Operation manual for fluke pm6685

Figure Example of an INPut subsystem command tree. The keywords placed in square brackets are optional nodes. This means that you may omit them from the program message.

You can only do this if the header path of the new leaf-node is the same as that of the previous one. If not, the full header path must be given starting with a colon. The command tree shows the paths you should use for the command syntax. Leaf nodes are the last keywords in the command header, before the parameters.

Decimal data are printed as numerical values throughout this manual. Numeric values may contain both a decimal point and an exponent base The Command Reference chapters explicitly specify which keywords are allowed by a particular command. The instrument always allows MINimum and MAXimum as a data element in commands, where the parameter is a numeric value. You can use suffixes to express a unit or multiplier that is associated with the decimal numeric data.

Valid suffixes are s seconds , ms milliseconds , mohm megaohm , kHz kilohertz , mV millivolt. Notice that you may also send ms as MS or mS.

MS does still mean milliseconds, not Mega Siemens! Response messages do not have suffixes. The returned value is always sent using standard units such as V, S, Hz, unless you explicitly specify a default unit by a FORMat command. A Boolean parameter specifies a single binary condition which is either true or false. You must enclose expression program data in parenthesis. Three possibilities of expression data are as follows:.

This data starts with a preamble that contains information about the length of the parameter. A macro is a single command, that represents one or several other commands, depending on your definition. You can define 25 macros of 40 characters in the counter. One macro can address other macros, but you cannot call a macro from within itself recursion. You can use variable parameters that modify the macro. You can use both commands and queries as macro labels.

The label cannot be the same as common commands or queries. If a macro label is the same as a CNT-8X command, the counter will execute the. The commands to be performed by the macro can be sent both as block and string data. However, there are some things you must keep in mind:. If you use a controller language that uses double quotation marks to define strings. When using string data for the commands in a macro, remember to use a different type of string data identifiers for strings within the macro.

If the macro should for instance set the input slope to positive and select the period function, you must type:. Later when you use the macro label as a command, the counter will execute the sequence of commands. You can pass arguments variable parameters with the macro. See the example below. This example defines a macro AUTO, which takes two arguments, i. This removes all macro labels and sequences from the. You cannot overwrite a macro; you must delete it before you can use the same name for a new macro.

When you want to execute a CNT-8X command or query with the same name as a defined macro, you need to disable macro execution. Disabling macros does not delete stored macros; it just hides them from execution. Now macros can be executed by using the macro labels as commands. This query gives a response containing the definition of the macro you specified when sending the query. Status reporting is a method to let the controller know what the counter is doing. You can ask the counter what status it is in whenever you want to know.

You can select some conditions in the counter that should be reported in the Status Byte Register. The counter will place a detected error in its Error Queue. When you read the queue, the first error will come out first, the last error last. If the queue overflows, an overflow message is placed last in the queue, and further errors are thrown away until there is room in the queue again. Bit 2 in the Status Byte Register shows if the instrument has detected errors.

This can then interrupt the GPIB controller program when an error occurs. Further description of all error numbers can be found in the Error Messages chapter. If more than one error occurred, the query will return the error that occurred first. When you read an error you will also remove it from the queue. You can read the next error by repeating the query. When errors occur and you do not read these errors, the Error Queue may overflow.

Then the instrument will overwrite the last error in the queue with the following:. This error shows that the instrument has received a valid program message which it cannot execute because of some device specific conditions. This error shows that the instrument could not properly complete some device specific operations. This error will occur when the Message Exchange Protocol is violated, for example, when you send a query to the instrument and then send a new command without first reading the response data from the previous query.

Also, trying to read data from the instrument without first sending a query to the instrument will cause this error. This is the first level of initialization. The controller program should start with this which initializes the IEEE-interfaces of all connected instruments.

It puts the complete system into remote enable REN-line active and the controller sends the interface clear IFC command. The command or the command sequence for this initialization is controller and language dependent. Refer to the user manual of the system controller in use. Device clear is the second level of initialization. It initializes the bus message exchange, but does not affect the device functions.

The command is useful to escape from erroneous conditions without having to alter the current settings of the instrument. The instrument will then discard pending commands and will clear responses from the output queue.

For example; suppose you are using the Counter in an automated test equipment system where the controller program returns to its main loop on any error condition in the system or the tested unit. To ensure that no unread query response remains in the output queue and that no unparsed message is in the input buffer, it is wise to use device-clear. Such remaining responses and commands could influence later commands and queries.

The third level of initialization is on the device level. This means that it concerns only the addressed instruments. Use this command to reset a device. It initializes the device-specific functions in the Counter. Use this command to clear the status data structures. Even if you do not have these interface board or use these computer languages, look at the examples anyway. They give you a good insight on how to program the instrument efficiently. To be able to run these programs without modification, the address of your counter must be set to All these programs start with a declaration containing three lines of setup information for the interface.

This declaration must be merged with the programs prior to running them. The declaration is printed below, but it is also available as a file on the diskettes delivered with your interface. The file name is DECL. This program uses limit testing to check that the frequency is above a preset value.

Frequency profiling visualizes frequency variations for a certain time. This program gives an output file called:. If this file is imported to a spreadsheet program, for instance Excel, you can create a graph like the one in the figure below. Figure This figure is the results of frequency profiling on a sweep generator.

This program makes a quick array measurement and stores the results in the internal memory of the counter. Then it writes the results to a file called MEAS. The measurement results as a function of the samples can be visualized in a spreadsheet program such as Excel. The program reads a command from the controller keyboard and sends it to the counter, then it checks the status byte using Serial Poll. It determines the reason for Service Request, and reads query responses and error messages.

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Secure with hose clamps. Reconnect the negative battery cable when finished. Do not remove fuel filter when engine is hot, as spilled gasoline may ignite. DO NOT spread hose clamps further than necessary. Ensure clamps grip hoses firmly over filter after installation. Warm engine by running for a few minutes. Remove the oil drain hose A, Figure 20 from the cable clamp C that is located on the engine deck on the right-hand side of the frame.

Place the drain hose down through the hole E in the engine deck. Place a small pan under the oil drain hose to catch the oil. Using the appropriate tools, remove the cap B from the oil drain hose A and drain the engine oil into the pan. After draining, replace the cap and wipe up any spilled oil. Reinstall the oil drain hose into the cable clamp to retain the hose during normal operation.

Place an absorbent shop cloth under the engine oil filter. Remove the engine oil filter and replace with a new one. Remove the shop cloth and wipe up any spilled oil. Engine Oil Drain A. Oil Drain Hose B. Cap C. Cable Clamp D. Oil Filter E. Hole for Drain Hose Inspect Muffler and Spark Arrester Inspect the muffler for cracks, corrosion, or other damage Remove the spark arrester, if equipped, and inspect for damage or carbon blockage.

If replacement parts are required, make sure to use only original equipment replacement parts. Disassemble parts to apply grease to moving parts when grease fittings are not installed.

Deck Lubrication Not all greases are compatible. Keep oil and grease off belts and pulleys. Remember to wipe fittings and surfaces clean both before and after lubrication. Grease the front caster. Repeat process for the other side of the machine. Before removing the reservoir cap, make sure the area around the reservoir cap and fill neck of the reservoir is free of dust, dirt, or other debris.

Unscrew the reservoir cap B, Figure Look down the filler neck of the hydraulic oil reservoir A and observe the oil level. Reinstall the reservoir cap. Have a suitable container ready to catch any spilled oil. The manufacturer recommends this be a dealer-only service item.

Locate the transmission oil filter B, Figure 26 at the rear of the battery compartment under the seat. Lubricate the new filter base with a few drops of transmission oil. Fill the filter half full of oil. Clean the area around the filter base and remove the filter.

Do NOT drain the hydraulic system oil. Run the unit for several minutes and check the transmission oil level. Checking Hydraulic Oil Level A. Hydraulic Oil Reservoir B. Repeat step 5 until the air is out of the system. Battery Compartment A. Mower blades are sharp. If there are no flats on the spindle shaft, wedge a wooden block between the mower blade and the mower deck housing to keep the mower blade from turning. Remove the mower blade from the unit.

See Removing the Blade. Discard the mower blade if it has any of the below conditions. Has more than. Mower blade is bent or broken. If the cutting edges are not sharp or have nicks, sharpen the blades. See Sharpening the Mower Blades. A C Figure Mower Blade Cutting Edge B.

Square Corner C. Air Lift D. New Mower Blade B. Mower Blade in Dangerous Condition If notch measures. Sharpen the mower blades with grinder, hand file, or electric blade sharpener. Sharpen the mower blade by removing an equal amount of material from each end of the mower blade. Keep the original bevel A, Figure 30 when grinding. DO NOT change the mower blade bevel. Balance the mower blades before installing.

Sharpening the Mower Blade A. Mower Blade Bevel B. Keep mower blades balanced. Balancing the Mower Blade A. Nail R 1. Clean the mower blade to remove any dried grass or other debris. See Figure Put the mower blade on a nail in a vise and turn the mower blade to the horizontal position. Check the balance of the mower blade. If either end of the mower blade moves downward, sharpen the heavy end until the mower blade is balanced. See Sharpening the Mower Blades for proper sharpening instructions.

Repeat the process until the mower blade remains in the horizontal position. Reinstalling the Mower Blades 1. Reinstall each mower blade with the air lifts pointing up towards the mower deck as shown in Figure B A D Figure Tightening the Mower Blade for Installation A. Mower Blade Mounting Bolt B. Flat Washer C. The alignment of the control levers, the placement of the levers how close the ends are to one another and the height of the levers can be adjusted. To Adjust the Handle Placement Loosen the jam nuts and adjust the placement bolt C, Figure 34 in or out to properly adjust the lever end spacing.

To Adjust the Handle Height Remove the mounting hardware and reposition the handle either up or down from its original position. You will need to readjust the handle alignment as described above. Control Lever Adjustment A. Placement Hardware B. Ground Speed Control Lever Speed Balancing Adjustment A C N ep o ro t fo du r ct io n If the rider veers to the right or left when the ground speed control levers are in the maximum forward position, the top speed of each of these levers can be balanced by turning the adjustment bolt s A, Figure Only adjust the speed of the wheel that is traveling faster.

To Reduce the Speed of the Faster Wheel 1. Loosen the securing nut. Retighten the securing nut when adjustment is complete. Top Speed Adjustment A. Top Speed Adjustment Bolt B. Control Lever Base C. Alignment Hardware www. NOTE: Perform this adjustment on a hard, level surface such as a concrete floor. Neutral Adjustment LH side shown A. Adjustment Linkage Rod B.

Disengage the PTO, engage the parking brake and turn off the engine. There are three nuts B, Figure 35 on the linkage rod A. The first two are to be used together to turn the rod and the third towards the front of the machine is used to lock the rod in place.

Loosen the jam nut that locks against the ball joint and turn the linkage rod to adjust. Lock the jam nut B against the ball joint when neutral is achieved. NOTE: This adjustment should not be performed while the machine is running.

It may take several attempts to achieved neutral, depending upon how much the machine creeps. Disengage the PTO, stop the engine, block the front wheels, remove the ignition key, and engage the parking brake. Locate the brake spring A, Figure With the parking brake engaged, measure the compressed spring length. If the spring is not within this range, release the parking brake and turn the adjustment nut B to compress or release the spring. Engage the parking brake and remeasure the spring.

This may damage the brake mechanism. Parking Brake Adjustment A. Brake Spring B. Adjustment Nut If this does not correct the braking problem, see your Snapper Pro dealer. Move the ground speed control levers into the operating position, pull levers rearward and release.

Move the ground speed control levers out towards the neutral position. If the levers do not align with the notches in the neutral lock plate, it is necessary to adjust the adjustment linkage rod B, Figure Neutral Return Spring Adjustment A. Set Collar B. Adjustment Linkage Rod C. Neutral Return Spring D. Neutral Return Bushing E. Pull the ground speed control lever rearward and release to check position. If the ground speed control lever does not align itself with the notch in the neutral plate, then move the set collar A forward or back on the adjustment linkage rod B until the speed control lever aligns with the notch.

Retighten the set collar. Make sure that the neutral return bushing D is seated correctly in the spring stop plate E. Pull the ground speed control lever rearward and release to check position again.

Adjust as necessary to align the ground speed control levers with the notches in the neutral lock plate. It is important to note that after every adjustment of the neutral return rod, the lever must be pulled rearward and released to properly check the neutral position.

Check Lift Rod Timing N ep o ro t fo du r ct io n 1. Park the machine on a flat, level surface. Disengage the PTO, engage the parking brake, turn off the engine, and remove the ignition key.

Rear tires must be inflated to 15 psi 1,03 bar ; front tires to 25 psi 1,72 bar. To check the lift rod timing, measure and record the distance between the lift pivots and the rod pivots.

Repeat for other side of unit. If the measurements for the rods are equal, no further adjustment is required. Remove the cutting height adjustment pin and lower the mower deck. Block up the mower deck until all hanger chains are slack. Refer to Figure Turn the clevis clockwise to shorten the distance between the rod pivots or counterclockwise to lengthen the distance between the rod pivots. Tighten the jam nut against the clevis. Remove the blocks from the under the mower deck.

Remove the cutting height adjustment pin from in front of the deck lift pedal arm. Lift mower deck and reinstall adjustment pin in desired mowing height. Adjust Here Coarse Adjustment Procedure When adjusting the deck level, the coarse adjustment procedure should be used to make the majority of the adjustment and the fine adjustment procedure should be used to complete the adjustment.

Hanger Chain Adjustment N ep o ro t fo du r ct io n 1. Park machine on a flat, level surface. Disengage the PTO, stop the engine and engage the parking brake. Slide the chains down in the slots until the chains are tight and tighten the nuts See Figure Slide the chains down in the slots until the chains are tight and tighten the nuts. Remove all 2 x 4 blocks from under the mower deck. Position the outside mower blades so that they face front-to-back Figure Measure from the front tip of the blade from the cutting edge to the ground.

Measure from the rear tip of the blade from the cutting edge to the ground. Repeat this process for the other side of the machine. Adjust Here 1. Position the outside mower blades so they face front-toback. Remeasure the front tip of the blade from the cutting edge to the ground. Measure the rear tip of the blade from the cutting edge to the ground.

Repeat the process for the other side of machine. Fine Adjustment A. Jam Nut B. Fine Adjustment Bolt www. Park the tractor on a smooth, level surface such as a concrete floor. Lower the mower deck to its lowest cutting position and remove the mower deck guards. Injury may result if the breaker bar is prematurely released while the spring is under tension. Slide the drive belt over the edge of the stationary idler pulley B.

Carefully release the tension on the breaker bar or the combination wrench. Remove the old belt and replace with a new one. Make sure the V-side of the belt runs in the pulley grooves Figure Carefully release the tension on the breaker bar. Carefully release the tension on the combination wrench. Reinstall the mower deck guards. Run the mower under no-load condition for about 5 minutes to break-in the new belt. C Figure Idler Arm B.

Stationary Idler Pulley C. Spindle Pulley B. Spring-loaded Idler Pulley D. Park the machine on a smooth level surface such as a concrete floor. Disengage the PTO, engage the parking brake, turn off the engine and remove the ignition key. Lower the mower deck to its lowest cutting position. Measure the coil length of the mower belt tensioner spring A, Figure Loosen the jam nut C.

Retighten the jam nut. Mower Belt Tensioner Spring B. Anchor Eyebolt C. Jam Nut D. Adjustment Nut 38 www. Remove the hardware that secures the clutch anchor pad to the PTO clutch.

Use extreme caution when removing this spring. Pump Drive Belt B. Crankshaft Pulley C. Pump Pulley D. Idler Pulley E. Idler Arm F. Spring G. Spring Anchor Eyebolt R N ep o ro t fo du r ct io n 4. Loosen the nut on the spring anchor eyebolt G, Figure 47 to release the majority of the belt tension.

Use caution and remove the nut to completely release the tension. Remove the old belt and replace it with the new one. Reinstall the spring anchor eyebolt G into the anchor tab and loosely fasten the nut. Tighten nut. Reinstall the clutch anchor pad to the PTO clutch and secure with the hardware previously removed.

Reinstall the PTO drive belt. Avoid spilling electrolyte. Keep flames and sparks away from the battery. If not done in this order, the positive terminal can be shorted to the frame by a tool. Disconnect the cables from the battery, negative black cable first B, Figure Clean the battery terminals and cable ends with a wire brush until shiny.

Reinstall the battery and reattach the battery cables, positive red cable first A. Coat the cable ends and battery terminals with petroleum jelly or non-conducting grease. A 40 www. Ventilate the battery well during charging. A voltmeter can be used to determine condition of battery. When engine is off, the voltmeter shows battery voltage, which should be 12 volts.

When engine is running, the voltmeter shows voltage of charging circuit which normally is 13 to 14 volts. Both batteries must be of the same voltage.

Position the vehicle with the booster battery adjacent to the vehicle with the discharged battery so that booster cables can be connected easily to the batteries in both vehicles.

Make certain vehicles do not touch each other. Wear safety glasses and shield eyes and face from batteries at all times.

Be sure vent caps are tight. Place damp cloth over vent caps on both batteries. Connect the second cable negative - to other post of booster battery.

Make final connection on engine block of stalled vehicle away from battery. Do not lean over batteries. Start the engine of the vehicle with the booster battery. Wait a few minutes, then attempt to start the engine of the vehicle with the discharged battery. More than thirty seconds seldom starts the engine unless some mechanical adjustment is made.

After starting, allow the engine to return to idle speed. Remove the cable connection at the engine or frame. Then remove the other end of the same cable from the booster battery. Remove the other cable by disconnecting at the discharged battery first and then disconnect the opposite end from the booster battery.

Discard the damp cloths that were placed over the battery vent caps. N ep o ro t fo du r ct io n A dead battery or one too weak to start the engine may not mean the battery needs to be replaced. For example, it may mean that the alternator is not charging the battery properly. If there is any doubt about the cause of the problem, see your dealer. Jump starting is not recommended. However, if it must be done, follow these directions. Both booster and dis-charged batteries should be treated carefully when using jumper cables.

Charging a Completely Discharged Battery R 1. Be aware of all the safety precautions you should observe during the charging operation. If you are unfamiliar with the use of a battery charger and hydrometer, have the battery serviced by your dealer. Add distilled water sufficient to cover the plate fill to the proper level near the end of the charge.

If the battery is extremely cold, allow it to warm before adding water because the water level will rise as it warms. Also, an extremely cold battery will not accept a normal charge until it becomes warm.

Always unplug or turn the charger off before attaching or removing the clamp connections. While charging, periodically measure the temperature of the electrolyte. Charge the battery until fully charged until the specific gravity of the electrolyte is 1. The best method of making certain a battery is fully charged, but not over charged, is to measure the specific gravity of a cell once per hour.

The battery is fully charged when the cells are gassing freely at low charging rate and less than 0. Jump Starting WARNING WARNING R Any procedure other than the preceding could result in: 1 personal injury caused by electrolyte squirting out the battery vents, 2 personal injury or property damage due to battery explosion, 3 damage to the charging system of the booster vehicle or of the immobilized vehicle. Do not attempt to jump start a vehicle having a frozen battery because the battery may rupture or explode.

If a frozen battery is suspected, examine all fill vents on the battery. If ice can be seen or if the electrolyte fluid cannot be seen, do not attempt to start with jumper cables as long as the battery remains frozen. Never expose battery to open flame or electric spark — battery action generates hydrogen gas which is flammable and explosive.

Do not allow battery acid to contact skin, eyes, fabrics, or painted surfaces. Batteries contain a sulfuric acid solution which can cause serious personal injury or property damage.

To avoid engine damage, do not disconnect battery while engine is running. Be sure terminal connections are tight before starting. Fuel vapor is also toxic if inhaled, so never store the unit in any structure used for human or animal habitation. Be sure the spark plug opening is protected from foreign objects with a suitable cover. Drain fuel system completely or add a gasoline stabilizer to the fuel system. If you have chosen to use a fuel stabilizer and have not drained the fuel system, follow all safety instructions and storage precautions in this manual to prevent the possibility of fire from the ignition of gasoline fumes.

Remember, gasoline fumes can travel to distant sources of ignition and ignite, causing risk of explosion and fire. NOTE: Gasoline, if permitted to stand unused for extended periods 30 days or more , may develop gummy deposits which can adversely affect the engine carburetor and cause engine malfunction. To avoid this condition, add a gasoline stabilizer to the fuel tank and run the engine a few minutes, or drain all fuel from the unit before placing it in storage.

N ep o ro t fo du r ct io n Before you store your unit for the off-season, read the Maintenance and Storage instructions in the Safety Rules section, then perform the following steps: Never store the unit, with gasoline in engine or fuel tank, in a heated shelter or in enclosed, poorly ventilated enclosures. Gasoline fumes may reach an open flame, spark or pilot light such as a furnace, water heater, clothes dryer, etc. Handle gasoline carefully. It is highly flammable and careless use could result in serious fire damage to your person or property.

Drain fuel into an approved container outdoors away from open flame or sparks. Drain crankcase oil while engine is hot and refill with a grade of oil that will be required when unit is used again.

Prepare the mower deck for storage as follows: a. Remove mower deck from the unit. Clean underside of mower deck. Coat all bare metal surfaces with paint or light coat of oil to prevent rusting. Clean external surfaces and engine. Prepare engine for storage. Clean any dirt or grass from cylinder head cooling fins, engine housing and air cleaner element.

Cover air cleaner and exhaust outlet tightly with plastic or other waterproof material to keep out moisture, dirt and insects. Completely grease and oil unit as outlined in the Normal Care section. Clean up unit and apply paint or rust preventative to any areas where paint is chipped or damaged. Be sure the battery is filled to the proper level with water and is fully charged. Battery life will be increased if it is removed, put in a cool, dry place and fully charged about once a month.

If battery is left in unit, disconnect the negative cable. Starting After Long Term Storage Before starting the unit after it has been stored for a long period of time, perform the following steps. Remove any blocks from under the unit. Install the battery if it was removed.

Unplug the exhaust outlet and air cleaner. Fill the fuel tank with fresh gasoline. See engine manual for recommendations. Check crankcase oil level and add proper oil if necessary. If any condensation has developed during storage, drain crankcase oil and refill.

Inflate tires to proper pressure. Check fluid levels. Start the engine and let it run slowly. DO NOT run at high speed immediately after starting. Be sure to run engine only outdoors or in well ventilated area. The troubleshooting guide below lists the most common problems, their causes and remedies.

See the information on the following pages for instructions on how to perform most of these minor adjustments and service repairs yourself. If you prefer, all of these procedures can be performed for you by your local authorized dealer. WARNING To avoid serious injury, perform maintenance on the tractor or mower only when the engine is stopped and the parking brake engaged. Always remove the ignition key, disconnect the spark plug wire and fasten it away from the plug before beginning the maintenance, to prevent accidental starting of the engine.

Engage parking brake. Place in OFF position. N ep o ro t fo du r ct io n Parking brake not engaged. PTO electric clutch switch in ON position. Out of fuel. Engine flooded. Fuse blown. Battery terminals require cleaning. Battery discharged or dead. Wiring loose or broken. Solenoid or starter motor faulty.

Safety interlock switch faulty. Spark plug s faulty, fouled or incorrectly gapped. Water in fuel. Gas is old or stale. Recharge or replace. Tighten loose connections. The LCD is used to show both the measurement result and the state indicators of the instrument setting. The LEDs show standby and gating. The LCD has segments that are multiplexed with a ratio of They are connected with a serial I 2 C bus to the microcomputer on the main board.

The clock frequency of the drivers is approximately kHz, set by R Its current consumption is set by the resistors RR The backlight dissipates approximately 1. The front panel pushbuttons are connected in a matrix. The scanning signals H0 to H3 come from the main board. If a push button is pressed and H0 to H3 is high, one of the output signals V0 to V7 will be high. The front unit is fixed to the main board unit with three screws.

The electrical connection is made with a lead flat cable to the main board. Components not necessary for explaining the function are omitted from the figures in this chapter. For the complete set of components, see the circuit diagrams in Chapter 8, Drawings and Diagrams. The input amplifier has MHz bandwidth and is of the split-band type.

It contains four main stages: the signal adaptation stage, the impedance converter stage, the comparator stage, and the buffer stage.

The 50 or 1 M impedance modes are selected by relay K1. Depending on selected attenuation, the 1 M input impedance is determined by different combinations of resistors. In x1 attenuation mode K2 is closed and K3 is open the impedance is determined by resistor network R22 to R In x11 attenuation mode K2 is open and K3 is closed the same network as in the x1 case is involved plus the resistors R3 to R5 and R18 to R The input capacitance in parallel with 1 M is 24 pF at x1 attenuation and 12 pF at x11 attenuation.

The series resistor R1 immediately after the selector serves both as current limiter together with the voltage limiter see below and as impedance matching resistor. The x1 attenuator consists of a resistive low-frequency divider, which reduces the input signal by a factor of 2, and a capacitive high-frequency divider. The capacitive part is formed by the variable capacitor C2 in parallel with RR23, and the parasitic capacitance across RR The capacitive attenuator is adjusted via variable capacitor C2 to the same attenuation value as the resistive attenuator.

The x11 attenuator also consists of a resistive low-frequency divider and a capacitive high-frequency divider. The capacitive divider is formed by the variable capacitor C1 and the parasitic capacitance at the node where R5, R18 and R22 meet. The analog signal from the input stage is fed to an amplifier stage where split-band technique is used to get good frequency response over a wide range.

This means that the high-frequency contents of the signal are fed to a high-impedance AC-coupled FET transistor stage Q1. The low-frequency contents are fed to a DC-coupled operational amplifier stage with negative feedback from the output of the converter stage buffer. The low-frequency path handles frequencies up to approximately 5 kHz.

The high-frequency signal is fed to the gate of Q1. The high impedance at the gate is converted to a low impedance at the source. The source is connected to the base of HF transistor Q2, the summing point for the two signal paths. The low-frequency signal is divided by the two resistors R27 and R28 before it is coupled to the input pin 2 of the operational amplifier U1.

The resistors R37 and R38 at the operational amplifier output pin 6 center the output swing, and capacitor C6 stabilizes the operational amplifier stage.

A voltage limiter that protects the impedance converter against overvoltage is placed between the attenuator and the impedance converter. The voltage limiter consists of resistor R35 and the diodes D1. The low-frequency path goes from the operational amplifier to the base of transistor Q3, the collector of which is connected to the base.

A buffer amplifier with high driving capacity is used to get a linear output in the load resistor R over a swing of 2 V. This amplifier consists of a driver stage Q2, an output stage Q13, and a current generator Q4.

From the output of this second amplifier stage, the signal is fed back to the op amp pin 3 via the divider chain R29 to R The trimmer potentiometer R31 sets the gain of the low-frequency path equal to the high-frequency gain of about 0. Capacitor C5 is connected to operational amplifier pins 1 and 8 to achieve stable operation. The trimmer potentiometer R33 between pins 1 and 5 on the operational amplifier is used for adjusting the offset voltage of the operational amplifier.

The channel A filter connected to the output of the second amplifier stage is a kHz low-pass LC filter. It consists of the coil L1 and the two capacitors C18 and C19 in parallel.

The filter is controlled by the relay K4. The filter output is connected to the input of the comparator stage. The comparator stage converts the analog signal from the impedance converter stage to a square wave.

This circuit consists mainly of the high-speed integrated comparators U8A and U8B plus a separate trigger level circuit connected to the comparators at pins 9 and 13 via resistors R87 and R This covers a dynamic range of 6. The counter is provided with adjustable hysteresis, i. It is connected to the latch enable inputs of the comparator, pin 5 and 7 for Comparator I and pin 17 and 15 for Comparator II.

The buffer is a differential amplifier consisting of the two transistors Q32 and Q33 whose bases are fed differentially from the two comparator outputs.

Resistor R serves as a current generator that is switched alternately to the two collector resistors R and R The trigger level circuits generate the trigger voltage levels to the input comparators. The trigger level range is —3. The input amplifier attenuation is. Input si gnal A. The trigger level circuits generate a DC level that has the same attenuation.

This means that the output of this circuit has a range of —1. A dual 8-bit DAC is used. The supply voltages to the trigger level circuits are filtered by R and C to prevent noise originating in the digital circuitry from influencing the trigger levels.

The ground plane under the trigger level circuits is separated from the rest of the ground plane, and the planes are connected only at the front of the counter. With this arrangement there is a total trigger level range of.

This signal has a range of 0 V to approximately 1. To get exact voltages, 0. The power supply generates four regulated DC supply voltages to the counter, as well as some other supply voltages for special purposes. The main building block of the power supply is a primary switch mode power module U After a line power filter in the power inlet, a fuse of 1.

The fuse F1 should only blow if a catastrophic error occurs on the primary side of the power supply. A short-circuit on the secondary side should not affect the primary side. To minimize the inrush current to the capacitors at the connection of the power cord, an NTC resistor R is used. The resis-. The AC voltage is rectified in the bridge rectifier D9 and filtered in C C65 suppresses noise from D9.

L6 and CC83 serve as a filter at the input of U All inputs and outputs of the power module have HF chokes. The module is mounted with distance washers on the main board. From the module there are three DC voltages outputs. The three DC voltages from the power module are used for generating the following four supply voltages in the counter:.

At stand-by, the four main supply voltages are switched off, but as described above, some parts of the instrument should not be diconnected. Therefore the power module will never be switched off. The PM has consequently only a secondary power switch. It is also possible to open the relay by changing the position of J The inverting output of the flip-flop will be low, disconnecting K5 via Q The inverting output of the flip-flop will be high, engaging K5. Inserting the power cord into the power inlet will cause a pulse on the reset input, via C This is done in remote mode and during RAM-testing.

An NTC resistor, serving as a. There are also analog blocks included in the pin QPF package. The MUX block is a switchboard for incoming and internal signals involved in the measuring process. Some signals are divided by 2 to make it possible to measure higher frequencies.

The trigger slope is controlled by the MUX block as well. These functional units form an essential part of the Auto Trigger System. The oscillator block generates, selects, and distributes the reference clock for the circuit. The active semiconductors of the standard oscillator are included in this block. The crystal is connected to pins X1 and X2. A built-in pulse generator having the 10 MHz clock as a reference can generate pulses with controllable duration and repetition rate at the OUTPUT connector.

The level is fixed TTL.