The Lemon Fool

What are these, any ideas?

(My image)


Julian F. G. W.

I'm not sure exactly but it's got to be something to do..............with co-ax? A sort of blank end? But why you'd bother I dunno

looks familiar is it AV? like a bnc/coax blanking end

ah, we concur even if wrong doug, As to why, termination to stop signal reflection, to close the circuit perhaps?

doug2500 wrote:I'm not sure exactly but it's got to be something to do..............with co-ax? A sort of blank end? But why you'd bother I dunno

kempiejon wrote:looks familiar is it AV? like a bnc/coax blanking end

ah, we concur even if wrong doug, As to why, termination to stop signal reflection, to close the circuit perhaps?

And ... Yes, but F-type, not BNC (google BNC to see the difference). Typically used with satellite kit. The theory is you put them onto unused ports to electronically "close" them and stop them picking up and interference.

What I can't work out is..if it's just a b**** why do you need the spigot bit and the high dome protrusion in the cap thing? Why not just a plain cap? Must be more to this than meets the eye.

doug2500 wrote:What I can't work out is..if it's just a b**** why do you need the spigot bit and the high dome protrusion in the cap thing? Why not just a plain cap? Must be more to this than meets the eye.

There's ... a 50 or 75 ohm impedance inside to match and close the circuit.

There may well be but you might as well be speaking mandarin to me

I did think that this one might be identified fairly quickly.

Correct answers — these are terminators. They can be used to stop reflections in unused coaxial cables (such as unused satellite TV cables). There is a short video here showing a wave in a slinky spring. Note how the wave gets reflected back the other way, https://www.youtube.com/watch?v=fMJrtheQfZw. In this example, the far end is fixed but, if you were to try it with the far end loose, you would still get a reflection (it would send a wave going back by "pulling" (due to inertia) rather than "pushing" (due to spring compression)). A way to stop the reflection would be to attach the far end to a box that could slide on the floor. (Ignore static friction — I'm trying to explain something here!) A suitable weight within that box would give it the right amount of friction such that it could absorb the energy from the wave without reflecting any back.

It a terminator, an impedance (probably just a resistor — I might cut one in half and have a look) performs this function with the signal on the coax.

If you use a splitter to split a UHF or satellite TV signal (for example), fitting one of these to an unused outlet provides a dummy load so that the impedances of the other outlets remains correct.


Julian F. G. W.

VSWR
That is all

AleisterCrowley wrote:VSWR
That is all

How we can tell AC isn't on the board of P & O Ferries?

He gave a valid reason for termination