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Wirsri?rcddsrrninssthe~opwrtingdist.nCc
(where
the
DC voltage
drop
is
the
limiting
factor).
Ths
following
eqlutioas
apply for a
wndnctor
size
of
#22
AWG.
a
minimwn
user
station voltage of
18.0
volts,
d
a
minimum
power
supply voltage
as
stated
below.
For
Modds
PSlO, PSM, PS31, PM, PS60,
usa
Vmin
=
28.4
VDC:
D-
(feet)
P
322,181 1
Ibt
(-
. .
1.
Dh-
(mtgs)
=
99,133 1
Im
(milliPmperes)
For
Models
PS8, PSl5
(Vmin
=
24.0
MC):
(feet)
=
185,874
1
Im
(rmllumpcrcs
.
.
1
Dhce-
(map)
=
56,654
1
I&#
(milli.mpsrss)
Exnmpk:
Ths
CM300URM300L
with
25
ohm
~usarupto60
. .
.
With
a
PS8
supply
the
maximum
cpahg~for
this
anti011
is
185,874160
' '
=
3098
fkt
(944
mstas).
Asd
with
a
PS3l-y
the
muimom
opsnting
dishlLce
=
5370
feet
(1652
mtgs).
md a
usa
station with
25
ohm
phollg
(37mA)
is
185,874EV
=
5024
feet
(1531
-).
System
circuit
grd
should
not
b
ktly
cond
to
'euth'or'chssis'zmund(dirseclvmesnsacamectionm
ohmmtawwld&).
~gCT81.lionisb~to
its
own
chassis
via
a
0.1
microfaad
capacitor,
stabli6biug
arPdiofi.qllcIIcy(RF)~toraduesndio~
in~cefmmndiotnnsmi~.
To pre-vent
a
buildup of voltage
acm(g
tbe
system
ca-
plci~,thcpowsrsuppIyhsablssdsr~toch.ssis
ground
(22
kilohms).
If
the
system
hs
no
RTS
Systems
pow-
supply,
add
a
bleeder
mistor
at
a
cmotnl
point
in
the system.
The benefit of
not
'earth'
gnnmdiug
the
RTS
System
circuit
nzum
is
that
continued operation
is
possible
during
nn
accidmtrl
system
ground
fault. This awidmtal
grounding
uo
happm
whea
a
wire
is
pinched
or
a
cable
scraped.erossasbprpedge.
Oncrceidentalgrwndcmb
told by the
system
until
the
fault
can
be
cleared
md
(with
luck) bcfm
a
sccolld
ground
fnult
can
cause
noise or
overload or bring the system down.
Anotha bmsfit of not
"earth"
grounding the
circuit
return
is
tht
it prevents
the
htmhtion of
noise
through
'earth"
curw(s
from
other
equipmeat.
If
the RTS
Systmes
circuit
gmund~tsthsc~l~nts,itisWrdythattheywillbc
hevd
is
interfering
noise on
the
d4on line.
Wirin~lC&&g (See
Cable
Wiring
Di
in
Section
7,
Application
Momati011)
Two
chmd
'TW'
applications, or
single
cllmld,
thma
wiro
appli~&~~
IMY
USE
ather
e
~~C~O~IIODC
cable
(for
canrmimcs)
or
hmhvkhl-pair
cable
(Isss
expensive
tbrmmicqhomcnble).
SIandadwircrizcforthe~
is#2zgougswiroforinkm=&h.
Foryt
iumWi01u
arch
chtlmd
should have m i~~J~wdually
shieldedtwistalpirof.tlasr#2zgurgewirc;wrchis
8723
for
2
~bmnd~,
UUCI
mn
for 3
cbmnels.
POX
plenum
md
I
or
2CV'
C
wiring,
use
Bddea
88723
md
88777.
Ths
plaaum
able
hna
a
slighUy
smaller
d*metcr,
isTefbninsul.tsd,
d.boutthree.
timgthepriceof
8723
1
8777.
WireusingcableWi~,Section7,toreduce
intdemim
UUCI
help
maintain
a
low crossc.1L fip
bstmea*.
The
audio
a&
Liac
levd
is
bchmwa
1OdBu
md
OdBu
(bchvecn
0.24
.ad
0.77
volts
rms).
Thwe
levels
are
low
~to~t~into&equipmmt(suebas
TV
amsns)
yet
high
amugh
to
minimirs
extend
inmfemcetotheTWSpttm.
The
200
ohm
Liac
impdaw
is
high
enough
to
uUow
mnnmmication
om
liae
lengths of
1.6
kilometers (one
mile)
d
low
mwgh to permit m
d#lrule
speech
bmdwidth with
3.2
kilomttefs of
dated
cable.
In
most
systems
the
200
ohm
impcdpace
gives
a
high
fidelity
bmndwidth with low lwsar.
When
using
equipmeat
in
nia
or
conditions
of excessive
moisturr,
always
protect
the
equipment with plastic
covers
md make sure
uU
cable
c~ll~ectcns
me
lifted out of
mud,
mow or moisture md pmtected with plastic. Wpter mud
dsnowin~~~~cpnca~s~noise.
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