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

[matthew@xxxxxxx]

Oh crikey we're even getting technical with the battery choice now!
So what battery/bulb combo makes a good tester?

--- In ukha_d@y..., "Ian Lowe" <ian@w...> wrote:
> One quick warning!!!
>
> don't use a PP3. if you do have a short you will incinerate the
thing...
> especially if you clip it on then wander to the other end with a
bulb!
>
> Ian.
> ----- Original Message -----
> From: <matthew@m...>
> To: <ukha_d@y...>
> Sent: Saturday, June 16, 2001 12:13 PM
> Subject: [ukha_d] Re: *muppet alert* How do I use my multimeter?
>
>
> > 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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