Atlas 210x, Инструкция по установке, эксплуатации и обслуживанию

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3-16. MODULATION LEVEL
Modulation level is adjusted with the Mic. Gain control. When the transceiver is coupled into a proper 52 ohm
load, voice peaks will be reaching about 16 amps., although the ammeter cannot respond quickly enough to show
these peaks. Adjust Mic. Gain for average readings of 5 to 7 amps. Do not run the gain above this level, or you
will flat-top and distort the transmitted audio, as well as cause splatter up and down the band. ALC will help
reduce this danger, but it is still possible to over-modulate, so Mic. Gain must be carefully adjusted.
3-17. ALC
The ALC control is located on the front panel of the transceiver, and is concentric with the MIC. GAIN control. It
is the inner ring with a black set screw indicating its position. ALC is the abbreviation for "Automatic Level
Control," and refers to transmitter modulation level. It aids in preventing over-modulation which causes flat-
topping of the power output stages, distortion and splattering outside the channel. Full counterclockwise setting of
this control provides no ALC, while full clockwise setting is maximum ALC. Normally, a setting around 12
o'clock will be satisfactory. Some variations between bands may be noted. By having the ALC control on the front
panel, you can utilize its advantage most effectively. Too little control will make it easier to over-modulate, while
too much control will limit output power. Try various settings and ask for signal reports until you become familiar
with its effect. If you have a panoramic scanner, this is, of course, the best way to monitor your output signal.
318. CW TRANSMISSION
The Function Switch has a CW position which switches the transceiver into CW transmit mode. A jack on the
back is provided for insertion of a standard 1/4 inch diameter 2 conductor phone plug coming from the CW key.
Keying is accomplished by bias cutoff of the I.F. Amplifier. The keying circuit operates at less than 10 volts
positive to ground, and draws less than 5 milliamps., so any of the electronic keyers will work ok.
In CW transmit mode, the carrier frequency is automatically shifted approximately 800 Hertz. This makes it
possible for one transceiver to QSO another transceiver on CW without having to constantly tune the dial back and
forth. On 160, 80, and 40 meters the transmit frequency is shifted lower than the receive frequency, while on 20
meters it is shifted higher. The sideband Selector switch must be in the "NORM" position for CW operation.
Send-receive changeover must be made with the Function Switch, and it may be a bit inconvenient to pass through
the TRANS position every time. The serious CW operator will want to install the semi-break-in accessory kit in
the 220-CS console. This item installs in back of the power supply, and includes a sidetone oscillator with volume,
pitch, and delay controls. Refer to paragraph 2-18 for alternate switching method.
In CW mode the Mic. Gain control becomes a Carrier Insertion control. With key down, advance this control
clockwise until the meter reads 12 amps. This will be 200 watts input power (at nominal supply voltage), and
output will be about 90 watts. (On 10 meters the meter will read 8 to 9 amps., or approximately 120 watts input.)
For Novice Class operation, insert 5.5 amps of carrier for 75 watt legal power limit.
For RTTY/SSTV operation, the input should be controlled for a meter reading of 6.5 amps for 90 watts input.
Heat sink temperature is always the limiting factor on power input, and should be monitored from time to time.
Refer to paragraph 3-18.
3-19. HEAT SINK
Adequate ventilation for the heat sink is particularly important in CW operation, since average power input is
higher than in SSB transmission. Keep a check on heat sink temperature, and if it is running uncomfortably hot to
the touch, back down on carrier insertion, or make the transmission shorter.
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