HAMTRONICS R302 Series Installation Operation & Maintenance

INSTALLATION, OPERATION, & MAINTENANCE
GENERAL INFORMATION.
The R302 is the latest in a series of popu-
lar receivers for demanding applications
which require exceptional sensitivity and se-
lectivity. It is especially suited for repeaters,
audio and data links, and remote control. The
R302 was designed to provide instant setup
without lengthy waits to obtain channel crys-
tals. It is a single-channel vhf fm receiver
available in several models for reception in
the 144 MHz ham band, the 148-174 MHz
commercial band, or 216-226 MHz.
The R302 is our 8th generation vhf fm re-
ceiver, and it packs in features you've told us
are important to you during our 40 years of
designing receivers. It's up to the difficult jobs
you've told us you have.
The R302 retains all of the popular fea-
®
tures Hamtronics receivers have been noted
for. It uses triple-tuned circuits in the front
end and excellent crystal and ceramic filters in
the i-f with steep skirts for close channel spac-
ing or repeater operation. The i-f selectivity,
for instance, is down over 100dB at ±12 kHz
away from the carrier, which is 40-50 dB bet-
ter than most transceivers. Low noise fet's in
the front end provide good overload resis-
tance and excellent sensitivity.
The R302 is designed for narrow-band fm
with ±5 kHz deviation. The audio output will
drive any load as low as 8Ω with up to 1 Watt
continuous output. The receiver may be used
with either voice or fsk data up to 9600 baud
using an external data interface unit. An ac-
cessory TD-5 CTCSS Decoder unit is available
for subaudible tone control.
The R302 features a positive-acting, wide-
range squelch circuit and additional output
terminals for low-level squelched audio and
discriminator audio as well as COS.
There are several models, which have mi-
nor variations in parts and microcontroller
programming, to provide coverage as shown
in table 1. Channel frequency is controlled by
a synthesizer with DIP switch channel setting.
The TCXO (temperature controlled xtal os-
cillator) provides a temperature stability of
±2ppm over a temperature range of -30°C to
+60°C.
INSTALLATION.
Mounting.
Some form of support should be provided
under the pc board, generally mounting the
board with spacers to a chassis.
holes should be provided in a front panel for
the bushings of the SQUELCH and VOLUME
controls. After sliding bushings through panel,
washers and nuts can be installed on the out-
©2010 Hamtronics, Inc.; Hilton NY; USA. All rights reserved. Hamtronics is a registered trademark.
HAMTRONICS ® R302 VHF FM RECEIVER:
side of the panel. Be sure to provide support
for the board; do not rely on the controls to
support the board, since that could cause a
break in the pcb solder connections.
The receiver board relies on the mounting
hardware to provide the dc and speaker
ground connections to the ground plane on
the board; so metal standoffs and screws
should be used for mounting.
Electrical Connections.
Power and input audio or data signals
should be connected to the solder pads on the
pc board with #22 solid hookup wire, which
can be
feedthrough capacitors used on the cabinet in
which it is installed. Be very careful not to
route the wiring near the components on the
left hand side of the board, which contains
sensitive loop filter and vco circuits which
could pick up noise from the wiring.
Power Connections.
The receiver operates on +13.6 Vdc at
about 200 mA peak with full audio. Current
drain with no audio is only about 45 mA. A
well regulated power supply should be used.
Be sure that the power source does not
carry high voltage or reverse polarity tran-
sients on the line, since semiconductors in the
receiver can be damaged. The positive power
supply lead should be connected to the re-
ceiver at terminal E3, and the negative power
lead should be connected to the ground plane
of the board through the mounting hardware
or the shield of the coaxial cable. Be sure to
observe polarity!
Speaker.
An 8-ohm loudspeaker should be con-
nected to E2 with ground return through the
mounting hardware. Use of lower impedance
speaker or shorting of speaker terminal can
result in ic damage. The receiver can also
drive higher impedances, such as the 1K to
20K input impedances of repeater controller
boards. There is no need to load down the
output to 8 ohms.
Note that the audio output ic is de-
signed to be heatsunk to the pc board through
the many ground pins on the ic. When run-
ning moderately low audio levels as most ap-
plications require, it is no problem to use an ic
socket; so we have provided one for your con-
venience. If you will be running high audio
levels, check to see if the ic is getting hot. If
so, you should remove the ic socket, and sol-
3/8-inch
der the LM-386 ic directly to the board for
better heatsinking.
Antenna Connections.
The antenna connection should be made
attached to a connector
to the pc board with an RCA plug of the low-
loss type made for rf. We sell good RCA plugs
with cable clamp. See A5 plug on website.
If you want to extend the antenna con-
nection to a panel connector, we recommend
using a short length of RG-174/u coax with the
plug and keep the pigtails very short.
We do not recommend trying to use di-
rect coax soldered to board or another type of
connector. The method designed into the
board results in lowest loss practical. When
soldering the cable, keep the stripped ends as
short as possible.
We recommend you always use anten-
or
nas with a matching network which provides a
dc ground on the driven element to avoid
static buildup damaging the input stage of the
receiver.
OPTIONS.
Repeater Use.
E5 provides a COS (carrier operated
switch) output which may be connected to a
COR module to turn a transmitter on and off.
The output level is about 8V unsquelched and
0V squelched. There is a resistor in series
with the output to limit current. Therefore,
the voltage that appears at the COR board will
depend on the load resistance at the input of
that board. For best results, be sure that the
input resistance of the COR board is at least
47K. If the input resistance is too low, no
damage to the receiver will occur; but the
squelch circuit hysteresis will be affected.
If your repeater controller uses discrimi-
nator audio, rather than the speaker output,
filtered discriminator audio is available at E4.
The level is about 2V p-p. Note that discrimi-
nator audio is not
squelched. If you need audio which is
squelched, take it from Repeater Audio termi-
nal E1.
If your controller uses low level audio and
Table 1. Quick Specification Reference
Model R302-1 138.000 - 148.235 MHz
Model R302-2 144.000 - 154.235 MHz
Model R302-3 154.200 - 164.435 MHz
Model R302-4 164.400 - 174.635 MHz
Model R302-5 216.000 - 226.235 MHz
Model R302-6 220.000 - 230.235 MHz
Sensitivity (12dB SINAD): 0.15 to 0.2µV
Squelch Sensitivity: 0.2µV
Adjacent Channel Selectivity:
±12 kHz at -100dB!
Image Rejection: 60-70dB
Modulation Acceptance: ±7.5 kHz
Frequency Stability: ±2ppm -30°C to +60°C
Audio Output: up to 1 Watt (8 ohms).
Operating Power: +13.6Vdc (+10 to +15Vdc)
at 45-200 mA, depending on audio level.
Size: 4 in. W x 2-7/8 in. D (plus pot. shafts)
Revised: 12/20/10
de-emphasized or
- Page 1 -