Heathkit IM 11 Manual

Page 1

Assembly

and

Operation TABLE OF CONTENTS I;

of the
Specifications................... 2
mtrOdUCtiondOOOOOCIGOOOIOOIICOO 3
Circuit Description. . .......... . . . 4

B E Construction Notes ................ 5

VACUUM TU PartsList..................... 6

V 0 LT M E T E R Proper Soldering Techniques. . . . . . . . . 8
Step-By-Step Procedure. . . . . . . . . . . . 9

MODEL IM-11

Step-BY'Step Assembly: 0 o o n o o o a o o a 10

Range Switch Assembly ........... 10
Front Panel Mounting. ........... 12
FrontPanelWiring.............. 14
Circuit Board Wiring. . . . . . . . . . . . 15
ConnectingCable............... 18
Wiring Circuit Board To The Panel. . . 18
Mounting The Battery Spring. . . . . . . . 18
Meter, Bracket, And Circuit Board

Installation ..... . . . . . ..... . . . . 19
Finalering.................. 20
Preliminary Test. ............ 22
Preparation Of Test Probe And Leads. 22

Test And Calibration.............. 25

UsingTheVTVM .............. 26
InCase OfDifficulty........ ...... 30
Troubleshooting Chart. . . .. . . . .. . .. 30
Maintenance. . . . . ........ . . . . . . 31
AccessoryProbes................. 32
Service Information. . . . . . . . . . . . . . 32

Service................ ..... 32

Replacements. ..... . 33

Shipping Instructions. . . . . . . . . . 34
Warranty... ..... . 35
Schematic..................... 35*

*Fold-out from page.

The Heath Company reserves the right to discontinue instru-
ments and to change Specifications at any time without incur-
ring any obligation to incorporate new features in instruments
previously sold.

HEATH COMPANY

BENTON HARBOR.

MICHIGAN Cflfiémfi 12/30/66
All rights reserved

Page 2

P4802

SPECIFICATIONS

ElectronicDCVoltmeter-
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InputResistance

Sensitivity............ .......
Circuit......

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Electronic AC Voltmeter -
7 ms Ranges. . .

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7 Peak-to-Peak Ranges ..............

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Frequency Response (5 V range). . .

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input Resistance And Camitance. ......

Electronic Ohmmeter -
7 Ranges. ..................... ,.

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Multipliers......
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0-1.5, 5, 15, 50, 150, 500, 1500 volts full scale;
up to 30,000 vow with accessory probe.

11 megohms (l megohm in probe) on allranges;
1100 megohms with accessory probe.

7,333,333 ohms-per-volt on 1.5 volt range.
Balanced bridge (push-pull) using twin cm.
1.3% run scale.

0-1.5, 5, 15, .50, 150, 500, 1500 rm: scales
(.853 d pesk-tO-pesk).

0-4, 14, 40, 140, 400, 1400, 4000.
news cpstoI mo (Goonsource).
16% mu scale.

1 megohm shunted by 35 up! (measured at
inputterminale).

Scale with 10 0 center X1, X10, X100, X1000,
XIOK, XIOOK, XIMEG. Names .1 (lino 1000
megohms with internal battery.

4-1/2", 200 no. movement, polystyrene case.

Combined AC-OHMS-DC switching probe, single
jack input for probe and ground connections.

1% precision type.

Printed circuit; etched metal process.

1. - 12AM, twin triode meter bridge.
1 - 6AM, twin diode AC rectifier.

Page 3

Battery.......

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CabinetSizeAndFlnilh...n.......

Net Weight. . . .

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Page3

141/2 volt 1mm: cell.
105-125 volts, 50/50 cps AC, 10 watts.

7- 3/8" high x 4-11/16" wide x 4-1/8" deep,
charcoal gray.

34/2 lbs.

INTRODUCTION

The HEATHKlT Model lM-ll Vacuum TubeVolt-
meter is intended for use by servicemen, en-
gineers, and maintenance men to make acCurate
measurements or! DC+, DC-, AC rms and peak-
to-peak voltages, plus resistance. The designis
simple and rugged, yet accurate.

The instrument employs vacmimtubes for recti-
fication and amplification on all measurement
junctions to insure good sensitivity andstability
at operation. Precision resistors areusedinthe
voltage divider networks to provide high accu-
racy.

The confusing tangle 0! test leads coming from the
front panel of most VTVMs is eliminated by the
use of a combination AC-OHMS-DC switching test
probe and a single Jack input oonnectioniorboth
test probe and ground leads. The l megohm
resistor in the probe is switched into operation

when the probe switch is set on DC. This iso-
lating resistor allows DC component voltagesto
be measured separately, even when high fre-
quency AC voltages are present atthe test point.

The VTVM has a very high input impedance (11
megohms on DC and 1 megohm shunted by 36
uni on AC). Consequently, the circuit in which
the voltage is being measured will notbe sig-
nificantly loaded by the VTVM. Most nonelec-
tronic voltmeters (VOM) have a much lower in-
put impedance over the most frequently used
ranges oi test voltages. Consequently, when a
VOM is used to measure voltages in high im-
pedance circuits, the indicated voltage willbe
appreciably less than the actual voltage. The
amplifier section of the VTVM also enables the
VTVM to accurately measure much higher re-
sistances than can be measured with a VOM.