For
PNI
8 lixed station installations, ,12ndard A coils and B batteries arc
normally suppli«I. These large batteries will give in excess
of
200
hours
of
s,rvicc. A
sp«ial
battery cable
is
,vaihblc
for use with
the"'
batrcries, having
at
one
end
a connector which
fits
the power plugon the chassis and
at
the other
end spade lugs and l»ttery plugs for connection to the
"A"
and
"B"
batteries
respectively.
The
s,rvice life ratings which ha,•c been quoted above for the
thr,e
different types
of
battery available with this e<juipmcnt
uc
based
on
anassumed
continuous
discharsc
of
) minutes
transmit•}
minutes receive.
Con.sideubJy
longc, s,rvicc life will be rcali•«I
if
the discharge conditions 2re
lcs.,
stringent
than those
s1a1«1.
The
transmitter ·,,ill deliver a carrier pow
er
output
of
2 to
2.S
watts
10
a
resistive load,
on
any
one
of
three crystal<onlroll«I
fre<juencfcs
bctw«n
3.0
a.•d
.6.0
megacydts.
This
carrier can
be
keyed for C.W. Op<fltion, or
100%
soecch modulated for )bdiolclephone operation. On Radiotelephone Oi"'ralion
the carrier
is
controlled
by
the
"press-to-talk" switch incorporated
in
the
microphc,ne, the transp,itter b,,ing turned offand the rcccivcr
tum«!
on
when
the "prc.ss-to-12lk'' button is released.
The
receiver
is continu0tuly
tunable
over
the
.s.1mc
frequency
ringe
a.S
the
transmitter, the dial being
alibr,t«I
directly in megacycles. The
receiver
em•
ploy, six
vmcuum
tubes in a superheterodynecircuit, providing high sensitivity,
selectivity.
siJtnal
to noise ratio. and
im.1ge
atte
nu
.iti
on.
Automatic volume
control
is
us«! for telephone reception but IS automatically remov«I when the
receiver is switch«! over for the reception
of
C.W. signals.
TRANSMITTER-RECEIVER DESCRIP'I'ION
Rdcren
ce should
be
made
to
the
Oia,i:r,ms
of
Connections contained in
the
b'ack
of
this m1nu1I when reading the following technical description. The
o,·cra.11
cabintt
is
constructed
of
aluminum, we:athtrproof constroction being
used throu,thout. The transmitter and recdvtr
are
built on a common chassis,
which
fits
into the upper compartment of the cabinet where
it
is secured by
screws
thr0<1,1th
the top
.of
the front oanel and thcou~h the sides
of
the cabinet.
The
lower
half
of
the cabinet provides accommodation foe the portable bottery
and
the
telegraph
key,
and stowage
for
the whipantenna. earphones and micro-
phone when not in
us,.
In
the
PNIB
the loudspeaker
is
also mounted in
this compartment. .
B21terv
volt•~•
is
supplied, from one
of
the thrc, tvpes
of
battery
1lceady
described, through a four conductor cable, terminating in 1 locking type
plu,1t
connector which
fits
into a rectpt.acle mounted
in
2
ffJnge
un
der
the
front
p1ntl
at
the centre
of
the transmitter receiver chassis, This receptacle
is
bbelled
"Power". Another simil,r receptacle labelled "Audio'' and mounted
on.the
umc
Ran,lle
as the · Power'· receptacle. receives the plug from the microphone•
headset assemblv. Locat«I between these recepta<les, but towards the rear
of
the chassis.
is
a small jack which rcccivts the plug
on
the lead-in from
the rod antenna.
2
I,
