©1995 Hamtronics, Inc.; Hilton NY; USA. All rights reserved. Hamtronics is a registered trademark. Revised: 8/31/05
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FUNCTIONAL DESCRIPTION.
The CC432 is a low-noise receiving
converter designed, in several models
with variations in tuned circuits, to
convert signals in the uhf range to an
i-f frequency in the hf or vhf range.
Following is a list of common CC432
Converter models.
Model #
Input Range
Output
Range
CC432-2
432-434
28-30
CC432-5 435-437
28-30
CC432-3 435.5-437.5 28-30
CC432-4 432-436
144-148
CC432-9
439.25 ATV
61.25 (Ch 3)
The converter is available in three
configurations: pc board kit with case
and BNC jacks, pc board kit less case
(RCA jacks on board), and wired and
tested unit in case with BNC jacks.
THEORY OF OPERATION.
The circuit for the converter is rela-
tively simple. A GaAsFET rf amplifier
is coupled to a mos fet mixer through
a triple-tuned circuit for selectivity.
An overcoupled double-tuned mixer
output tank circuit is used to achieve
a wide bandwidth.
Oscillator Q3 uses fundamental
crystals in the 14-16 MHz range for
easy frequency trimming. The collec-
tor circuit is tuned to the third har-
monic of the crystal frequency, about
42-48 MHz. Q4 triples this frequency
again to about 126-144 MHz. Then,
Q5 either triples this again to the 378-
407 MHz range, or in the case of the
two-meter output model, it doubles to
about 288 MHz. Double-tuned cir-
cuits are used throughout the multi-
plier/injection chain for signal purity.
Following is a summary of the fre-
quency scheme for each model.
Model Injection
Xtal
Freq.
CC432-2 404 14.962962
CC432-5 407 15.074074
CC432-3 407.5 15.092592
CC432-9 378 14.000000
CC432-4 288 16.000000
CONSTRUCTION.
Note that uhf equipment requires
precise construction using short, di-
rect leads. Seat parts as close to the
board as possible without over-
stressing the leads.
Be sure to follow instructions as
given and don't arbitrarily do things
differently. Refer to the component
location diagram and parts list during
assembly.
CAUTION
: The chip capacitors are
very small and easy to damage, mix
up, or lose. Leave them in the plastic
carrier strips until time to install.
CAUTION
: Static handling pre-
cautions are required for the fet's.
The small geometry and high imped-
ances make FET's heat and static
sensitive; so be careful. It is good to
discharge your hand to a grounded
metal object just before picking up a
transistor, and the use of a grounded
soldering iron is mandatory. A heat
sink is not necessary while soldering if
you are careful to apply no more heat
than necessary.
Do not be overly anxious about
blowing out the fet's if you observe
these precautions. The transistors are
all factory tested and wrapped in foil
to ensure that they arrive in good
condition. There is no warranty cov-
erage for damage which occurs in
construction or handling; but re-
placement transistors are moderately
priced.
------------------------
a. Set board on bench or in hold-
ing jig oriented as shown.
b. Begin by tack soldering the two
FET's (Q1 & Q2) to the foil on the top
of the pc board. Orient the drain
(long) leads as shown.
Lettering on the
transistors should be up.
(See detail at
the left side of the diagram.) Carefully
bend the leads at right angles toward
the bottom of the FET's, and install
them in the four holes for each tran-
sistor. Solder the pads under the
board.
c. Install the six small variable ce-
ramic capacitors and the one piston
variable capacitor, orienting them as
shown. See parts list for values.
d. Install chip capacitors and re-
sistors on top of board as follows. Use
small tweezers to handle them. Be
careful not to drop them, because
they are difficult to find. Since they
have no markings, be sure to leave
them in the package until installed so
you can tell the values apart. Refer to
parts list for values. (An additional
chip resistor will be installed on the
bottom of the board later.)
Note where capacitors and resis-
tors are to be positioned. They must
straddle the area between a pad on
the board and the ground plane, with
one electrode soldered to each. Do all
of one value at a time; then start the
next value of capacitor, and so on un-
til done.
Apply a little solder to the pads
where one end of each capacitor will
be positioned. Do not apply solder to
the ground plane yet, just the pads
isolated from the ground plane. (You
can pretin the isolated pads for all of
the chip capacitors and resistors now,
but install only one value at a time.)
Pick up one part at a time, re-
moving it carefully from its carrier
strip by peeling back the tape with a
knife or diagonal cutters. Set the part
in place. Then heat the solder on the
pc board pad, and allow the solder to
bond to the electrode on the part.
When the solder melts, the part will
seat down on the board in the molten
solder. (It is essential that this proc-
ess be done relatively quickly so the
solder doesn't oxidize and so there is
still a little flux left where the capaci-
tor electrode sits.)
After one end of each of the parts
is soldered and the positions have
been confirmed to be correct, solder
the other end of each part to the
ground plane. Repeat for other values
of chip capacitors and resistors.
e. In like manner, solder chip re-
sistor R2 on the bottom of the board
as indicated in the detail view to the
right of the diagram.
f. If RCA jacks are to be used (no
case), install them on the board. Ori-
ent them with the center conductor
tab toward the circuitry on the board,
rather than toward the edge of the
board. Solder ground tabs to ground
plane on top of board, and solder cen-
ter contacts under board. If the pc
board will be installed in a case, the
RCA jacks will not be used; in this
case, tack solder a 1" length of #20
bus wire to the pad for the center
conductor of each of the jack posi-
tions, bringing the free end of the wire
out the top of the hole to be connected
later to the BNC jack, as shown in the
diagram.
g. Tack solder the shield in place
between Q1 and L2 as shown. The
front of the shield should be flush
with the front edge of the board. Cut
top corners of the shield on a 45° an-
gle just a little to remove sharp edges.
h. Install all disc and monolithic
HAMTRONICS
®
CC432 UHF RECEIVING CONVERTER
ASSEMBLY, INSTALLATION, OPERATION, AND MAINTENANCE