Requirements for a 1500 Watt
Contest Capable HF Amplifier
Last updated
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 |