20 Megahertz Sweep/Function Generator

New 3.1 MHz carrier frequency.

With 1/100th of a Hertz resolution.


The GB-4000 is the only Frequency  Generator capable of running 8 frequencies simultaneously


The GB-4000 is capable of outputting all frequencies from 1 to 20 million hertz.

The GB-4000 is also capable of sweeping from 1 to 20 million hertz.


(View our printable brochure)

Power and Running Multiple frequencies

Back in the 1950's they built a ray tube instrument that would run 10 frequencies simultaneously. So running multiple frequencies is not a new concept. This is why we built the GB-4000 to be able to run multiple frequencies. Yet today there are some unknowledgeable people who want to disparage running multiple frequencies. Successfully running multiple frequencies is directly tied to power. If you have enough power then it is possible to do this. Below we have given answers to the most commonly asked questions.

Some people have asked? Does running multiple frequencies reduce the power level of the frequencies? The answer to that question would be yes. This is why we built the GB-4000 with the ability to output 5.4 watts peak power at 100% duty cycle using an RF (Radio Frequency) carrier frequency. Using an RF carrier frequency is the only way the power level could be increased. The original 1950’s equipment did not use an RF carrier frequency so they could only output one audio frequency at a time with only 1/5th of one watt of power (0.20% of one watt). This power level worked very well with only one audio frequency. In order to overcome this limitation the GB-4000 uses two separate circuits.

The Audio Mode circuit has no RF carrier frequency and 0.75 watts power output. It is used for frequencies from 1 Hertz to 400,000 Hertz. Frequencies used with this Audio Mode circuit can be physically felt from 1 to about 20,000 Hertz.

The RF Mode circuit is used for frequencies from 1 Hertz to 20 million Hertz. The 3.1 MHz carrier frequency can also be used with this circuit. Because of the RF carrier any audio frequencies cannot be felt. Using this method it is possible to use 5.4 watts peak power and makes it possible to run up to 8 frequencies simultaneously.

Logically if you use 2 audio frequencies using this RF circuit you would want to double that power level (2 X 0.20 = 0.40% of one watt) to 0.40% of one watt. If you run up to 8 audio frequencies you would want at least 8 times that power level or 1.60 watts peak power. This is why the GB-4000 has 5.4 watts of peak power output so that it has over 3 times the power capability needed for running 8 audio frequencies simultaneously at the original 1950’s capability of 0.20 watts of power for one audio frequency.

Some people also ask if they can only run multiple frequencies. The answer to that question is no. The GB-4000 gives you the flexibility to switch from running one audio frequency at a time to being able to run up to 8 audio frequencies at a time. You can choose how you want to run the frequencies.

Many people want even more power than the GB-4000 power levels per audio frequency. If you want more power then you can purchase the SR-4 15 watts RMS or 30 watts peak power amplifier and you will have 3.75 watts of peak power for each frequency, if you run 8 audio frequencies simultaneously. If you decide to only run 4 audio frequencies simultaneously then you would have 7.5 watts of power for each frequency. And if you only run one frequency you can have up to 30 watts of peak power for a single audio frequency.

If you want even more power than 30 watts peak power then you can purchase the M.O.P.A. gas tube amplifier which is a 207 watts maximum peak power instrument. With this instrument you could run up to 8 audio frequencies simultaneously with up to 25 watts of power for each audio frequency.

We look at it as going from good to better to best.

What separates the GB-4000 from other frequency generators available today?

While almost all manufacturers only run one frequency at a time the GB-4000 can run from 1 to 8 frequencies simultaneously for a superior multi-frequency waveform. The benefit of running frequencies simultaneously is a time saving feature. If you run 8 frequencies one at a time it would take 40 minutes to run them all but if you run them simultaneously then it would only take 5 minutes to run all 8 frequencies.

The GB-4000 can output up to 8 frequencies simultaneously up to 40,000 Hertz and 2 frequencies up to 20,000,000 Hertz. Each frequency is generated and output in a pure waveform. With its 20 MHz (20 million Hertz) frequency range it has the ability to generate millions of individual frequencies in pure waveforms which can be put into individual channels and run as sequences of individual or multiple frequencies.

Some manufacturers claim that running multiple frequencies simultaneously causes the purity of each individual waveform to be lost as well as creating the possibility of canceling out or creating other frequencies.

Rarely are other frequencies created and when they are they are generally beat frequencies which are considered beneficial. Those who run multiple frequencies simultaneously are seeking the benefits of using multiple frequencies. The time saving benefit is the main reason most people prefer to use multiple frequencies.

Even though frequencies combined together may seem to lose their individual clarity, all the components of each frequency are present. Think of an orchestra playing many different instruments. Though they combine together to make beautiful music, each instrument’s full sound components are still present and nothing is lost.

In order for a frequency to be canceled out, the same frequency must be introduced 180 degrees out of phase. Since the GB-4000 does not output the same frequency 180 degrees out of phase the canceling of a frequency is not possible.


The GB-4000 FREQUENCY GENERATOR Technical Specifications
and Features………

  • Stand Alone Frequency Generator: Unlike some generators on the market today the GB-4000 was designed
    to be a simple to use, easy to operate, stand alone frequency generator requiring no complicated computer
    interface to use all of its features. Computer operated generators generally work well but many people do not
    feel comfortable having to use a computer to operate all of a frequency generator's options. Our customers
    appreciate that they are not required to have a computer to operate any of our instrument's capabilities. The
    computer software for programming frequencies into the GB-4000 is an option, not a necessity. Its software
    was designed specifically not to be a hard to use computer interface. But it is for programming channels with frequencies and restoring any lost programmed channels that may be accidentally deleted by the user.

  • Frequency range:1 to 20 million Hertz.

  • Audio range now increased from 1 to 40,000 Hertz to 1 to 400,000 Hertz.

  • Frequency output: digitally accurate frequencies converted to analog using a DAC for full analog harmonics.

  • Carrier wave frequency: New 3.1 MHz RF (Radio Frequency) carrier which produces the harmonic sideband frequencies used in the 1930's, 1940's and 1950's equipment.

  • Carrier wave On and Off capability: Carrier wave can be turned off so the user can operate it as a standard low audio frequency generator.

  • Waveforms: Square and Sine wave.

  • LCD: Displays all frequencies on the LCD - not hidden program numbers like other frequency generators.

  • Programmable channels: 2000.

  • Channel capability: 48 frequencies in sequence or 8 groups capable of holding 8 frequencies each.

  • Computer software: GB-4000 programmable software included.

  • Output multiple frequencies: Up to 8 audio frequencies simultaneously.

  • Eight audio frequency range: 0.1 to 40,000 Hertz with 1/100th of a Hertz resolution.

  • "RF Mode" circuit capable of outputing 8 frequencies simultaneously from 1 to 40,000 Hertz and two frequencies from 1 to 20 million Hertz.

  • Duty cycle capability: 10% to 90% square wave duty cycle (Other frequency generators typically can only run a 50% duty cycle)

  • Gating or pulsing range: 1 - 5000 Hertz.

  • Gating duty cycle range: 10% - 90%.

  • Channel sweep: 2 to 20,000 Hertz or 1 to 10,000 Hertz + and - of the target frequency or frequencies in all 2000 channels.

  • Standard sweep: 1 to 20 million Hertz making it capable of running both narrow and broad range sweeps.

  • Converge sweeps: Two frequencies from 1 Hertz to 20 million Hertz.

  • Outputs: Four - 2 red and 2 black (other frequency generators have only 2 outputs).
  • Power output: Variable up to 5.4 watts peak power.

  • Voltage output in audio mode: 36 volts peak to peak.

  • Voltage output in RF mode:Over 110 volts peak to peak making it 27 times more powerful that standard frequency generators.

  • L.E.D: RF indicator light confirms RF output.

  • AC adapters: Two switching 110/240 volt power supplies for worldwide use.

(View our printable brochure)

Want more power than 5.4 watts? Then the SR-4 may be what you are looking for. It was developed for those who want to have more power. It connects to the GB-4000 using a BNC cable and BNC connections. Like the GB-4000 it outputs through wires. This method has been used for many years and works very well.

The SR-4 1-15 watts RMS power or 1 to 30 watts peak amplifier only amplifies the RF (radio frequency) frequencies output by the GB-4000. It amplifies the output of the GB-4000 from 5.4 watts to 30 watts depending on the frequency used.

In Audio Mode no RF carrier frequency is used. Also in Audio Mode the GB-4000 outputs about 36 volts peak to peak which is about 0.75 or 3/4 of a watt. The GB-4000 goes up to 400,000 Hertz in Audio Mode at 36 volts. In RF Mode almost the full frequency range of the GB-4000 goes up to 110 volts. With the SR-4 Amplifier it goes up to almost 30 watts peak power or over 200 volts.

Why Power 0utput Is Important In A Frequency Generator

When comparing the various instruments, power output is a very important consideration. This is the reason the GB-4000 uses a carrier frequency so that more power can be output.

The power output of most frequency generators on the market today that do not use an RF carrier frequency is only about 0.20 of a watt.  The GB-4000 with the use of an RF carrier is 5.4 watts peak power and is over 27 times more powerful than these instruments.  With the use of the optional SR-4 amplifier it is 150 times more powerful.

(Click here to go to the SR-4 Amplifier page)