Joining TV coax

[Brian Gaff]

Cheapskates probably.

Brian

[Ian Jackson]

Just how 'reliable' do you need a cable joint to be?

Few of my cable joints fall apart that often.

Nein, ich bin kein Deutscher.

No - but some ways are a lot less 'proper' than others.

But you're sort-of right. You could argue that the 'proper' way is the one that does the job for the absolute minimum of cost and effort, and just performs adequately over the time it is required to work.

As I have not yet mastered the art of 'slodering', I can't really comment. Did you check the RLR of your joint (preferably with a TDR)?

[Ian Jackson]

Indeed - but to be perfectly frank and honest, it probably works absolutely perfectly in all of the situations where it's likely to be used!

[Jim GM4DHJ ...]

shocking

[Jim GM4DHJ ...]

people can be too fussy .....

[Robin]

No doubt sensible but you remind me that I once bodgered temporarily an old downlead of ancient brown coax which was filling with water by cutting it and making a deliberately loose joint at the bottom of a loop so the water dripped out. I found it quite scary to pull the aerial lead out of the telly and see water drip.

[The Natural Philosopher]

In the very distant past I did, when I worked for Marconi radar.

It wass better than a connector.

[Bill Wright]

Philosophy

A large part of being an effective and experienced tradesman or engineer is knowing what you can get away with. The reason for this is that an excess of anything wastes money and adds unnecessary complexity.

DIY aerial and dish installs fall into two categories, in general. The first is that necessary items and procedures are omitted. The second is that unnecessary items and procedures are included. Examples are, coax not taped to the mast and coax taped to the mast every two inches.

In the case of these connectors, they fall down because they are not significantly cheaper or quicker than the far better alternative, and any faults that they cause are likely to be subtle and thus might not be immediately apparent. Installed inaccessibly they present a small risk that is easily avoided.

Bill

[Bill Wright]

I used to do rental aerials on a block of flats in Ponty where there was no communal system. The downleads came down 11 floors to the ground floor. If the junction box cap came off the aerial the water really flowed out into the back of the VCR.

Bill

[Bill Wright]

There's prejudice against soldering because it's a skill.

Bill

[Bill Wright]

Totally.

I did and it came out better than connectors.

Bill

[Dave Liquorice]

Aye, even though they look cheap and nasty F-type plugs and a barrel is designed to be constant impedance.

I'd probably not bother with self amalgamating tape in a floor void, unless the is was a suspended floor over bare earth. Ordinary heat shrink will protect the joint but won't keep moisture out, capillary action between the heatshrink and cable jacket. Adhesive lined heatshrink would be better but can be a pain to get off again and doesn't really flex very well. Self amalgamting tape doesn't suffer these problems.

[charles]

if the water got into thenback of tehnTV set, there could be quite spectacular eht arcing

[Marland]

You can get self adhesive copper foil in various widths, the small stuff is often available in hobby shops as people who build dolls houses use it for lighting circuits before they cover it with paper. I have a roll of the heavier gauge stuff 20mm width and have used that to join the screen of a coax when I needed to extend the cable on a cctv camera in the garden . Then the whole joint was covered with a bit of 15mm plastic pipe slid on before the joint was made, that was then filled with resin. Has survived in all weathers for a few years now.

GH

[Ian Jackson]

For connections outside, I always spray the connectors with a touch of WD40 before screwing everything together (plus maybe a second squirt afterwards), I then wipe it off (but not so it's 'squeaky clean'), and then apply stretched self-amalgamating tape. [As the cable is still slightly greasy, it's sometimes a bit difficult to get the SA tape 'started'.] I've had connections that, 30 years later, have been just as shiny as the day I made them (no sign even of tarnishing, let alone water ingress).

[Ian Jackson]

Well done - but in less-skilled hands it could be an absolute balls-up!

While the F-male is essentially a perfect match, the F-female is invariably somewhat capacitive. [The same goes for some other types of connector.]

Most F-female barrels only have two leaves or fingers - and these are the worst. However, there are some that have four thin fingers - and not only do these contact the inner conductor more evenly, their impedance is usually better.

But despite these limitations, physically the most sanitary and expedient way of joining a drop cable is usually with two males and a female barrel.

[Bill Wright]

The Russian Vega table models had the aerial socket centrally above the tube neck. I saw the aftermath of an explosion this caused.

Bill

[Martin Brown]

Do you have something against inline F-type female sockets? Or do you already have a big bag of males?

It is surprising what you can get away with in practice.

[Mathew Newton]

Good point! I think I was just picturing the bag of plugs I had, and I'm not sure I even knew you could get inline females. Perhaps that's what I'll use as then it'll effectively just be the one connection.

[Mathew Newton]

I seem to be struggling to find them - do you have a link Martin?