M405P

MAOSP PORTABLE EXTENDED RANGE YU METER Range: 30 dBm to +30 dBm in 2 dB steps for 0 VU reading: Frequency Response: +/-0.25 dB from 20 Hz to 20 kHz_ -30 dB down at 60 Hz with filter in_ Noise: Signal to noise ratio better than 50 dB measured from 0 VU meter reading_ Total Harmonic Less than % from 20 Hz to 20 kHz Distortion: (measured with any specified input level and at 0 VU output level) Source Impedance: 150/600 ohms_ Input Impedance: Selectable, 150/600/20K ohms + /-50 unbalanced, floa ting above ground. Attenuator Tracking: +/-0.25 dB per step (non cumulative) Meter Ballistics: Complies with ANSI VU meter standards Headset Output: 0 dBm (approx 600 ohms). Battery Life: More than 40 hrs: continuous use_ Typically 30 days at 2 hrs: per day intermittent use. Dimensions: 5.00" wide x 9.00" high x 5.00" deep (12Smm x 225mm 125mm) Weight: 7 Ibs. (3 kg) net. 1 -

WARD-BECK SYSTEMS LTD_ GENERAL MAOSP PORTABLE EXTENDED RANGE_VU METER The M4OSP Extended Range VU Meter is battery operated, portable instrument designed for the measurement of trans- mission, noise and VU levels throughout an audio system_ The instrument produces a VU indication on 1/2 inch meter for input levels from 50 dBm to +30 dBm over 20 Hz to 20 kHz bandwidth_ The active circuitry utilizes FET devices to achieve high impedance operation with minimum current demand (less than mA) The M4OSP is operated continuously from the internal Alkaline cells for more than 40 hours 0r typically 30 days of intermit- tent use. Input connections to the meter may be via binding post terminals or telephone type jack conveniently located on the front panel. An output jack provides an indepen- dent 0 dBm approx) 600 ohm level for use as headsct monitor or auxiliary line amplificr. An input attenuator; calibrated in dB steps, accommodates the full 80 dB range in one continuous 300 degree rotation_ front panel selector switch is provided to permit the M4OSP to operate in the match- ing or bridging modc (for use with untcr- minated or terminated transmission lines), as well as allow the instrument to operate directly with 150 or 600 ohm system im- pedances In addition, a 60 Hz notch filter may be switched in to permit measurements to be obtained in the presence of hum 2-1

WARD-BECK SYSTEMS LTD. CIRCUIT_DESCRIPIION MAOSE PORTABLE EXTENDED RANGE_VU_METER The signal input to the M4OSP Extended The preamplifier output is via capacitor Range VU Meter may be via binding post C5. The output amplifier comprises trans- terminals J2 and J3 Or telephone jack JI. istors Q3 through Q7. The circuit is an An input via Jl automatically disconnects operational amplifier functioning in the the binding post input circuit which is inverting mode and with feedback resistors connected to the normal springs of the Rl4 and R22 determining the gain Filter jack switch SW3 inserts a parallel T-type filter_ comprising resistors Rl5 through R2] and The input amplifier configuration is un- capacitors C6 through C9_ The filter prod- balanced but floa ting with respect to uces a sharp 60 Hz notch with greater than chassis ground and can, therefore, be 30 dB attenuation_ Locating the filter utilized in conjunction with balanced audio components within the feedback loop lines without introducing disturbances produces high-Q response characteristics with 3 dB points at 50 and 70 Hz Matching/bridging impedance switch SWZA,B determines the ioad presentcd by Output coupling capacitor Cll connects the the instrument to the source (matching or signal tO the VU meter via switch SW4 2OK ohm bridging). When a 150 or 600 ohm Resistor R33 provides the required ma tching impedance selected source iS switch driving impedince, while SWZA R34 and C13 compensates the input of the instru- introduces high [requency compensation to ment to present the proper line termination restore meter rectifier losses. Zener diodes and simultaneously adjusts the instrument CR9 and CRIO offer vol Itage_ protection against gain to produce the correct meter meter overdrive. Headset jack J5 delivers indication for 150 or 600 ohm line meas- approximately dBm to 600 ohm load urements when meter MI indicates VU. Coupling capacitors Cl and C2 prevent dc When selected to the TEST position, SWZD voltages, which may be present on line, applies test load to from the battery interfering circuit with the instrument and provides visual indication circuitry. of The the signal is applied to the battery condition (refer to operation sect- instrument amplifier via calibrated ion). dB/step rotary attenuator R3, resistor R4 and coupling capacitor C3_ The calibrated attenuator accommodates an 80 dB range and allows the M4OSP to measure input levels from 30 dBm to +30 dBm for VU meter reading: Clipping diodes CRl and CR2 in conjunc- tion with R4 limit the signal input ampli- tude to the amplificr and meter circuits. QI FET and Q2 PNP transistor form vcry high impedancc complementary pre- amplificr: Hence, the calibrated potentio- meter, R3 operates unloaded The preampli- fier gain is dctcrmined by the ratio of resistor networks R9 to RIO and Rl or R9 to Rl2 and R13 depending 0n thc selection of switch SW2. This produccs Simultan- eous 6 dB gain adjustment when the match- ing input impedance is selected to 150 or 600 ohms 3-[

WARD-BECK SYSTEMS LTD. OPERATIONAL_DESCRIPTION MAOSP PORTABLE EXTENDED RANGEVU METER (Refer to Front & Rear Layout B405-04-016) 1) VU Meter movement. Standard scale this output source offers the capability movement complies to ASA VU Meter of driving 600 ohm line to approxi- standards. mately dBm and hence adapts the M4OSP for booster amplifier appli- 2) TEST /OFF/150/600 switch (SW2) cations with visual indication of activates the instrument in the 150/600 program transmission. Low level input and bridging positions. In addition the signals from -50 dBm may be adjusted battery condition is measured in thc via the M4OSP amplifier circuit to "TEST position. produce 0 dBm at JS output The "150/600 MTC

MAUSP PORTABLE EXTENDED RANGE YU METER The M4OSP is designed for dependable, If it is necessary to interchange com- trouble-free service: However, a8 with all ponent to determine the cause of a fault, high quality electronic equipment; reg- remove the suspected component with ular schedule of inspection should be estab- small soldering iron and a desoldering tool. lished. Any accumulation of dust should Place the soldering iron and the desolder- be periodically removed with a soft brush ing tool on the solder connection to be and vacuum hose desoldered. When the solder melts thor- oughly, press the plunger release trigger. If The active circuitry may be inspected by any of the lead connections stick to the removing the instrument front panel_ printed circuit board, free them with Remove the two 4-40 screws on top and scribe or a similar sharply pointed instru- two rubber feet at the bottom that secure ment: Carefully remove the component the front panel to the meter case. which, if proven to be satisfactory, may be used again for other applications The component board may be removed for inspection by removing the tWo nuts which To install the new component, shape the secure the PC board to the meter terminals. leads to the correct spacing: Insert the part In this manner access may be gained to the and fold the leads under the printed solder side of the PC board. circuit board to firmly hold the component Clip off the excess wire leaving about 1/16 When it is necessary to install new bat- inch. Solder the new leads, using tcries resin core remove the four screws from the solder and clean the board with an inert battery door and replace batteries Install fluid such aS perchlorethelyne_ new batteries and secure battery door by teloca ting the 4-40 retaining screws The location of components is shown in drawing B142-06-002, If a fault is suspected measuring the dc voltage present at the transistor clectrodes may assist to determine the cause. When comparing the measurements listed in the voltage chart consideration should be given to the fact that; for dircct coupled sections; a fault in one circuit may cause abnorna conditions in other circuit areas within the same section. 5 -

WARD-BECK SYSTEMS LTD DC_VOLTAGE CHART MAOSP PORTABLE EXTENDED RANGE_YVU_METER VE VB VC Q1 4.6 22 Q2 22.5 22 10.6 Q3 10.5 22.5 Q4 10.5 21.8 Q5 22.4 21.8 11.6 Q6 11.2 11.6 22.5 Q7 11.2 10.7 CONDITIONS UNDER WHICH VOLTAGES ARE MEASURED No signal applied. 2. Battery voltage 27 volts_ BA TTER Y CURRENT DRAIN (no signal applied) 1,25 mA- 6 -

WARD-BECK SYSTEMS LTD

All Ward-Beck Systems Ltd , products are warranted against defective materials and workmanship for a period of one year from the date of shipment. Ward-Beck Systems Ltd, will repair Or replace, at its option and without charge , all said products O parts thereof which upon 'factory inspection prove to be defective during the warranty period, provided that: 1) the original serial numbers are intact and have not been tampered with _ 2) the purchaser shall return any equipment O parts thereof to Ward-Beck Systems Ltd. only after obtaining prior authorization and shipping instructions from the factory (Ward-Beck Systems Ltd. Ieserves the right to inspect or repair equipment on the purchaser'$ premises) , and 3) the purchaser assumes the obligation for all expenses incurred in connection with the ship- ping and return of such goods, once authorization has been obtained_ This warranty does not cover items normally considered expendable, such as fuses and lamps_ This warranty does not cover damages caused by misuse, accident, neglect, unauthorized alteration; repair by unauthorized personnel, or damage caused by act of God, war, or civil insurrection . In no event shall Ward-Beck Systems Ltd. be liable for consequential damages_ Ward-Beck Systems Ltd . , shall have the right to final determination as to the applicability of this warranty. Ward-Beck Systems Ltd. reserves the right, at any time and without notice, to make changes in its equipment, components specifications, Or designs, as may be warranted by progress in state-of-the-art or technology. Ward-Beck Systems Ltd. . reserves the right to make design changes _ additions to, and improvements in its pIO- ducts , without obligation to instali suci revisions in products previously manufactured_ The warranty set forth herein is in lieu of all other warranties expressed or implied, including the warranties of merchantability and fitness. WBS WARD-Beck sySteMs 841 Progress Avenue, Scarborough, Ontario, Canada MIH 2X4. Tel: (416) 438-6550. Fax: (416) 438-3865. Toll Free 1-800-771-2556 Tow/8906/5M,

WAAD-BECK SysteMs LTD_