RE: Re: *muppet alert* How do I use my multimeter?

["Keith Doxey" <ukha@xxxxxxx>]

Either you are not making proper contact with the probes or you may be
picking up some induced voltage.

Resort to the low tech method.
Battery and bulb. Battery at one end, bulb at the other. If the bulb lights
OK then the cable is OK. If it flickers, (which it would do if your 0.7 to
170 reading is accurate) then the cable is knackered :-(

Keith

> -----Original Message-----
> From: matthew@xxxxxxx [mailto:matthew@xxxxxxx]
> Sent: 16 June 2001 11:07
> To: ukha_d@xxxxxxx
> Subject: [ukha_d] Re: *muppet alert* How do I use my multimeter?
>
>
> Ian
>
> Thanks for your help. I set the meter to 200 ohms and the results are:
>
> 1) 1
>
> 2) Anything from 0.7 to 170!!!
>
> The meter is a digital one and for test 2 i would have expected a
> constant readout? I'm not waving the cable around and the prongs are
> firmly pressed down.
>
> Any comments?
>
> matt
> --- In ukha_d@y..., "Ian Lowe" <ian@w...> wrote:
> > two quick tests matt:
> >
> > make sure both ends are "clean" (ie not shorting
together core and
> screen)
> >
> > Measure resistance between core and screen: if you get a dead
short
> > (anything up to about 15-20 ohms) then your cable has stretched
> internally
> > and the core and screen are touching.
> >
> > then take one end and twist it together so the core and screen
are
> shorting:
> > go to the oter end and emasure: anthing *Except* a dead short
means
> your
> > cable has been damaged and one of the conductor paths is broken.
> >
> > Ian.
> >
> > ----- Original Message -----
> > From: <matthew@m...>
> > To: <ukha_d@y...>
> > Sent: Saturday, June 16, 2001 10:36 AM
> > Subject: [ukha_d] *muppet alert* How do I use my multimeter?
> >
> >
> > > Having put in quite a long run of coax from node zero
(garage) to
> the
> > > loft as the downlink from the aerial, I noticed that about
12"
> from
> > > the ceiling of the garage it has gone a bit floppy.
> > >
> > > Suspecting the coax may have broken inside (bugger!) I've
gone out
> > > and bought a cheapo multimeter.
> > >
> > > I've stripped the end in the loft, and twisted the braided
screen
> > > around the solid core. Back in the garage, the options on my
meter
> > > are 2000k, 200k, 20k, 2000 or 200 ohms. I guess the plan is
to set
> > > the meter to one of those, touch one prong on the core and
one on
> the
> > > screen and look at the value displayed.
> > >
> > > Trouble is I have no idea what I'm looking for. I don't know
what
> > > values will tell me the cable is broken and what values will
tell
> me
> > > im ok. I also have no idea what OHMs to set the meter to.
Assuming
> > > the cable isn't broken, is there some way I can test the
strength
> of
> > > signal ie. how much loss there is over the run? I'm
reckoning on
> four
> > > runs of coax from the loft to the garage and it's CT100
cable but
> if
> > > the losses are too great I'll have to get some CT125.
> > >
> > > Any help and advice gratefully listened to!
> > >
> > > Yours muppetationally
> > >
> > > matt
> > >
> > > (ps. I promise one day I will contribute something
worthwhile to
> this
> > > group rather than just ask questions all the time!!!)
> > >
> > >
> > >
> > >
> > > ____________________________________
> > > Automated Home UK
> > > http://www.automatedhome.co.uk
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> > >
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> > >
>
>
>
>
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