Heathkit HN 31 Manual

Page 1

Assembly
and
Operation

of the
-HEATHKIT TABLE OF CONTENTS

Specifications.................... 2

CANTENNA
DUMMY Schematic...................... 3
R F L O A D Construction Notes. .

MODEL HN'31 Parts List...........

Circuit Description. . . . . . . . . . . . . . . . 2

OOOOOOOOOOOOOO 3

Step-By-Step Assembly. . . . . . . . . . . . . 5
PartsMounting................ 5
Component Wiring.............. 8

Initial Operation Check. . . . . . . . . . . . . 9

FinalAssembly.................. 9

Operation.OOOOOOOOOOCOOOOOOOOOO10

InCase OfDifficulty.............. . 10
Warranty ............. Inside front cover

Customer Service .......... Inside rear cover

HEATH COMPANY
BENTON HARBOR. MICHIGAN 49022

COpyright © 1965
Heath Company
A rights reserved

Page 2

Page 2 - HEATHKIT'

SPECIFICATIONS

Impedance.....................

Voltage Standing Wave Ratio (VSWR)

Power Dissipation Capability. . . . . . . . . . . . .

Size. 0 I O O O I O

O I O O I O O O I O I O O O ........

NetWeight....... ......

50 9.

Less than 1.5 up to 300 me.

Less than 2.0 up to 400 me.

1 kilowatt maximum (ICAS).
8-7/8" high x 7" diameter, overall.

1-1/2 lbs (oil not included).

The Heath Company reserves the right to discontinue instru-
ments and to change specifications at any time without
incurring any obligation to incorporate new features in

instruments previously sold.

CIRCUIT DESCRIPTION

The Model HN- 31 "Cantenna" Dummy RF Load
was designed as a small convenient package
capable of handling a kilowatt of power. (See
Figure 1). The oil-cooled, temperature- stable
resistive element provides a very low VSWR
(voltage standing wave ratio) up to 400 mega-
cycles. A special circuit is incorporated to
provide a DC voltage for monitoring relative
output power.

Refer to the Schematic Diagram on Page 3 for
a better understanding of the following descrip-
tion.

When power is applied to the circuit, R1, the 50

1000

$2 resistor element (dummy load), absorbs this
power and converts it into heat. The heat is
dissipated into and stabilized by the oil bath
which envelops the resistor element,

The output circuit, used for monitoring, is iso-
lated from the 50 Q resistor element (input cir-
cuit) by R2. This relatively high impedance
separation allows only a portion of the input
voltage to pass to R3 of the output circuit. The
voltage developed across R3 is presented to D1.
(Keep in mind that this voltage is relative to the
input RF power). Half-wave diode rectifier D1,
combined with filter capacitor C1, presents aDC
output voltage for monitoring purposes.

POWER INPUT T0 LOAD
IN WATTS
u:
o
o

.l

TIME

20 30 40 50 60 120
IN MINUTES

Figure 1