Icom IC-720 Instruction Manual page 19

5-5-2 AM TRANSMITTING
a. Set the controls the same as for SSB.
b. Set the Meter Select button to RF (out), and push the
transmit button (in) or depress the PTT switch on the
microphone - the Transmit LED will light. Speak into
the microphone in a normal level voice, the meter needté
will move to indicate the output RF. (The maximum
carrier Power in AM is 40W.)
c. With the Compressor Control in the off position the RF
output cannot be varied. Turn the Compressor on,
completely counterclockwise, and then while speaking
into the microphone carefully rotate the knob clockwise
5-5-2 TRANSMITTING
Transmitting AM signals is essentially the same as SSB
transmission. The maximum carrier power in AM is 40W.
The VOX and speech compressor are not operable in AM.
5-6 OTHER OPERATIONS
5-6-1 VSWR READING
The final transistors in the ІС-720 are of excellent design,
and are protected by circuits incorporated in the set. They
can be expected to have an indefinite life for there are no
cathodes to burn out. However, they can be destroyed by
abuse and then have to be replaced.
When in doubt about antenna systems, use the lowest
power setting possible to achieve meaningful readings. Use
a good tuner or transmatch when necessary. Always use
caution and exercise judgement when testing RF power
generators.
ІС-251А/Е
ог
ІС-260А/Е
=1у—
5-6-2 WWV RECEPTION
5-6-3 SIMPLE FREQUENCY ALIGNMENT
A very sophisticated frequency counter, and other very
accurate equipment are needed to fully align the IC-720,
However, simple frequency alignment can be accomplished
utilizing the WWV signal.
b. Push the CW button; a 800Hz beat will be heard.
d. Rotate the Frequency Set Control, located under the top
access cover so that the two tones are the same pitch.
If
the tones are difficult to adjust because of a difference
in their strength, adjust the CW sidetone level with the
CW Moni Control, located nearby, until the levels are
the same.
e. WHEN ALIGNING THE FREQUENCY DO NOT PUT
THE UNIT IN THE TRANSMIT
MODE. Be sure that
the Receive/Transmit button is out, that the VOX is
off (out), and that you do not touch the PTT Switch on
the microphone.
5-6-4 SATELLITE COMMUNICATION
At present there are two active satellites for amateur use,
with more being planned. OSCAR 7 and OSCAR 8
launcehd іп 1974 and 1978, respectively. Satellite com-
munications сап be made using ап IC-251A/E ог IC-260A/E
for transmitting and the IC-720 for receiving. For opera-
tion, and frequency information, refer to the chart below.
Communication satellites move at very high speeds, the
down-link signals can be heard at a higher frequency than
the receive frequency as the satellite approaches, and а lower
frequency as it travels further away. Further information
on satellite communication can be found in various amateur
periodicals and books.
АО-7: АО-8 FREQUENCY CHART
MODE A
UP LINK DOWN LINK
FREQUENCY FREQUENCY
145.85MHz 29.4MHz
{ /
145.95МН2 29.5MHz
BEACON FREQUENCY
АО-7 29.502МН2
АО-8 29.402MHz