The PRECISION Series EV-20 Vacuum Tube Voltmeter and
Multi-Range Test Set is a modern sensitive high impedance
measuring instrument specifically engineered to meet the
rapidly expanding requirements of present and future
electrical, electronic and communications fields, — A.M.,
P.M. and TV.
Although compact, in terms of physical dimensions, Series
EV-20 affords the full functions of EIGHT distinctly
individual instruments, stressing the utmost In performance,
ease of manipulation, stability and accuracy (not usually
associated with electronic test meters). It provides true
ZERO-CENTER OPERATION ON ALL D.C. V.T.V.M. RANGESt
The EIGHTH facility is available thru use of the optional
SERIES RP-10-A Vacuum Tube Probe which is directly
attachable (plug-in cable) at the front of the EV-20 panel.
Incorporating a miniature type 9002 tube, this latter
accessory provides for direct measurements of audio
super-sonic, R.P. and U.H.F. voltages as required for
special service and laboratory applications. (Series RP-10-A
Probe may be obtained from the same source of supply from
which EV-20 is purchased).
All instrument functions have been engineered to afford a
maximum of operational simplicity by reducing the number of
switching and connecting operations to an absolute minimum.
For example it will be noted that the 1000 ohms per volt
functions are available to the operator without
necessitating connection of the instrument to the ροτ/er
line: In addition the H.F. accessory Probe and D.C. V.T.V.M.
isolating Probe are both provided with their individual
Instrument Panel Connectors, eliminating repetitive
insertions and disconnections*
Before proceeding into the actual use and operation of the
Series EV-20’s eight functions, it will be found desirable
to examine the following condensation of the outstanding
features and overall coverage of this most complete instrument:-
1. VOLTAGE REGULATED BRIDGE CIRCUIT:- Stabilized bridge
circuit provides a high degree of direct reading V.T.V.M.
accuracy with complete freedom from minor tube variations.
Incorporates 1 - 6C4, 1 - 6X4, and 1 - 0A2 Voltage
Regulator. Regulated plate voltage power supply minimizes
undesirable meter shift due to A.C. line voltage variations.
2. TRUE. ALL-ZERO CENTER V.T.V.M.:- Provides in ONE
OPERATION, BOTH magnitude and polarity of voltage at any
test point, WITHOUT reversal of test prods. Common terminal
grounded for maximum safety, stability, and simplicity of
A zero-center V.T.V.M. is ideal for P.M. discriminator
adjustments, bias measurements, etc., as well as the only
simple solution to "blind” tests wherein test polarity is an
3. DIRECT READING HIGH FREQUENCY VOLTAGE SCAIES:- Includes
special low range compensated scale for maximum low voltage
reading accuracy in addition to direct reading scales to 120
V. Peak. A built-in bridge balancing network minimizes
zero-shift effects of Probe tube contact potential.
4. SHIEU3ED COAXIAL TEST AROSE:- A universal,
circuit-isolating, coaxial probe is furnished as original
equipment. This permits direct D.C. voltage measurements In
signal carrying circuits, without materially disrupting
5. DUO-BALANCED ELECTRONIC-BRIDGE OHMMETER:- Effectively
eliminates the gross Inaccuracies oftentimes associated with
vacuum-tube-ohmmeter readings. BOTH ends of the ohmmeter
scales are Individually electrically adjusted, providing
unusually high accuracy throughout entire ecale length. A
single "OHMS” scale serves for ALL SIX resistance ranges.
V.T.V.M. and OHMMETER zero settings remain essentially
unchanged for any series of voltage or resistance range
6. OHMMETER BATTERIES QUICKLY AND CONVENIENTLY REPLACEABLE
FROM REAR OF INSTRUMENT.
7. FULL VISION 4-5/β" RECTANGULAR METER:- Employs large,
wide faced, easy reading scales. 200 microampere D'Arsonval
type movement. Rugged, double-sapphire bearing construction. ,
8. EACH INSTRUMENT INDIVIDUALLY CALIBRATED at multiple
points with four internal calibrating controls, sealed
against laboratory standards. Assures strict adherence to
specified tolerances and duplicate performance of each and