Philco 121 User manual

• • • • • • • • model38-38,CodL121
SERVICEBULLETINNo. 290 lo, members ol
RADIO MANUFACTURERS SERVICE
Electrical Specifications
TYP ..: OF (.;IR CU JT : Six tube, battery opera ted superhelerody ne circuit, hav inJ.:
two liming rangC"s covering broadcast and sho rt- wave freciuencies; Automatic
\·111u111cControl: Tone Con tr ol, and a class " B" output stag<'.
INT ERMEDIATE FREQ UENCY: 470 K . C.
TUNING RANGES: Two - Range 1, 5.lO to 1720 K. C.
Range 2, $.7 to 18.0 M. C.
POWER OUTPUT: I watt.
PHILCO TUBES USED: One 1C7G, 1st Det . & O,c.; one 1D5GT, I. F. amplifi er;
on,, 1H4(;, 2nd Del. (A.V.C.); one tE5GP, Isl Audi o ; one IH4G, Audio
Driver, and one IJ6 G, ou tput.
TYPE AER IAL : '"L"' type, Philco Part No. 45-2428.
CAB INETS AND SPEAKERS USED: Cahlnet
Type
BATTERIES REQ UIRED :
T
K
X
Speaker
Use d
KR26
HRlO
HRlO
"A" Batte ry: Two volt storage batte ry Philco t ype 172R or Dry "A"
hatt ery Philco Part No . 41-8011.
If a dry A l:!attery is used, a ballast lamp "type IFI" MUST be inserted in
t lie socke t provided in the (41-8011) batte ry. This lamp acts as a voltage regu lator
and maintains a constant potent ial of tw o vol ts on the filament of th e tubes .
"BC" Battery: Philco battery Part No. 41-8007 is used to supply "B" and
"C" voltages. This batter y con tains a soc ket into which the receiver battery cab le
plug is inserted.
Alignment of Compensators
EQUIPMENT REQ UI RED : (I ) Signal Generator, having a fun1amental
frequency range cove ring the tuning and int ermediate frequencies of th e receiver.
Philc o 11odel 07i A. C. opera ted Signal Genera tor or Model 088, battery operated
Signal Generator which have th e required frequency range .are the correct instru•
rnents for thi s purpose; (2) Output meter, Philco Model 026 circuit tester incor-
pora tes a sensitive ou tput meter and is recommended; (3) Philc o Fibre Handl e
Scr ew Driv er, Part -:,.Jo.17-i059 and Fibre \·Vrench, Part ~o . 316-t.
OUTPUT METER: The 0!6 Outpul ~Jete r is conn ected to the plate termin als
c,f ti1e lj 6G tube . Adju st the meLer to use th e (0-30) volt sca le and advance th e
atte nuat or contr ol of th e genera tor until a readable indicat ion is noted on th e
ou tput meter after sig nal is applied.
DIAL CALIBRATION: In order to adjust th e receiver correctl y t he dia l
must be aligned Lo track properly with th e tuning condenser. To adjust th e dial
proceed as follows:
1. Turn t he tuning condenser t o maximum capacity posit ion (p lates fu lly
meshed ).
2. Holding the tu nin g conde nser in thi s position, loosen the dia l clamp; th en
turn the dial until the indicator is ce nt ered on th e middle index line. Tighten clamp
1n thi s position. See Fig . 3 Cw
16A 168
'-._,/
7 7A
@)@@
Fi~. !. Locations of Co mp cnsators - Top of Chassis
1ST. AUDIO
~
A PHIi.CO Service Plan
Fli, 1. Socket Voltaiies, Underside of Chassis
The vol tages indi cated by ar rows were measured with a Philco 026 Circuit Tester
which contains a sensitive vol tm eter. Volume Con tr ol at minimum, range switch
in broadcast position.
INTERMEDIATE FREQUENCY CIRCUIT
Insert th e signal genera tor shielded outp ut lead into the "Med" jack on the
panel of Lhe generator. Conn ect the other end of the output lead through a .I mfd.
condenser to the grid of th e IC7 G Det. Osc. tub e and the gro und connectio n of
th e sig nal generato r to the chassis. Set th e signa l generator and receiver co ntr ols
and ad 1ust the I. F. compensators as follow s:
I. Set Signal Generato r at 470 K. C. Turn "M ultiplier" Con trol to 1000
and adjus t the attenuato r for a readab le indication on th e outp ut meter.
2. Turn the receive r dial to 580 K. C.
3. Receiver Vo lume Control maximum.
4. Range Sw itch Broadcas t Po siti on.
5. Adju sl compensa lors (16B), (16A), (15B ) and (15A) for maximum output.
lf the ou tput metn goes off sca le when adjus ting the compensators retard signa l
genera tor "attenuator."
RADIO FREQUENCY CIRCUIT
1'.mlng Ran iie: 5;7 to 18 M. C.
I. With one end of th e shie lded lead of th e signal genera tor outp ut cable in
th e '"Med" jack, connect th e other end through a 400 oh m carbon resistor to the
"'Ant." termina l of the aerial panel of the receiver . The output lead ground must
be connected to the "G nd" terminal or to the chassis.
2. Set the controls and adjust the R. F . compensat ors as follows:
Volume Ranie Slinal Generator Compensators
Control Switch and Receiver Dial In Order
Max. 2 18 M. C. (4B) See Not e A
Tuning Range: 530 to 1720 K . C.
Remove the 400 ohm resistor fr om the generator outpu t cable and rep lace
with a 200 mmfd. conaenser. Then set the controls and adjust the compensators
as follows:
Volume
Control
Max.
Max.
Max.
RanJ!e
Switch
I
Signal Generator
and Receiver Dial
1500 K . C.
580 K . C.
1500 K. C.
Compen sators
In Order
(7A), (4A)
(7)
(7A), (4A)
NOTE A-T o accurately adjust t he high frequency oscilla tor co mpensator to
th e fu ndamental instead of the image signal, turn the oscillato r compe nsator to the
maximum ·capaci t y positi on (clockwi se). From this position slowly turn the com 4
pcnsator coun ter•clockwise until a seco nd maximum peak is ob taine d on the output
mete r. Adjus t the compe nsator for maximum outpu t using this second peak. The
first peak from maximum capacity position of th e compensator is the image signal
and mu st not be used in ad ju sting the compensator.
If the above procedure is correc tl y performed , the image sig na l will be found
(much weaker) by turning th e receiver dial 940 K. C. below the frequency :being
used on the high frequency range.
Copyright 1937 Philco Rad io & Television Corparation
philcoradio.com

(
PageZ
Schem.
No.
Replacement Parts
Description Part
No.
1 Antenna Transformer Range (2) . .... ... 32-2558
2 Antenna Transformer Range (1) ........ 32-2667
3 Condenser (0.6 14 £, tubular) ............. 30-4519
4 Tuning Condenser ... . . .. .......... . .. 31-2025
5 Oscillator Coil Range (2) .......... • . ... 32-2668
8 Oscillator Coil Range (1) . . ........•.... 32-2559
7 Padding Condenser ..... ...... . .. . . . .. . 31-6188
8 Resistor (120,000ll, ½ W.) ..... . ...... 33-412339
9 Condenser (3500 1414 £, Mica). .. . . . . . . . . . 30-1094
10 Condenser (.05 14
£,tubular) ............. 30-4444
11 Resistor (1000 ll ½ W.) ..... ....... . ... 33-210339
12 Resistor (5000 ll, ½ W.) .... ..... ...... 33-250339
13 Electrolytic Condenser (4-2-2 ,.I) .... . 30-2241
14 Resistor (2000 ll, ½ W.) ............... 33-220339
18 First I. F. Transformer .... . ......... .. 32-2664
18 Second I. F. Transformer . .. . . . . . . . . . . . 32-2666
17 Oondenser (110,.,.f, Mica) . ..... . . ..... 30-1031
18 Resistor (1 megohm, ½ W.) ............ 33-510339
19 Volume Control.. ............... •..... 33-5234
20 Condenser (.016 ,.rtubular). .. . . . . •. . . . 30-4358
21 Resistor (8000 ll, ½ W.). . . . . . . . . . . . . . . 33-280339
22 Reeistor (I megohm, ½ W.) ............ 33-510339
23 Resistor (I megohm, ½ W.) ..... . . . .... 33-510339
List
Price
$0.70
1.60
.20
5.00
1.25
.50
.20
.40
.20
.20
.20
1.50
.20
2.20
GLOWING BEAM
INDICATOR
\
PHILCO Service Bulletin
@'
~
~
...... ~
(26)h_-j
11
t
.23
~r®
;~-®
\
No. 290
24 Condenser (ll01414f,Mica).... ... ..... 30-1031
28 Condenser (.016 ,.r,tubular)..... .. ... 30-4515
28 Qondenser (.15 ,.r,tubular) ... ... ... .... 30-4191
27 Resistor (240,000ll, ½ W.) .......... .. 33-424339
28 Resistor (240,000 ll, ½ W.). . . . . . . . . 33-424339
29 Resistor (I megohm, ½ W.)....... . . . 33- 510339
2.20
.20
.20
1.00
.20
.20
.20
.20
.20
.20
.25
.20
.20
.20
.20
.20
2.00
1>1111Calibration t,j
DIRECTION OF ROTATION
FROM REAR or SWITCH. ~iC-2,,.:1;--.____A_4_A_s_~-i-:~----:::-t-,--1-z...~~---~-j_ _____ L_j
1
4
j4 i,421•' :~ ~ !
30 Resistor (99,000ll, ½ W.)....... .. . 33-399330
31 Condenser (.02 14£,tubular) .. . . . . . . . . . 30-4215
32 Input Transformer... .. . . . . . . . . .. . . . 32- 7637
33 Condenser (.004 ,.£, tubular) .. . . .. . . . . 30-4456
34 Condenser (.004 ,.r,tubular) ........... 30-4456
35 Output Transformer. . . . . . . . . . . . . . . . . . 32-7758
38 Cone and Voice Coil Assembly......... 36-3540
37 Power and Tone Switch ..... . .. . ...... 42-1351
38 Resistor (900ll, I W.).. .. . . . . . . . . . . 33-1223
39 Range Switch. . ..... .. .... . 42-1358
40 Pilot Light. . . • . . . . .. . . . . 34-2150
Cable (Battery)... . . . . . . . •. . . 41-3198
Cable (Speaker)...... . ..... . . .. . . . . 41-3326
Clip (Mtg. R. F. Trans.) 28-5002
Dial. . . . . . . . . . . . . . . •. . 27-5333
Dial Washer . . . . . . . . . . . . . . . . . . . . . . . . . 27-4598
Dial Clamp . . . . . . . . .. . . . . .. 27-5089
Knob (Tuning). . . . . . . . . . . . . . . . . • . . . . 27-4330
Knob (Vernier)... ...... ... .. . ...... 27-4331
Knob (Tone, Volume) ........ . ...... . . 27-4332
Mtg. Rubber (Chassis) .. . ............. 27-4564
Mtg. Rubber (Tuning Condenser) ....... 27-4599
Mtg. Rubber (Screen Bracket) .......... 27-4670
Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27-5320
Shield (Tube). . . . . . . . . . . . . . . . . . . . . . . . 28-2725
Socket Assembly (Pilot Lamp). . . . . . . . . . 38-9002
.Socket (6 prong) ............ .. ........ 27-6086
Socket (7 prong). . . . .. . . . . . . . . . . . . . . . . 27-6087
Terminal Panel (Ant.)...... . . •. .. . . . . . 38-8849
Vernier Drive Assembly ... . .. . ..... . .. 31-2072
.20
.20
1.50
1.00
•20
.75
.22
1.40
.40
.60
.03
.11
.u
.10
1.00
sw,rcH sHowN IN Pos- °nc--t---=---.;.;,:;.;:.,;.)., __ _j
1 1 - ITION No 1 (BROADCAST) B+90VOLTS
J 2 SHOWN FROM REAR OF YELLOW-
CHASSIS (BOTTOM VIEW) BLACK-TR 8- C+ BLK ~WH ITE-TR .
G) RA~~~ 2 (2)RAANNd"E 1 @Rf,;gr_ 2 0R~:cc.TRANSFORMERS 5HOWN WITH
- \.,_u=J==E..!1 INDEX SLOT IN rRONT ,
Schem.
No. Description
MODEL38-38T
Bezel Frame Assembly
Bezel Gasket.
Bezel Glass
Bezel Ring ..
Speaker KR-26 .
MODEL38-38 K,X
Bezel Frame Assembly.
Bezel Gasket
Bezel Glass
Bezel Ring .. . . .. . • .. .. .
Speaker <HR-20).
Battery (A).
Battery (B).
Fig. 3. Schematic Dia11.ram 38-10, Code Ill
Part List
No. Price
40-6124 $0.90
27-8311 .01
27-8298 .05
28-5078 .55
36-1353 10.00
40-6128 1.05
27-8313 .OJ
27-8300 .06
28-5080 .70
36-1351
172R
41-8007
PHILCO RADIO AND TELEVISION CORPORATION
Parts and Service Division
July, 1937 Philadelphia, Pa. Printed in U.S. A. Fl!!.. 4. Part locatlons, Underside of Chassis
"'
':i
0
>
f;J
a:
"'
':i
0
>
~AA-N A+
Lf.=470 KC.
philcoradio.com