User's Manual

Page 4 of 17
1. GENERAL INFORMATION
1.1. Introduction
The OM Power model OM4000 HF is a manual tuning power amplifier, designed for use on
all short wave amateur bands from 1.8 to 29.7 MHz (including WARC bands) and all modes. .
It is equipped with a two pieces of ceramic tetrode FU728F.
1.2. Specification
1.2.1. Parameters
Frequency Coverage Amateur Bands 1.8 – 29.7 MHz including WARC
Power Output 1500W PEP continuous output – no time limit
Input Power Usually 50 to 70W for full Output Power
Input power can not exceed 100W !
Input Impedance 50 Ohm, VSWR < 1.5 : 1
Power Gain 15 dB
Output Impedance 50 Ohm unbalanced
Maximum Output SWR 2 : 1
SWR protection Automatic switching to STBY, when reflected power
is 350W or higher
Intermodulation distortion 31dB below nominal output
Suppression of harmonics < -50 dBc
Tubes 2x FU728F Ceramic tetrode
Cooler Centrifugal blower + Axial blower
Power supply 240V – 60Hz
Transformers 2 pcs of toroidal transformer 3kVA
Dimensions 485x200x455mm (width x height x depth) (19”x8”x18”)
Weight 43 kg (94.8 lbs)
1.2.2. Protection Circuits
There are 11 special protection circuits used in the amplifier. They are activated when one or
more of next parameters exceed defined values or some unwanted occasion occurs.
• VSWR too high
• Input power too high
• Output power too high
• Plate voltage too low
• Anode current too high
• Screen current too high
• Grid current too high
• Mistuning of PA
• Hot switching protection
• Soft start for protecting your fuses
• “switch-on blocking “ at opened amplifier