tv coax plugs

[CB]

In my youth I seem to remember high quality plugs with a small grub screw on the plastic spacer for the purpose - haven't seen one like that for a good while however.

[Charles Hope]

any right angle one that I've seen uses a grub screw.

[Andy Burns]

The metal Maplin ones have a grub screw

According to the reviews, even the cheapo plastic ones have a screw, but it doesn't work too well ...

[Ian Jackson]

In message , Ian Jackson writes

Just to follow up - this is the correct way to deal with the braid - and centre pin.

[Graham.]

It was a lot more important to solder the inner when TV was delivered via VHF especially Band I

Also not soldering the inner of a B.L plug that is carrying DC to a masthead amp is asking for trouble.

[Charles Hope]

I'd expect far greater losses from an un-soldered joint at Band V

[Graham.]

It's a commonly held view given that feeder losses are so much greater at UHF, but it's wrong.

Even if it's open circuit at DC there will still be a few picofarads of capacitance, and capacitive reactance decreases as the frequency increases.

[Charles Hope]

How about reading the manufacturers tables? eg: URM43. 100MHz loss 13dB/100m 600MHz 34

URM67 50 MHz 4.5 800 MHz 18

[Graham.]

I'll repeat it and highlight the important word.

It's a commonly held view **given** that feeder losses are so much greater at UHF, but it's wrong.

The view that the same amount capacitive coupling attenuates the signal more at UHF than at VHF is wrong,

Feeder losses increase with frequency, that's a given!

[Andy Wade]

The are vastly better connectors than the old Belling-Lee around in the TV/AV world these days.

For DIY use the Cabelcon 'self-install' products (no crimp or axial compression tools required) are really good. Here's a selection from Ebay

There's also these neat right-angle versions

[Indy Jess John]

Thanks. I have been doing it right.

Jim

[tony sayer]

He's right on that one!.

And thats taking decent cables, not the ones sold for TV use that have sod all copper in them.

I believe the noble member for Rotherham Lord W Wright did quite a bit of work on that a while ago?..

[Terry Casey]

If the cable has a generous quantity of braid (as it should have) this wont work because there is not room inside the body to accept both clamp and braid.

The correct way - based on pictures provided by Belling & Lee 50 years ago but recreated from memory - is as shown here:

It will probably be found easier to solder the centre pin first - this should make it easier to trim the braid with flush bladed cutters.

The ring of braid compressed between the clamp and the insulator when the plug is assembled provides a true coaxial termination.

[Ian Jackson]

In message , Terry Casey writes

Those drawings show essentially what I described. The text says "Now do a haircutting action - trim the braid as close to the aluminium part as possible and smooth what's left back along the cable". I take that as meaning "Try to trim off most of the splayed braiding - but it's OK to leave a few longer strands on".

[Terry Casey]

The distinction I was trying to make is that, using cable with significantly more braid than in the pictures you previously linked to, it will be impossible to get the clamp into the body BEFORE it is trimmed, thus the need to trim it as closely as possible to the clamp/insulator assembly.

If you gave me a piece of coax with as skimpy a braid as that in those photographs, I throw the cable away and start again with something decent!

[Brian Reay]

Do they?

I can't recall seeing that myself. If you look at the grip, the way it goes is obvious, there is usually a rim to guide the inner insulation. Plus the claws are tightened by the hole compressing them, like a collar.

[John Rumm]

Note sure if that adds anything... he just said that the feeder losses are higher at UHF, but that does not necessarily mean that termination losses are as well.

[Terry Casey]

There are two issues here and it important to address them both. The orig>

The first part is very obviously wrong, as has been already been said.

The attenuation of any cable increases in a ratio of ~4:1 between channel B1 (or E2) and Channel E68.

However, if there is an open-circuit anywhere, part two comes into play.

On a broadband cable network with a continuous series of carriers the effect, when viewed on an analyser, is startlingly clear!

Usually caused by the contractor (usually) who built the original network failing to tighten the screw securing the centre conductor on a tap or splitter ...

[Bill Wright]

A quick calculation suggests that I have fitted at least 52,875 coax plugs in my life, so far.

Bill

[Davey]

.. which, if all laid end-to-end, would reach to ??