Heathkit HR-10B - Detector-Audio Output; Power Supply; Construction Notes

Page 4
with
exceptionally good selectivity.
Amplified IF signal from the plate of V3 is
coupled through second IF transformer T2 to
the grid of IF amplifier tube V4A. Tube V4A
again amplifies the IF signal. At this point in
the circuit the Beat Frequency Oscillator (BFO)
signal from V4B may be beat with the IF signal
by turning the BFO switch to BFO. The intro-
duction of the BFO signal produces an audible
signal for Continuous Wave (CW) or Single
Sideband
(SSB) reception, The output from V4A
is coupled through IF transformer T3 to tube V5.
DETECTOR-AUDIO OUTPUT
Tube V5 is the detector stage. This tube de-
tects the audio signal from the IF signal. This
audio signal is then coupled through capacitor
C35 and the AF GAIN control to the grid of the
first audio stage V6A. The amount of audio
signal applied to the grid of V6A can be regu-
lated by the AF GAIN control. This in turn
regulates the amount of audio signal that will
be amplified by V6A. From tube V6A, the audio
signal is coupled by capacitor C38 to the grid
of tube V6B. Tube V6B further amplifies this
audio signal and feeds it through audio output
transformer T4 to the Speaker jack.·
POWER SUPPLY
The power supply uses tube V7 as a full- wave
rectifier with power transformer T6. Filtering
of the DC voltage is provided by resistors R44
and R43,
and capacitors C55, C56, and C57.
CONSTRUCTION NOTES
This manual is supplied to assist you in every
way to complete your kit with the least possible
chance for error. The arrangement shown is
the result of extensive experimentation and
trial. If followed carefully, the result will be
highly
stable and dependaUe performance. We
suggest that you retain the manual in your
files for future reference, both in the use of
the
equipment and for its maintenance.
UNPACK THE KIT CAREFULLY AND CHECK
EACH PART AGAINST THE PARTS LIST.
In so
doing, you will become acquainted with the
parts. Refer to the information on the inside
covers of the manual to help you identify
the components. If some shortage or parts
damage is found in checking the Parts. -List,
please read the Replacements section and sup-
ply the information called for therein.
Most kit builders find it helpful to separate the
various parts into convenient categories. Muffin
tins or molded egg cartons make convenient
trays for small parts. Resistors and capac-
itors may be placed with their lead ends in-
serted in the edge of a piece of corrugated
cardboard until they are needed. Values can
be written on the cardboard next to each
component. The illustration shows one method
that may be used,
Resistors generally have a tolerance rati11,g of
1 O% unless otherwise stated in the Part~ List.
Tolerances on capacitors are generally even
greater. Limits of +100% and -20% are common
for electrolytic capacitors.
We suggest that you do thefollowingbeforework
is started:
1. Lay out all parts so that" they are readily
available,
2. Provide yourself with good quality tools,
Basic tool ·requirements consist of a screw-
driver with a 1/4" blade; a small screw-
driver with a 1/8" blade; long-nose pliers;
wire cutters, preferably separate diagonal
cutters; a penknife or a tool for stripping
insulation ,from wires; a soldering iron (or
gun) and rosin core solder. A set of nut
drivers and a nut starter, while not neces-
sary, will aid extensively in construction
of the kit.