Works with a variety of different signal generators or computer audio.
( Click on the picture for a larger view )
The 500 watt SPA4 signal processor and amplifier is available assembled and tested, complete with a high-efficiency fan-cooled heat sink assembly.
The price of the SPA4 assembled and tested with the HS2 heat sink and fan is $350.00
(Kit version also available,
less HS2 and fan.)
The SPA4 amplifier has been designed to provide researchers with an integrated audio signal processor and high power amplifier system capable of accepting an input signal from multiple frequency sources while providing enough output power at 3.1 MHz to operate large plasma tubes.
The SPA4 accepts inputs from a wide range of signal sources,
including laptop and desktop computers
having a line level output or headphone jack, CD players, DVD players, MP3
players, Most cell phones, the UDB1108S, the Spooky2, the GB-4000, the F-165,
F-175 and other F-series units, the PROGEN II 4050, or any other frequency
generator that is capable of producing a square, sine or triangle wave output
or a 5 volt modulated 3.1 MHz signal.
Standard carrier frequency of 3.1 MHz is supplied unless otherwise specified at time of order.
The powerful but quiet cooling fan mounted on the rugged HS2 heat sink allows the PA2 to be operated at full power for as long as the researcher desires. A separate power supply for the cooling fan is not needed, because the PA2 provides power for the fan.
The outout amplifier MOSFET in the SPA4 is connected to the circuit board with clamping screws, so that it may be easily and rapidly replaced should the need arise - no soldering is required.
has been designed so that its output matches a standard 50-ohm load
impedance, making it possible to connect the output of the SPA4 to a
conventional antenna tuner or to the our LC31 coupler system.
SPA4 Technical Specifications:
DC Power Supply Input:
RF Power Output:
Input Audio Signal Waveform and
The left side photos are of the SPA4 output waveform across a 50-ohm dummy load.
The right side photos are of the SPA4 output waveform across a Cheb 8-inch Phanotron tube.
The SPA4 was coupled to the Phanotron tube using the 3.1 MHz link coil coupler.
The carrier frequency was 3.1 MHz. The modulation duty cycle was approximately 50%.
Modulation frequency 20 Hz.
Modulation frequency 2 KHz.
Modulation frequency 20 KHz.
Modulation frequency 200 KHz.
RADIO FREQUENCY WARNING NOTICE
The SPA4 contains a high-frequency switch mode power
supply module designed to furnish a high voltage alternating current at a
frequency of approximately 3.1 MHz across a 50 ohm resistive load impedance.
· The SPA4 is to be used as a research device only, or as part of a complete system to drive a plasma tube.
· Do not touch, or allow other persons to touch, any of the internal circuitry of the SPA4 while power is applied to the SPA4.
· Dangerous RF voltage will be present when the SPA4 is operating. Contact with this RF voltage may cause painful radio frequency burns.
· The SPA4 is not intended to be used for any form of radio transmission in any manner whatsoever.
· The SPA4 is not intended to be connected to an antenna or to any radiating element or to be used for any form of radio communications in any manner whatsoever.
· The SPA4 is designed solely to be used as a source of power to operate a plasma tube.
· All electrical connections to the output terminals of the SPA4 are to be made by the use of properly shielded 50-ohm coaxial cable capable of handling at least 500 watts at 3.1 MHz.
· All connections to the SPA4 are to be made in such a manner as to minimize any RF radiation from the connecting wires.
· The operating frequency range of the SPA4 has been restricted to a 1 MHz portion of the spectrum centered at 3.1 MHz.
· Use of the SPA4 may be regulated by your local authorities. You are responsible for complying with local regulations and laws.
This web site and all contents including pictures, text and diagrams is Copyright © 2012 - 2014 by Ralph M Hartwell.