Silicone Grease on LNB Copper Coax Question

Minuno

Standard Member
I'm fitting a new LNB for my neighbour today and bought some silicone grease to prevent the woven copper sheath degrading over time, can I ask please do you smear this on the woven copper braid and also on the copper central core that slides into the LNB or just on the braid? Not being an expert I don't know if it's just in the strands or also on the central copper core?.

Any help please?
 

grahamlthompson

In memoriam
Dip the prepared end of the cable into the grease to cover everything.
 

Minuno

Standard Member
Dip the prepared end of the cable into the grease to cover everything.

I'm just concerned about getting grease inside of the actual LNB unit?, so strip the cable , fold the strands back , and insert al this into the silicone grease ?. It won't short anything ? Thanks. If the copper inner core is covered in grease how is the signal transferred thanks?.
 

TJT1

Distinguished Member
The plug 'cuts through' the grease when you screw it on. Don't put too much in the plug itself. a smear on the central conductor and a smear on the threads of the LNB. Then wrap the whole lot in self amalgamating tape for a really water and corrosion proof connection.
 

grahamlthompson

In memoriam
I'm just concerned about getting grease inside of the actual LNB unit?, so strip the cable , fold the strands back , and insert al this into the silicone grease ?. It won't short anything ? Thanks. If the copper inner core is covered in grease how is the signal transferred thanks?.

The grease is a dialectric it won't short anything, it's effectively an insulator. Thoroughly grease unused outputs, it will prevent moisture corroding them. It's great for your car battery terminals as well. The lnb is sealed there's no way it can get inside the lnb. As already said the connection cuts through the grease and at the same time stops moisture corrosion.

Satcure recommend you push the prepared end into silicone grease and then screw on the f connector.

If you have 4 connections to make, tape can be awkward I use lnb boots (slide them over the cable before fitting the f connector.

Moulded Rubber Boot x 5 by electrosmart® for Weather: Amazon.co.uk: Electronics
 
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Minuno

Standard Member
Thanks for all the help on this. What I can't understand, is the need to grease the central core?, when you push this into the hole in the screw thread connection won't the grease cause problems?, or am I ok to liberally cover the full prepared end in grease?. and the signal will be ok even covered in grease ( as nothing bites on the central core ).

Appreciate all of the advice thanks
 

grahamlthompson

In memoriam
When you screw on the f connector the central core goes up the hole in the socket, no matter how much grease you put on it will make contact. If you are using WF65 shotgun cable you may need to put a small kink in the core as it is much thinner than 100 grade cable.

How to fit F Connectors to coaxial cable for Sky and Freesat
 
I only know of one company/person who recommends silicon grease on F connectors, though it can do no harm. I've never used it and I have been in the satellite dish game since 1988. I've also never had corrosion problems. The secret is covering joints with self amalgamating tape. I don't like screw on F connectors, professionals never use them. Better to use crimp or compression connectors.
 

pedro2000uk

Distinguished Member
I only know of one company/person who recommends silicon grease on F connectors, ...

CHANNEL MASTER did - but what did they know lol

don't think I've come across any sky installers using it & you'd think sky would insist if it mattered that much, there again... loads of sky installs have been done with cheapo screw on f connectors & so many call outs with them coming lose / falling off.

never liked crimp on - even with gel [was that silicone gel] - I don't like the idea of deforming the radio guide

and how do you use self amalg' tape over a greased fitting-

boots can hold water as can badly applied self amalg tape

Nowadays, although dearer including the tools you need, the most reliable are quality self sealing compression f connectors, properly prepped with a tool & good coax.. no rubber boots/ no self amalg' / no grease - & still shiny copper years later

there's some higher quality screw on f connectors with sealing rings that are pretty good, it also relies on prepping the coax properly & a good fit- no long strands of copper sticking out... that makes for a bad seal on the coax outer,

the advent of pull down covers on lnbs have helped a lot

older aerial connectors in plastic cases where the lids would come off or get pecked off needed sealant though - they not only corroded, the open plastic cases could then form a reservoir & the coax, especially spaced dielectric, could act like a pipe carrying rain water into your tv.
 

neilball

Well-known Member
F-Conn Industries DB6U connector is good for outdoor use. Ideally you use their coax prep/stripper tool, and their "double bubble" compression tool makes for rapid, good quality terminations.

There are plenty of other connectors in the F-Conn range, but note that they use a different compression tool with interchangeable tips for the different fittings.
 

pedro2000uk

Distinguished Member
Is there any particular brand of compression f connectors that you would recommend?

The easiest compression f connectors to get hold of & recommend are probably Cablecon now, they used to need much more force to fit, especially if you were doing multiple connections on a big IRS, now they even do a self install version that doesn't require a compression tool if you are only doing a few & once made up, are very solid & highly waterproof, even on in line joins & there's a newer quick fit compression version I noticed at a recent trade show that requires very little force to fit.

You can get high quality screw on f connectors that are better made with better made bodies / join, more accurate threads, form a tight fit on coax & have sealing rings in the connector that are well worth considering if you are only doing a few connections. Combined with modern pull down weather covers on lnbs & weather covers on diseqc switches etc. are pretty good, you can still use boots but I'd use self amalgamating tape on in line joins.

For any f connector, the cable needs to be prepped properly & not with long strands of braid, there's a universal standard prep now for coax which is best made with a prep tool if you are doing a lot, but you could use a sharp knife for just a few, about 5mm of exposed braid/foil & dielectric & you can vary the length of center core depending on fittings but it should be around 8mm. If you prep coax like that & fold the copper braid back & fit & good quality, tight fitting screw on f connector with sealing ring, that makes for a pretty decent semi pro connection & far better than using cheap, badly made f connectors badly made up with straggles of braid sticking out.

Price isn't a fail safe indicator either, nor is just being a compression f connector, some retailers sell cheapo screw on f connectors at very not cheap prices & some compression f connectors fall short, I tested loads years ago & discarded quite a lot I wasn't happy with until gravitating towards those I knew worked well long term, so you have to do a little leg work but you won't go far wrong with Cablecon or Thomas & Betts.
 

pedro2000uk

Distinguished Member
Cheap coax. .

Using cheap coax renders most of the above pretty useless in most cases .. the waterproof characteristics of decent f connector fittings does usually require them to be fitted to equally good coax .. cheap coax can cause them to leak etc. .

Some cheaper tough commercial coax can be made into a good job, if it's genuingly tough coax and a good fit for the connector, they can typically use alluminium braid and foil or Ali coated plastic/ cheaper alloys / copper coated steel core which does the job albeit with more attenuation for the ali .. copper coated steel core doesn't lose too much and is a lot tougher. . But all those will rapidly deteriate if any moisture gets in hence decent self sealing connectors can make it all a good/ tough job say on an IRS or cabling for cable where the attenuation is less of an issue than say motorised on the weakest satellites. Some use gel to cover the ali braid / foil through the coax.

Avoid very cheap coax, they are usually not tough enough and can kink or damage far too easily when installed round buildings and over roofs etc. and are unlikely to be resistant to UV damage or a sharp set of teeth or beaks.
 

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