Other Switching Amplifiers

These compact, switching amplifier PWBs have been designed for high efficiency and versatility and can be adapted to a wide variety of applications. The Output PWBs are either a full bridge or half bridge (usually used in pairs). The outputs are fully protected against open, shorted, or reactive loads of zero power factor.

Some PWBs include a transformer suitable for high frequency applications; most are directly coupled, and require external DC blocking capacitors and an output transformer. Several Output PWBs may be combined for higher output by putting equal voltage transformer secondaries in series. Contact the factory concerning your specific needs.

OUT-18 - This compact board is appropriate for multi channel, high power, low duty cycle applications. Packaged as an S18-26 in a submarine compatible enclosure, it was used in an upgrade to a US Navy sonar system.

OUT-26 - The S26-2A module is a 1,500 VA rated assembly and contains an analog pre-amplifier, PWM modulator, 2 output PWBs, and output filter. This module is 7 x 10 x 5 inches without heat sink. This assembly requires external heat sinking. An adequate heat sink for air cooling with a 20% duty operation may be attached to the top of the standard module. The S26-2 is an S26-2A module packaged in an 8.75 inch high rack mounting enclosure and is delivered ready to use, including the DC supply and output transformer.

OUT-27 - This very narrow PWB is 3.5 inches wide and includes a preamp and PWM modulator. It operates from a 48V supply. It is cooled by making contact to one edge.

OUT-38 - This 1,000 VA amplifier is just 6 x 15 inches and includes an analog Preamp, PWM modulator, four quadrant bridge amplifier, some output filtering, and an A/B switch to redirect the output to two different loads. It is conductively cooled with an expanding card-lock along one 13 inch edge. This unit is especially suitable for under water applications utilizing conductive cooling to the enclosure.

OUT-40 - This 1,500 VA amplifier is 4.5 x 14 inches and includes an analog Preamp, PWM modulator, four quadrant bridge amplifier, and an output filter. S40-2

General Specifications of Switching Amplifiers

Load power factor range	0 - 100% capacitive or inductive
Protection	No combination of passive loads or input signals, including overdrive, short or open will cause amplifier failure.
Ambient temperature	0 - 40 degrees C

PWM units only
Distortion (THD)	below 20 kHz: 2% max, 0.2% typical
RMS noise (re max output)	-60 dB gated on -120 dB gated off
Input impedance (analog)	5 k ohm
Input voltage for full output	1 V RMS for full output

Individual PWB Specifications

Model	OUT-18	OUT-26	OUT-27	OUT-38	OUT-40
Output VA	2,500	750	600	1,000	1,500
Max duty cycle	1%	100%	100%	20%	100%
Bridge configuration	Full	Half	Full	Full	Full
Heat sinking	none	Clamp	Clamp	Clamp	Air

Max frequency kHz	50 PWM	260	85 PWM	85 PWM	85 PWM

Input signal	Analog 1VRMS	Digital TTL	Analog 1VRMS	Analog 1VRMS	Analog 1VRMS

Connection Method	96 DIN	96 DIN	DB-25	Double Ended Plugs	35 EDAC
Width	6.0	4.5	3.0	6.0	4.5
Length	12.0	8.3	15.75	13.0	14.0
Thickness	2.5	1.2	1.0	0.8	1.3

Main DC Supply needed	250	48-59	48-59	250	250
Aux Dc supply needed	+12	12	+12	+12	+12
Amplifier Photograph	OUT-18	OUT-26	OUT-27	OUT-38	OUT-40

All units rated at 100% duty must have adequate heat sinking.
Be advised that connection to these PWBs and external wiring may affect performance.
These high performance PWBs require knowledgeable connections to work properly.
Consulting services are available from Instruments, Inc.

Wired and Tested Amplifier Assemblies

Model	S18-26	S26-2A	S26-2
	18 Channels	Module	Rack Mount

Input power needed	440 V 3ph	48-59 VDC	115/230 VAC
Input Signal	Analog	Analog	Analog

Frequency Range (-3 dB)	10-200 kHz	50 Hz - 40 kHz	50 Hz - 40 kHz
Modulation	PWM	PWM	PWM

Output VA	2,500 VA/chan	1,500	1,500
Output Watts	10 mSec	1,500	1,000

Max duty cycle	1%	100%	100%

Size (inches)	18 x18x 60	7 x 10 x 5	8.75 high
Weight (pounds)	700	15	65
Amplifier Photograph	S18-26	S26-2A	S26-2

For heat sink on S26-2A module, add 3 lbs, and 1.6 in. to the 5 in. dimension.
For output transformer cost, size, and weight, contact factory.
For terms and foreign sales see PRICE POLICY on front page.
Specifications and prices subject to change without notice.