DX-302 Communications Receiver
(200-0220) Operation Faxback Doc. # 45534
Before operating your DX-302, you should have an antenna and ground
connected. And, of course, you must either have the power cord connected
to a standard AC outlet or load 8 type C batteries (open Battery
Compartment and install batteries as illustrated). Or, connect the DC
power cord to a source of 12 Volts DC.
Since you are probably most familiar with the standard broadcast band radio
reception, you might prefer to use the DX-302 there first.
1. Turn the receiver on by rotating VOLUME clockwise.
2. Set MODE switch to AM.
3. Set PRESELECTOR BAND switch to 0.5 ~ 1.6.
4. Set ATTEN and LIGHT to their center positions and SELECTIVITY to upper
position.
5. Set RF GAIN to 10.
6. Adjust MHz Tuning so '1.' appears in the Digital Frequency Readout.
7. Use kHz Tuning to tune in a station above 1,000 MHz.
8. Adjust PRESELECTOR TUNE to the same frequency (adjust for maximum
reading on the meter).
9. To tune in stations below 1,000 MHz, adjust the MHz Tuning so a '0.'
appears in the Readout. Then adjust kHz Tuning for the desired station
frequency. Once again, adjust PRESELECTOR TUNE to the same frequency
(for maximum reading on the Meter).
10. Often you can peak-up the sensitivity by slightly readjusting the MHz
Tuning. Try it.
Tuning VLF and LF Frequencies
Once you've become familiar with the DX-302 operation on the standard
Broadcast Band frequencies, you can try the low frequencies from 10 kHz up
to 500 kHz.
1. Set PRESELECTOR BAND Switch to the appropriate position to cover the
frequency you will tune. When you use the 0.01 ~ 0.15 MHz position,
set PRESELECTOR TUNE to the "SET position.
2. Set PRESELECTOR TUNE to the approximate frequency you will tune to
(unless tuning to the 0.01 ~ 0.15 MHz spread (for this coverage,
leave at "SET" position)).
3. Set MHz Tuning so '0.' is displayed.
4. Set kHz Tuning to display the desired frequency.
5. Try readjusting MHz tuning slightly for maximum sensitivity.
6. If not on 0.01 ~ 0.15 MHz position of PRESELECTOR BAND, adjust
PRESELECTOR TUNE for maximum signal reception.
See "Special Operating Notes"
Tuning Frequencies Above 2 MHz
The rest of the bands are quite easy to tune.
1. Set PRESELECTOR BAND Switch to the appropriate position.
2. Adjust PRESELECTOR TUNE to the approximate frequency you are going to
tune to.
3. Adjust MHz Tuning to display the desired MHz number.
4. Adjust kHz Tuning to display the desired kHz number.
5. Adjust PRESELECTOR TUNE for maximum signal reception.
6. If you are tuning for SSB (single sideband) or CW (Continuous Wave or
"code" as the more common term is), set MODE switch to LSB/CW or USB/CW
and SELECTIVITY switch to NARROW. Adjust BFO PITCH to precisely tune
in the signal.
7. Often for optimum sensitivity, you'll find that it helps to make a
slight readjustment of MHz Tuning.
8. If you are in the AM mode and noise is excessive, set MODE SWITCH to
AM/ANL position.
SPECIAL OPERATING NOTES
Your DX-302 is a fine example of technical achievement in the field of
communications equipment. It is simple to operate and yet has all the most
wanted features and controls - plus the fact that it is a continuous-
coverage receiver (tunes ALL frequencies from 10 kHz to 30 MHz). Short
Wave listening is a great hobby - your skill will grow with experience and
of course experience only comes with practice. This section has a number
of hints relating to the proper use of your Receiver. We can't possibly
turn you into an expert SWL just by giving you thorough instructions - but
these hints might help.
The Antenna connection can affect reception in unusual ways on a Receiver
of this design. Because the Preselector/RF stages are not automatically
tracked with the oscillator, it is possible that strong local signals will
produce spurious reception effects.
For example, long wires of 50 feet (15 m) or more connected to either of
the ANTenna terminals can deliver a very high 'RF' signal to the back of
the set. The result is a tendency to overload the input and you tune the
spurious responses.
Solutions to this type of effect:
1. Be sure PRESELECTOR BAND Switch is set to the approximate position
of the band you wish to receive. Tune PRESELECTOR TUNE for maximum
signal reception.
2. Try tuning down the RF GAIN control.
3. Try readjusting MHz Tuning very slightly.
4. Try switching in the ATTEN (use 20 dB position first, then 40 dB if
necessary).
5. Try connecting the antenna to the other ANTenna connector.
6. Use a shorter antenna when operating below 2 MHz
Preselector setting and tuning is important for best sensitivity and
maximum spurious-signal rejection. Always be sure the PRESELECTOR BAND is
set correctly for the frequency you are tuning to. If you detune the
PRESELECTOR, the S-meter reading will drop. If you set the PRESELECTOR
BAND Switch to the wrong position, you may not completely lose reception of
the signal; but this does not imply that this signal will be received at
another frequency. An improper setting of the Preselector may result in
false signal tuning. Proper setting and tuning of Preselector will help to
eliminate crossband reception problems.
MHz Tuning does have a slight effect on the sensitivity of the Receiver.
For optimum reception, tune for best sensitivity (and minimum spurious
response). You'll note that above the extreme upper end of any given MHz
spread , the kHz display will blank out, although you can still tune in
signals for about 30 kHz. This allows you to tune both above and below the
MHz band 'edges' without having to change MHz tuning. The same is true for
below the extreme low end of each MHz spread.
Operation of the RF GAIN control effects the overall sensitivity of the
Receiver. Normally, you'll want to leave RF GAIN at maximum (10). If you
are near a very strong signal, you can use RF GAIN to reduce the volume of
the received signal; if you don't do this, the strong incoming signal can
'swamp' the input stages of the Receiver and may result in unusual types of
signal reception and distortion problems. Also, you may realize that the
S-Meter is accurate only when RF GAIN is set to maximum.
The MODE Switch determines the type of signal that your Receiver recovers.
For standard broadcast and international short wave signals, use the AM
position. For code or SSB signals, use either USB/CW or LSB/CW position.
If pulse-type noise interferes with reception of AM signals, use the AM/ANL
position. You may notice that with the AM/ANL position (Automatic Noise
Limiter), the signal reception seems to drop slightly; this is normal (thus
it is best not to use the ANL mode unless noise is a serious problem).
When tuning SSB and code signals, adjust the kHz tuning control very
slowly. In the Ham bands, much of the activity is in code or SSB. If the
SSB signal is very strong, proper reception will be improved if you adjust
RF GAIN away from maximum. If you tune through an SSB signal and you are
in the AM mode, there will only be a fluttering sound (you'll be able to
tell that a signal is there, but won't be able to understand anything).
Use one of the SSB modes and slowly adjust the kHz Tuning and/or BFO PITCH
until the voice sounds are normal. When improperly tuned, voices will have
a low gutteral sound or will sound like "Donald Duck". Tuning of SSB
signals takes a little patience and practice.
If you tune through AM signals while using the USB or LSB mode, you will
have a very annoying background tone, which varies with the setting of the
Tuning controls. If this happens, set MODE to AM.
As you have noticed, there are two Modes for SSB signals - LSB and USB
(Lower Side Band and Upper Side Band).
The following chart shows you the normal SSB mode of operation for the Ham
bands:
Meters Frequency Sideband Used
80 3.5 to 4.0 MHz Lower
40 7.0 to 7.3 MHz Lower
20 14.0 to 14.35 MHz Upper
15 21.0 to 21.45 MHz Upper
10 28.0 to 29.7 MHz Upper
When receiving SSB signals, the precise frequency is display frequency +2
kHz if you are using the LSB mode. For the USB mode, the precise frequency
of the transmission is the display frequency -2kHz.
When tuning SSB or CW signals, you should put the SELECTIVITY switch in the
NARROW position. You will also find this position helpful when trying to
receive AM signals through heavy interference.
The Standby mode is always incorporated in high quality communications and
Ham-type Receivers. Using this mode, you leave all the main circuits 'on',
but disable the audio portion. Thus, you can leave the Receiver on (to
maintain maximum frequency stability) and yet are not disturbed by the
audio. However, don't leave in the Standby position for many hours if you
are operating from batteries (or batteries will wear out).
The DX-302 also provides for rear panel muting. Ham radio operators
require this ability when operating a transmitter (while transmitting, the
Receiver must be disabled. Connecting the MUTE screw terminal to ground
will disable the Receiver. This muting function can be activated by remote
switching (normally available via the transmitter).
A pair of headphones is a great asset for serious SWLing. They make it
much easier to hear and understand some of those weak and distant stations.
We strongly suggest you consider purchasing a pair of communications
headphones - 8 ohm impedance type. Your Radio Shack store has some good
choices.
You can use 12 volts DC to power your receiver. For example, if you want
to mount the Receiver in a vehicle, or take it on a field trip, a source of
12 Volts DC will operate it. Connect the 12 volt DC power to the connector
on the rear using the connector cord provided; if you are using this in
conjunction with a vehicle, be sure you use a 12 volt NEGATIVE ground
electrical system (almost all current US vehicles use negative ground
systems). Be sure you connect the external power leads with the correct
polarity: + to + and - to -. (When external DC power is connected, the
internal batteries are automatically disconnected).
(CC/wr-07/13/98)
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