhyMe1]

I moved my 1.2m dish last weekend and in the process managed to break the F connector on my SG9120b at the output to the LNB. I was tightening the connector (not too tight I would say) when it made a crunching sound. Well, that was the end of that. I couldn't unscrew the connector, so I cut the cable just past the connector and sealed it and bypassed the motor by putting a splitter to the LNB. Luckily, it was the output and not the input or else the motor would be dead.

At about the same time, I also managed to break the connector at my LNB - I just didn't notice until today when I had sketchy reception on a sunny day. I was about to test signal at the LNB and I was removing the cable from the LNB when the F81 connector came with it. In both of these cases it was bound to happen. From pictures I found here, the connector on the motor is soldered to the board and it doesn't seem that anything stronger than the circuit board and solder is holding it in place. As for the LNB, it is only soldered and the F81 is threaded in but no nut or even glue is holding it to offer resistance. I bought both from WSI and their warranty specifically names connector breakage as outside of the warranty. Anyway, I have replaced the LNB and bypassed the motor, so I have "fixed" the problem. It is too bad that things aren't built or designed to withstand the same "stress" as a $2 splitter.

I had a STAB motor outside for years without a problem. I bought a new house and tried to remove the cable from the motor but the rain and dirt glued the connectors to the cable. When I tried to take the cable off..... crunch..... all it did was spin Took the motor apart and found out the same as you.

 

[Cham]

Silicone dielectric grease works well in these F connectors to keep water and air away from surfaces that might corrode. I use it in outdoor RF connectors all the time, especially where access is limited like on a tower or other difficult to access places. Kind of messy though for a connection that would require disconnecting often for testing etc.. Doesn't seem to affect RF properties in the connection, at least up to 2.5GHz I often work with.
c

 

[Tron]

I overtightened the F-81 on my SG-9120B, then when I loosened it, the entire barrel spun. I opened the motor, and inspected the circuit board. The fix is easy, just be sure to have a can wrench handy when you put everything back together.

 

[skysurfer]

Silicone dielectric grease works well in these F connectors to keep water and air away from surfaces that might corrode. c

what's the application of the grease? Connect coax to LNB and then goop the whole outside (bare metal and part of the coax/lnb) with the grease or goop the LNB f-connector threads, goop the inside threads of the coax's f-connector, then make the connection?

 

[Bongu]

Pacificrim,
Unfortunately, most of the motors and LNBFs are made for low cost and mass production. The extra nut and the pigtail connections cost money to include in the design and the final product. You may think to yourself "it cant cost but a few pennies to have it done right." When production runs of LNBFs and motors are in the tens of thousands, those "pennies" add up to big dollars FAST.

Skysurfer,
The proper application of dielectric grease that I am aware of is that you squirt a gob of it into the connector before you screw it to the LNBF, motor, switch, or receiver.

 

[pacificrim]

I appreciate it is a race to the bottom. Kids working in factories, making junk - including a cheap Chinese splitter I bought on ebay that doesn't thread on any known connector. Having said that, I can't think of any device (especially one meant for outdoor use and extreme weather) with a floating connector. Anyhoo, I plan to take it apart at some point when I have a reason to take down a perfectly mounted and peaked motor and dish and fix it. Junk.

 

[AcWxRadar]

Hey y'all,

I am sorry to hear that some of you have learned the frailties of the F-connectors on some of your components. Especially for your outdoor components. This happens on occasion, but it is not entirely a sign of poor manufacturing workmanship. If you are using only your fingers to tighten and loosen the connectors, the attached F-connectors should never "spin" loose from the housing. However and obviously, there are times when this does occur through no fault of the user. Not every piece of equipment is beyond some manner of error.

Regardless, everyone must understand that when it is said that connections must be "finger-tightened" only, they mean this literally. These are not pressurized water pipes or garden hoses. If you leave the connections a bit loose, the electrons are NOT going to leak out like water from the hose fittings. I don't want that to sound like I am preaching the practice to you or cutting you down for not following the instructions implicitly, but the fact is there and that is, as they say, the way that it is.

If you feel that you must use a wrench, then you must utilize TWO wrenches. One to hold the F-connector barrel and one to attach the cable end. But, this should not be done either as you do NOT want to tighten these metal-to-metal connections in this fashion. There is a physical property of metals that many people do not comprehend. It is generally referred to as "fretting".

The anomaly of fretting is a loosely used term that describes the end result of a physical property of certain materials, expressly metals, for the atoms of one metal piece to actually "jump ship" and migrate to the adjacent piece of metal. Over time, the migration of the atoms of the two metals can actually build a solid bond between the two metal components, just like welding them together. The tighter you make the connection of the threads, the faster and more readily this occurs because it places the two metal surfaces that much closer to eachother. So, when you tighten the connections with a wrench, you are actually promoting the condition that you wish to avoid.

The proper method to install connectors is to use a non-conductive (dielectric) grease and finger tighten the connections.

The dielectric grease deters moisture entry and thus deters oxidation and corrosion and it also deters fretting. Leaving the connection just a wee bit loose will majorly deter fretting. As long as the center conductor and the outer threaded fittings are in contact with their proper counterparts, that is ALL that you need. The signal will pass just fine.

If you have neglected your outdoor connections, never use a SINGLE wrench to remove them. Always use one wrench to hold the F-connector barrel and one wrench to loosen the cable end. Otherwise, if the connector is oxidized or fretted, the whole thing will want to turn on you and the first thing that will give out is the electrical connection to the inside of the motor or LNBF. That is the weakest link and the part that you do NOT want to break.

Again, to repeat myself because it is important for everyone to understand, DO NOT TIGHTEN your connectors more than gingerly and gently finger tight and absolutely DO use some sort of quality dielectric grease and a rubber "booty" to deter moisture entry. And remember, the tighter you make the connection, beyond just being mechanically secure, the more you are defeating your purpose.

RADAR

 

[Cham]

Great post Radar as usual!

Skysurfer,
The "goop" comes in a tube like toothpaste. I just squeeze some into the open male F connector (or N, TNC, etc) and attach the connector to the receptical as you normally do finger tight only. It takes very little to do the job, a 1oz tube last a long time! Some will get onto the threads and act like regular grease and keep them from corroding as Radar indicates above. You can use tape or shrink tube to protect the connection exterior as you see fit but I don't bother myself.

Automotive parts suppliers carry it as ignition sealant or by the proper name "silicone dielectric compound". Google is your friend
-C.

 

[Mikey11]

i use 90 degree connectors on my SG9120 for two reasons....

one....they give better cable clearance so the cables will not come into contact with the moving dish

two....the reasons listed in this thread....once you install a 90 degree connector you never have to undo it or mess with it again....if you need to remove the cable for whatever reason you unscrew the cable from the connector....NOT FROM THE MOTOR!!

 

[beavs2112]

for those interested the actual torque setting for an F-series connector is 40 in-lb. hxxp://www.scte.org/documents/pdf/standards/ANSI_SCTE%20147%202008.pdf

 

[pacificrim]

Neither of these WSI products are capable of the 2 wrench method and the fact that nowhere does it say anything about only being finger tight. I still maintain that I have never seen any piece of cable or satellite equipment where the f connector is not supported or attached to the chasis - until now. I appreciate the feedback on this thread and I am glad I was able to work around the problem. Thanks.

 

[Tron]

Strange... On my SG-9120s (both original and "B" models), there is a nut and washer on both F-81 connectors. This was the case on the one that loosened up on me as well. There is a "lip" around the fittings which requires one to use a thin can wrench designed to fit inside CATV security shields to reach the nut in order to loosen or tighten it.

 

[AcWxRadar]

i use 90 degree connectors on my SG9120 for two reasons....

one....they give better cable clearance so the cables will not come into contact with the moving dish

two....the reasons listed in this thread....once you install a 90 degree connector you never have to undo it or mess with it again....if you need to remove the cable for whatever reason you unscrew the cable from the connector....NOT FROM THE MOTOR!!

This is a really swell way to go, Mikey11. Routing a straight cable connection directly out of some motors or LNBFs can be cumbersome due to the clearances and angles. As long as you use 90° connectors that are properly rated for the frequency (should be 3 GHz), this is a good way to go. Only drawback is simply that it is an additional connection which is just another possible link that could lead rise to a problem, but then again, it's just one connection.

for those interested the actual torque setting for an F-series connector is 40 in-lb. hxxp://www.scte.org/documents/pdf/standards/ANSI_SCTE%20147%202008.pdf

Nice addition, Beavs! Good information to have.

RADAR