Requirements for a 1500 Watt Contest Capable HF Amplifier

Last updated February 23, 2005 by K6IF

 

Summary: For those of us who operate an automated SO2R contest station on a budget, the last piece of equipment to be automated is frequently the amplifier(s). The high level goal of this project is to build an amplifier that solves this problem that allows a competitive HF contest station to automate amplifier band switching and tuning at a reasonable price.

 

Requirement

Minimum

Desired

Frequency Coverage

160, 80, 40, 20, 15, 10 meter bands

160, 80, 40, 20, 15, 10 meter bands

Modes

CW, SSB

CW, RTTY, SSB

AC Power

240 volts, 60 Hz

110, 120, 220, 240 volts, 50 or 60 Hz

Power Output

1500 watts CW key down for 5 minutes into 1.0:1 SWR load

1500 watts CW key down forever into a 1.5:1 SWR load

Class

AB

AB

Linearity

Suitable for SSB

Suitable for SSB

Drive power for 1500 watts out

90 watts

70 watts or less

Input Attenuation (overdrive prevention)

No

Yes, Automatic

Output SWR

1.5:1 at full rated output

3:1 at full rated output

Band switching

Automated

Automated

Spurious Output

47 db down from fundamental

60 db down from fundamental

Sensors

Supply voltage, supply current, output power, reflected power, single heatsink temperature sensor

Supply voltage, supply current, output power, reflected power, drive power, multiple heatsink temperature sensors, current for each power module, bias voltage for each power module, reflected power between RF section and filter section

Meters

Supply voltage, output power, reflected power

Supply voltage, supply current, output power, reflected power, heatsink temperature, bias voltage

Meter Output to PC

No

Yes

Protection

Over voltage, over current, high reflected power, high heatsink temperature

Over voltage, over current, high reflected power, high heatsink temperature, bias out of spec, current out of balance, high reflected power between RF section and filter section, over drive

Drive inputs

1

2

Antenna Outputs

1

2

Input selection

N/A

Automatic

Antenna selection

N/A

Automatic

Materials Cost

$2500 or less

$2000 or less