Western electric 101 d brochure

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101D

Average Direct Interelect-rode Capacitances

Grid to Plate ......................................... 6.4 pnf
Grid to Filament ...................................... 4.4 upf
Plate to Filament ...................................... 2.9 pnf

These values are for a based tube without socket.

Filament Rating

Filament Current ................................... 1.0 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 at
as near 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 this resistance change has stabilized.

Characteristics-Figure 3 shows typical curves of plate current as a function of grid voltage for
several values of plate voltage. The grid and plate voltages are measured from the negative end
of the filament. Figures 4, 5 and 6 show corresponding amplification factor, plate resistance and
transconductance characteristics respectively. Figure 7 shows plate current as a function of plate
voltage for several values of grid voltage.

Operating Conditions and Output-Figure 3 shows the range of permissible operating plate
and grid voltages included within the area ABCD. A number of recommended and maximum
operating conditions and the corresponding values of amplification factor, plate resistance, trans-
conductance 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 include 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 12000 ohms. The peak value of the sinusoidal
input voltage Em, which gives the indicated output Pm, and harmonic levels F21, and Fgm, in each
case is numerically equal to the grid bias. For a smaller input voltage E3. the approximate levels
may be computed from the following relations:

_ E_s 2
P - Putz...)

E
F2 = F2, + 20 logic-L
Es
F; = F3, + 40 logw Efi
E

Microphonic Noise

For a plate voltage of 130 volts, a grid bias of -9 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 32 db
below 1 volt. The range oflevels of individual 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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