Figure 5 Diagram Of Top Of Chassis - RCA AR-88 Instructions Manual

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Figure S-Diagram of Top of Cluusis
t.F
Alignment - The intermediate frequency is 4H
e:The
most satisfactory method of I· P alignment is
by means of a sweep oscillator and cathode ray oscillo;
graph. Pollow the sequence as given below.
Oaci1Iograph Connections ..•....................•...• Vertical "HI" to Terminal C on last I·P Transformer
(L47, L48), Vertical "LO" to chassis
Dummy Antenna ................................... : ..•. Insert in series with generator output. 0.01 mfd.
Connection of Generator Output Lead ............••.......•....•.................... " See chart below
Connection of Generator Ground Lead ......•.•....•••............•........................ To chassis
Position of Power·Transmit·Receive Switch ..........•........................... Position 3 (Rec. Mod.)
PO$i.Uon of R·P Gain Control. . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Pully clockwise
l1'oeition of Selectivity Switch .........•............• ' ....................................... Position 2
Position of Noise Limiter and A VC Switch .......... '" ........................... " Position 4 (AVe)
LOCATION OF PARTS AND AUGNMENT ADJUSTMENTS ON CHASSIS
Step'
1
Generator Connections
6SG7-lrd I·P Grid
6SG7 - 2nd I,P Grid
Trimmer Adjustments (See Pig. S')
L47, L48
Trimmer Punction
4th I·P Transformer
3rd I·P Transformer
2nd I,P Transformer
2
1
4
6SG7 1st I·P Grid
MA7 -1st Det. Grid
L41, U2, U3, L44
US', L36, U7. U8
L32, L33
1st I,P Transformer
Before
performing step 4 abo've. set crystal phasi,ng
control
C7S' at approximately one fifth of its maxi·
mum
capacity. This is approximately its final setting
and changing it appreciably will slightly detune the
first
I-P transformer.
With Selectivity Switch in Position 2 the I·P band
width is normal without over,coupling in the trans'
formers. With Selectivity Switch in Position I, the
second and third I· P Transformers are expanded and
n
over-coupled. It is well in going through the alignment
steps outlined above to check the I,P curves on the
oscillograph screen with switch in Position 1 to see
that the curves expand symmetrically.
Adjustment of Crystal Phasing Control- This ad-
justment is best made by means of a signal generator
and a high resistance sensitive DC voltmeter such as
the RCA Junior Voltohmyst. Place Selectivity Switch
in Position 3. Connect the generator to the grid of the