Dielectric grease

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#1
Tried to find it in forum search but my question is on dielectric grease. We use it on our fleet in the lighting connections etc. I was told to use it on the coax connectors and at the antennas then I read on dx website they sell permarex and not to use on the contacts just threads and air space but you can use theirs on the contacts. Just wondering on yall's thoughts on the proper and or not to use on rf connectors. Thank you
 
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#2
A properly weather sealed connection won't need anything else. In the cellular and two way radio industry, properly installed connectors mated/torqued correctly, and sealed per industry standards will work just fine. I've pulled apart connections that were installed 20+ years ago that were shiny and clean inside.

Some dielectric greases can migrate into the coaxial braid. Knowing 100% how it will interact with the jacket, center insulator, connector o-rings, etc. would be hard to do.

You won't see it recommended by companies that make high end connectors, cable manufacturers or big industry players, so that should probably indicate something.

I do use it on electrical connections where appropriate, though. Trailer harnesses, vehicle wiring, bulb sockets, etc. I did use dielectric grease to seal up most of the electrical connections on my UTV, due to some frequent water crossings.

There was a company (might still be) that sold some sort of connector foam that was marketed towards radio amateurs and TV installers. Never tried it. I've noticed that some amateurs seem to have a thing against good weather sealing of connectors, though.
 
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#3
I think the best is on the threads, not on contacts...grease is an insulator. Anti seize is great too. I love dielectric grease on the battery contacts... keeps them corrosion free. Aerospace and marine environments use it. I guess the factor will be what part of the country you live in...high humidity or wet locations or dry desert area?
 

krokus

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#4
Like mmckenna said, avoid the grease, and seal the RF connectors. Self vulcanizing tapes and ScotchKote can do wonders. (Those are what the Navy uses on shipboard connectors.)

I have not checked on using liquid electrical tape, as the external seal, over the tape. It might not have as long of a life, and I wonder if the solvents would cause an issue.

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#5
Countless times have I witnessed someone applying grease all over a NMO mount, then threading the antenna on covering the contact. As was said, it's a insulator. Doesn't work out to well!
 

W9BU

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#6
I do use it on electrical connections where appropriate, though. Trailer harnesses, vehicle wiring, bulb sockets, etc.
Permatex makes a dielectric grease that's intended for use on spark plug wire boots. It can be found in small tubes in most auto parts stores. I use just a small dab of it on the threads of NMO mounts when I install antennas. Just a small dab.
 
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#7
Dielectric grease is used more often in the satellite and cable TV industry on F connectors than with two way radios. On F connectors a small dab is placed on the center conductor and gets squished into the female side and eventually the threads when the connectors are screwed together. One of the more popular brands is called "Stuf" and it will dry up and get "cakey" loosing its properties after time in the sun.

As a trainer in satellite installs I'm supposed to cove the proper use of it but have never recommended using it as modern compression F connectors are internally sealed with O rings and they also use specialized external rubber doughnuts than add to the connector seal on some products. External use of electrical tape or other common weatherproofing used for two way radio is never used in satellite or cable TV installs.

I have experimented with dielectric grease on two way radio coax connections and really see no need for it if typical external weatherproofing is used.

Edit: Adding a link to Stuf info. https://manuals.solidsignal.com/STUF SS.pdf
 
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iMONITOR

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#10
Don't use RTV silicone sealant on electrical or coax connectors. When curing it releases acidic vapor and will corrode copper. I know a lot of people that made this mistake.
 
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#11
Silicon Grease on RF connectors and NMO Mounts

When I was working at a research field site for M. I. T. many years back, we used some high vacuum silicon grease on our high voltage connections for the radar transmitter. Have also used it for my RF connections on everything outside dealing with the ham radio antennas.

One big point about the 3 M High Vacuum grease is it doesn't migrate when it gets hot. It stays in place unlike the normal silicon grease that gets shipped with many of the RF connectors today.

I have also used the 3 M High Vacuum grease on the threads of my NMO mounts for years. Keeps them from seizing up the treads on the mounts. Great stuff. Note, you don't need to use very much. A little on a Q-tip goes a long way.
 
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#12
I too use silicon grease on my NMO mounts. Threads and o-ring. Keeps the scar from the hole saw on the roof from rusting. A little on the outside bottom of the whip where it contacts the mount or roof and you have a completely sealed antenna mount that will stay bright and shiny for years.

Also not in favor of packing connectors with grease as mentioned. There are better ways and done right will keep out moisture 100%.

Besides the auto parts store you can get silicon grease at the hardware store. Usually larger quantity and cheaper. Go to plumbing and look for faucet lube.
 
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#14
A light film on contact points is a good idea but more than that can cause problems.
You never want to put a big blob of grease in ANY rf connector
 

belvdr

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#15
I think the best is on the threads, not on contacts...grease is an insulator. Anti seize is great too. I love dielectric grease on the battery contacts... keeps them corrosion free. Aerospace and marine environments use it. I guess the factor will be what part of the country you live in...high humidity or wet locations or dry desert area?
Maybe I'm reading you incorrectly, but are you saying dielectric grease is an insulator? If so, wouldn't that render your battery useless or at least less useful?

I've never really thought about that until now, especially since I use it on my car battery and spark plug boots.
 
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#17
I think some are confusing silicone grease and its cousins to dielectric grease, which is completely different. Using various greases on the threads of your NMO mount is one thing but if your flooding the inside of an RF connector with grease to displace moisture, the grease needs some special properties beyond silicone grease.

Dielectric grease products like "Stuf" are formulated to mimic the dielectric constant of the dielectric in the coax and internal plastic or Teflon insulators inside the connector. These greases are designed to have a big blob put on the center pin of the connector and the grease is in contact with the RF flowing through the connector.

Yes its an insulator but just like a car battery contact, when you mate the two connectors or put the battery cable on your battery, the grease is displaced and you have the same metal to metal contact as with no grease. Except now that metal to metal contact is surrounded and sealed with grease to keep conductive moisture out. You would not use a "dielectric grease" on NMO threads or battery contacts.
 
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#18
Maybe I'm reading you incorrectly, but are you saying dielectric grease is an insulator? If so, wouldn't that render your battery useless or at least less useful?

I've never really thought about that until now, especially since I use it on my car battery and spark plug boots.
Dielectric grease is not an conductor.
The reason it works on a battery connection is that when you tighten down the connection, the grease is forced out of the way and a good metal to metal connection.
The remaining grease stays in place and protects the connection from oxidation and moisture.

Using it on spark plug boots keeps the water out and keeps the plug boot from sticking to the plug.

There are conductive greases that work well on battery connections, they seal out oxygen, but don't interfere with the connection, either.
 

belvdr

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#19
Cool, thanks!

Dielectric grease is not an conductor.
The reason it works on a battery connection is that when you tighten down the connection, the grease is forced out of the way and a good metal to metal connection.
The remaining grease stays in place and protects the connection from oxidation.

Using it on spark plug boots keeps the water out and keeps the plug boot from sticking to the plug.

There are conductive greases that work well on battery connections, they seal out oxygen, but don't interfere with the connection, either.
That makes sense now. Thanks for the clarification.
 
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#20
When I was working at a research field site for M. I. T. many years back, we used some high vacuum silicon grease on our high voltage connections for the radar transmitter. Have also used it for my RF connections on everything outside dealing with the ham radio antennas.

One big point about the 3 M High Vacuum grease is it doesn't migrate when it gets hot. It stays in place unlike the normal silicon grease that gets shipped with many of the RF connectors today.

I have also used the 3 M High Vacuum grease on the threads of my NMO mounts for years. Keeps them from seizing up the treads on the mounts. Great stuff. Note, you don't need to use very much. A little on a Q-tip goes a long way.
Yes, Dow Corning...used it at nasa JPL lab. Tasty stuff..
 
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