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ATR-30 Instruction Manual 

Ameritron Antenna Tuner 

1.0 INTRODUCTION 

The ATR-30 is a high power antenna tuner. The ATR-30’s roller inductor "T" matching network 
continuously tunes all frequencies from 1.8 through 30 MHz. It also features a built-in 3 kilowatt peak or 
average detecting directional power meter. The ATR-30 has rear panel connectors for coaxial and wire 
feedlines. A heavy duty, high voltage insulated, current-type balun allows use with balanced feedlines. 

Properly tuned, the ATR-30  safely operates on all bands with RF power levels (CW or SSB) of  3 
kilowatts with load impedances from 35-500 ohms. Matching range also extends from one ohm to 2500 
ohms (5 ohms to 500 ohms on 160 meters) at slightly reduced power ratings. Peak and average forward 
power, reflected power, and SWR are displayed on an illuminated cross-needle meter. 

An internal six position antenna-selector switch selects three coaxial line outputs, or a single wire line-
balanced line output.  Two coaxial line outputs, ANTENNA 1 and 2,  are available in either “tuned” 
(with tuner's matching network in line) or “direct” (no matching circuit) configurations. 

Coaxial output port ANTENNA 3 is available only as a direct (no matching system) configuration.  
WIRE / BALANCED LINE  positions are available only as  “tuned” configurations. 

 

1.1 

Understanding Power Ratings 

Unlike amateur radio service amplifiers (commonly rated in RF power output delivered to 50 ohm 
resistive loads), tuners have no standard power rating method. Power level descriptions (i.e. “3 kW 
Tuner”) used for tuners often carry over from the time when amplifiers were rated by peak power input.   

For example, the Kilowatt Johnson Matchbox was deigned to handle a typical 1000 watt dc input plate 
modulated AM transmitter. Such transmitters developed 3000 watts PEP RF output on AM. Matching 
tuners were called one kilowatt tuners.  

Years later SSB became popular. The Heathkit SB-220 was called a two kilowatt amplifier, even though 
rated CW output was approximately 600 watts. Tuners from the same era were called 2 kilowatt tuners, 
because they safely handled the 2 kilowatt PEP input SB-220. The 2 kW tuner only had to handle 600 
watts of CW  and 1200 watts PEP SSB to be compatible with a 2 kW amplifier of the same era.  

Around 1980, the FCC changed the amateur radio power rating system from dc power amplifier input 
power to RF envelope (output) power. Most tuners stayed with the old system, and no longer follow 
amplifier power ratings.  Typical “1500 watt tuners” safely handle only 400-600 watts CW, and 600-900 
watts PEP SSB.  

Note:

  This tuner is rated by true RF 

output 

power, not by the old method of using amplifier 

peak input

 

power. 

Load conditions and control settings greatly affect tuner power ratings. T-networks typically handle 
more power on higher frequency bands into higher load impedances. The worst operating condition (for 
T network tuners) is a low-impedance capacitive-reactance load. T-network tuners handle the least 
power on 160 meters with low-impedance capacitive-reactive loads. 

Follow the guidelines in this manual to avoid exceeding the ratings of this tuner! 

 

 

 

 

Summary of Contents for ATR-30

Page 1: ...o standard power rating method Power level descriptions i e 3 kW Tuner used for tuners often carry over from the time when amplifiers were rated by peak power input For example the Kilowatt Johnson Ma...

Page 2: ...times higher than the average voice power reading Forward power is displayed on the left hand FORWARD meter scale This scale is calibrated from 0 to 300 watts and is read directly in the 300 watt LO M...

Page 3: ...unter lamps will not function 2 Locate the tuner in a convenient location at the operating position If random wire or balanced lines are used the rear panel ceramic feed throughs may operate with high...

Page 4: ...with the ANTENNA SELECTOR 3 Position the ANTENNA TRANSMITTER and INDUCTANCE controls at the following settings Band ANT TRANS IND Band ANT TRANS IND 160 M 1 38 20 M 5 81 80 M 2 63 17 M 6 82 75 M 2 1...

Page 5: ...r 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 pe...

Page 6: ...fences may work well enough in many cases especially if they are connected together with multiple wires but the best RF grounds are radial systems or multi wire counterpoises Radials and counterpoises...

Page 7: ...otherwise perfect antenna system very difficult or impossible to tune One example where this problem occurs is on 80 meters when an odd quarter wave 60 to 70 foot open wire line is used to feed a half...

Page 8: ...lf wave or shorter dipole antenna on 160 meters can be a disaster for both your signal and the tuner The best way to operate 160 meters with an 80 or 40 meter dipole antenna is to load either or both...

Page 9: ......

Page 10: ...log below to record settings for your antennas You may want to copy this chart and post it by your tuner Antenna type Frequency MHz Transmitter Antenna Inductor 1 8 1 8 2 0 2 0 3 5 3 5 3 5 3 75 3 75...

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