Western electric 104 d schematic

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Wesrem Electric Company
No. | O4-D VACUUM TUBES

(Dome)

Classification-Filamentary, power amplifier triode

This tube replaces the D-86327 tube and has been assigned the old code number 104D. It
includes an improved filament, a new mechanical design using transverse mica supports and is

mounted in a dome type bulb. The electrical characteristics are essentially the same as for the
D-86327 tube.

Applications-Voice frequency and carrier frequency amplifier for telephone repeater equipment
requiring greater power outputs than can be obtained from the 101D or IOIF type tubes.

Volume limiter in carrier telephone equipment.

Amplifier in various testing apparatus.
Dimensions and Connections-The outline diagrams of the tube and base, giving the dimen»

sions and the arrangement of the electrode connections to the base terminals are shown in Figures
1 and 2.

Base and Mounting-This vacuum tube employs a medium, founpin bayonet type base having
special contact metal at the ends of the pins. It is suitable for use in a \Vestern Electric 100L,
100R or similar type socket, preferably provided with contacpmetal contacts.

The tube maybe mounted in either a vertical or horizontal position. Ifmounted in a horizontal
position the plane of the filament, which is indicated in Figure 2, should be vertical. To assure
adequate ventilation the tubes should be mounted with not less than 2% inches between centers
when two or more tubes are used.

Copyright. 194]. Wrslcrn Electric Company. Incorporated

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Western Electric Company
No. | O4-D VACUUM TUBES

Average Direct Interelectrode Capacitances

Grid to plate .......................................... 4.9 loaf.
Grid to filament ....................................... 4.1 wf.
Plate to filament ...................................... 3.4 qu.

These values are for a based tube without socket.

Filament Rating

Filament current .................................... 1.00 ampere, d.C.
Nominal filament voltage ............................ 4.5 volts

The filament of this tube is designed to operate on a current basis and should be operated as
near to the rated current as practicable.

The filament resistance of this tube increases slightly during the first 2000 hours of operation.
The voltage given above is the nominal value after the resistance has stabilized.

Characteristics-Typical curves showing plate current as a function of grid voltage for several
values of plate voltage are shown in Figure 3. The grid and plate voltages are measured from the
negative end of the filament. Corresponding amplification factor, plate resistance and trans-
conductance characteristics are given in Figures 4, 5 and 6 respectively. Plate current as a function
of plate voltage for several values of grid voltage is shown in Figure 7.

Operating Conditions and Output-Permissible operating plate and grid voltages are
included within the area, ABCD in Figure 3. A number of recommended and maximum operating
conditions and the corresponding values of amplification factor, plate resistance, transconductance,
and performance data are given in the table.

Recommended conditions or others of no greater severity should be selected in preference to
maximum conditions wherever possible. The life of the tube at maximum operating conditions
will be shorter than at less severe conditions.

The performance data shown includes the fundamental power output in milliwatts and the
second and third harmonic levels in db below the fundamental for values of load resistance equal
to the plate resistance and for a load resistance of 5000 ohms. The peak value of sinusoidal input
voltage E,,.., which gives the indicated output Pm, and harmonic levels F2. and F1, in each case
is numerically equal to the grid bias. For a smaller input voltage E, the approximate levels may
be computed from the following relations:

13, 2
P P" (E...)
Eon.
F2 = F2... + 2010g10 E
I

E u.
FJ = F3... + 4OIog10 E-
l

Mlcrophonlc Noise

For a plate voltage of 130 volts, a grid bias of -20 volts, and a load resistance of 100,000 ohms,
the mean microphonic output level of this tube, measured in a laboratory reference test set is 31 db
below 1 volt. The range of levels ofindividual tubes extends from 20 to 40 db below 1 volt. Since
microphonic noise output depends on the type and intensity of the mechanical disturbance which
produces it, the values given here are useful chiefly for comparison with the levels of other types
of tubes which have been tested in the same way.

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