DRAKE R8A - NOISE BLANKER; CW OPERATION; RTTY OPERATION; SSB OPERATION

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Getting Started cont'd. 18
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NOTCH TONE SQUELCH PASSBAND OFFSET RF GAIN VOLUME
CENTERED CENTERED COUNTER-CLOCKWISE CENTERED CLOCKWISE COUNTER-CLOCKWISE
FIGURE 10
NOISE BLANKER If the default ‘AUTO’ settings have been programmed by
The NOISE BLANKER NB_ provides two settings which will
reduce or eliminate much noise interference encoun-
tered, The (n) (or narrow) setting is for short duration, high
impulse noise such as automotive ignition noise. Theiw) (or
wide) setting is to reduce longer duration impulses.
Unfortunately, there exists no blanker capable of eliminat-
ing all possible noise either atmospheric or man-made,
Another side effect of the NOISE BLANKER use is on AM
signals. Occasionally, if a strong AM signalis tuned in and
the NOISE BLANKER is engaged, blanking can occur on
modulation peaks causing a popping or breaking up of
the audio. If this is noticed, be sure the NOISE BLANKER is
off.
CW OPERATION
For general tuning in CW mode, the 1.8 kHz bandwidth is
recommended since the 0.5 kHz bandwidth is very nar-
row. When the desired signal is found, tune the receiver
until an approximately 800 Hz audio note is heard, then
select the 0.5 kHz filter. If interference is present, the
passband offset can be employed to reduce or eliminate
the interfering signal.
RITY OPERATION
In RTTY mode, the receiver selects the user programmed
bandwidth (1.8 kHz recommended) filter and positions it
for the 2125 Hz mark and 2975 Hz space high tone group.
When receiving other shifts such as 425 Hz or 170 Hz, the
PASSBAND OFFSET may need to be adjusted to pass both
tones equally. Additionally, the selected IF bandwidth
should not be smaller than the shift of the received signal.
Therefore, the 0.5 kHz bandwidth filter can not be used
when receiving a 850 Hz shift RTITY signal but could be
selected for a 425 Hz or 170 Hz shift RTTY signal.
SSB OPERATION
Tuning in a single sideband (SSB) signal can be somewhat
frustrating for the first time listener. With the ‘AUTO’ band-
width selected in either of the receiver's SSB modes, LSB
(lower sideband) or USB (upper sideband), the receiver
will select the 2.3 kHz bandwidth, 10 Hz tuning steps and
Slow AGC setting.
the user, then those particular settings are recalled. Gen-
erally, LSB is used below 10 MHz and USB is used above 10
MHz.
First, be sure the PASSBAND OFFSET control is centered.
When initially tuning in the desired station, tune slowly. If
the station is unitelligible, try the other sideband again
tuning slowly. A station tuned in on the wrong sideband
is totally unreadable but a station mistuned on the right
sideband may sound like “Donald Duck’. Further tuning
will resultin a more normal voice sound. Once the station
istuned in, the PASSBAND OFFSET can be used to alter the
audio response of the received SSB signal. Refer to
PASSBAND OFFSET OPERATION for details. Additionally, if
adjacent stations are causing interference, the 1.8 kHz
bandwidth filter may be selected in conjunction with the
PASSBAND OFFSET to further reduce or eliminate interfer-
ing signals.
FM OPERATION
Frequency modulation (FM) is perhaps the easiest mode
to use onthe receiver. When the FM mode isselected the
receiver defaults to PRE only. No AGC or BANDWIDTH
settings are used in FM mode. In fact, attempting to
activate these buttons will result in an error beep. Addi-
tionally, NB, NOTCH, PASSBAND OFFSET, and RF GAIN
controls are not used.
Most FM transmissions are above 29 MHz and are gener-
ally amateur radio in nature. A very active frequency,
when conditions permit, is 29.660 MHz.
Peculiar to FM transmissions is the fact that a stronger
signal on the same frequency or close to the same
frequency will completely cover up a weaker signal. Also,
there are no controls to help reduce or eliminate an
interfering signal. This is not a fault of the receiver but of
the FM mode of transmission. However, to help in elimi-
nating the background hiss, the SQUELCH control may be
used to quiet the receiver during periods of no signal.