Exhibit 8
9 -
17
9
Pressing either the PREV or NEXT buttons during this period will result in changing the screen to one of the 14 available
information screens described in S.4-4 below. This action will not influence the warming-up process, so you may pass
through all information screens, for instance to monitor the High Voltage value or the Exhaust Air temperature. You can
also return to the old one to see how many seconds are still needed for the tube's heater.
N O T E
When you intend to have a short operating break, it is better to leave the amplifier in standby mode instead of turning it
off. Tube life is shortened by repeatedly turning on and off the tube heater supply. However, if you unintentionally power-
off the amplifier, it is best to switch it on again immediately. When the pause is short (up to 1 minute) and the cathode is
still warm, the warm-up period is shortened significantly, which reduces the waiting time and prolongs the tube's
expected life.
After the indicated period expires, the ON/OFF button stops flashing and lights green constantly. If the auto-operate
function is selected to ON (see S.5-2), the green OPER LED lights too. The last used (one out of 14) information screen
appears on the LCD, for instance: "WARMING UP: Ready".
The bargraph on the upper line always indicates the peak forward power (as well as during OFF LINE).
In order to turn the amplifier off press shortly the red ON/OFF button. If you are not going to use the amplifier for a long
time, it is best to turn it off using the Main Power switch (on the rear panel) as well.
4-2. Changing Operate and Standby Modes
With the Auto-Operate function disabled (see S.5-2), the OPER button changes two modes alternatively.
When Auto-Operate is ON, the amplifier will be maintained to operate mode by default, unless you use the OPER button
manually to go to standby (then Auto-Operate is suppressed temporarily). Pressing OPER again would restore the Auto-
Operate.
4-3. Tuning
Tuning is possible only in operate mode, so press the OPER button in order to illuminate its LED (unless Auto-Operate is active).
a) Preliminary information.
Tuning the amplifier is a procedure of matching the impedance of the currently used antenna to the optimum tube load resistance. This will ensure
maximum plate efficiency and RF gain at nominal output power, with minimum IMD at that.
Please note, that the REFLECTED POWER readings and the measured VSWR depend on the load impedance only, and not on the amplifier tuning. If
the load impedance is different from 50-Ohm pure resistive (nominal), the REFLECTED POWER reading will always indicate reflected power presence
(even at excellent tuning). The proper tuning will allow you to operate at greater power without distortion or danger to the amplifier.
Note also that the real OUTPUT POWER in the load is equal to the difference between the FORWARD- and REFLECTED- readings. For instance, at
a reading of FORWARD 1200W, and of REFLECTED 200W, the real OUTPUT POWER is 1000W (into a 2.6:1 VSWR load). At very high VSWR (no
antenna or badly mismatched antenna), the FORWARD and REFLECTED readings will be almost equal, while the real OUTPUT POWER (the
difference between them) will be practically zero.
The amplifier can operate safely if the following rule is obeyed: "REFLECTED POWER < 500W". Matching is assured for loads with VSWR up to 3:1.
Nevertheless, for some loads and bands matching is possible at even higher VSWR. For instance, you'll get a
** REFLECTED POWER ** soft-fault protection trip at full-scale (1200W) forward, with more than 500W reflected (700W output power), when antenna
VSWR exceeds 4.5:1.
C A U T I O N
Using a feeder of coaxial cable at VSWR > 3:1 on HF, and particularly on 10 and 6 meters bands, is not recommended.
At such high values of VSWR, the high voltages, high currents, and heat associated with line losses, risk permanently
damaging your coaxial cable or antenna switch.
Update tuning periodically, even if you have not changed band or antenna, in particular when a significant change in the environment occurs (snow,
ice, newly appeared or removed massive objects, alien wires nearby etc.) that would cause significant changes in the antenna impedance.
N O T E
If you use more than one antenna per band, it is necessary that you select the proper antenna BEFORE the next step.
Retune after selecting a different antenna for the same band, since both impedances may differ substantially (unless
their VSWR is excellent, i.e. below 1.2:1 for both).
C A U T I O N
Do not switch the BAND switch knob while transmitting with the amplifier! Hot switching (while transmitting) will
eventually destroy the band switch, not covered by the warranty!
C A U T I O N
When tuning, do not apply continuous drive longer than 3 minutes and after that pause 1-2 minutes for tube cooling.
Содержание 1000
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