Transformer Corp. of America 25-94 Schematic

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Product Information:
Model:25-94
Manufacturer:Transformer Corp. of America

Schematics Content:

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Page 1:

Pigs 622-1;-2
f" TRANSFORMER GORP. OF AMERICA
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TRANSFORMER CORP. OF AMERICA
CLARION
MODELS 84 &: 85
READJUSTING TRIMMERS
To readjust the trimmers on these super-
heterodyne receivers it will be necessary that
a good design of 175 k.c. oscillator he em-
ployed and that a dependable broadcast test
oscillator be on hand so that stages handling
intermediate frequency and those handling
radio frequency can be thoroughly checked.
It is advisable to use a bakelite screw driver
when making any of these adjustments.
First, connect the 175 k.c. oscillator output
leads from the control grid cap of the first
detector tube to ground. Do not remove any
of the tubes from the sockets, and it is not
necessary to disconnect the grid cap clip from
the first detector tube. Reset trimmers No.
5, No. 6, No. 7 and No. 8 for maximum out-
put. While this test oscillator is working into
the intermediate frequency stages, no ad-
justment of the tuning condenser on the re-
ceiver will have any effect, inasmuch as the
intermediate frequency stage is fixed tuned,
If your test oscillator is properly designed,
it will supply exactly 175 k.c., and when trim-
mers No. 5. No. 6. No. 7 and No. 8 are set
and turned for maximum output, they will
be correctly adjusted.
Next, disconnect the 175 k.c. test oscillator
and connect to the antenna binding post of
the receiver, the output lead from your
broadcast test oscillator or tune in a broad-
cast signal around 1400 k.c., then reset trim-
mer No. 2 and No. 1, respectively, for maxi-
mum output. This adjustment will track the
first detector and r. f. stages.
To check calibration of the receiver,
whether it be high or low, trimmer No. 3
(oscillator) should be reset until a station of
known high frequency is brought in at the
correct dial marking with peak volume. If
your broadcast test oscillator is accurately
calibrated, it might be used in place of the
broadcasting station signal. In this adjust-
ment, a broadcast station or test oscillator
signal at about 1400 k.c. should be chosen.
The setting of the trimmer at 1400 k.c. is
more critical than it would be at 600 k.c.
The next adjustment is important and not
easily explained in writing, so pay close at-
tention to the following instructions. We
will now balance the oscillator to the r. f.
and first detector stages.
Tune the external broadcast test oscillator
and the receiver both to 600 k.c., then slowly
increase or decrease the capacity of No. 4
(oscillator padding trimmer), at the same
time and continuously tuning back and forth
across the signal with the receiver tuning
condenser gang. The output meter needle
will now be swinging up and down in step
with the Variation in tuning. Watch the peak
of this swinging closely and readjust No. 4
trimmer until the swinging needle reaches
its highest peak.
Retune the receiver and broadcast test os-
cillator to 1400 k.c. and re-check trimmer No.
3 to make sure that the adjustment of No. 4
has not thrown the receiver out of calibra-
tion. If it has, then readjust No. 3 until the
calibration is correct, (as previously ex-
plained), and check on trimmers No. 2 and
No. 1, to make sure that the adjustment of
No. 4 has not reduced the sensitivity.
CONTINUITY TESTS
(Applicable to completely and partially in-
operative sets and circuits)
A 175 k.c. test oscillator should be con-
nected to the grid cap of the first detector
tube so that the modulated signal can be
reproduced in the loud speaker. This indi-
cates that the first detector and intermediate
frequency stages are operating. To deter-
mine if the oscillator is working, a broadcast
test oscillator should be connected- to the
grid cap of the first detector tube. No signal
will come through unless the oscillator tube
and stage are functioning correctly. The r. f.
tube, of course, can be checked lastly by
connecting the broadcast test oscillator to
the antenna and ground binding posts of the

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TRANSFORMER CORP. OF AMERICA
'????""7'" CLARION MODELS AC 94 5: 25-94
SHIELD "* O d. 'D
mra. nam. aura 1 Q Z. f-4 _ C
5 * con v | >>-4 u _U d
nEAD1NGsyj1'AKEN WITH WESTON MODEL 565 ANALYSER wjjF*? ?
I ' Type A \ B cm. aria cm. Ip' sc
No. Stage Tube Volts Volts Volts Volts Norm. Volts
'27 'fm aes. TW51 ' frzimri 160 | 9,5 W 10. [ Mil 75.
Volume control position Full." Line Voltage 115-60 cycle. 2
NOTE: Filaments and <-athmles nf R.F`., LF., uml iirst dr-tector are 95 volts positive with respect to ground.
NOTE: Since resistance tolerances in the sets are plus or minus 10%, and tuhes.may vary over 20%, your.
readings may disagree with the above by plus or minus30%.
FOR SPEAKER DATA REFER T0 PAGE 622-K-1
FOR TRIMMER ADJUSTIENT DATA REFH TD PAGE 622-K-3

Page 4:

CLARION
AC MODELS
94 3? 25"94 T1zANsFoRr.rER CORP. OF AMERICA
l`0N'l`INUI'1'Y TEST TABLES
cimm 1 Frm T.. 1 n...1?>>; RESISTANCE TABLE
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yn Deanna VVVVVV _RQ.jglrg?zV V VV??&Vzr1\{Vg{p elm 1 0.2 VV Rrrirwr zip, rra ao: Amrr Rerxmr 5.4 1 gpm
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1"..' 'f< . Rfi@;R2'i" *if* "'*" ?'f'i"' '__ 5-3 Bin; mrarmr" Black, wir; wound Arms Resistor 6.9 zsu
A, v. c. crm nm, m. prorrg 5' A. v. c. grad dip 1.0 k?rimr up, yrlldv ao\:iVAcr?rr Resistor .1 500,000
A. v. c. screen ne?r.n1.,.m.g ? A. v.c. mm. prong 3.0 Y. -. - - - f--f ~7~____" f-, f .
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zrrd De; Grid nm. m. pm.; 2 zrra der. grad pm; | a_s 'Wim ,, _ _ . di'i_____ __4__ i`_
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hue. nm 1zm.n1.pr?..gV_V VV__V` Pm rlrairrorr _VV _Visa V mime GMES f ~f 1 ~)f ' - f 11 ' Y
orc. Grad nm. m. prong 1or?, grid prvng 1 0,5 mrirmr Wire wumm ggi VA?r>>5VRg???wr _V 5.9 V~ Vz}q
Power mrs, Pri. V .\ci?n? V 1A,c.r11.,, "1 an 2"2,,.,,,{;,,f'}{;,.,,,_ ".1...i*" ?.fXS??r..r?r. .5 f zoom
??w==' ffm- Sw- ACMSS Q0 alms 9/8 _ znn Qu. Grid 'Rik 'vrljrw hndy, blmgk _ VV ln Y Y
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Top Vlew '\ gg.; S fx, /??
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"?iw' "'"' _ 'i _ ? Bottom View

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