Patterson Radio Co. 212 Schematic

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Product Information:
Model:212
Manufacturer:Patterson Radio Co.

Schematics Content:

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Page 1:

PAGE 9-4 PATTERSON

MODELS 208,508,408

PATTERSON RADIO CO.

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(C)John F. Rider, Publisher

Page 2:

PATTERSON PAGE 9-5

Alignment

1. F. AUGNMEN'L-AU- MODELS

in the following instructions tar alignment the term V. T. V. M.
shall be understood to mean Vacuum Tubs Voltmeter or eye tube.
and the term "resonance" means that the meter shows the greatest
swing toward zero. or that the eye tube shows the narrowest darlr
section. Turn band selector switch to band "a" or No. l. Place
service oscillator in operation on 465 Kc. Connect grid ot voltmeter
to A. V. C. buss and ground of voltmeter to chassis. A convenient
place to connect the voltmeter grid is on the terminal for the eye
cable. This is located underneath on the floating R. F. section and
between the back end of wave change switch and first R. F. tube
socket. Connect to the terminal to which the green lead in the eye
cable is connected. ln lieu of a V. T. V. M. the eye tube itself may
be used as a resonance indicator (adjusting for the narrowest dark
section) although this method is seldom as accurate as when using
a V4 T. V. M. Another method which is by far the most accurate of
all and which we strongly advise wherever possible is the use of
the cathode ray oscilloscope and rotary sweep generator. This
method will be discussed later in these notes.

Note.- Reler to sketches in Figures 9, 10 and ll for position of
various tubesA coils and other components on all models.

CAUTION: Before making any adjustments on l 2 tube model. be
:ure that the high fidelity switch is in the off position and remains
there during adjustments. See tuning reference first page. Do not
attempt to bend any of variable condenser plate flaps during
alignment, particularly an the 12 tube models. The variable can-
densers are all carefully calibrated during the original alignmenl
and should not require any further calibration during the life of
the radio.

Remove grid cap trom second I. F. tube (6K7) and apply oscillator
output lead to grid of this tube and adjust trimmers on No. 3 I. F.
transformer until resonance is indicated on V. T. V. M. The service
oscillator output should be set for a quite high output when making
this adjustment. Next remove oscillator lead and replace the cap
on this tube. Then remove grid cap ot tirst t. F. tube (6K7) and
apply service oscillator _output lead to grid oi this tube and repeat
adjustment as before this time adjusting trimmers on No. 2 I. F.
transformer until V. T. V. M. indicates resonance. Reducing service
oscillator output as necessary to obtain an easily readable indica-
tion. Next remove service oscillator lead and replace cap on first
I. F. tube. Then remove cap from the Modulator tube SAS or 6L7
(as the case may be) and apply service oscillator output lead to
grid ot this tube, this time adjusting trimmers on No. 1 1. F. trans-
former, reducing service oscillator output as required and adjusting
for resonance. Now without making any further changes. go over
all I. F. trimmers one by one carefully readjusting tor exact reson-
ance. This completes the alignment of the I. F. amplifier.

CAUBRATION 0F VARIOUS BANDS-840 TUBE MODELS ONLY

Note: Refer to Figures 6, 9 and 10 tor location of various coils and
trinuners. (Refer to Fig. 5) tor location ol padding condensers.

BAND "A" (OR-No. l) BROADCAST

Connect V. T. V. M. to A. V. C. buss and chassis ground. as
described above for l. F. alignment. 'Turn band selector switch to
band "A" (or Na. l). Place service oscillator in operation on 1400
Kc. and connect service oscillator output lead to antenna terminal
of radio through a .0001 condenser ar less or through standard
dummy antenna. it will be necessary to keep the service oscillator
output control well reduced during the following adjustments.

Set main tuning dial ot radio to 140|] Kc. and adjust trimmer "A"
in side of oscillator coil. Figure 4. to resonance. Next adjust trim-
mers "A" on the antenna and modulator coil to resonance. Next
set service oscillator to 600 Kc. and let radio dial to 600 Kc. adjust

service oscillator and radio dial to 1400 Kc. and retouch trimmer
"A" on oscillator coil to resonance.

ment of Band "A,"

(C)Jehn F. Rider, Publisher

PATTERSON RADIO CO.

Alignment and Calibration Procedure

padding condensers, "AP" to resonance. (Only a solid bakelite or
mb" in'umling me" drive' will be 'maxme 1?' "dlmung "Y Change hand switch to band "B" or No. 2. set both service oscil-

?f_|h? quding CQndem" ul Wen U5 N?'_3 I- r" un "dian 'WSW lator and radio dial to 4 M. C. and adjust trimmer "B" on oscillator
dnvsf Wm be mummmy 1?' "u om" "dlmlmenu'l New' 195?* bolh coil to resonance. Next adjust trimmers "B" on antenna, R. F. and

It may be well at this time also to recheck trimmers "A" on the condenser "BP" to resonance. Reset both service oscillator and radio
antenna and modulator calls. This completes calibration and align- dial to 4 M. C. and recheck, trimmer "B" on oscillator coil to reson-

MODELS 208,508,408

` BAND "B" (OR NO. 2) SHORT WAVE BAND

Turn band selector switch to Band B, leaving all connections
made as before for "A" band set service oscillator at 6 M. C. also
set radio dial at 6 M. C. and adjust trimmer "B" on oscillator coil
to resonance as indicated on V. T. V. M. Next adjust trimmers "B"
on antenna and modulator coils to resonance. Change both service
oscillator and radio dial to 2 M. C. and adjust "BP" padding con-
denser to resonance. Reset both radio dial and service oscillator
to 6 M. C. and recheck trimmer "B" on oscillator coil for resonance.
This completes calibration and alignment of Band

BAND "C" (OR N0. 3) SHORT WAVE BAND

Turn band selector switch to Band Set radio dial and service
oscillator to 17 M. C. and adjust trimmer "C" on oscillator coil to
resonance, it may be well to turn trimmers "C" on both antenna and
modulator coils in about one turn before making above adjustment.
Then after oscillator trimmer has been set retune trimmers "C" on
modulate coil to resonance slowly turning main tuning dial back
and forth slightly as adjustment is being made until resonance is
indicated on V. T. V. M.. retouching oscillator trimmer "C" as
necessary to keep it on the desired spot on tuning dial. Next adjust
trimmer "C" on antenna coil to resonance without rocking main dial
next set service oscillator and radio dial to 6 M. C. (Band "C") and
adjust padding condenser "CP" to resonance, reset radio dial and
service oscillator to 17 M. C. and recheck oscillator trimmer "C" for
resonance. This completes adjustment of Band "C."

Note: When making adjustments of modulator trimmers on all
models and particularly the highest frequency bands. loosening of
the modulator trimmer loo far may cause a false resonance indica-
tion caused by the oscillator curve being "crossed over" removing
oscillator lead or changing oscillator frequency, will readily show
if this has occurred as no change in resonance indication will be
apparent, also the set will be quite dead at the high frequency end
of the band the true resonance point is with the modulator screwed
in about one turn or less from the point where blocking occurs. The
true resonant point will be quite apparent an resonance indicating

X BAND (OR NO. 4)

(For models equipped with long wave weather cr
European band only.) Change wave band switch to
"X" band. Set service oscillator and radio dial to
400 Kc.. adjust oscillator trimmer "XOT" to reson-

9 ance. Then adjust trimmers "XMT" and "XAT" to
M resonance. Then set both radio dial and service oscil-
B'B later to 150 Kc. and adjust padding condenser "XP" to
9.5 resonance. Reset both service oscillator and radio dial
e again to 400 Kc. and recheck trimmer "XOT" for reson~

ance. This completes the calibration and alignment of
FIG. 6 all bands.

Calibration of Various Bands
12-Tube Model Only

BAND "A" (OR NO. l) BROADCAST

Note: Refer to Figures 8 and ll tor location ol various coils and
trimmers. Refer to Figure 7 for location of padding condensers.

Connect V. T. V. M. and A. V. C. buss and chassis ground as
described above for 1. F. alignment. Turn band selector switch to
Band "A" (or No. 1). Place service oscillator in operation on 1400
Kc. and connect service oscillator output lead to antenna terminal
through a .0001 condenser or less or through a standard dummy
antenna. It will be necessary to keep service oscillator output con-
trol weil reduced during the following adjustments. Set main tuning
dial of radio to 1400 Kc. and adjust trimmer "A" on oscillator coil.
Figure 6. Next recheck trimmer "A" on antenna, R. F. ond modula-
tor coils to resonance. this completes alignment of band "A."

BAND "B" (OR NO. Z)

modulator coils each in turn to resonance. Now change both service
oscillator and radio dial to 1.5 M. C. ( i500 Ka). and adjust padding

ance. This completes alignment at Band "B."

Page 3:

PAGE 9-6 PATTERSON

MODEL 128

Change band switch to band ' " or No. 5. Set service oscillator
cmd radio dial to 12 M. C. and adjust trimmer "C" to resonance.
Next adjust trimmers "C" on modulator coil rocking radio tuning
dial slowly back and forth as adjustment is being made. resetting
oscillator trimmer il and as necessary to keep calibration correct at
this point alter resonance has been reached trimmer "C" on anten-
na and H. F. coils may be adjusted to resonance without touching
any other controls. Next set both radio dial and service oscillator
to' 5 M. C. and adjust padding condenser "CP" to resonance. Then
reset both radio dial and service oscillator to 12 M. C. and recheck
trimmer "C" on oscillator coil to resonance. This completes align-
ment of band "C" or No. 3.

BAND "D" OR N0. 4

Change band change switch to Band "D" set service oscillator
and radio dial to 20 M. C. and adjust trimmer "D" on modulate
coil slowly rocking main tuning dial to 9 M. C. (Band D or No. 3)
and adjust padding condensers "DP" to resonance. Then reset both
service oscillator and radio dial to 20 M. C. and recheck to reson-
ance, this completes alignment of Band D.

Note: When making adjustments of modulator trimmers on all
models and particularly the highest frequency bands. loosening
ot the modulator trimmer too far may cause a false resonance indi~
cation caused by the oscillator curve being "crossed over" remov-
ing oscillator lead or'dhanging oscillator 'frequency will readin
show if this has occurred as no change in resonance indication will
be apparent also the set will be quite dead at the high frequency
end ot the band, the true resonance point is with the modulator
screwed in about one turn or less from the point where blocking
occurs. The true resonant point will be quite apparent on resonance

indicating devices.

'"X" BAND OR N0. 5

(For models equipped with long wave weather

hand only.)

Set band change switch to "X" bond. Set both serv-
ice oscillator and radio dial to 400 Kc.. adjust trimmer
"XOT" to resonance. Then adjust trimmers "XLT,"
"XHT," and "XMT" each in turn to resonance. Then
set both service oscillator and radio dial to 150 Kc.

F This completes all alignment.

IGlIathode Ray Oscilloscope
Alignment

For the service man who is equipped with a cathode ray oscil-
loscope and rotary sweep circuit. a very accurate alignment of the
intermediate amplifier is possible. Owners of such equipment are
usually familiar with the necessary procedure as this point is
usually covered thoroughly in the instructions furnished with the
equipment. More detailed information than that usually furnished
with cathode ray equipment may be found in Iolm Rider's book.
"The Cathode Ray Tube at Work." An I. F. output connection in-
tended for cathode ray alignment is incorporated in all Patterson
37 models. With chassis upside down and facing back of chassis
it will be found in the lower left hand comer of chassis adjacent
to the phono terminals and rubber corner rest. In the 8 and 10 tube
models the adjustments should be made on the second stage first,
then the first stage, then through the modulator and first I. F. trans-
former or practically the some procedure as when aligning by any
other method. The curve on the 8 and 10 should be round nosed and
about 10 Kc. wide at the summit. The high fidelity switch having
no effect on the resonant curve in thes'e models. ln the 12 tube model
the above procedure should be followed out with the exception
that the high fidelity switch must be in the "off" position during

ln this model the I. F. curve will be very sharp and not round
nosed. after alignment has been completed the high fidelity switch
may be turned on for a chock. in which position the curve will re>>
main symetrical but become very broad with possibly a very slight
shitt in the I. F. frequency in some cases. Ii this is not the case. a
misadjustment has been made in the alignment procedure and the
high fidelity switch should be turned off and alignment rechecked

PATTERSON RADIO CO.

and adjust padding condenser "XP" (very slowly) to 2 IF
resonance. Reset both service oscillator and radio dial De'?i
to 400 Kc. and recheck trimmer "XOT" to resonance,

cont. inue d . Voltage

OPERATION OF PHONO COMBINATION MODELS

The following imtructions are for models equipped with phono-
pickup and motor. To place phonograph in operation turn radio
on in usual manner with top cover: raised. Turn toggle switch on
top panel to position marked "Phono." Start motor by pulling lever
extending from under turn table on right hand side forward. Lift
pick up and pass over turn table toward the center of turn table.
adjusting stop lever located between turn table and pickup hinge
until motor turns oil at a point just past when the last grooves in
record stop, not including the stop grooves. which are elliptical.
This point may vary with individual records while some records
have no stop grooves at all. The best position for stop lever can'
easily be determined, however, after a lew records have'bee'n-
tried. The speed control is located on the left hand side extending
from under the turn table and is clearly marked. Use that speed
which gives the best or most natural results. This speed is ordi-
narily 'IS revolutions per minute for fast records. strchoscopes
tor various speeds and line frequency may be purchased for very
small cost, which make it possible to obtain the exact speed. These
stroboscopes are self explanatory. On those models equipped with
two speed motors a third lever extends from under the turn table
on which speeds are plainly marked, one being 78 R.P.M,, the
other 33% R.P.M. for slow speed records. The usual volume and
tone controls are still in service and may be used at will while
playing records.

VOLTAGES

The following tables show characteristic voltages at various

points through a normal chassis.
All Voltages Moasurable Under The Following Conditions:

Transformer line tap in 110-115 V. position line voltage 115 V.
60 cycles. Band change switch set on Band No. 2. No antenna. No
signal being received sensitivity adjustment set at maximum posi-
tion. All voltages listed measured from point indicated to chassis
(ground), all readings taken on standard 1000 ohm per volt. Volt-

8 TUBE CHASSIS

Plum scruu cathode _sunt-"ur
sr 5K7 200 v. App so v. App. 2 v. App. 'ned to cathode

1 rr sta 200 v. App. so v. App. 2 v. App. 'ned to cathode
557 zoo v. App. so v. App. 2 v. App. 'ned to cuthudu

out ut ers 200 v. App. 200 v. App. is v. App.

"'Measurable with AC Voltrneter only.
'Not actual. (measured through 500.000 ohms).

rut lute. aso v. App.
10 TUBE CHASSIS

nr 6K7 _ an v. App. 2.5 v. App 'nut-1 tu cathode
oss. 6x7 . 255 v. App. 0 v. App Tied to cumude
Moa. 51.7 . eo v. App. a v. App 'ned to cuthudu
1 is srcv . so v. App. 2.5 v. App 'ned to cathode
2 rr 5K7 . so v. App. 2.5 v. App 'ries tu cathode
out. cor . u v. App.
Audie sow .
output ere . 295 v. App, 10 v. App.
output ers 2:45 v. App 2:5 v. App. is v. App.
nest. sxaa mute No. 1-550 v. Ac. mute ns. zwsso v. Ac.

'Not actual. (measured through 500,000 ohms).
"Measured only with AC Voltmeter.

Isl Filter Cond. 325 V. DC

2nd Filter Cond. 250 V. DC

I2 TUBE CHASSIS

Plate Screen Cathode Supprauor
nr 6K7 250 v. App. 110 v. App. 2.5 v. App. 'rtea to cathode
RF 5K7 250 V. App. 110 V. App. 2.5 V. App. 'l'le i0 Cathode
orc. 5K7 250 v. App. no v. App. 0 v. App, 'ned to cathode
Mod. 61.7 250 V. App. 110 V. App. 3 V. App. Tied to Cathode
ZDIF 250 V. App. 110 V. App. 2.5 V. App. Tied to Cathode

output ers 325 v. App. zso v. App. 20 v. App.
output ers :izs v. App. 250 v. App. zo v. App.
EYE SGS Target 250 V. A: . 0 V. App.
Heat. 5X4G "Plato No. 1-330 V. Plate N0. 2430 V. AC.

'Measurable with beat oscillator switch turned on.
"Measurable only With AC Voltmefer.
""th actual, (measured through 500,000 othl.
lst Filter Cond. 350 V. App.
2nd Filter Cond. 235 V. APP,

(C)J'ohn F. Rider, Publisher

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