Western electric 215 a brochure

Page 1

215A

BELL SYSTEM PRACTICES SECTION AB46.125
Transmission Engineering and Data Issue 1, September 1936
Vacuum Tube Data A T & T Co Standard

Wafer/1 flecfric
215A Vacuum Tube

Classification-Small, filamentary triode

Important features of the 215A tube are its small size and low filament power consumption

Applications
Audio-frequency and intermediate-frequency amplifier
Detector

Oscillator

Dimensions-Dimensions. outline diagrams of the tube and base, and the arrangement of the
electrode connections to the base terminals are shown in Figures 1 and 2.

Base-Small, four-terminal, bayonet base having silver contacts.

Socket-Four-contact, bayonet-slot type preferably provided with contact-metal contacts, such as
the Western Electric 125B socket.

Mounting Positions-The 215A tube may be mounted in any position.

Copyright 1936 Western Electric Company, Incorporated

Page 2

215A

Average Direct Interelertrode Capacitanees

Grid to plate ....... . ... . . .. .. ........... 2.6 uyf.
Grid to filament. , , ., ., . .. . .. ........... . .. 1.6 uni.
Plate to filament. , , _ __ .. . . . .. .. . ., 1.2 uni.

Filament Rating

Filament current. .. .. .. .. .. .. .. . . . 0.25 ampere. dc.
Nominal filament voltage. . . . . . ....... 1.0 volt

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

ics of a typical 215A tube are shown in Figure 3 as
functions of grid voltage for several vaiues of plate voltage. Corresponding amplification factor,
plate ' stance. and transcondnctance characteristics are given in Figures 4, 5 and 6, respectively.
Plate current character.stics as functions of plate voltage are shown in Figure 7 for several values
of grid voltage. The grid and plate voltages for all of these characteristics are measured from the
negative end of the filament.

Operating Conditions and Output-Permissible operating conditions are included within the
area. ABCD. in Figure 3. Amplification factor, plate resistance, transconductance. and performance
data are given in the table on page 3 for a number of typical amplifier operating conditions repre-
sented by selected points within this area. Typical detector operating conditions for both plate current
and grid current detection are also listed in the table. The less severe operating conditions should
be selected in preference to maximum operating conditions wherever possible. The life of the tube
at maximum conditions may be shorter than at less severe conditions.

The performance data include the fundamental power or voltage output and the second and
third harmonic levels for the indicated values of load resistance and input voltage. The funda-
mental output is given in terms of the power. Pm, in milliwatts for values of load resistance, R. equal
to and double the value of the plate resistance. rp. and in terms of the voltage, Epm, in peak volts
for values of load resistance five times the plate resistance. The second and third harmonic levels,
Fgm and 1:3,, are given in decibels below the fundamental in each case. The peak value of the
sinusoidal input voltage. Egm, is numerically equal to the grid bias for each operating condition.
For a smaller input voltage, Eg, the output and harmonic levelsrexcept for the lowest values of
third harmonic. are given approximately by the following relations:

P=Pm

Egm
E

E =E... i

p D Em

F2= Fgm L 20 log) Em

E
F3=F3m + 4010g10 gm
E.g

The level of the third harmonic in the 215.-\ tube is usually low and may differ widely in individual
tubes. The values given in the table are for a typical tube.

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