9900:1 cutoff span Frequency  3 versions 0.1 Hz to 990 Hz 1 Hz to 9 900 Hz 10 Hz to 99 000 Hz Gain- switchable to x50 (+34 dB) Signal level indication 2 rugged racks AC or optional DC power 1 compact single channel rack Very easy to use Switchable HighPass / LowPass Single ended / Differential Inputs AC / DC / IEPE inputs Usually in stock   BenchMaster 21M pdf data sheet (75 kB).   Order Now

The Kemo BenchMaster 21M is a versatile multi-channel electronic filter unit offering simple manual adjustment of the cutoff frequency by easy-to-read thumbwheel switches. Up to nine channels can be fitted in a standard 19" frame; a compact 1 channel unit is also available for benchtop use.

Summary Specification

Channels	1 per card
Control	Manual Front panel switches / thumbwheel  External control option
Frequency (specified at order)	0.1 Hz - 990 Hz (3 ranges)  1.0 Hz - 9 900 Hz (3 ranges)  10 Hz - 99 000Hz (3 ranges)
Gain	x1, x2, x5, x10, x20, x50
Filters	Switchable Highpass/Lowpass - with Pulse/Flat modifiers
Filter Responses (specified at order)	03, 05 (Butterworths), 07, 09 (Bessels),  13 (anti-aliasing),  37, 41 (general purpose)
Input Coupling	AC / DC, Single ended / Differential, set by internal jumper
Input Overload Indication	Indication of absolute input signal overload
Signal Level Indicator	Single 3 colour, 4 signal level, off / green / yellow / red.
Card Size	2 series 21 slots (100 x 220 Eurocard)
Racks, Size and weight	21.18 Rack - up to 9 channels, 420 x 155 x 350mm (16.6x6.1x13.8"), 10 kg (22 lb) maximum. 21.5 Rack - up to 2 channels, 153 x 155 x 350mm (6x6.1x13.8"), 3.5 kg (8 lb) maximum  special order 21.1 Rack - 1 channel, 56 x 106 x 300 mm (2.2x4.2x11.8") 1 kg (2.2 lb) maximum
Power	21.18 rack  90 -120 / 180-240 Vac 50/60Hz - Optional DC power  21.1 rack 9 - 30V DC power

Frequency Range
A BenchMaster 21M filter covers a cutoff span of 9900:1, implemented as three decades with two digit resolution. Three base frequencies are available; these are 0.1Hz, 1Hz and 10Hz, giving maximum cutoff frequencies of 990Hz, 9900Hz and 99kHz respectively.

Gain and Signal Level Indication
The updated BenchMaster 21M has more gain. Two front panel switches give gain of  x1, x2, x5 and x1, x10, operated in combination to give up to x 50 gain (+54dB). The front panel has a 4 stage signal level indicator, off for low signal, green for up to +/- 7 volts signal level, the orange to +/- 9.5 V, and red above this. This indicator gives a guide for setting the gains, as well as indicating possible signal overloads. 

Filter Responses
The BenchMaster 21M has been updated to add the standard range of Kemo filter responses. The filter response is specified at order, any questions about which one contact us and we are pleased to advise you. 

Other Features
Indication of signal input overload is provided. Input AC coupling is provided; this is permanently active in highpass mode and can be switched in or out in lowpass and bypass modes. The differential / single-ended mode is selected by an internal on board jumper. IEPE inputs are set by a front panel switch, with front panel indication of correct connection. Inputs and outputs are on BNC connectors.
DC power, 9-30V DC input is available as an option. Please check our page about DC Power.