The VBF 42 is our top of the range 2 channel laboratory filter/amplifier, with gain, 5 built in filter responses, easy control, and versatile filter configurations. 

Filter cutoff range 1Hz to 255kHz Gain -20dB to +70dB 5 built-in filter responses 2 Lowpass, 2 Highpass, and Bandpass 135 dB / Octave filters Separate / series / parallel modes Manual and RS232 control GPIB interface option Non-volatile setup storage Wide dynamic range   VBF 42 pdf data sheet (70 kB)   Order Now

The VBF42 variable filter offers high performance and a wide range of features in a compact 1U case. Care has been taken to maximise ease-of use resulting in a simple, uncluttered front panel design and crisp, bright back-lit LCD display for all parameters.

The two filter channels can be independently controlled as well as internally connected in series or parallel. To implement a wide range of bandpass and bandstop filters, as well as independent lowpass and highpass channels.

Summary Specification

Channels	2
Control	Menu driven LCD and thumbwheel FICL GPIB or RS232
Frequency	1 Hz - 255 kHz (4 ranges)
Bandwidth	> 1MHz, 1 Volt signal, 0dB gain, filter highpass and bypass
Input Gain	0 dB to +40 dB, in 20 dB steps, with switchable -10 dB attenuator
Output Gain	-10 dB to + 30 dB in 2 dB steps
Filters	5 Switchable; 2 Lowpass / 2 Highpass and Bandpass
Filter Responses	L1, L2, H1, H2, B1
Input Coupling	AC / DC
Input Type	Single ended / Differential
Size	1U 19"
Power	90 -120 / 180-240 Vac 50/60Hz

Frequency Range
All VBF42 channels can be programmed to provide cutoff frequencies between 1Hz and 255kHz in four 255:1 ranges. 

Gain Range
The gain of each channel can be programmed between -20dB and + 70dB in 2dB steps (including the switchable 10dB input attenuator). Up to 40dB of gain is available before the filter, the rest is post-filter. Input overload monitor LEDs are visible on the front panel. Input AC coupling may be selected if desired.
The inputs are differential, with a front panel switch to convert them to single-ended. Inputs and outputs are BNC, mounted on the front panel.

Response Shapes
Each channel in the VBF42 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. Using the filters as a pair, either in series or parallel, allows a huge number of combinations (we make it around 130 million) for extracting, rejecting or band-limiting signals.

The combination of series or parallel connection of the VBF 42 channels, coupled with the 5 filter responses allows some very complex filter combinations. 

Operational Features
All parameters are controlled using three 'menu' buttons and a rotary control. Both the filter amplifiers and the interface settings are controlled in this way. All settings are non-volatile, and on power-up the unit returns to the last programmed state. Up to nine complete sets of setup information may be stored and recalled at any time. 'Ratio Tuning' enables filter channels to be tuned with a constant ratio between cutoff frequencies (ideal for bandpass and notch use).
RS232 capability is built-in on the VBF42M; GPIB interface is available as an option. The VBF42M implements a high level control language which allows device independent instrument drivers to be produced.
The VBF42 is another product in a range of high performance variable active filters which includes the VBF44, a 4 channel version of the VBF42, and the VBF40, a multichannel version, with the same electronic performance.

  VBF 42 pdf data sheet (70 kB)      Order Now