RCA Victor TRK-12, Manual

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TRK9, TRK90, TRKI2, TRKI20
Miscellaneous Data for Radio Chassis
Precautionary Lead Dress
(1 ) All A 'C leads should be twisted together and dressed
away from parts in chassis to prevent hum pickup.
(2 ) Keep pilot light leads away from 6R7 grid.
(3 ) Yellow, green, and black leads from fidelity switch to
1st i*f transformer must be twisted together and dressed
away frqm chassis.
(4 ) Yellow, green, and black leads from fidelity switch to
2nd i-f transformer must be twisted together and dressed
away from chassis.
Victrola Attachment
A jack (X '1 6 ) is located near the antenna terminal board
for convenience in plugging in a Victrola Attachment. T he
cable from the Victrola Attachm ent should be terminated in
a Stock No. 31048 plug to fit the jack.
Figure 31— Functions o f Feedback Sw itch
(T R K -9 and TR K -1 2 only)
Feedback Switch (S8 and S9)
(TRK-9 and TRK-12 on ly )
Counter-clockwise position
(with feedback)
Clockwise position
(without feedback)
1. Provides inversed feed­
back by connecting part
of secondary -of output
transformer in cathode
of 6J5 2nd-audio tube.
1. Removes reversed feed­
back and grounds cath­
ode of 2nd-audio tube.
2. Disconnects compensat­
ing network (R22, C43,
C54, C40) from plate cir­
cuit of output tubes.
2. Connects compensating
network (R
22
, C43, C54,
C40) to plate circuit of
output tubes.
3. Connects grid of 2nd
audio to high side of 1st
A-P plate resistor R17,
for maximum input.
3. Connects grid of 2nd
audio to low side of 1st
A-F plate resistor R17,
for reduced input.
A Connects capacitor C53
(.005) from plate of 2nd
audio to chassis.
4. Disconnects C53 from
plate of 2nd audio.
FEED BACK X8
Figure 32— Connections and Colors o f Loudspeaker and Cable