©1990 Hamtronics, Inc.; Hilton NY; USA. All rights reserved. Hamtronics is a registered trademark. Manual revised:10/2/07
- Page 1-
FUNCTIONAL DESCRIPTION.
The COR-3 module is designed for
operation with Hamtronics fm exciters
and receivers and CWID board to pro-
vide repeater operation. The unit
may also be used with other makes of
transmitters and receivers if the re-
quired interface signals are available.
The COR-3 module features a
courtesy beep tone, which helps to
prevent talk over by encouraging us-
ers to wait a short time before picking
up the repeater. After the waiting pe-
riod, a beep sounds on the repeater
and the time-out timer is reset. Wait-
ing this short period allows any new
party to break in and identify himself.
The unit comprises four main circuits.
1. An electronic carrier-operated
relay provides operating power to the
exciter in the transmitter enclosure
whenever the receiver squelch is open.
U1-B senses the presence of a COS
signal from the receiver and keys the
first timer, U1-A, which provides the
courtesy wait period. That trips timer
U1-D, which provides the silent re-
peater tail. That timer, in turn, keys
Q1/Q2, which switches the B+ to the
exciter. If the receiver should be held
on for longer than the legal transmit
period, (e.g., 5 minutes), time-out
timer U1-C automatically shuts down
the transmitter until the receiver is re-
leased.
2. An audio oscillator and pulse
generator circuit provides the beep
signal. The output of timer U1-A trig-
gers one-shot multivibrator U2-C/D
when the waiting period elapses. The
one-shot keys square-wave oscillator
U2-B. The audio output is integrated
by an R/C network to create a sign-
wave tone, which is applied to the
mixer for output to the exciter audio
circuits.
3. Audio mixer stage U2-A mixes
three audio inputs from the receiver,
the CWID, and the beep generator to
provide the audio for the transmitter.
The receiver audio level is set at the
receiver to a predetermined level. Pots
on the COR-3 board adjust the levels
of the CWID signal and the beep tone
to the desired levels relative to the re-
ceiver audio.
4. A speaker amplifier which pro-
vides adjustable drive for a local
speaker separate from the repeater
audio, U3, avoids having to use "L"
pads, etc. and compromising local
audio for benefit of repeater. This
allows the receiver audio to be run at
a low level to avoid distortion.
Refer to catalog for complete
COR-3 module specifications.
CONSTRUCTION.
There is no special construction
sequence; but following are some
notes regarding various parts.
a. Resistor bodies are designated
as circles on the assembly diagram for
those which are mounted vertically.
b. Note the polarity of ic's, transis-
tors, diodes, and electrolytic capaci-
tors.
c. Trim pots may be marked with
significant figures and multipliers,
such as "105" for 1 megohm.
d. Terminal pins for E1-E15
should be cut from the metal carrier
strip, then snapped in place from top
of board using care not to crush them.
Firm pressure with a pair of fine nose
pliers grasping one wall of the pin will
cause it to snap and lock into hole.
e. Use ic sockets for U1 and U2
but not for U3, which must be sol-
dered to the board for heatsinking.
f. Be careful not to interchange re-
sistors which have similar appearing
color bands, eg., 150K and 510K or 1
meg and 10 meg.
INSTALLATION.
The
COR-3
module
can
be
mounted with standoffs in the four
corners of the board. No special
shielding is required. Connections are
made to the terminal pins either by
soldering hookup wires into hollow top
of pin or wrapping around pin and
soldering. Following are descriptions
of required interface connections.
When used with Hamtronics exciter,
receiver, and CWID boards, required
interface levels are assured. When
used with other equipment, some care
must be taken to be sure compatible
interface connections are arranged.
Referring to the Repeater System dia-
gram, it can be seen that the ex-
citer/pa and the receiver are mounted
in rf tight boxes with feedthru capaci-
tors used at control and audio signal
entrances.
a.
COS
OUTPUT
FROM
COS
OUTPUT
FROM
COS
OUTPUT
FROM
COS
OUTPUT
FROM
RECEIVER.
RECEIVER.
RECEIVER.
RECEIVER. This control signal at E7,
taken from the squelch stage in the
receiver must be about +3 to +10 Vdc
when the squelch is open and near
ground when squelch is closed.
b. AUDIO FROM RECEIVER.
. AUDIO FROM RECEIVER.
. AUDIO FROM RECEIVER.
. AUDIO FROM RECEIVER. The
high level audio output from the ic in
the receiver, which normally feeds the
speaker, is connected to E6 on the
COR-3 board instead. The COR-3
board applies it to the audio mixer
stage for application to the exciter.
The receiver audio is also connected
through a (user supplied) 100K SPKR
VOL control to E14. A speaker am-
plifier on the COR-3 board amplifies
the signal from the SPKR VOL control
to provide an isolated signal for a local
speaker on the repeater panel. The
nominal audio level at E6 should be
1.5V p-p at full 5 kHz deviation on the
receiver.
c.... LOCAL SPEAKER
LOCAL SPEAKER
LOCAL SPEAKER
LOCAL SPEAKER connected to
E15 on COR-3 board should be an
8-ohm speaker. Up to 2W of audio
can be obtained from the COR-3
speaker amplifier. Note that the
speaker must return to ground.
d. B+ FOR COR
B+ FOR COR
B+ FOR COR
B+ FOR COR----3 BOARD
3 BOARD
3 BOARD
3 BOARD should
be
+13.6Vdc
connected
to
E3.
Ground should be tied to E10 unless
a good ground is picked up through
the mounting hardware from the
chassis. Current drain depends on
speaker level and amount of current
supplied to exciter keyed B+ line, but
normally should be about 600-700
mA.
e. KE
KE
KE
KEYED B+ TO EXCITER
YED B+ TO EXCITER
YED B+ TO EXCITER
YED B+ TO EXCITER at E1
is +13.4Vdc (slight drop in Q2) at up
to 600 mA. Because the pa is class C,
it is unnecessary to switch the B+ to
the pa.
f. REPEATER AUDIO
REPEATER AUDIO
REPEATER AUDIO
REPEATER AUDIO from E5 is
connected to the microphone input of
the exciter. A 500 ohm dynamic mi-
crophone can also be connected to the
same exciter input. Resistor R47 pre-
vents the microphone from being
loaded down.
g. LOCAL KEY
LOCAL KEY
LOCAL KEY
LOCAL KEY input E12 may be
grounded by the local microphone PTT
switch to key the transmitter locally.
h. Connections to CWID are as
shown on the Repeater System dia-
gram. ID TRIP normally is high and
goes low when the receiver squelch
closes and the beep timer elapses to
provide a pulse to trip the id. The ID
KEY signal normally is low and goes
high to key the COR circuit while the
CWID runs. The CWID audio output
should be tied to E4, the input to the
audio mixer on the COR-3 board. The
CWID input level at E4 normally is
about 4kV p-p.
i. Outputs at E2, E8, and E11
drive front panel led's to indicate re-
peater status. Led's are not supplied
with this kit, but they are supplied in
the hardware package if you bought a
complete Hamtronics Repeater Kit.
HAMTRONICS® COR-3 MODULE: INSTRUCTION MANUAL
