ANT.
WESTINGHOUSE MODELS 1015X & 1015Y
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Ca 6 149
Range Selector Wiring Diagram
I.F. Amplifier:
The intermediate frequency amplifier consists of 2 W.6K7
tubes in a two stage transformer coupled circuit. The windings
of all three I.F. transformers are resonated by fixed capacitors
and are adjusted by moulded magnetite cores, (both primary
and secondary) to tune to 460 Kc. A third winding, L15, in
the first S.F. transformer is placed in aeries with the mein secon-
dary L14 when the fidelity control switch 8-8 is thrown to the
"broad" position (see schematic diagram), thereby increasing
the coupling between the primary and secondary circuits with
consequent broadening of the band width of the I.F. amplifier.
The increase band width of the I.F. amplifier therefore causes
less attenuation of the higher audio modulation side band fre-
quencies, permitting higher fidelity reception.
Second Detector and A.V.C.:
The modulated signal, as obtained from the output of the i -f
system, is detected by one of the diodes of the W -6H6 tube,
Audio frequency secured by this process is paned on to the
control grid of the W -6F5 for amplification before final reproduc-
tion. The d -c voltage, which results from detection of the signal,
is sad for automatic volume control. This voltage, which
develops coron resistor RI4 is applied as automatic control grid
bias to the first detector and i -f tube. through a suitable resistance
filter.The other diode of the W -6H6 tube is used to supply normal
bias to the fret detector and id radiotrons until such time as
the rectified signal voltage is great enough to overcome the
normal hiss voltage and start the automatic volume control
action.A portion of the range selector switch (8.7) is used to change
the minimum bias on the radiotron controlled by the AVC
voltage, so as to reduce the minimum bias and increase the
sensitivity of the receiver on the "medium wave" and "short
wave' position. R.F. Alignment Points
When adjusting the Air Dielectric R.F. trimmers, it is neces-
sary to use a special tool (See H-29644 in parts list) to slacken
the lock nut on the trimmer, previous, to the adjustment, and to
tighten it again after the adjustment. .mother special tool
(See H-29643 in parts list) is available for making the actual
adjustment to the trimotor. The adjustment should be made
upward or downward on the plunger with a twisting motion -
The special tool designed by the Canadian Westinghouse Com-
pany for this purpose is double ended: one end having a pin for
the R.F. adjustments, the other end is a special socket screw
driver for use in making I.F. ad ustments.
1500 AC. 41
5000 KC.
17000 KC. ®
I500 KC. *
5000 KC, 0
17000 KC. ®
1500 KC. OO
5000 KC. ®
14000 KC, ®
[E11lE1ll-1
600. KC
SERIES TRINiN1ER
ANT.
DET.
DSC.
The procedure outlined below should be followed in adjusting
the various trimmer capacitors and molded corn:
WHEN ALIGNING THE R.F. CIRCUITS, THE CHAS-
SIS BOTTOM SHIELD MUST BE IN PLACE ON THE
CHASSIS AND SECURELY FASTENED WITH ALL OF
THE RETAINING SCREWS. IF THE CHASSIS BOTTOM
PLATE IS REMOVED, COIL SHIELDING WILL BE IN-
COMPLETE AND THE R.F. CIRCUIT WILL OSCILLATE.
WHEN ADJUSTING I.F. CORES WITH THE CHASSIS
BOTTOM PLATE REMOVED OR DOING TROUBLE
SHOOTING ON THE CHASSIS, OSCILLATION MAY BE
PREVENTED BY USING A SHORT LENGTH OF WIRE
WITH TWO CLIPS TO CONNECT TOGETHER THE PAR-
TITION SHIELDS BETWEEN THE ANTENNA AND
DETECTOR COILS, AND BETWEEN THE DETECTOR
AND OSCILLATOR COILS.
I.F. ADJUSTMENTS USING CATHODE
RAY EQUIPMENT
1. Set up the Cathode Ray Equipment in the manner re-
commended
mended by the ,manufacturer of the equipment. The fre-
quency modulated oscillator should be connected to the control
grid cap of the W -6K7 second I.F. radiotron (with grid lead in
place), through a .001 Mfd. capacitor. The grounded side of
the test oscillator output should be connected to the receiver
chassis frame. The cathode ray oscillograph vertical terminals
should be connected to points indicated on the radiotron socket
voltage diagram.
2. Place the receiver in operating condition with the fidelity
switch on the tone control in the counter -clockwise or selective
position. The antenna and ground terminal should be short
circuited and if necessary the gang condenser adjusted so that
no stray signals are fed into the I.F. amplifier during the adjust-
ment.Adjust the test oscillator to supply a 460 Kc. audio -modulated
signal. Increase the output of the test oscillator until a deflec-
tion is noticeable on the oscillograph screen. The figures ob-
tained represent several waves of the detected signal, the ampli-
tude of which may be observed as an indication of output. Cause
the wave -image formed to be spread completely across the screen
by adjusting the "Horisontal gain" control. The image should
be synchronized and made to remain motionless by adjusting the
proper oscillograph controls.
3. Adjust the two magnetite core screws of the third I.F.
transformer (see radiotron socket voltage and I.F. terminal
location diagram) to produce maximum vertical deflection of the
Bcillograph image. This adjustment places the transformer in
exact resonance with the 460 Kr. signal.
4. Set up the cathode ray and test oscillator equipment in
the standard manner to provide a frequency modulated signal
and a "double trace" image.
5. Adjust the frequency of the test oscillator until the two
traces move together and overlap with their highest points
exactly coinciding.
6. Now readjust the two magnetite core screws on the third
I.F. transformer so as to cause the two traces on the oscillograph
screen to coincide throughout their lengths and have maximum
amplitude.
7. Without altering the adjustments of the apparatus, shift
the "Ant." output of the test oscillator to the control grid cap
of the W -6K7 first I.F. radiotron (with grid lead in place), through
the .001 mfd. capacitor. Adjust the test oscillator output so
that the amplitude of the image is approximately the same as
used for adjustment (6) above.
8. The two second I.F. transformer magnetite core screws
should then be adjusted so that they cause the forward and re-
verse traces to become coincident throughout their lengths and
have maximum amplitude.
9. Without altering the adjustments of the apparatus, shift
the "Ant." output of the test oscillator to the input of the I.F.
system; i.e., to the grid cap of the W -6L7 first detector (with
grid lead in place) through the .001 mfd. capacitor. Regulate
the test oscillator output so that the amplitude of the oscillograph
image is approximately the same as used for adjustment (8)
above.
10. The two first I.F. transformer magnetite core screws
should then be adjusted so as to cause the forward and reverse
waves to become coincident throughout their lengths and have
maximum amplitude.
11. Note width of oacillographic image at a point which is
50% of maximum amplitude. Turn receiver fidelity control to
extreme clockwise position (high fidelity position). Note width
of oseillographic image at a point which is 50% of maximum
amplitude. Under normal conditions the Tatter measure,nent
should be approximately 60% greater in width than the former
measurement. The image should also appear slightly double
humped. These conditions indicate proper broadening of the
band width of the I.F. amplifier.
12. Turn range selector to "Medium wave" position and
note increase in amplitude. The amplitude should increase
several times. It may he necessary to decrease output of test
oscillator to keep image on screen.
I,F. ADJUSTMENT WITHOUT CATHODE
RAY EQUIPMENT
In most cases provided the I.F. transformers have not been
very badly put out of adjustment, it is possible to secure reason-
ably good results by alignment with a simple 460 K.C. audio
modulated oscillator and standard output indicator. The adjust-
ment should be made in a similar manner described fhr the
cathode ray equipment, but of, course, the I.F. cores should be
adjusted for maximdm output indication only. The adjustments
must be done in the order given and must be done carefully or
unsatisfactory operation of the high fidelity switch will result.
No attempt should be made to adjust the I.F. cores with the high
fidelity switch in the clockwise or "broad" position.
R.F. ADJUSTMENT
Before attetaptiag R.F. alignment itis necessary to set the
pointer in the correct position with relation to the gang con-
denser plates. This is done by setting the pointer to the angle
of the border line of the dial immediately below the 530 K.C.
calibration point, with the gang tuning condenser in full mesh.
"Short -Wave" Trimmer Adjustments
Connect the "ANT" output of the test oscillator to the antenna
terminal of the receiver through a 400 ohm resistor. Set the
receiver range selector switch to its "short wave" position and
its dial pointer to 17000 Kr. Adjust the teat oscillator to 17000
Kr. Adjust oscillator 17000 Kc. trimmer until maximum output
is reached. Two peaks may be found with this circuit. The
peak with minimum capacitance (plunger nearly out) should he
used. Tighten lorknut. Adjust detector 17000 Kc. trimmer
until maximum output is reached while slightly rocking the gang
condenser. Two peaks may be found with this circuit; the peak
with maximum capacitance (plunger nearly in) should be used.
Tighten lockout. Adjust antenna 17000 Kc. trimmer until
maximum output is reached, while slightly rocking the gang
condenser. Two peaks may be found with this circuit; the peak
with maximum capacitance (plunger nearly in) should be used.
Tighten lockout. Check the image frequency by changing the'
receiver dial setting to 16,080 Kc. the image signal should be
received at this position, indicating that the adjustments have
been correctly made. No adjustments should be made while
checking for the image signal.
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Radiotron Socket Voltages and I.F. Trimmer Locations
The meter readings given inthe diagram wetaken with the
re and and bandies posts hort circuited nd with 1010 vats
antennaAll reading* .re actual perating conditions sod In sums cars
r'll be nec.ry to allow for meter resistance. All D.C. voltage
ead diallowings
are taken with respect to the chassis triune. All «tllngs .re
-Iit -14.. a.
nnn
given for normal operation- If readings are taken with a set umbrae.
circuit. that are not intended to wcA,ate. may smote. thusincrements
r .mean vmemar and derre.aing plate st rreen .solemn The
aalyrt able may aim uur dedecreasing rolls., to cease
oscillating. en`,. increasing current .m aerre..ma ynlwe.
In some cases the socket contacts of "blank" radiotron pins are used as terminals for chassis parts. The voltages shown above
on such contacts are circuit voltages, not radiotron voltages.
