Heathkit HR 20 Schematic

Page 1

ANTENNA
INPUT

.4-

59
I1;
63

by.

.OI
pFD

V2A
I/Z SEAS
MIXER

XTAL FILTER

V3

5526
1ST. IF AMI?

V23
I/Z 6EA3
VFO

O

.005 L1
FD
.. = I
ION
III ..
GAIN
-: __® 1 _I'l
G9,? . .I I.
1- p.
(5
I I
OFF / l J
I
AVG FAST I
swrrcn _ C ' "J M g
- 5L0?) _.
6" A - 6:537
gm. pm '5: 5? ® 5° AM DETECTOR V7A
v43 sww m 2 l__IE_A_M_E_ ______ .80 NOISE LIMITER V2 5558 V2 6EBB
I/Z SEAS "'' " " .01 @ IST AUDIO
~ " 3- POWER AMP. .
"s METER I. l I: .é A? 9- a
l l I '-:-;- 'e'fi - ,- . 05-.
I- I I _ .ooI --- .® ® III-o
I" . I LIMITER ::: 9
: l I \I J 30K
.-- ---.' I 9-
|
' @
__ I ;:+ 220 3-:
r~ I 10 F0 _ zouFo -
25 .Ol UFDI
"s" METER __ I
ADJUST I _ _ ::
CONTROL _ I " '
- I
.
NOTES; @ 4000
IOW I337

SCHEMATIO OF THE
HEATHKIT®
MOBILE RECEIVER
MODEL HR-ZO

BANDSWITCH WAFERS ARE WN IN so METER POSITION.
FUNCTION SWITCH IS SHOWN IN AM POSITION.
MIC SWITCH IS SHCMN IN OFF POSITION.

ALL VOLTAGE READINGS ARE DC FEW POINT INDICATED TO
CHASSIS GRWND AND IRE MADE USING AN II MEGCHM VTVM.

10% VARIATION IN READING SHOULD BE ALLWED Fm DIFFER
ENCES IN METER CALIBRATION.

ALL RESISTORS ARE 1/2 WATT UNLESS SHCMN OTHERWISE.
ALL CAPACITUI VALUES ARE IN puf UhlESS SHONN OTHERWISE

ALL RESISTOR VALUES lRE IN OHMS | K = LWO GIMS. MEG -
1.000.000 OHMSI.

VII-TAGES SHWN ARE BASED ON USING THE HEATHKIT
TRANSISTW POWER SUPPLY.

BATTERY TERMINAL POTENTIAL IS 12.6 VOLTS - VARIATIONS WILL
CAUSE CWRESPONDIM DIFFERENCES IN READING.

ALL VmTAGES ARE BASED OH "NO SIGNAL' CONDITIONS. WITH
MAXIMUM RF GAIN

THE FOLLWING WILLATCR GRID VOLTAGE!) ARE MADE WITH
A RF PROBE AT OSCILLATCR PIN 9;

so METERS - 5 V
40 METERS - 2 V
20 METERS - 6 V
IS METERS - 3.5 V
l0 METERS - 3 V

wuzmc SHWN I5 Fm NEGATIVE GROUND VEHICLES.

3600

SIDE BAND

SELECTOR
SWITCH

§ .=.

PRODUCT

IM-I

DETECTOR T:-

V 6
0A 2
VOLTAGE

REGULATOR

3 3 O
a
600

F I LA MENT
vows: $535:

REGULATOR | f

0F F'ON 3W.
0N AUDIO
CONTROL

\I

FIL+

VJ

"-\/

Page 2

ANTENNA
INPUT

Page 4

V
2V J- SBJI
"K m V BE 5° AM DETECTOR
V48 SLOW NOISE LIMITER
1/2 6EA8 '0
"s" METER .
we @ ®
\
I z:
/ .0: 27cm
(3) i @
DOS
LLFD
25
"S" METER O
ADJUST
CONTROL _
NOTES;

SCHEMATIO OF THE
HEATHKIT®
MOBILE RECEIVER
MODEL HR-ao

BANDWITCH WAFERS ARE SHCAVN IN 30 METER POSITION.
FUNCTION SWITCH IS SHWN IN AM POSITION.
AVC SWITCH IS SHCMN IN OFF POSITION.

ALL VOLTAGE READINGS ARE DC FEW POINT INDICATED TO
CHASSIS GRWND AND ARE MADE USING AN II MEGCHM VTVM.

10% VARIATION IN READING SHOULD BE ALLWED Fm DIFFER
ENCES IN METER CALIBRATION.

ALI. RESISTORS ARE IfZ WATT UNLESS SWIM OTHERWISE.
ALL CAPACITOR VALUES ARE IN puf UNLESS SHWN OTHERWISE

ALL RESISTOR VALUES ARE IN OHMS | K =1.ooo GIMS. MEG -
1.000.000 OHMSl.

VRTAGES SHWN ARE BASED ON USING THE HEATHKIT
TRANSISTW POKER SUPPLY.

BATTERY TERMINAL POTENTIAL IS 12.6 VOLTS - VARIATIONS WILL
CAUSE CWRESPONDIM DIFFERENCES IN READING.

ALL VmTAGES ARI-I BASED ON "N0 SIGNAL ' CONDITIONS. WITH
MAXIMUM RF GAIN

THE POI-LOVING OSCILLATW GRID VQTAGES ARE MADE WITH
A RF PROBE AT OSCILLATGR PIN 9:

so METERS - 5 V
40 METERS - 2 V
20 METERS - 6 V
IS METERS - 3.5 V
I0 METERS - 3 V

RIMS SHWN I5 PM NEGATIVE GROUND VEHICLES.

SIDEBAND
SELECTOR
SWITCH

3600€
1

PRODUCT
DETECTOR

IMH