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

[matthew@xxxxxxx]

Thanks Keith. I've got to turn the power off in a mo to decommission
the sockets in the room above node zero so when its off I'll test the
wire again to see if it was induced voltage causing the problem (the
wiring to be decommissioned runs next to the coax at the moment).

If i still get funny readings I will hunt out a bulb and a battery
from somewhere and try the low tech method.

Cheers

matt

--- In ukha_d@y..., "Keith Doxey" <ukha@d...> wrote:
> 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@m... [mailto:matthew@xxxxxxx...]
> > Sent: 16 June 2001 11:07
> > To: ukha_d@y...
> > 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!!!)
> > > >
> > > >
> > > >
> > > >
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> > > > http://www.automatedhome.co.uk
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> >
> >
> >
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