AMERITRON ATR-20 Manuale di istruzioni - Pagina 5

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ATR-20 Instruction Manual

9. After adjusting the tuner for minimum SWR, the amplifier may be turned on. The METER switch

should be placed in the HI position, and the amplifier tuned according to the manufacturer's

instructions.

10. For quick retuning of the tuner, record the control settings for each band and use them as starting

points.

Note: Maximum power handling occurs when both the TRANSMITTER and ANTENNA

capacitors are set at the lowest front panel numbers that permit matching the antenna.

Following this guideline will insure maximum power handling capability and efficiency, and

the least critical tuning adjustments.

4.0

OPERATING HINTS

1. While this tuner is designed to have the largest tuning range possible, there are limits to the range of

individual components. Some antennas may require either more or less capacitance, or more or less

inductance than practical components provide. In these special cases, SWR may not reduce to 1:1. If

the SWR is higher than acceptable, changing antenna or feedline length will probably bring the

antenna impedance within the useful tuning range.

2. When adjusting the tuner, use the lowest number on the TRANSMITTER and ANTENNA, and the

highest INDUCTOR number, that produces a good SWR. This reduces tuner losses and increases

tuner power rating.

WARNING:

1. Never operate the tuner with the top removed. Voltages inside the tuner can cause painful RF burns.

2. Never rotate the ANTENNA SELECTOR switch while transmitting. Doing so may permanently

damage the switch.

3. If you use balanced or single wire feedlines, locate the tuner where the rear terminals can NOT be

contacted by people, wiring, or metallic objects. The single wire and balanced line connections will

generally have high voltages when used. Be sure the tuner case is properly grounded.

4. Disconnect all antennas from the tuner during lightning storms. Do not depend on lightning

"protectors".

5. Tune with low power (i.e. less than 100 watts). Apply high power only after tuning up.

4.1

In Case Of Difficulty

If the tuner fails to tune, double check all connections and follow the tuning procedures again. Be sure

to use enough inductance (lower number) and have the capacitors open far enough (higher front panel

numbers).

If the tuner arcs at the rated power levels, double check all connections and follow the tuning

procedures again. The typical RF power rating of this tuner is 1200 watts PEP into load impedances

between 25 and 800 ohms, and less into higher or lower impedance loads. Always use the least amount

of inductance (highest number) and the greatest capacitance (lowest number) possible that still allows

matching the load on the operating frequency.

Note: If internal arcing occurs it may be necessary to reduce transmitter output power or modify

antenna or feedline length.

Ameritron Antenna Tuner