World Leader Presents the Incredible VBF 44 PDF Download Image 3

4 channel Filter/Amplifier  
5 Built in Filter responses

  • Filter cutoff range 1 Hz - 255 kHz
  • Gain -20 to +70 dB
  • 5 Built in Filter Responses
    2 Lowpass, 2 Highpass, and Bandpass
  • 135 dB/Octave filters
  • Manual and computer control
  • Easy to use
  • Wide dynamic range
  • 'Stereo' and 'Track' filter tuning modes

Kemo VBF 44 four channel versatile signal filter


The Kemo VBF44 is a benchtop filter offering unparalleled versatility. It contains 4 precision electronic filter channels. Each filter channel can be used independently to produce a 4 channel programmable filter/amplifier, or in pairs to produce 2 channels of bandpass, bandstop and other composite filters of many kinds. The VBF 44 is now built in a compact stainless steel chassis and stainless steel laser cut rear panel, with upgraded system cooling.
The VBF 44 is part of the Kemo VBF 40 series of filters, also available is the full rack VBF 40  for 1-16 channels. Easy to use front panel controls, BNC input/output connectors, and a very versatile set of filter responses make the VBF 44 a top range laboratory filter.

Summary Specification

Channels 4
Control Manual LCD and push button
Ethernet FICL II interface
Frequency 1 Hz - 255 kHz (4 ranges)
Bandwidth > 1 MHz,  1V signal, 0dB gain, highpass filter and filter bypass
Input Gain  x1, x2 (+6dB), x5 (+14dB), x10 (+20dB), x20 (+26dB), x50 (+34dB), x100(+40dB)
Output Gain  x1, x2 (+6dB), x5 (+14dB), x10 (+20dB)
Filters  5 Switchable; 2 Lowpass, 2 Highpass, and Bandpass
Filter Responses  L1, L2, H1, H2, B1
Input Coupling  AC / DC / IEPE (4mA 24V)
Input Mode Single ended or differential
Signal level  +/- 10V pk-pk (usually with 'headroom')
Signal Level Indication 4 colour level LED on panel 
Size 145 x 482 x 420 (3U 19" x 16")
Power 90 -120 / 180-240 Vac 50/60Hz

Frequency Range
Each filter in the VBF44 tunes over a frequency range of 1 Hz to 255 kHz in four decade ranges. A low frequency version with 0.01 Hz to 10 kHz range is also available.

Gain Range
The inputs (differential, switchable to single ended) have gain to +40 dB and the output stages provide -10 dB to 30 dB. In dual 2 channel mode signals are connected to two pairs of BNCs on the front panel; the two filters in one group share input and output amplifiers to minimise the building up of errors. In 4 channel mode signals are connected to rear panel BNC connectors.

A Flexible Response
Each filter in the VBF44 offers five responses - high slope elliptic lowpass and highpass, flat passband linear phase lowpass and fast settling highpass, and bandpass with characteristics similar to 1/3 octave. The filter can also be bypassed and the unit used as a programmable amplifier.

Keeping in Tune
All VBF44 parameters are displayed on large, bright LED digits and are adjusted with a rotary control and push buttons. All selections are non-volatile, and 3 complete set-ups can be stored and recalled when needed. Plug-in GPIB and RS232 interface cards are available, and all digital circuitry is opto-isolated from the signal path.
Several tuning methods are provided to simplify the application of the VBF44 in the dual 2 channel mode. Cutoff frequencies can be 'locked together' once the desired composite filter shape has been set. Subsequent adjustment of the reference channel cutoff frequency will cause the other channel to retune automatically to preserve the selected response shape. This is called 'tracking' mode and is invaluable for tuneable bandpass and bandstop filters.
In 'stereo' mode the instrument sets two identical composite channels, useful for audio signals and quadrature baseband signals in image processing, SONAR, and Doppler studies. These modes can be used manually and through the computer interfaces.

Easy Connections

VBF 44 Top range dual channel electronic filter rear panel 
The VBF 44 is easy to use and connect to, all 4 channel connectors are available on the laser cut and marked rear panel.

Related Systems
The VBF 44 is part of a range of filters.
The VBF 40 is a 19" rack for 1-16 channels of VBF 40 series filters.