United American Bosch Corp. 305-A Schematic

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Product Information:
Model:305-A
Manufacturer:United American Bosch Corp.

Schematics Content:

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Page 1:

Boson msn s 13 0
UNITED AMERICAN BOSCH CORP. 3?h,,"gi?
Resistor Colm' Code
SCHEMATIG WIRING DIAGRAM - MQPEL 505A
c-1 ) vuimna. C-11 .5 - 2 p1y R3 - 25,ooo ohm
0-2 _ V C-12 .0004 mica _ R4 - 305300 ?hm>>V _
c-4 vo to 140 mr. 0- C-*14 ms - z ply R6 - 2,0001 ?hm= N
c-5 .os - 2 ply , 0-15 .ooasf la"p1y nv - 25;??? ?'"?? f
c-6 ~ uasf' 2 ply * f V -C-16 e msd; W R5 500.000 ?hm_
C-7 .01 - 3 ply _ C-l7 4_mfd. _ 'l ~ R9 v 500,000 ohms
G-8 70 to 140 mmf. ' C-'18 ;01 4 ply ' R10 100,000 ohmo
C-9 'I - 80 mf. Rl - volume control R11 ' 5 ?hm5 (mid WP)
G-10 1-eo mmf. R2 - :soo ohms R12 - 40? ?hm=
RESISTOR coma `C01;)E A I
500 ohms or?lnge J f black - ,. brown
400 ohm yellow - f black , - 'brmm
2000 ohmk red - _N V black 0 . - fed .
7500 ohmo ' violet - green -'_ rod -
25,000ohms red - green - orange
50,000 ohms orange - black - orange
100,000 ohms 'biown - 'black - yellow
500,000 ohms green - black - yellow

Page 2:

PAGE 3-14~ BOSCH _
MODEL 305-A
Voltage UNITED AMERICAN BOSCH CORP.
Adjustments
M A W Stage Tube g Fil . Plate Screen Cathode Grid
Output 47 2. 5 235 248 0 17
Note: The se values are readingscf e high resistance voltzneter from each
socket terminal to ground. The filament voltages are, of course, anvexoep-
tien. Cathode readings are given for those tubes having the grid at ground.
The values are only approximate and will vary with the line voltage and the
type of meter employed. '
3 A ALIGNING INSTRUCTIONS --- MODEL 305-A
1. Connect volume indicator to speaker. _
2. Set volume control on max. '
3. Connect generator to grid of lst I. F. tube, and adjust beth oondensers
' on coil nearest the back of' set to max. output.
4. Sensitivity should be 3200`m. v.
5. Connect signal generator to grid of lst det.; adjustgboth oondensers on
forward coil to max: output. `
. Sensitivity should be 30 m. v. with gang closed.
6. Check I. F. stability.
OSC ILLATOR ADJUSTMENT
l. Connect R. F. signal generator to antenna lead.
2. Set scale to 100 with gang closed tight.
, 3. Withgenerator set at 1400 K. C. and dial scale at 2l,, peak the os-
cillator trim condenser. This condenser is the baok alignment con-
denser on gang. 'F
4. Check sensitivity at 1400 K. C. Limits 5 m. v.
Set dial 50 1000 K. C. Limits 10 m. v.
Set dial 89 600 K. C'. Limits 30 m. v.
Set dial _BOO K. C. Limits 20 m. v. '
If it is neoessary~to improve sensitivity at 600 or l0(DK. C., adjust
plates until the set reaches the sensitivity limits. If bending
rvlates does not help, change tubes.

Page 3:

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