- 2 Independent Channels each switchable
high / low pass
- Highpass / Lowpass / BandPass / Bandstop and Notch in one instrument
- 0.01Hz - 99.9kHz filter range
- Ethernet based interface (option)
- Simple front panel operation
- Input gain to x 500(+54dB)
- Signal level indication
- Switchable filter modifiers
- Six models
- Usually ex-stock delivery
BenchMaster 8 pdf data sheet (75 kB)
 Order
Section |
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BenchMaster 8 Laboratory Filter
Click image for larger picture |
The BenchMaster 8 series of variable filters
are now in their 5th generation, two channels of high performance analogue
filter, plenty of gain, signal level indication, and flexible input front
end all in a compact, solid 1U high package. This versatile instrument has
set the standards for laboratory and industrial filtering, providing a
reliable general purpose filter amplifier with a frequency range,
and filter responses to suit virtually all applications. BenchMaster 8's use
specially manufactured components to ensure close tolerances and good
channel matching. The latest version is a complete redesign, giving
improvements in signal to noise ratios, overall noise, and a clearer front
panel. Modern manufacturing techniques allow us to offer quick deliveries.
The BenchMaster 8 uses no fans, and is silent in operation.
Summary Specification
|
Channels |
2 per
unit (independent) |
| Control |
All
functions by front panel switches.
Optional
External control, 10BaseT text based FICL II
interface.
|
| Frequency |
0.01 Hz to 99.9 kHz, in 5 ranges |
| Gain |
1, 2, 5, 10, 20, 50, 100, 200, 500, (+54 dB) |
| Filters |
Switchable highpass / Lowpass |
| Filter Responses |
6 types. 4 and 8 Pole Butterworth 03,
05
, 4 and 8 Pole Bessel
07,
09,(see
note) General Purpose
41, and Sharp Elliptic
13. |
| Filter Bypass |
Yes |
| Filter Modifiers |
Flat, Butterworth, Pulse ( not all
operate with all filter responses) |
| Signal Invert |
Yes |
| Input
Coupling |
AC / DC (
Matched AC coupling on Differential Input) |
| Input
Mode |
Single
Ended / Differential |
| Input
Overload |
Absolute
Input overload indication (single ended or differential) |
| IEPE |
4mA 24V
current source |
| Signal
Level |
+/- 10 V
pk-pk. (Usually with 'headroom') |
| Signal
Offsets |
+/- 50%
on output, +/- 50% on output single ended only. Factory fitted option. |
| Signal
Level Indication |
3 colour,
4 signal level, off / green / yellow / red |
| Size |
1U 19" |
| Power |
90 -120 / 180-240 Vac 50/60Hz
Optional 9 - 30 V DC, with AC 'power brick' |
Frequency Range 0.01Hz to 99.9kHz
The BenchMaster 8 offers a cut-off frequency range of 0.01Hz to 99.9kHz, covered
by five three-digit ranges. Frequency is set with three rotary decade switches
and a range switch.
Lowpass / Highpass
Each channel can be independently set to high or low pass, over the range 0.01
Hz to 99.9 kHz.
Flexible Input
Single ended or differential input can be set, with overload indication on the
input signals. Input signals can be DC or AC coupled, with matched coupling for
AC differential input. A 24V DC 4mA source for IEPE transducers is provided,
with LED indication of correct operation of the transducer. Green shows correct
operation, red shows short circuit, and nothing indicates open circuit.
Input Gain
The BenchMaster 8 has two stages of input gain, x1, 2, 5 (0,+6,+14 dB), as
precision differential amplification controlled as one front panel switch, then
x 1, 10, 100 (0,+20,+40 dB) as a separate switch control. This combination is
easy to use and allows amplification of small signals. The amplification is
applied to the signal before the filter stages. The filter stages can be
bypassed, so the BenchMaster 8 can be used as a pure amplifier, and if required
the two channels can be linked in series to give x 250 000 (+108 dB) gain.
Signal Level
Indication
BenchMaster 8 filters have a signal level
indication LED fitted to each channel between the input gain stages and the
filter.
Signal level indication - 0%- off -10% -
green - 70% - orange -
95% - red.
 Three Switchable Response Modifiers
Each BenchMaster 8 has 3 filter modifier settings:-
Butterworth - provides a -3dB
at cut off type response, the normal operating position for the Butterworth
response
8.03 and
8.05.
Flat - a flattened amplitude
response up to the cut-off frequency, the normal operating position for
responses
8.13 and 8.41.
Pulse - a minimum overshoot
response, the normal operating position for the Bessel response 8.07 and
8.09.
The use of these modifiers makes for a very versatile filter, especially
when coupled with the Series/Parallel mode. For Butterworth filters (8.03
and 8.05) the use of the flat setting allows 2 filters in series to provide
correct shape double strength filters. Without these modifiers 2 Butterworth
filters in series would have -6dB at cut off, but with one filter in the
series, set to 'flat' the correct -3 dB at cutoff is maintained. This allows
96 dB/octave Butterworth filters to be set on a BenchMaster 8.03.
NOTE not all modifiers work with all filter responses.
Series / Parallel
Operation
The two channels of the BenchMaster 8 can be used in three connection
modes:-
Separately - each filter operates independently of the other.
Series - the signal enters channel 1 and then channel 2 in series, this is
used for bandpass filtering, and 'double strength' filtering using both
filters set the same.
Parallel - the two channels operate in parallel, this used for band stop and
notch filtering.
The use of series and parallel filter connection, with the filter modifiers
and the gain, give for a very versatile set of filter shapes and
possibilities from the BenchMaster 8.
 +
|
 +
|
+
|
+
|
|
Lowpass and separate Lowpass |
Highpass and separate Highpass |
Lowpass and separate Highpass |
Highpass and separate Lowpass |
 |
 |
|
Highpass and Lowpass in series =
Bandpass |
Lowpass and modified Lowpass in series
= true double strength filtering |
|
|
|
Highpass and
Lowpass in parallel = Bandstop
|
Highpass and Lowpass in
parallel = narrow Bandstop (Notch) |
All the curves above were measured on a standard
BenchMaster 8.03, by using a combination of the series/parallel control and
the filter response modifiers.
Easy Manual Control
The BenchMaster 8 is designed for easy manual operation. The
controls are laid out in an easy to understand logical way. All manual
controls are on the laser cut and laser etched front panel. Bearings are
fitted to the control knobs to ensure smooth long life operation. In most
cases the operation of the BenchMaster 8 is intuitive. Some of us at Kemo
have been filter users, we have used Kemo products on site late at night
cold and tired, so we like to keep things simple and easy to operate.
Block Diagram of BenchMaster 8
Optional External Control
BenchMaster 8 units are fitted with control
logic for the optional Kemo
FICL
II
interface for external computer control. This is a text (ASCII) over a
10BaseT, RJ45 plug, Ethernet style hardware interface. This provides an
operating system independent interface. The interface stores current
data, verifies incoming commands, and then executes them.
Simple text commands are used, the screen image shows typical commands
sent via HyperTerminal.
freq,1,250 - sets channel 1, frequency to value 250
icpl,1,dc - sets channel 1, input coupling to DC.
fran,1,L2 - sets channel 1 to range L(lowpass) 2 (102)
igna,2,5 - sets channel 2, input gain block A to x5.
rdbk,2 reads back all the current settings for channel
2.
The RDBK (readback) command gives a listing of all the commands.
RDBK,A will readback all the settings for both channels.
Typical response time to send commands to one channel and implement the
settings is about 200mS. The RDBK files can be stored as text files, so
test setups can be stored for measurement audit purposes. |
|
Six Models, Six Filter Responses
BenchMaster 8.05 - 4 Pole
Butterworth response 24 dB/Octave. (
Data sheet Response 8.05 )
BenchMaster 8.03 - 8 Pole Butterworth
response 48dB/Octave. (
Data sheet Response 8.03 )
BenchMaster 8.09 - 4 Pole Bessel response NOTE the
filter modifiers Flat and Butterworth are not available with this response
BenchMaster 8.07 - 8 Pole Bessel response
NOTE the filter modifiers
Flat and Butterworth are not available
with this response
BenchMaster 8.41 - General Purpose, very flat
to cut off, linear phase.
BenchMaster 8.13 - Sharp Elliptic type
filter. -93dB at twice cutoff. (
Data sheet Response 8.13 )
Amplitude click for larger images Phase
Optional DC Power
9-30V DC input is available as an option. Power input by 'XLR' type connector,
with an AC 'power brick' to power the unit from mains when available.
Please check our page about DC Power.
Other Features
The BenchMaster 8 is manufactured using the latest surface
mount technology, independent linear power supplies for the logic and
analogue circuits. The BenchMaster 8 is housed in a solid aluminium case,
ready for rack mounting, and with handles which protect the front panel
controls. The front panel is laser cut and marked stainless steel, and most
of the internal and external fasteners are stainless steel, vibration
resistant where possible. It is even possible to turn off the LED
indicators, for use in dark optical laboratories. This latest version is a
complete redesign, and one that all the staff at Kemo have contributed to,
it is a product we feel proud of, and after over 40 years of building
filters one that has considerable expertise built into it.
Ordering Information
Please order as:-
BenchMaster 8.05, 4 pole Butterworth
BenchMaster 8.03, 8 pole Butterworth
BenchMaster 8.09, 4 pole Bessel
BenchMaster 8.07, 8 pole Bessel
BenchMaster 8.13, 8 pole sharp anti-aliasing type filter
BenchMaster 8.41, 8 pole general purpose linear phase filter
SPECIAL NOTE - a BenchMaster 8 can be supplied with any two filters from the
above selection, so a unit can be supplied with one 8.03 channel and one 8.41
channel.
Please specify if Optional Interface or DC power is required.
BenchMaster 8 pdf data sheet (75 kB)
Order Form
|
- Versatile 2 channel
bench top filter, gain to x500 (+54 dB), interface Usually ex-stock
