Hickok 539C - Socket and Special Test Notes; Tube Socket Numbering and Connections; Meter Reverse Function; Top Cap Connections

11. Socket Numbering. Sockets are wired according to EIA numbering, and the
numerical values of the lettered dials are as follows:
A
B
C
D
E
F
G
H
J
K
1
2
3
4
Selector Positions
P
R
S
.T
U
V
.W
.X
Y
•• Z
1
•• 2
3
. 4
o
1
2
3
4
5
6
7
8
9
W
X
y
Z
Socket Connections
No Connection
1
2
3
4
5
6
7
8
9
10
11
12
No Connection
12.
Meter Reverse. Directly below the indicating meter is a switch marked RE-
VERSE-NORMAL. With certain tubes such as the 117N7, the meter, when set on
NORMAL, will deflect backwards (to the left) when push switch P3 is pressed for recti-
fier test. In such case turn the meter switch to REVERSE which will cause the point-
er to move up the scale. After this test has been made, return the switch to NORMAL.
13. Top Caps. There are two jacks in the upper center of the control panel mark-
ed GRID and PLATE. These are used when making connection to the top cap of the tube
being tested. On the data chart in the NOTATIONS column opposite tube types having
top caps, is the notation CAP = G, or CAP = P. G means that the top cap is connected
to the GRID and P, to the PLA TE jack.
14. Special Notes. Power line voltage varies with different localities. It may also
vary with the different hours of the day.
While a
national survey indicates that the average voltage for the USA is 117 volts,
it does not mean that every locality maintains a constant voltage at that level.
Occasionally we have had the complaint that a used tube will test GOOD, but will
not work in the radio receiver; but when a NEW tube is substituted, the receiver will
operate correctly. The answer is this: Tubes are built to specifications. Our tube
testers are designed to test tubes in conformity with these specifications.
The used tube that would not perform in a certain receiver was not receiving its
specified filament voltage. The new tube performed because of its initial reserve cap-
acity. The used tube would have performed if it had received its specified filament
voltage.
Tube failure frequently occurs in A. C. - D. C. sets where several tubes are con-.
nected with their heaters or filaments in series. Sometimes, even though the power
line voltage is normal, a series tube with abnormally high filament resistance will rob
its companion tube of its normal filament voltage. The robbed tube apparently fails; .
but when tested under specified conditions, the tube will test GOOD.
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