Philco 48-1000 User manual

PHILCO SERVICE
.SERVICE
Phiico Television Receiver, Model 48-1000

MODEL48-1 000
SPECIFICATIONS
Description:
Ten-inch, direct-view,table-model,
televisionreceiver.
FrequencyRange:
Television broadcast channels 1
through 13.
Number of Tubes:
Twenty-six.
Antenna:
Provisions fortwo antennas, one
each forthelowand high bands.
Transmission Line:
300-ohm balanced type.
ChannelTuning:
Eight-position Turret - Tuner, with
snap-intypecoils forthe designated
channels forthe televisionbroadcast-
ing area in which the receiver isto
be used.
Intermediate Frequencies:
Video carrier—26.6 megacycles.
Audio carrier—22.1 megacycles.
Operating Voltage:
110—120 volts, 60 cycles, a.c.
Power Consumption:
275 watts.
Power Supplies:
325 volts d.c. at300 ma., 7300 volts
d.c. at200 microamperes(approx.).
Audio Detector:
Ratio-type FM detector.
A.F.C.:
Automatic tuningwithelectronic
control.
A.V.C.J
Automatic levelcontrol of picture
and sound.
Tone Control:
Continuouslyvariable,treble to
bass.
BassCompensation:
Tapon volumecontrol.
Audio Output:
2.5 watts.
Speaker:
Six-inch, permanent-magnet,
namic, 3.2-ohm voicecoil.
dy-
Picture Presentation:
Ten-inch directview,magnetic(par-
tially permanentmagnet) focus, mag-
neticdeflection.
D-C Restoration:
1N34 crystal diode.
Deflection Generation:
Hard-tube oscillators.
2
COPYRIGHT, 1947, PHILCO CORPORATION

MODEL 48-1000
GENERAL DESCRIPTION
PhilcoTelevisionReceiver,Model48-1000,
is a wide-bandsuperheterodynevideoreceiver
combinedwith anFM audioreceiver,incorporat-
ingthe mostmoderncircuitdevices.Outstand-
ing circuitadvancesinclude the PhilcoPrecision
ChannelSelector,whichgives greater selectivity
and higher gain inthe radio frequency circuits,
automatictuningwithelectroniccontrol,which
counteracts any frequency drift ofthe incoming
signal, and automaticcontrol of picture and
sound,whichovercomes the fading of high-fre-
quency signals.Theseadvancements,combined
withprecisionconstruction,reduce the number
of operatingcontrols tofive, thussimplifying the
use ofthe receiver.
INSTALLATION AND OPERATION
CHOOSING A LOCATION FORTHE RECEIVER
In selectinglocations forthe receiver and
antenna, the owner ofthe televisionreceiver will
decide the exactlocation forthe installation.
However, the television serviceman canbeof
assistance tothe owner inthe selection ofa good
location, andcan thereby do much to promote
ownersatisfaction.Certainfactorsshould be
brought tothe owner'sattention in choosing the
receiver location.These factors include:
Room Lighting
The roomneed notbe dark to view the
televisionprogram; a smallamount of general
lighting is evendesirable. The receivershould
be so located thatsunlight or light fromlamps
will not falldirectlyupon the picturescreen, or
cause glare or reflections inthe eyes ofthe audi-
ence. It is advantageous to be ableeasily to
darken the roomsomewhat for viewing of day-
time programs. The picture will appearclearer
if the receiver isnot placednear a window, so
thatdaylight will notbe directly in back of,or
on eitherside ofthe picturescreen.
SeatingSpace
The picture canbe viewedcomfortably, by
mostpeople, from a distance of between fiveand
fifteen feet. For thisreason, it is well to locate
the receiver so that an area of about five feet by
fifteen feet is available, or easilyarranged,direct-
ly in front ofthe receiver. In this way, guests
may be accomodatedmostconveniently.
Power Facilities
The chosenlocationshouldprovide easy
access toan electrical outlet, andif convenient,
a groundingpoint.
Interference Sources
Although thenew Philco television circuits
arenot easilydisturbed by outsideelectrical
disturbances, itis advisable,wherepossible, to
locate the receiver andthe transmissionline at
a distancefromelevators,largeelectricmotors
and similarsources of possibleinterference.
Alternate Receiver Location
If it appearsthatthere aretwo possible
locations forthe receiver,considerationshould
be given to providingfacilities in case the owner
wishes to move the receiver ata later date.
Usually,thisrequirement canbemetby making
the transmissionline long enough to reach the
alternatelocation and coiling the excessline at
someconvenient point along the lead-inroute.
Figure 1 illustratessome ofthe items tobe con-
sidered in choosing the location forthe receiver.
WINDOW
/DOOR
CLEAR
AREA
FIGURE 1. RECEIVER LOCATION.

MODEL48-1000
TELEVISION ANTENNAS
When the location forthe receiver has been
selected, the antennashould be installed. The
antenna isa veryimportantpart ofthe installa-
tion andthe following factors enter into the
installation problem.
Very-high-frequency radiowaves,such as
those used in television,havesomecharacteristics
different from thoseused in ordinarybroadcast-
ing. The mostimportant difference isthe straight-
line travel of television waves,called line-of-sight
propagation. The televisionbroadcastdoes not
follow the curvature ofthe earth'ssurface so
thatreliablereceptionbeyond the horizon isnot
possible. The broadcast canbe intercepted bya
hill or otherobstruction,thuspreventingrecep-
tion bya receiverlocatedbehindsuch an obstruc-
tion. For thisreason, itis necessary to locate
the antenna as high as possibleabovesurround-
ing objects.Anotherpeculiarity of television
waves is thatthey reflect from solidobjects. By
thisaction, a televisionsignal can reach a receiv-
ing aerial from morethan one direction, often
resulting in reception ofthe same signal from
the same broadcastingstation at slightly differ-
ent times.This effect producesmultiplepictures,
or ghosts, onthe televisionscreen.Reception by
multiplesignalpathsmusttherefore be avoided.
Televisionreceptionrequires theuseof
special antennas. The mostcommontype isthe
half-wave dipole,consisting oftwo rods,each
DIPOLE KIT
HIGH FREQUENCY 45-1523
LOW FREQUENCY 45-1525
AERIALFROM KIT
45-1525
HOLES SHOWN IN PAIRS FOR
CHANNELNUMBERS AS SHOWN
1,2, 3.45,6
.ERIAL FROM KIT
45-1523
7 12
813
HOLES FOR CHANNEL 127
NUMBERS AS SHOWN 138
9
10
TP-2635
FIGURE 3. DIPOLE AND REFLECTORAERIAL.
a quarter-wavelong,separated byan insulating
member. Seefigure2. This type of antenna is
bi-directional since it receivesequallywell in
eitherdirection at right angles tothe line ofthe
rods, but receivesverypoorly in eitherdirection
in linewith the rods.Such an antenna canbe
usedwhere itis desired to receive from two
directions, and wherereflections, or ghosts do
not interferewithsuchreception. Where inter-
ference occurs, itis necessary tousea moredirec-
tionalantenna,such asa dipole-with-reflector,
shown infigure3. Such an antennareceivesbest
only from the directionindicated, and therefore
tends to suppressreflectionsarriving atthean-
tenna from otherthan the direction in which the
antenna is aimed. Moreover, the dipole-with-
reflector will provide a strongerreceivedsignal.
The length ofthe sections ofthe dipole
antenna is basedupon free-space wavelengths.
Thislength canbe convertedinto the physical
length byuseofthe following formula:
Length in feet
of each
Vi-wave rod
234
Television channel frequency in megacycles
TP-2629
FIGURE 2. SIMPLEDIPOLEAERIAL.
The followingtableshows the length ofthe
dipole(consisting oftwo quarter-waverods)
andthe reflector for eachtelevisionchannel.

MODEL 48-1000
Channel
Number
1
2
3
4
5
6
7
8
9
10
11
12
Frequency
(me.)
44-50
54-60
60-66
66-72
76-82
82-88
174-180
180-186
186-192
192-198
198-204
204-210
Dipole
Length
(in feet)
10.00
8.20
7.50
6.80
5.90
5.50
2.65
2.56
2.48
2.40
2.33
2.26
Reflector
Length
(in feet)
10.50
8.60
7.85
7.15
6.20
5.80
2.78
2.69
2.60
2.52
2.44
2.37
FLAT ROOF SLOPING ROOF PEAKED ROOF
BOTH
STAGGERED SPLICE OF
TRANSMISSION LINE
FIGURE 5.
TP-2634
RECEIVER-AERIAL CONNECTIONS.
TP-2631
FIGURE 4. AERIAL-MASTINSTALLATION.
Antennas canbe constructedwhichoperate
with fair efficiency overeither thelowor high
band ofthe televisionchannels,making itun-
necessary to employ "cut" dipolesexcept in
installationswheresignalstrength is abnormally
low, or where interference or reflections areex-
ceptionallytroublesome.
Transmissionlines forusein television re-
ception are specifically designed to match the
antenna. For thisreason, itis necessary to employ
the type of line specified forthe receiver. For
all 1948 ModelPhilcoTelevisionReceivers, 300-
ohm parallel-wireline,Part No. 45-1514, is re-
quired.Installation of thislineshould be care-
fully made,withspecialregard to properly secur-
ingthe line at intervals ofnot morethanthree
feet, to preventvibration or othertypes of damage
tothe line.Connections tothe receiver are made
by means ofa four-prong plug and jack. See
figure5.
Televisionantennainstallationsmust be
madewithspecialemphasisupon the following
points.
1. The antennamust be placed ina high
position,clear ofall obstructions, andin line-of-
sight ofthe transmittingstation.
2. The antennamust be properlyaimed to
obtainmaximumsignalstrength and freedom
from echoes and interference.
3.In areas oflow signalstrength, itmaybe
necessary tousean antenna of specific length to
obtainbestresults.