Bendix Radio Div. 1217D Schematic

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Model:1217D
Manufacturer:Bendix Radio Div.

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Page 1:

PAGE 19~20 BENDIX

MODEL l 21 7D

Fig, 1 Model 12170

BENDIX RADIO DIV.

SPECIFICATIONS

Power Requirements
105 - 125 volts, 60 cycles AC

Power Consumption (including phonograph)
180 watts

Tuning Frequency Range

Tube Complement
Total 14

8 mechanical type for any AM, SW, or FM

Loudspeaker
12~inch diameter electro-dynamic.

Record Changer
Automatic - twelve 10>>inch or ten 12-inch
standard records.

Maximum Power Output

Overall Dimensions
Height 34", width 31", depth 18%,".

CIRCUIT ANALYSIS

The Model 1217D radio provides radio re~
ception of the Standard AM Broadcast Band,
the Shortwave Band from 6 to 15.5 megacycles,
and the FM Band from 88 to 108 megacycles.
Phonograph reproduction is provided through
the audio amplifier from a high impedance
phono jack located on the radio chassis. A
standard superheterodyne circuit is used, with
one stage of tuned radio frequency on all three
bands. A low impedance loop antenna installed
on the back cover of the cabinet is used on both
the Standard Broadcast and Shortwave Bands.
A built-in dipole antenna is used on the FM
Band, An outside antenna for the AM Bands
may be connected to the binding screw marked
ANTENNA on the rear of the cabinet. A 300
ohm outside FM dipole antenna may be con-
nected to the terminals marked FM DIPOLE
but the built~in dipole must be disconnected
when an outside antenna is used.

CHASSIS CODE CHANGES

The schematic shown in Fig. 8 is for the
code D radio chassis and the code C amplifier
chassisA The data given below indicates the
circuit changes incorporated in the different
chassis as compared to this schematic.

RADIO CHASSIS
CODE C CHASSIS

First audio amplifier, SSN7, and AM demodu-
Iator, GHG, filaments were connected from pin
#1 of .I4 to ground, instead of being isolated
from ground and in parallel with the FM
detector GHG filament.

The audio output of the FM detector trans-
former (T5) was connected directly to pin #1
(grid) of the SSN'7 first audio amplifier. This
deleted C85. 86, 87, R72, and 73, Cathode byA
pass capacitor, 088, was not used; cathode
resistor R60 and grid resistor R59 were con`
nected to ground through a common 10K

De-emphasis filter capacitors in the output ~
circuit of T5, C51 and C53 were .002 mfd and

The Hush-O-Matic circuit shown in Fig, 9
was used in this chassis.

The 7F8 dual triode is used as an oscillator-
mixer in the FM circuit and is made inoperative
by removing its plate voltages when the range
switch (S1) is in any but the FM position.
Likewise, the 6BE6 is used as a converter for
the Standard Broadcast and Shortwave Bands
only, and has no plate voltage applied to it when
_S1 is in the FM or PH (phono) positions. One
half of the 6H6 (pins 3 and 4) AM demodulator
tube is used in the delayed AVC circuit for FM.
The first triode section (pins 1, 2 and 3) of the
6SN7 in the radio chassis is used only when the
range switch, Sl, is in the FM position, but
does not have the B plus removed from its
plate When Sl is in any of the other three
positions. The 6AQ6 and 6BA6 are used as
amplifier-rectifier and control tubes for the
Hush-O-Matic circuit and are inoperative on
radio reception.

AMPLIFIER CHASSIS

CODE B

The hum-balancing potentiometer R76 and
the voltage divider network consisting of R74
and R75 were deleted. The transformer Filament
winding used only for the FM detector (SHG)
was center tapped and this tap connected to the
cathodes of the 6V6 output tubes.

Some chassis coded B were identical to code

ADJUSTMENT 0F HUM-BA LANCING
POTENTIOMETER

The hum-balancing potentiometer, R76, on
code C amplifier chassis should be adjusted
with the range control in the FM position and
the volume control at minimum, Adjust R76 to
obtain minimum hum from the loudspeaker.

(C)John F. Rider

Page 2:

Bendix 69 Series

This model appears on pages 19-1 through
19-8 0] Rider'a Manual Volume XIX. The
location of trimmer C3c on gang capacitor in
Figure 8, Trimmer Location Diagram,
should be on terminal 4, rather than ter-

Air King A400. Minstrel: Ch. 470

This model appears on page 16-1 0/
Riders Volume XVI. The following mate-
rial should be added to that which ap-
pears in the Manual. The Voltage and
resistance measurements follow.

'mal ml v'an 20,0o0 Loco axsra'r/lkcl
use? 2 _1.3 -o.e ~o.c 5.2 ass
'1st AP <1 c -o.6- 0.13 2 nan
3515 2 Ac Ac inc
'122 +122 over Sour

Atl. aasrsrillcas Ill olrlls mlmss o'rllKawIsa llo'ran.
Au. votrica Alla llasrs'rlulcs rmAsllllBrlBll'rs mas lun

I-F Alignment

Connect an output meter across the
voice coil4 Connect the signal generator
to the primary of the antenna transformer
through a 10()qu capacitor.

Set the signal generator to 455 kc and
fully mesh the receiver tuning capacitor.

Keep the receiver volume control at
maximum and the output of the signal
,generator sufficient to give a readable
deflection on the output meter and adjust
i-f trimmers C15 and C14 for maximum.

Tor rlloNr vlrw "'

The lop ,front view of the Air King A400,
showing tubes and trimmer locations.

R~F Oscillator Adjustment

Keeping the same setup as used for
Lf alignment, set the signal generator for
1600 kc and adjust oscillator trimmer 013
for maximum output.

Set signal generator and receiver forl
1400 ko and adjust antenna trimmer 012
for maximum output.

' The parts layout and alignment points
are shown in the accompanying diagram.

The bolLam front m'ew a] the Air King
A400, showing parts layout.
Bendix 12l73. 12171)

Model 1217B appears on pages 19-9
lhl'ol/.gh 19-19 0/ Riders Manual Volume
XIX and Model 1217D appears on pages
1930 through 19-33 of Ruiefs Manual Volf
lame XIX. Hum can be corrected by
removing the shielded lead between the
tlro chassis from the plug assembly and
running it in through a separate connector.
All of the hum pickup is taking place at
the eight-prong plug on the radio chassis.
With the cable running in through the
chassis about two inches away from the
plug assembly, the hurn level is so low
as lo be almost immeasurable.

This model is thesame as Model 9-209
appeal-ins on paves 19-19 through 19.21 sf
Ihder's Volume XIX.

This model is thesame as Model 7151, ap-
pearing on pages 18-12 of Rider's Volume
XVIII, except for the following changes
Capacitor C55 (10 ani) connected from
pin 1 of the 7178 tube to ground has been
removed. The 0.003-uf capacitor C9 has been
changed to 1500 auf.

The position of the trimmers has been
changed. Looking at tho front of the set,
they are: C49 (broadcast trimmer), C51
and C52 (f-rn r-f trimmer).

A coil has been placed in the cathode
lead of the 7Q7 tube before this lead is
connected to C50. Capacitor C53 (15 auf)
has been changed to a variable capacitor
and is now connected between L5 and
ground, instead of across L5. The junction
of C50 and the cathode lead of the 7Q'I
tube is connected to the ground side of
this capacitor.

The 22,Mohm resistor, R51, connected
between R13 and ground has been elimin
ated. The side of ClB that is not connecteo
to R13 is grounded directly. The side of
the tone control, R14, previously connect
ed to C19 has been left open. R20 has been
changed from a 470,000-ohm resistor to a
l-megohm variable resistor. The movable
arm of R20 is now connected to pin 5 of
the 7F7 tube, and one side of R20 is con-
nected to the junction of C21, C22, and
023. C56, the 1500-plnf capacitor across the
filaments of the SBAG tube, has been re-

The first two models appear on pages
18-6 through 18-12 0]' Riders Volume
XVIII. The following changes have been
mode in production. Model K-ZSQ incor-
porates these changes. _

A 3-gang tuning capacitor is used, neoes
sitating changes in the r-f amplifier circuit.
'The 100,000-ohm resistor connected to the
grid (pin 1) of the BAGS r-f amplifier has
been changed in value to 1 megohm. The
load which was formerly connected from

CHANGES PAGE 20-1

the bottom of this resistor to the junctionl
of resistors 7 and 8 (1 megohrn and 4.7
megohms, respectively) is now connected
directly to resistor 4 (100,000 olurls) and
to D5 of switch section 2 roar. Resistors
7 and 8 have been eliminated.

The band-pass coil and the Htl-auf
capacitor which were connected between
the plate (pin 5) of the GAG-5 lube and
the third grid (pin B) of the 6SB7Y oscll-
lator convertor tube have been removed.
A connection has been made from the
plate of the 6AG5 tube through a lUO-plai
capacitor to DS of switch section 2 rear.
The third grid of the SSB7Y is stlll con-
nected to D2 of switch section 2 rear.>
The 100,000-olllrl resistor, which was for-`
merly connected between D1 of switch
section 2 rear and the junction of D4 ol
the same switch section and the 1000-ohm
resistor, has been removed. There is a
connection from D1 of switch section 2
rear and C1 of switch section 2 front,
indicutfd on the schematic by the black
dot on these connections.

The 0,005uf capacitor connected to C7
of switch section 2 front has been removed,
as has the wave trap and 100an capacitor
connected lo C1 of the same switch
section. The third section of the ganged
tuning capacitor is connected between Cl
and ground, and is shunted by the i-m
converter trimmer, and also by a bandY
pass coil <49) in series with a 0.05-ai
capacitor. A 100,000-ohm resistor is con-
nected from the junction of this capacitor
and coil to D4 of switch section 2 rear.
A 0,01-af capacitor in series with a coil
is connected from this common ground
point lo the junction of the 47000hln
resistor and the r-l choke in the plate
circuit of the 6AG5 r-f amplifier. A 47,000-
ohm resistor has been connected in the
line going between A3 of switch section
1 front and the junction of the 47,0000hm
resistor, the 470,0000hm resistor, and the
100-nnf capacitor in the filter circuit of
the a-ni detector.

The following step should be included in
the a-m alignment table on page 18-1
between steps 6 and 7.

Step Connect Set generator Set Gang

Generator Al At
Binding Post
Adjust To Oblain
BC R-F Trimmer Maximum ,
Output

The following additions should be made
to the parts list.

Ref. Part. Description

21 25456 ell-asf ceramic capacitor

34 25182 lil-af tubular Cnpacitol, 200 volts

so 26271 Tunlnz capacitor

46 13166 Loop smenna miouse, .083; Kose)

le mal Imp antenna (GK-oss. .057;

41 38932 F-m antenna wil

50 25181 0.05-uf tubular capacitor. 200 volts

sl :tacos rum maven" wil

sz 38934 nm cseillatur coll

'ls was Pilot lamp, zso mi (mom. .naar

'ls 42m Pilot lamp, Males ss (K-'sm
22m Pickup cable (GK-usa, oss, K-call
zzlcu Pickup cable lGK-css. oss. - s1~

slizl A-m dlsl glass (renal, -oasl
31122 Fun ulal glass lK-osl, -osai
class A.m dial glass (li-289)
:um dial glass 4K-sz)
allal Dial sssutcheon (Keel. -ossl
$2192 DIll drive 60rd (45 inches)
stool Band swivel. lever llc-om, -ossl

54310 Band switch lever (lt-259)
59451 Knobs (lt-054, ~oasl

92229 Dial background (Ii-084)
60565 Eseutchecn backing (lc-289)

H-zsll-l Cabinet and carton for K-osl (walnut)
H-zss~2 Cabinet and carton for K-om (blonde)
H-zas-l Cabinet and carton for K-oxa lwnlnntl
Hass-2 Cabinet and canon lm- K-ose lblcndel
11-315 Cabinet and nal-ton lor K-zss

? John F. Rider

Page 3:

BENDIX PAGE

BENDIX RADIO DIV.

GENERAL

lt is not necessary to remove the two chassis
from the cabinet if the FM channel only is to
be aligned. An FM test socket is provided on
the chassis sideplate (facing outward in normal
mounting position) at which the various volt-
ages from the ratio detector are available for
either meter or oscilloscope measurements,

If the BC and SW channels are to be aligned,
it is advisable to remove the radio chassis from
the cabinet in order to gain access to the BC
and SW AVC voltage used for output indication.
It is rather difficult to align the BC and SW RF
and IF sections when the volume control is full
"ON" because of background noise accompany-
ing the high gain of' the audio amplifier. A DC
vacuum tube voltmeter connected to the junc-
tion of R20 and C40 (lug 3 of SLE-See Figs.
7 & 13) will provide an accurate and stable in-
dication of RF output, at the AM demodulator,
for alignment of the BC and SW bands.

Unless the various circuits of each channel
are very much out of alignment, adjustments
madev in the SW circuits will not affect the BC
circuits and adjustments made in the FM cir-
cuits will not alter either the BC or SW circuit
adjustments. However, if any of these channels
are badly out,0f alignment necessitating con-
siderable adjustment, 'it is best, after these
adjustments have been made, to go back and
check the adjustment previously made on the
other channels.

An un-modulated (CW) signal of the proper
radio frequency may be used for meter align-
ment of all three channels (BC, SW, and FM),
but it is convenient to use a 400 cycle AM signal
during alignment and occasionally advance the
volume control to be sure the correct signal is

tuned in.
Before making any adjustment, allow the

receiver and signal generator to warm up for
at least five minutes. IMPORTANT: All ad-
justments must be made in the order in which
they are given; ie., the BC band must be
aligned first, followed by the SW, and last, the
INSTRUCTIONS FOR REMOVING
THE CHASSIS

If, for any reason, it is necessary to remove
the radio chassis from the cabinet, proceed as
per following instructions:

Remove the power cord plug from the
wall receptacle, and remove all control
knobs and push-buttons by simply pulling
them straight up from the panel. The cabi-
net back cover and AM loop assembly may
be detached from the chassis by pulling the
loop leads out of their receptacle on the
chassis, after the small wood screws hold-
ing the assembly on the cabinet have been
removed. The FM antenna is disconnected
from the chassis by removing the three
prong plug at the rear of the chassis. All
power cables and leads may be disconnected
at convenient plugs and jacks in the
chassis. The speaker is connected to the
amplifier chassis by a 5-pr0ng plug on the

After all connecting leads and cables have
been disconnected from the chassis, remove the
four hexagon-head machine screws which hold
the chassis mounting rails in the cabinet. The
two upper machine screws are removed from
inside the record changer compartment. The
two lower bolts are located below the radio
chassis and removed from the chassis side of
the cabinet. Note: When replacing the chassis
in the cabinet, be sure dial glass is up snug
against the control panel when the four mount-
ing screws are tightened and that they are
tightened securely.

PUSH-BUTTON ADJUSTMENT

The mechanical type of push-button tuning
used with this receiver makes possible the
selection of any one of eight pre-selected
stations. Any push-button may be adjusted to
select any station in the three tuning bands.
However, more accurate tuning of the SW and
FM stations will be obtained if the lower four
buttons E, F, G and H, Figures 2 & 3, are
used for stations within these bands.

1. Remove all push-buttons by pulling
straight up from the panel.

2. Manually tune in the desired station,

3. Release the screw adjacent to the push-
button shank and push the shank in firmly
as far as it will go while holding the tuning
control knob.

4. Release the shank and tighten the locking

5. Rotate the tuning control to a different

` position and check the push-button setting
by again depressing the shank previously
adjusted. The tuning dial should auto-
matically return to the stations previously
tuned in. However, in some cases it may
not be exactly on the peak frequency of the
stations. In such cases, continue as follows:

6, Re-tune the station manually to its peak
frequency, and note whether it is necessary
to increase or decrease the frequency set-
ting for optimum tuning.

7. If it is necessary to increase the dial
frequency setting, then the dial should be
set'at an additional increase beyond the
optimum point (approximately the amount
of the increase) and procedures 3, 4, 5 and
6 repeated. The push-button should then
tune in the station exactly on its peak

S. If it is necessary to decrease the dial
frequency setting, then the dial should be
set at a lower frequency from its optimum
point (approximately the amount of the
decrease) and the procedure in 3, 4, 5 and

9. Repeat the above procedures for the re-
maining seven push-buttons.

After the push-buttons have been set up as
previously described, the proper tab with its
transparent cover should be inserted together
in each push-button knob. The push-buttons
should now be placed on the proper shanks.

(C)John F. Rider

MODEL 1 17

Page 4:

"?1E 19-22 BENDIX

MODEL

2. Set s

ALIGNMENT PROCEDURE

EQUIPMENT REQUIRED

Signal Generator
FM, 10.7 MC and 88 to 108 MC.

Vacuum Tube Voltmeter
DC up to approximately 20 voltsA Ground,
or minus, must be isolated from the power

Oscilloscope

FM Test Circuit Plug
See Fig. 7 for details.

.01 mfd and 50 mmf (or less) capacitor
used for connecting signal generator to

Alignment Screwdriver
Must be 100% non-metalic and preferably
over 8" in lengthl

Alignment Socket Wrenches-must be non-

One 1A." hexagon, 8" long.
One Iii," hexagon, 6" long4
It' the "3," wrench has a hole through the
handle of sutlicient diameter to permit in-
serting the alignment screwdriver, the
locking nuts on L1, L2 and L3 can be
loosened or tightened at the same time
these padders are adjusted with the screw-
driver inside.

AM ALIGNMENT
Turn receiver and test instruments on and

allow to warm up for at least 5 minutes. (Input
voltage, 117 volts 60 cycles AC). Set volume
control to minimum, bass and treble controls
full counterclockwise,

range control to BC
hird from most counterclockwise position),

tuning gang fully closed. Set dial pointer to
Reference Mark at low frequency end of dial as
shown on Fig. 6. If built-in AM loop antenna

disconnected, the two contacts of the AM

antenna input _iack located on top the chassis

ust be shorted together. C69 and C4 should

be adjusted with loop connectedA

IF CHANNEL
1. Short :7:5 terminal on gang (C2-F) to

. See Fig. 2,

and connect to #3 gang terminal (CZ-F.)
through a .01 mfd capacitor. See Fig. 2.

3. Connect lou' range of V.T.V.M. to junc-

tion oi' R20 and C40 (lug 3 of switch Sl-E
is a convenient point~See Figs. 8 & 13),
and chassis ground, and adjust signal
generator attenuator to produce approxi-
mately 2 volts of AVC. on the V.T.V.MA

4. Adjust C24 (BC oscillator trimmer) for

maximum meter reading, keeping signal
input to produce approximately 2 volts
AV(`. Repeal these adjustments until no
further improvements can be made in any
one ot' them. NOTE: All adjustments
must be made with a completely non-

HL` OSCIliLATOlit ALIGNMENT
2. More signal input from #3 gang terminal

Remove short from #5 gang terminal.

to external AM antenna terminal (JI)
and set input frequency to 1475 KC CW
or AM. (V.T.V.M. remains connected as

Set 'tuning control to 1475 KC.

4. Adjust C24 (BC oscillator trimmer) for
maximum meter reading.

5. Set signal generator and receiver dial

6. Adjust BC oscillator padder C26 for max-
imum meter output4 Repeat~steps 2 to 5
until oscillator tracks correctly. Any change
in C26 will necessitate a readjustment of
oscillator trimmer C244

RF AND ANTENNA ALIGNMENT

FOR BC BAND

1. Change coupling capacitor connecting

signal generator to AM external antenna
terminal from .01 mfd to 50 mfd or less.
(Terminals of AM loop input jack must be
shorted together if loop is disconnected.)
Adjust signal generator and receiver tun-
ing control to 1475 KC.
Adjust BC oscillator trimmer, C24, BC RF
trimmer, C12. and BC antenna trimmer,
069, for maximum output. (If AM loop is
disconnected, C69 should be adjusted after
chassi is installed in cabinet.) Rock tuning.
gang slightly for maximum output as ad~
justments are made.
Check overall tracking at 580 KC and
965 KC. Maximum output should occur
within the i 10 KC of the indicated dial
pointer reading. If it falls outside these
limits, the plates of the gang rotor should
be bent to correct tracking, but this is
a dithcult operation and should be at-
tempted only by experienced technicians.
Bending the plates of the gang rotor will
likely cause mistracking on the shortwave
Repeat steps 3 and 4 until no appreciable
improvement can be obtained by additional
adjustments

SW ALIGNMENT
V.T.V.M. and signal generator remain con-
nected as for preceding step 5 of BC RF
and antenna alignments; range switch in
SW (most clockwise position).
Set signal generator and tuning control to
Adjust SW oscillator trimmer (C23), SW
RF trimmer (C11), and SW antenna
trimmer (C4) for maximum output, NOTE:
If circuits are badly out of alignment. it
may be necessary to apply the signal first
to terminal #3 on gang (CZ-E) until
oscillator is brought close to correct align-
ment. The local oscillator frequency in the
receiver should be adjusted to the RF plus
the IF (not below the RF). The correct
position can be determined by turning C23
all the way in (clockwise) and then out
(counter-clockwise) until the second peak
Tune receiver and signal generator to 6
MC and check calibration and output.
Maximum meter reading should be obtained
with the dial pointer i 100 KC ofthe 6 MC
dial reference mark and an AVC output
voltage not less than one-half of the AVC
voltage obtained at 15 MC, providing the
same voltage is applied to the antenna in
both cases.

(C)John F. Rider

Page 5:

BENDIX PAGE 19>>2'

BENDIX RADIO DIV.I

FM ALIGNMENT
Cw _ METER METHOD

Turn receiver and test instruments "ON" and
allow to warm up for at least five minutes.
(Input voltage, 117 volts 60 cycles AC.) Set
volume control to minimum, bass and treble
controls full counterclockwise, range control to
FM position (second from most counterclock-
wise position), and tuning gang fully closed.
Dial pointer should be over Reference Mark as
directed in first paragraph of AM Alignment.
Connect FM dummy antenna to FM antenna
binding screws on receiver.

1. Insert special FM test circuit plug, detailed
below, in test circuit jack JZ located on
left side of radio chassis. See Fig. 2 & 7.

2. Connect V.T.V.M. ground or "minus" lead
to point "B" and "plus" lead to IF pin on
test circuit plug.

3. Connect signal generator to #4 (02-8)
gang terminal through a .01 mfd capacitor
and short #6 gang terminal (CZ-C) to
chassis. See Fig. 2.

4. Adjust output of signal generator to obtain
10.7 MC CW and approximately 4 volts on

5, Adjust C358, C35A, C288, C28A, and
C46A for maximum meter reading, repeat-
ing all adjustments several times. NOTE:
It may be necessary to apply the 10.7 MC
signal to pin 6 of the 1st IF tube (7AH7)
and adjust C358, C35A, and C46A before
applying the signal to #4 gang terminal
and adjusting C288 and C28A.

6. Change V.T.V.M. "minus" to point "A"
(center tap of two 100 K resistors) of test
circuit jack and "plus" lead to audio

7. Turn signal generator "OFF" and set meter
to zero When no signal is applied to IF.

8. Turn signal generator "ON" and adjust
C468 for zero output on meter. It may be
possible to obtain two or more points of
adjustment at which a zero meter reading
can be obtained The correct one is the
one at which the meter passes through zero
most sharply with the minimum rotation

9. Alternately adjust C46A (3rd FM IF pri~
mary) for maximum DC voltage across
pins "B" and "IF" (meter connected as for
previous IF alignment), and C468 (3rd FM
IF secondary) for minimum DC voltage
from point "A" to "audio" NOTE: In
making this adjustment, the signal input
level should be adjusted to provide approxi`
mately 6 volts DC across pins "B" and
"IF" o_f test jack.

10. Remove short from #6 gang terminal and
change signal generator input from gang
to FM antenna. jack on> rear of radio
chassis, applying signal through FM
dummy antenna circuit shown in Fig. 3.

11. V.T.V.M. should be connected from point
"B" to "IF" of test circuit plug.

12. Adjust signal generator and tuning control
to 106 MC and output to produce approxi-
mately 10 volts on V.T.V.M.

13. Using a completely non-metalic l/j" hexa-
gon socket wrench, adjust FM oscillator
trimmer (C22), FM RF trimmer (C10)
and FM antenna trimmer (C1) for maxi-
mum output voltage read on V.T.V.M.,
rocking the tuning gang slightly as these
adjustments are made. NOTE: Be very
careful when adjusting these trimmers,
not to spring them and thus cause them t0,
become shorted.

14. Set signal generator and tuning control to

15. Adjust FM oscillator padder (L3), FM RF
padder (L2) and FM antenna padder (L1)
for maximum output voltage. The 3/5"
locknut on these padders must be loosened
before adjustments are made and tight-
ened after adjustments are completed.

16. Repeat steps 13, 14 and 15 until maximum
output voltage is obtained with the dial
pointer at 90 MC and 106 MC when the
signal generator is set at these respective
frequencies. Any adjustments made under
step 15 above must be followed by re-
peating the adjustments required under
step 13.

VISUAL METHOD

The antenna, RF, oscillator and first and
second IF stages are aligned with a CW signal
in the same manner described under the CW-
meter method of alignment The adjustment of
the third IF, or ratio detector, determines to
a considerable degree the fidelity and.tuning
characteristic of the receiver; therefore, the
visual method, using an oscilloscope and FM
signal, of aligning this stage may give better
results then the CW ~ meter method. Numerous
advantages can be given for either method.
The best method to use depends not only on the
type and quality of the test instruments avail~
able, but also on the ability and experience of
the technician.

Turn receiver and test instruments "ON" and
allow to warm up for at least five minutes.
(Input voltage, 117 volts 60 cycles AC.) Set
volume control to minimum, bass and treble
controls full counterclockwise, range control to
FM position (second from most counterclock~
wise position), and tuning gang fully closed.
Dial pointer should be over Reference Mark as
directed in first paragraph of AM Alignment.
Connect FM dummy antenna to FM antenna
binding screws on receiver.

1. Connect V.T.V.M. ground or "minus" lead

to AVC pin of test circuit jack (JZ) located
on left side of radio chassis. (See Fig. 2).

(C)John F. Rider

MODEL l 21 YD

Page 6:

PAGE 19-24 BENDIX

MODEL 121 7D

BENDIX RADIO DIV.

FM ALIGNMENT

The test circuit plug used for the CW -
meter method of FM alignment may be
used throughout the following visual align~
ment procedure for providing convenient
points of connections to the test circuit
jack. The two 100 K resistors connected to
the test circuit plug and used during the
CW-meter method are not needed when
the visual alignment procedure is followed,
but do not affect the circuit any great
amount and therefore may be disregarded.
. Connect signal generator to #4 (CZ-B)
gang terminal through a .01 mfd capacitor
and short #6 gang terminal (CZ-C) to
chassis. See Fig. 2 for gang terminal
Adjust output of signal generator to obtain
10.7 MC CW and approximately 6 volts
on the V.T.V.M.
. Adjust C358, C35A, C28B, and C46A for
maximum meter reading, repeating all ad-
justments several times.
Connect test equipment as shown in Fig. 4.
Some oscilloscopes have phasing controls
and a 60 cycle sine wave horizontal sweep
provided internally. If such an oscillo-
scope is available, the horizontal input
connection and phasing capacitor shown in
Fig. 4 are not required. The vertical input
to the oscilloscope is connected to the
AUDIO pin on the test circuit jack and
the ground of the oscilloscope connected to
the receiver chassis. Connect V.T.V.M.
ground or "minus" lead to point B and
"plus" lead to IF~pin on test circuit plug.
. Connect signal generator to #4 (C2B)
gang terminal (See Fig. 2) through a .01
mfd capacitor and short #6 gang terminal

. Adjust output of signal generator to obtain

10.7 MC FM and approximately 6 volts on
the V.T.V.M. The sweep width of the
FM signal must be at least 200 KC plus
and minus the center frequency. An "S"
curve similar to Fig. 5 should now appear
on the oscilloscope, but it will likely be
necessary to adjust the signal generator
frequency slightly in order to properly
center this "S" curve on the oscilloscope
screen. If a double trace appears, as shown
in Fig. 5b, adjust the phasing control
(may be built in the oscilloscope or the
phasing capacitor shown in Fig. 4) until
a single trace is obtained.

Adjust C46A (ratio detector primary) to
obtain maximum V.T.V.M. reading and
C46B (ratio detector secondary) for best
symmetrical "S" curve on oscilloscope.
Repeat these adjustments several times.
Remove short from #6 gang terminal and
change signal generator input from gang
to FM.antenna jack on rear of radio

chassis, applying signal through FM
dummy antennacircuit shown in Fig. 3.
V.T.V.M. should be connected from point
"B" to "1F" of test circuit plug.

Adjust signal generator and tuning control
to 106 MC CW and output to produce
approximately 10 volts on V.T.V.M.
Using a completely non-metalic 1A." hexa-
gon socket wrench, adjust FM oscillator
trimmer (C22), FM RF trimmer (C10)
and FM antenna trimmer (C1) for maxi-
mum output voltage read on V.T.V.M.,
rocking the tuning gang slightly as these
adjustments are made. NOTE: Be very
careful when adjusting these trimmers, not
to spring them and thus cause them to
become shorted.

Set signal generator and tuning control to

Adjust FM oscillator padder (L3), FM RF
padder (L2) and FM antenna padder (L1)
for maximum output voltage. The 3/3"
locknut on these padders must be loosened
before adjustments are made and tight-
ened after adjustments are completed.
Repeat steps 11, 12, 13 and 14 until maxi-
mum output voltage is obtained with the
dial pointer at 90 MC and 106 MC when
the signal generator is set at these respec-
tive frequencies. Any adjustments made
under step 14 above must be followed by
repeating the adjustments required under

It is possible to visually align the ratio
detector transformer (C46A & C468)
after the oscillator, RF and antenna cir-
cuits, have been aligned. In some cases this
may be desirable, especially if the output
of the FM signal generator is rather low at
10.7 MC. If this method is followed, align
the IF channel up through C46A (ratio
detector primary) and the oscillator, RF
and antenna circuits as directed above,
using a CW or AM signal and the V.T.V.M.
connected across the ratio detector load
resistor. (Point B and IF of the test cir-
cuit jack as shown in Fig. 2). Then, with
the oscilloscope and V.T.V.M. connected as
directed in step 5 above and the signal
generator still connected to the FM an-
tenna input through the FM dummy
antenna, apply an FM signal of any fre>>
quency between 90 and 106 MC and adjust
the receiver tuning control to center the
resulting "S" curve on the oscilloscope
screen. The ratio detector transformer
(C46A & C46B) may now be adjusted in
exactly the same manner as directed in
step 8, except that it may be advisable to
adjust the output of the signal generator
to produce approximately 10 volts on the
V.T.V.M. instead of 8 volts.

(C)John F. Rider

Page 7:

BENDIX PAGE 19-2 S

Em EEG _Ss R .QE
525;: NNQ 5550on x 9.51. _: Sago ~P

Rider

Page 8:

PAGE 19-26 BENDIX-

IMODEL 12171) BENDIX RADIO DIV. I

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ON FRONT PANEL r

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Fig. 12 Component Diagram-Bottom View Radio Chassis

(C)John F. Rider

Page 9:

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Fig, 8 Schematic Diagram

(C)John F. Rider

Page 10:

BENDIX PAGE 1927;'28

IX RADIO DIV, MODEL 12171)
socnU 71% vo co'wow snows u

Page 11:

BENDIX PAGE 1 -29

BENDIX RADIO DIV.

MODEL 121m

Rider

(C) John F.

Page 12:

PAGE 19~30 BEllDIX mmm.: nun-"n
IHODEL 1217D . BENDIX RADIO DIV.

m nun

BAND-SWITCH SHOWN
AT 3'w POSITION CLOCKWISE ,
BROADCAST BAND

BAND-SWITCH SHOWN
AT 4'" POSITION CLOCKWISE.
SHORT WAVE BAND

(C) John F. Rider

Page 13:

(C)John F. Rider

Page 14:

PAGE 19-32 BENDIX

MODEL 12171) BENDIX RADIO DIV.
REPLACEMENT PARTS LIST
Sink Nllkr Symllol Number I Demlplluu Shack Number Symh( Number I Desrrlpiion
4:04110 (015.14111 (41101100-10101" raw 004 m4( 400v i225" sung,"
"491mg" Mammal (DMNNEMS ICZZHSSM (MMM) liSlSTOl-Cemp. 1.5 meg VJ!
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cram (015,101 011401101400101011 1.110141144111111( :10% 500 "mm" "7U" "SWR-"W 3m '/'V

(C)John F. Rider

Page 15:

BENRIX PAGE 1973

BENDIX RADIO DIV. MODEL 1217D
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"Hmm (N45) ) "00(_Bm (Md "1001 PLUG-Single Contact Phono
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(C)John F. Rider

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