DX-440 AM/FM Direct Entry Communications Receiver
(200-0221) Operation - Part 1 Faxback Doc. # 17502
You can use the DX-440 to wake you up to your favorite station everyday.
And before you retire for the evening, you can set the timer so that the
radio turns itself off after an interval between 10 and 90 minutes. Make
the following settings with the power off.
SETTING THE ALARM
1. Press the TIMER button so that the display shows the current timer
setting (or 0:00) and STANDBY remains.
NOTE: The time setting disappears after five seconds, but STANDBY
remains.
2. While STANDBY is flashing, press UP or DOWN, or use the tuning knob, to
set the desired timer setting.
NOTE: *STANDBY stops flashing, if you do not change the time within
five seconds. If tis happens, you must return to the previous
step.
The timer uses a 24-hour clock (13:00 is 1:00 P.M.)
3. When the correct timer setting is displayed, simply wait. In about
five seconds, STANDBY stops flashing. A few seconds later . A few
seconds later, the display returns to the clock mode with STANDBY
still displayed.
NOTE: As long as STANDBY is displayed, the DX-440 comes on each day
at the time you set.
4. If you want to stop the DX-440 from coming on without changing
the timer setting, press TIMER so that STANDBY does not appear
on the display.
5. To check the timer setting, press TIMER so that STANDBY and the timer
setting are displayed. If the DX-440 is already in the STANDBY mode,
you must press TIMER twice to accomplish this.
USING THE SLEEP TIMER
To have the radio turn itself off after a period of 90 minutes or less,
proceed as follow:
1. Press the SLEEP button. The display shows SLEEP 90 in the upper right
hand corner.
2. If you want fewer than 90 minutes playing time, press the SLEEP button
again. Each time you press the button, the playing time reduces by 10
minutes.
To turn off the radio before it normally turns itself off, press the
POWER button.
SPECIAL TUNING TECHNIQUES AND CONTROLS
In addition to the standard tuning operations described previously, use the following controls for special operations.
RF GAIN CONTROL
This control adjust the receiver's sensitivity. For short wave and FM
reception, rotate the control to the MAX position, this provides the
maximum sensitivity. When you listen to the MW, standard AM band, or LW
band through external, rotate the control only as far as needed to obtain a
good signal. If you turn the knob further you might hear a distorted
signal. For weak stations, rotate the control to the MAX position. If you
encounter interferance, adjust the control in both directions until you get
the best compromise between your station and the interferance.
AM NARROW/WIDE SELECTIVITY SWITCH
Some station transmit their signal so that very little space exhist between their airspace and the station next to them on the band. If, while
tuning, you encounter interference, caused by the signal from an adjacent
station, press the button for the band you are listening to and select the
NARROW position. The interference is muted. For full reception leave the
switch in the WIDE position.
If you plan to listen to Morse code, referred to as CW (continuous wave),
set the BFO switch to the IN position. If you encounter too much noise
as you tune, set the AM NARROW/WIDE switch to the NARROW position.
USING HEADPHONES
While not in control,you might consider using headphones to obtain the best
reception. Many stations broadcast marginal signals. Only headphones can
capture the subtle difference between the signal from such stations and the
surrounding noise often encountered at night. Be sure that then headphones
terminate in a 1/8 inch plug. Insert the plug into the PHONES jack on the
side of the radio. When you plug the headphones in, you silence the
speaker.
Because the radio can receive stereo FM, when you listen to FM stereo
broadcast, be sure your are designed for stereo operation so that you
can obtain the full benefit of this feature.
USING THE LOCK CONTROL
Use this to prevent unauthorized use of the radio or to ensure that any
station you might be monitoring remains tunes in.
When you move the LOCK switch to the IN position, you disable the POWER
button and the tuning controls. If the radio is on when you use the LOCK
switch, you cannot turn off the radio or change the current frequency.
To release the LOCK function, set LOCK switch to the out position.
SPECIAL SSB/CW RECEPTION TECHNIQUES
Many station transmit unmodulated telegraph transmissions in the
shortwave band. To receive these special Morse code characters, the
radio uses a special circut, a beat frequency oscillator, to modify
the transmitted signal so that you can hear it. This particular type
of transmission is called continuous wave (CW) transmission.
Many stations transmit voice signals with a suppressed carrier in the
single side band mode. (SSB), part of the radio transmission spectrum
that lies to the side of the primary frequency signal. Amateurs tend
who transmit voice below 10MHz use the lower side band (LSB). Above
10 MHz, they use the upper side band (USB). Commercial utility
stations generally use the USB. A carrier has to be to make these
signal audible.
TO RECEIVE CW
1. Turn on the radio
2. Extend the antenna fully straight up.
3. Set the BFO switch to on.
4. Rotate the BFO PITCH control to the midpoint.
5. Rotate the RF GAIN control to the MAX position.
6. Press the AM button to select the AM band.
7. Tune in the CW station using the tuning knob, or enter the frequency
using the direct access buttons.
8. Adjust the CW tone using the BFO PITCH control.
9. Reduce strong signals by using the RF GAIN control. This also reduces
interference and noise.
TO RECEIVE SSB VOICE
1. Turn on the radio
2. Extend the antenna fully, in a straight up position.
3. Set the BFO switch to the IN position.
4. Rotate the BFO PITCH control to the LSB position for stations below
10MHz or to the MAX position.
5. Rotate the RF GAIN control to the MAX position.
6. Press the AM button to select the AM band.
7. Tune in the SSB station using the tuning knob, or enter the frequency
using the direct access buttons.
8. Rotate the BFO PITCH control to adjust the signal quality.
9. Rotate the RF GAIN control to dampen strong signals. This can improve
signal clarity as well.
NOTE: Before choosing another band, set the RF GAIN control to the MAX,
and move the BFO switch to the OUT position.
USING THE SHOULDER STRAP
1. Insert about five inches of the end of the strap into the hanger.
2. Pull the free end of the strap upward, and insert the end into the
lower edge of the strap buckle as shown in Figure 1.
3. Pull at least three inches of the strap through the buckle. Then bring
the end of the strap beneath the upper buckle. Refer to Figure 3
4. Pull the free end taught. Be sure that at least two inches of strap
extend from the upper end of the buckle. Slip the extra strap beneath
the belt loop.
To remove the shoulder strap, follow Figures 5, 6, and 7 to reverse the
procedure.
CHOOSING AN ANTENNA
The radio uses a telescoping antenna and internal ferrite bar antenna
for reception of signals between 150kHz and 1620 kHz. These antennas
provide acceptable reception for most stations . However, if you use an
external antenna, you can receive more signals, and the signals you receive
will be better.
FM BAND
Use a set of VHF-TV rabbit ears. Those made for TV-FM coverage can help
get better performance on the FM band.
Use an outdoor FM antenna. This type, specially designed for optimum FM
performance, requires rooftop (or simular location) mounting.
Use a combination TV/FM antenna.
NOTE: To use an external antenna, equipped with 300-ohm twinlead, connect
the twinlead's terminals to a 300-ohm to 75-ohm matching
transformer, Cat. No. 15-1253. Then insert the 75-ohn connector of
the transformer into an F-to - RCA adapter, Cat. No. 278-252.
Finally, insert the RCA type plug of the adapter into the RCA
antenna jack of the receiver. Be sure to move the antenna switch to
EXT.
AM-SHORTWAVE BANDS
For AM reception, you can use many different types of antennas.
Unfortunately, no single antenna can effectively cover the entire frequency
range of the DX-440, from 150kHz to 29999 kHZ.
A general purpose shortwave antenna, such as Cat, No. 278-758, can provide
better reception than either of the built in antennas. However, if you
want the best possible reception on one specific band, your antenna must be
a certain length.
Refer to the following charts. The first chart indicates the length if
wire required for optimum performance on the specified band. The second
chart gives you the required length of wire to receive the amateur radio
operator's bands.
Frequency Antenna Wire Length (feet)
150 kHz - 500 kHz 1440 lengths generally
520 kHz - 1600 kHz 441 impractical to erect
1600 kHz - 4500 kHz 153
4500 kHz - 12000 kHz 57
12000 kHz - 29000 kHz 22
Wave Length- Ham Band Antenna Wire Length (feet)
160 meter 246
80 meter 117
40 meter 66
20 meter 33
15 meter 22
TO CALCULATE ANTENNA LENGTH FOR A SPECIFIC FREQUENCY
You can determine the exact length of wire you need for a specific
frequency using the following information. The, obtain bare copper wire,
stand-off insulators, and and an appropriate length of lead-in wire. Be
sure to use a static discharge unit to guard against lightening damage.
For complete information, refer to THE RADIO AMATEUR HANDBOOK, published by
the American Radio relay League.
This formula results in a half-wave antenna.
Length of a 1/2 wave antenna= 468000/Desired Frequency (kHz)
For example, to pick up internal shortwave signals in the 19 meter band,
15100 to 15350 kHz, pick a representative frequency, such as 15350 kHz.
the formula becomes 468000/15350 = 30 1/2
SYSTEM GROUNDING
To ensure the best reception, always connect a ground wire to the external
antenna jack. Connect the single wire lead-in to the center terminal of
the RCA plug. Connect a suitable earth ground to the outer terminal of
the plug.
A suitable earth ground can be a clamp to a metal water pipe or a copper
rod driven several feet into the earth. Radio Shack sells a copper ground
rod (Cat. No. 15-530) and the appropriate hardware.
BAND ALLOCATION
To avoid interference and confusion, certain portions of the radio spectrum
have been set aside for specific purposes. Perhaps the most familiar
example is the 540-1600 kHz standard AM broadcast band.
Ham radio operators use the following bands:
160 meters = 1,800 - 2,000 kHz
80 meters = 3,500 - 4,000 kHz
40 meters = 7,000 - 7,300 kHz
20 meters = 14,000 - 14,350 kHz
15 meters = 21,000 - 21,450 kHz
10 meters = 28,000 - 29,700 kHz
International broadcasting stations have several bands set aside for them:
49 meters = 5,800 - 6,200 kHz
41 meters = 7,100 - 7,500 kHz
31 meters = 9,500 - 9,900 kHz
25 meters = 11,650 - 12.050 kHz
19 meters = 15,100 - 15,600 kHz
16 meters = 17,550 - 17,900 kHz
13 meters = 21,450 - 21,850 kHz
11 meters = 25,600 - 26,100 kHz
Note that the broadcast and hams share 7,100 -7,300 kHz, and interference
is heavy in that range.
Broadcast in tropical regions have special bands set aside for them. In
such areas shortwave is the only way to reach isolated locations:
120 meters = 2,300 - 2,500 kHz
90 meters = 3,200 - 3,400 kHz
75 meters = 3,900 - 4,000 kHz
60 meters = 4,750 - 5,060 kHz
The rest of the shortwave range is filled with marine,aeronautical and
military stations. Such stations usually use either SSB or CW, and can be
found outside the amateur and broadcast bands.
(/all-11/28/95)
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