BK PRECISION Instruction Manual Model 1856C 2.4GHz CounterCc INTRODUCTION ooo. ce ecececcceseeneseeeeeesaneeeeeseseneas P.1 SECTION il SAFETY SUMMARY 0000... eeeeeeseeeseeseeeeeeeeeseneven vee P.2 Sl steng toa CONTROLS AND INDICATORS .........cccesecceeesaeeeeeeees P.3 SPECIFICATION oo... ees eecceccccteeseeeeeeseeeeeeeenvenneess P.8 ECTION V PREPARATION FOR USE oo. eceseeecceeseeeseeseeeeees P.16 SECTION VI OPERATING INSTRUCTIONS [op] cee eee eee n eee eetee eee P.17 ONTENTS SECTION VIII MAINTENANCE AND CALIBRATION ...........00000eceeees P.28 TROUBLESHOOTING... ccecceceeccceraeeeecersaeseee esse P.31 FUSE REPLACEMENT AND VOLTAGE SELECTION...P.37Section I The 2.4GHz Frequency Counter is a highquality, lightweight counter capable of frequency measurements from 5 Hz to 2.4 GHz. The 2.4 GHz Frequency Counter ferature a special 50 0 - terminated input for use in high frequency VHF/UHF /microwave/cellular telephone systems, as well as a standard 1 MQ input for frequency measurements to 100 MHz. The counters utilize an eight-digit display which provides up to 10 Hz resolution to 2.4 GHz (Channel B). 1 Hz resolution to 100 MHz, and 0.1 Hz to 10 MHz (Channel A). In period mode, the unit measures the period required (in microseconds) for one cycle, over the range of 5 Hz to 2M MHz. At low frequencies, much greater accuracy can be achieved by period measurement than by frequency measure- ment. Totalize mode permits counting of individual events. The counting process can be gated, either manually by a front panel switch, or by a gating signal applied to a rear panel jack, for more exact electronic control. Operating mode and one of four decades of resolution are selected by front panel pushbutton switches. Easy-to-interpret readouts are provided by large bright digits, automatic decimal point placement, leading zero blanking, and LED display of proper measurement units. Overrange and GATE function (in- INTRODUCTION dication of a measurement in progress) are also shown on front panel indicators. A front panel HOLD switch is provided which "freezed" the display at the present reading, as well as a RESET button which clears the counter display and initiates a new measure- ment when released. A selectable x 10 attenuator and selectable 100 kHz low- pass filter are incorporated at the standard frequency input jack, for lessened susceptibility to noise and (in low frequency measurements) undesirable high frequency components. The 10 MHz CH.A and. 3.90625MHz CH.B time base is generated by a crystal controlled oscillator for good stability with regard to temperature ( + 10 ppm, 0 C to 40 C ) and Line voltage variution ( + 1 ppm for 10% variation). Other features include universal ac capability, a multi- position carrying handle/tilt stand for portability, and internal RF shielding. The exceptional accuracy, sensitivity, and range of these counters make them extremely valuable instruments for the scientist, engineer, and communications technician.Section II SAFETY Read this manual carefully to ensure your personal safety and to prevent damage either to the instrument or to equipment connected to it. Always operate from a power source that does not apply more than 250 Vrms between protective ground connection, through the grounding condcutor in the power cord, is es- sential for safe operation. To avoid electric shock, plug the power cord into a proper- ly wired receptable where earth ground had been verified by a qualified service person. Due to this unit is grounded through the power cord, do this before making any con- nections to the input terminals of the meters. Make sure that the power cord and the fuse are in good condition before use. When servicing, use only the power cord and fuse specified for the counters. To avoid personal injury, never operate the instrument without the panels or covers. Do not work alone. Trained person should be nearby to render aid if necessary.Section III CONTROLS AND INDICATORS / 6 2 545 (| *) [EXC (RSCUSIOR?? 1856C 2.4GHz COl f Hz, ScMe-2.4GH2 os % ha B 501 wn MAX care a Ha 0005s 0,250: ~~ D5ts 5s co C4 Cc co ea cj (Mit 100M Pe OSH YONHz 10MHz CHA O15 O.ts 4.0 10s Zz a m =o oo RESET HOLD FUNC GATE POWER A 5H2100MHz = ON iMQ ) }) 42Vpk WAX A 40 UW LI U W non So J 8 9 10 1712 13 14 1 Figure 1. Front Panel -~3-CONTROLS AND INDICATORS FRONT PANEL. Refer to Fig. 1. 1. 2. 3. POWER Switch. Turns the unit on and off. Display. Eight-digit display used for all readings. GATE Indicator. ing taken. Lights whenever a measurement is be- kHz/izs Indicator. In kHz Frequency or CHECK mode, indicates that the frequency displayed is in kilohertz. In PERiod mode indicates that the period displayed is in mi- croseconds. Not used in TOTALize mode. MHz Indicator. In MHz Frequency or CH B. (PRESCALE) mode, indicates that the frequency displayed is in mega- hertz. Not used in TOTALize mode. OVERFLOW Indicator. Lights whenever the range of the display is exceeded. One or more most significant digits are not displayed. Channel B Input Jack. Female BNC connector terminat- ed in a 50 ohm input resistance. Channel A Input Jack. Female BNC connector terminat- ed in a 1 megohm input resistance, shunted by < 40 pF capacitance. x10 Attenuator Switch. When this switch is pushed in, 10. 11. 12, 13. -4- the Channel A input is attenuated 10:1 before application to the counter. With the switch released (out), the signal is applied unattenuated. LPF (Low-Pass Filter) Switch. With this switch pushed in, the Channel A input is routed through a low-pass filter with a 30B point of approximately 100 kHz. When it is re- leased (out), the input is applied directly. RESET Switch. In all modes, pushing this momentary switch resets the counter to zero. When it is released, the measurement starts again. HOLD Switch. Functions as follows: a. All modes except TOTALize: Setting this switch to on freezes" the display at the existing reading and resets the counter. Releasing the switch starts a new mea- surement; the display is updated when this measure- ment is completed. b. TOTALize mode: Setting the switch to on "freezes" the display at the existing reading and halts the totalizing process. When the switch is released, counting resumes, provided that the gating signal at the rear panel TO- TALIZE START/STOP INPUT jack (18) is high (or jack is open). FUNCtion Switch. Pushing this momentary switch selects the six counter operating modes and lights the corre-sponding mode indicators as follows: a. KHz Frequency Mode Indicator. When selected, the unit measures the frequency of the signal at the Channei A Input (8). Readings are in kHz as indicated by the KHz/izs indicator (4). Resolution is selected by the GATE switch (14). This mode is automatically se- lected when the counter is powered ON. Note: Guaranteed frequency measurement range in kHz Frequency mode is 5 Hz to 10 MHz (above 10 MHz, display may show zero with no OVERFLOW indica- tion); sine wave sensitivity: 20 mV rms, 5 Hz to 10 MHz. b. MHz Frequency Mode Indicator. When selected, the unit measures the frequency of the signal at the Channel A Input (8). Readings are in MHz as indicated by the MHz indicator (5). Resolution is selected by the GATE switch (14). Note: Guaranteed frequency measurement range in the MHz frequency mode is 5 Hz to 100 MHz. c.CH B (PRESCALE) Frequency Mode Indicator. When selected, the unit measures the frequency of the signal -5- CONTROLS AND INDICATORS at the Channel B Input (7). Readings are in MHz as indicated by the MHz indicator (5). Resolution is select- ed by the GATE switch (14). d.PERiod Mode Indicator. When selected, the unit mea- sures the period of the signal at the Channel A input. Readings are in is as indicated by the kHz/ us _ indi- cator (4). Cycles Averaged; 1, 10, 100, or 1000 are se- lected by the GATE switch (14). e.TOTALize A Mode indicator. When selected, the unit counts cycles of the Channel A input and continuously displays that count. Totalization can be controlled by a gate signal at the rear panel TOTALIZE START/STOP jack (18). . f. CHECK Mode Indicator. When selected, the unit dis- plays the frequency of the internal time base, providing a general check of performance. 14. GATE Switch. Pushing this momentary switch selects the degree of display resolution in all modes except TOTALize as follows; a. 1/0.01s Indicator. When selected, the unit measures kHz or MHz Frequency with a 0.01s Gate Time, CH B Frequency with a.1 Gate Time, and PERiod for one cy- cle between display updates. This Gate Time is auto- matically selected when the unit is powered on. b. 10/0.1s Indicator. When selected, the unit measuresCONTROLS AND INDICATORS kHz or MHz Frequency with a 0.1s Gate Time, CH B Remark Frequency with a 10 Gate Time, and PERiod for 10 cy- For 2.4 GHz connter, Gate switch selections of cles averaging between display updates. 1/10/100/1000 are 25.6ms/256ms/2.56s/25.6s. c.100/1.0s Indicator. When selected, the unit measures kHz or MHz Frequency with a 1.0s Gate Time, CH B Frequency with a 100 Gate Time, and PERiod for 100 cycles averaging between display updates. d.1000/10s Indicator. When selected, the unit measures kHz or MHz Frequency with a 10s Gate Time, CH B Frequency with a 1000s Gate Time, and PERiod for 1000 cycles averaging between display updates. Note: Measuring the PERiod of low frequencies such as 10 Hz with 100 or 1000 cycles averaging will result in extremely long display update times.CONTROLS AND INDICATORS REAR PANEL. Refer to Fig. 2. 45. Fuseholder. 18. TOTALIZE START/STOP INPUT Jack. Input jack used 16. Line Cord Receptacle. : to control the totalization function, if desired. Unit stops to- 17. LINE VOLTAGE SELECT Indicator. Settings allow aa wneneyer ine signal an at this jack goes to a Universal Power Operation: 100/120/220/240 VAC, TL low level (or is connected to chassis ground). 50/60 Hz. 18 16 15 2 CAUTION ALWAYS DISCONNECT POWER CORD BEFORE REMOVING COVER TOTALIZE START/STOP. INPUT O O SV peak MAX OSC ADJUST REPLACE_LINE FUSE_WITH SAME TYPE Gov ( 96V-110V) 0.2004 20 (4 08V-1352V) BAG 20V (1 9BV=242V) 0.1258 ~ 40Y (246V-250V), 12 WATTS. [ EMPLACER PAR UN FUSIBLE DE MEME TYPE 50-60Hz Figure 2. Rear Panel 17 -7-Section IV FUNCTIONS Frequency. 2.4 GHz Frequency Prescaler. 100 MHz Frequency Period. FEATURES 8 Digits, 0.56. Low Pass Filter. Display Hold. SPECIFICATIONS Period Average. Totalize. Check (Self Test). 2-Position Attenuator. Remote Stop-Start. FREQUENCY CHARACTERISTICS Channel A: Channel B: (PRESCALE) 5 Hz to 10 MHz sinewave, kHz mode. 5 Hz to 100 MHz sinewave, MHz mode. 50 MHz to 2.4 GHz (2400 MHz)sinewave. Accuracy: Resolution: Channel A: Channel B: (PRESCALE) Display: + Ax Time base Error +1 count. 0.1 Hz to 100 Hz, kHz mode. 1 Hz to 1000 Hz, MHz mode. 10 Hz to 10kHz. Input signal frequency with decimal point positioned by GATE switch. Units of measurement (kHz, MHz) indicated on front panel by LED indicators and selected by front panel switches. Number of Digits Displayed See Tables 1 and 2. ~-SPECIFICATIONS Number Of Significant Digits Displayed Gate Time 10 SEC 1 SEC 0.1 SEC 0.01SEC Resolution .1 Hz 1 Hz 1 Hz 10 Hz 10 Hz 100 Hz 100 Hz 1000 Hz Function . kHz MHz kHz MHz kHz MHz kHz MHz Typical Frequency 100 MHz 10 MHz 1 MHz 100 kHz 10 kHz 1 kHz 100 Hz 10 Hz 5 Hz i co * | NM OA OO N O +~NOAAADNO =~DYO OA OO NO [= nNoOA MOD NO [-nyuorn aan | [H+NOoOR AON | -+nuonram | [.=-nNoOR OD * = Overflow Table 1. Number of Significant Digits Displayed for Typical Frequencies for Channel A Input and kHz or MHz Frequency Modes.SPECIFICATIONS Number Of Significant Digits Displayed Gate Time 25.6 SEC 2.56 SEC 0.256 SEC 0.0256 SEC Resolution 10 Hz 100 Hz {kHz 10 kHz Typical Frequency 50 MHz 7 6 5 4 150 MHz 8 7 6 5 520 MHz 8 7 6 5 2.4 GHz 8* 8 7 6 *=Overflow Table 2. Number of Significant Digits Displayed for Typical Frequencies for Channel B (PRESCALE) PERIOD CHARACTERISTICS Range: 0.5 us to 200,000 us. Display: us with decimal point. Frequency Range: 5 Hz to 2 MHz sine wave. Minimum Pulse Accuracy: +1 count+Ax time base er- Width: 250 ns. ror + A x trigger error* Number of Digits Resolution: 100 ps to 100 ns, switch se- Displayed: See Table 3. lectable in four decade steps. *Note: Trigger error is typically + 0.3% of reading divided by the number of cycles averaged, for input signals having better than 40 dB S/N ratio and greater than 100 mV amplitude. A: Display reading. ~10-SPECIFICATI ONS Number Of Significant Digits Displayed TOTALIZE CHARACTERISTICS Range: Capacity: Table 3. Number of Significant Digits Displayed for Typical Periods. 5 Hz to 10 MHz sine wave. 0 to 99,999,999 plus over- flow LED. Control: -11- Gate (CHA) 0.015 0.15 1.0s 10s Resolution O.1ps 0.01 us 0.001 us 0.0001 us Typical Corresponding (1 Period (10 Period (100 Period (1000 Period Period Frequency Average) Average) Average) Average) 05s 2 MHz 1 2 3 4 10s 1 MHz 2 3 4 5 10us 100 kHz 3 4 5 6 100 ps 10kHz 4 5 6 7 1000 ps 1 kHz 5 6 7 8 10,000 ps 100 Hz 6 7 8 8* 100,000 ps 10 Hz 7 8 8* 8* 200,000 us 5Hz 7 8 8* 8* *=Overflow Manual reset and hold from the front panel. Normally enabled, except when signal at back panel START/STOP jack is low.SPECIFICATIONS CHANNEL A INPUT CHARACTERISTICS (5Hz to 100 MHz input) Impedance: Connector: Coupling: Sinewave: Sensitivity: Maximum Input: Attenuator: Filter: 4MQ resistance, shunted by 40 pF capacitance. BNC on front panel. AC. 20 mV rms, 5 Hz to 30 MHz. 50 mV rms, 30 MHz to 100 MHz. See Fig 3. x1/x10, switch selectable. Low pass filter, - 3 dB point of 100 kHz, switch se-lectable. PERSCALE INPUT CHARACTERISTICS (50 MHz to 2.4 GHz input ) Impedance: Connector: Coupling: 50 ohms. BNC on front panel. AC. Sinewave Sensitivity: Maximum Input: 10 mV rms, 50 MHz to 600 MHz. 25 mV rms 601 MHz to 1.3 GHz. 50 mV rms, 1301 MHz to 2.4 GHz. 1Vrms. TOTALIZE START/STOP INPUT Logic Levels: Loading: Maximum Input: Standard TTL levels; low level inhibits totalizing, high ievel enables it. One standard TTL gate. 5V DC peak. TIME BASE CHARACTERISTICS (STANDARD): Type: Frequency: Temperature Factor Stability: crystal-controled oscillator 10 MHz.(CH. A) 3.90625MHz(CH.B) < 0,001%(+ 10 ppm from 0 ~40C ambinet) Maximum Aging Rate: + 5 ppm/yr. 12-SPECIFICATIONS 200 150 100 MAX. INPUT VOLTAGE (PEAK ACV & DCV) on Oo 0 100 S00 1K 1M SM 10M 40M 100M FREQUENCY (Hz) Figure 3 Maximum Input Protection Derating Curve. (Channel A input)SPECIFICATIONS DISPLAY CHARACTERISTICS Visual Display: OVERFLOW Indication: Display Update Time: Resolution: Eight 0.56" seven-segment digits with kHz, MHz, us, GATE, and OVERFLOW LED indicators. LED indicator lights when count exceeds 99,999,999 during any selected gate time. 1. KHz and MHz FRE- QUENCY Mode: User selected gate time plus fixed 200 ms interval. 2. Pre-scale Mode: User selected gate time plus fixed 640 ms interval. 3. PERiod Mode: User se- lected cycles averaging plus fixed 200 ms inter- val. 4. TOTALize Mode: Con- tinuous. Selectable in four steps as GATE kHz Time: Period 00is O.1 us 100Hz 0.1s 0.01 ws 10Hz 1.0s 0.001 us = 1Hz 10s 0.0001 s 0.1Hz RESET and HOLD Switches RESET: HOLD: Frequency follows: MHz Frequency Prescale 1000Hz 1OkHz 100Hz 1kHz 10Hz 100Hz 1Hz 10Hz Resets the display to zero. . In FREQUENCY and PERi- od modes, measurement in progress is stopped, and the last complete measure- ment is displayed. When HOLD is released, a new measurement begins. In TOTALize mode, counter is stopped but not reset, and the last count is displayed. When HOLD is released, count continues from where the counter stopped.SPECIFICATIONS GENERAL Power Requirements: 100/120/220/240 VAC (+ 10%), 50/60 Hz: 12w. (at normal line voltage) Dimensions (HxWxD): 267(W)x114(H)x298(D)mm (10.5"x4.5"x11.8") Weight: 2.2kg (4.85 1bs). Temperature and Humidity: Operation: 0 to+ 40 80% R.H. Storage: - 20C to+ 60 S70% R.H. Standard Accessories: Operator's manual, power cord. Optional Accessories: EB-10: 3 feet, 50Q BNC to BNC coaxial cables EB-11: 3 feet, 509 BNC to alligator clip coaxial cables -15-Section V Line Voltage Selection This product is intended to operate from a power source that does not supply more than 250 Vrms between the supply conductors or between either supply conductor and ground. Before connecting the power cord to a power-input source, verify that the line voltage indicator on the rear panel is cor- rected (see Figure 2). Grounding the Equipment A protective ground connection, the third wire in the power cord, is necessary for safe operation. To avoid electrical shock, plug the power cord into a properly wired receptacle before making any connections to the equipment input terminals. Do not remove the ground lug from the power cord for any rea- son. Use only the power cord and connector specified for this equipment. Fuses To avoid fire hazard, use only a fuse of the specified type, voltage rating and current rating for this equipment. See Con- trois, Connectors, and Indicators in Section Ill. PREPARATION FORSection VI PRELIMINARY Numbers in parentheses refer to items in CONTROLS AND INDICATORS" section and Fig 1, and 2. 1. Connect the unit to ac power. 2. Set the POWER switch (1) to on (pushed in). CAUTION 1. Application of input voltages higher than the limits listed in the "SPECIFICATIONS" section may damage the counter. Before applying any signal to the inputs, make certain that it does not exceed these specified maximums. . Engaging the x10 Attenuator switch (9) does not alter these upper limits. . Counter ground points are connected to earth ground through the counters ac power cord. Always connect counter (probe) ground only to ground points or isolated points in the circuit under test. OPERATING INSTRUCTIONS FREQUENCY MEASUREMENTS Using Channel A Input (5 Hz to 100 MHz) 1. Apply the signal to be measured to the Channel A input jack (8). Select measurement units of kHz Frequency with the FUNCtion switch (13). The kHz/us or MHz indicator (4,5) lights accordingly. Note: In kHz mode, maximum guaranteed fre- quency is 10 MHz. Maximum frequency in MHz mode is 100 MHz. Exceeding these ranges may produce unpredictable results, such as a display of zero, with no OVER- FLOW indication. Select the degree of resolution desired, using the GATE switch (14). The actual Gate Times of 0.01s, 0.1s, 1.0s, and 10s are given by the CH A labels below the LED indi- cators. Frequency is given by the display (2). The GATE indicator (3) lights while each measurement is in progress, and theOPERATING INSTRUCTIONS display is updated at the end of each measurement inter- val (when GATE goes off. until the new measurement is completed. 9. Pushing RESET (11) in frequency measurements resets Note: the display to zero. When the button is released, a new . : measurement begins, but the display remains at zero uniil Some measurement delay and display in- : at an; the new measurement is completed. stability may be encountered; see Display . Interpretation". Using Channel B (PRESCALE) input (50 MHz 5. The OVERFLOW indicator (6) lights whenever the range of 2.4 GHz) the display is exceeded. 1. Apply the signal to be measured to the Channel B 6. If necessary, engage the x10 Attenuator switch (9). When (PRESCALE) input jack (7). set to x10 (pushed in), this switch attenuates the Channel Lv CAUTION A signal by a factor of approximately 10 before application The maximum input limit to this jack is 1.5V to the counter. This helps prevent mis-counting caused by : . noisy or improperly terminated high-amplitude signals rms maximum over the input frequency y Properly 9 P gnals. range. The input impedance is 50 ohms. 7. \f necessary, engage the LPF (Low-Pass Filter) switch (10). 2. Engage the CH B (PRESCALE) Frequency mode with the This routes the Channel A input through a low-pass filter ( 3 dB frequency of approximately 100 kHz) before application to the counter. This helps eliminate counting 3. errors in low frequency measurements by minimizing ef- fects of high-frequency noise present on the input. 8. Engaging the HOLD switch (12) during frequency mea- 4. surements causes the display to freeze" at the existing reading. When HOLD is released, a new measurement begins, but the display continues to hold the old reading FUNCtion switch (13). Select the degree of resolution desired, using the GATE switch (14). The actual Gate Times of 1, 10, 100 and 1000 are given by the CH B labels above the LED indicators. Frequency is given by the display (2). The GATE indicator (3) lights while each measurement is in progress, and the display is updated at the end of each measurement inter- val (when GATE goes off).OPERATING INSTRUCTIONS Note: 1. Some measurement delay and display in- stability may be encountered; see "Display 2. Interpretation". 5. The OVERFLOW indicator (6) lights whenever the range of the display exceeded. 3. 6. Engaging the HOLD switch (12) during frequency mea- surements causes the display to freeze" at the existing reading. When HOLD is releassed, a new measurement begins, but the display continues to hold the old reading 4. until the new measurement completed. 7. Pushing RESET (11) in frequency measurements resets the display to zero. When the button is released, a new measurement begins, but the display remains at zero until the new measurement is completed. 8. The x10 Attenuator and LPF switches (9,10) have no effect in CH B (PRESCALE) Frequency mode. PERIOD MEASUREMENTS In period mode, the unit displays the period, or time re- quired for one cycle of the input signal to occur. The actual measurement is made by averaging over 1, 10, 100, or 1000 6. cycles. Maximum frequency is 3.5 MHz. Apply the signal to be measured to the Channel A input jack (8). Engage the PERiod mode with the FUNCtion switch (13). The kHz/xs indicator (4) lights to indicate that readings are in microseconds. Select the degree of resolution desired, using the GATE switch (14). (The GATE switch determines how many cy- cles are averaged in the measurement: 1, 10 100, or 1000, respectively, from left to right.) Period is given by the display (2). The GATE indicator (3) lights while each measurement is in progress, and the display is updated at the end of each measurement inter- val (when GATE goes off}. (At higher frequencies, the GATE indicator may flash too quickly to be seen). Note: Some measurement delay and display in- stability may be encountered; see "Display Interpretation. The OVERFLOW indicator (6) lights whenever the range of the display is exceeded. lf necessary, engage the x10 Attenuator switch (9). When set to x10 (pushed in), this switch attenuates the ChannelOPERATING INSTRUCTIONS A signal by a factor of approximately 10 before application to the counter. This helps prevent mis-counting caused by noisy or improperly terminated high-amplitude signals. 7. If necessary, engage the LPF (Low-pass Filter) switch (10). This routes the Channel A input through: a low-pass filter ( 3 dB frequency of approximately 100 kHz) before application to the counter. This helps eliminate counting errors in low frequency measurements by minimizing ef- fects of high-frequency noise present on the input. 8. Engaging the HOLD switch (12) during period measure- ments causes the display to "freeze" at the existing read- ing. When HOLD is released, a new measurement begins, but the display continues to hold the old reading until the new measurement is completed. 9. Pushing RESET (11) in period measurements resets the display to zero. When the button is released, a new mea- surement begins, but the display remains at zero until the new measurement completed. TOTALIZE MEASUREMENTS The TOTALize mode is used to count the total number of events occurring during a specific time period. This time period can be defined manually by front panel switch action, or for better accuracy, by a gating signal applied to the rear panel. Because of capacitive coupling of the counter input, events should occur at least five times per second for accurate count- ing. Maximum frequency is 10 MHz. 1. Engage the TOTALize mode with the FUNCtion switch (13). Any GATE (14) setting is ignored. If the counting is to be controlled electronically, connect the gating signal to the rear panel TOTALIZE START/STOP jack. A TTL high at this input enables the totalizing process; a TTL low disables it, holding the dis- play at the accumulated value. If no signal is connected, the jack is pulled high internally so counting occurs. Depress the RESET switch (11) to zero the counter. If no gating signal is connected to the TOTALIZE START/STOP jack, the unit starts counting as soon as the RESET switch is released. If a gating signal is connected, counting starts when RESET is released and the gating signal goes high. As the unit totalizes, it displays the count continually. Max- imum count is 99,999,999. If this is exceeded, the OVER- FLOW indicator (6) lights, and the count continues. Counting is halted by one of three methods: a. If the gating signal at the TOTALIZE START/STOP jack goes low, countifg stops and the display is held at the accumulated total. Counting resumes when the gatingOPERATIN G IN! STRUCTIONS signal again goes high. b. If the HOLD switch (12) is engaged, counting stops and the display is held at the accumulated total. Counting one {ec Gc De resumes when the switch released. FLOW nia te c. Pressing RESET (11) at any time clears the counter and GATE xt resets the display to zero. a. kHz Frequency/PERiod display. 6. If necessary, engage the x10 Attenuator switch (9). When set to x10 (pushed in), this switch attenuates the Channel e/ | wie xt A signal by a factor of approximately 10 before application pon ( fe itte/ue @ to the counter. This helps prevent mis-counting caused by _t noisy or improperly terminated high-amplitude signals. ee = J) OnE xt b. MHz F display. 7. If necessary, engage the LPF (Low-Pass Filter) switch (10). z Frequency display This routes the Channel A input through a low-pass filter et , ie 4 {3 dB frequency of approximately 100 KHz) before ap- OVER ( Lf Fe Tq plication to the counter. This helps eliminate counting er- FLOW ( ( _l KtHz/us @ rors in low frequency measurements by minimizing effects . of high-frequency noise present on the input. DISPLAY INTERPRETATION e _ | MHz @ Display Formats OVER ( tl I Sample displays are given in Fig. 4. in Fig. 4, a value of FLOW g te/m @ 1234.567 is displayed, and the kHz/us indicator is lit. This may GATE. xt represent either a frequency or a period reading; a glance at the mode switches indicates which is correct. c. CHB (PERSCALE) Frequency display. d. TOTALize display. Figure 4. Samples of Various Displays.OP. ERATING INSTRUCTIONS Assuming that Fig. 4 represents a frequency reading, the resolution displayed is .001 KHz, or 1 Hz;. If the MHz Fre- quency mode is engaged with the FUNCtion switch, leaving all else unchanged, the display changes to that of Fig. 4. This is the same frequency as in Fig. 4, but given in megahertz. Note that the resolution is now .00001 MHz, or 10 Hz, even though a different Gate Time was not selected with the GATE switch. The display resolutions vary with the FUNCtion and GATE se- lections. The frequency displays of Fig. 4 and b are obtained by en- gaging the 1.0s Gate Time with the GATE switch. A typical Channel B (PRESCALE) reading using this same Gate Time setting is shown in Fig. 4. Note that the resolution is now .0001 MHz, or 100 Hz. Fig. 4 gives a typical totalize display. Totalizations have no units, and are always integers (no digits to right of decimal point). At higher totalizing frequencies, the least significant dis- play digits tend to fade due to their rapid rate of change. Display Instability An uncertainty of +1 least significant digit is inherent in all digital measurements. However, greater display uncertainties can result from other factors, as follows: Noise or ringing on the input can cause false triggering. In some cases the display may be unstable, whereas in others it may appear stabie but at an incorrect reading. For Channel A measurements, this type of error can be reduced by using the attenuator and filter. Similar errors introduced by standing waves may be avoided by using proper terminations and cable lengths when appropriate. The Channel B (PRESCALE) input jack is provided with an internal 50 termmination, to void standing wave difficulties for measurements in 50 () systems. Uncertainty may be introduced by instability of the input frequency. This is common with LC oscillators; crystal- controlled oscillators are much more stable. In period measurements, uncertainty is introduced by trigger error (see "SPECIFICATIONS'). This uncertainty can be re- duced by taking the measurement over a greater number of cycles. Period and frequency are reciprocals of each other. At low frequencies, more digits can be obtained (lessening the effects of instability} using period mode. Similarly, high frequency accuracy is enhanced by using frequency mode. The "crossover" point between the two modes is 10 kHz.OPERATING INSTRUCTIONS Measurement Delays FUNCtion| GATE Time Display in all measurements (except totalize), the display is updated mode setting Resolution at the end of a finite measurement interval. The GATE indicator kHz 0.01s 100 Hz lights during this interval, which varies in length according to kHz 0.18 10 Hz operating mode and resolution selected. For some conditions, the delay can become significant. This should be kept in mind kHz 1.0s 1 Hz when changing resolution or operating mode, or when using kHz 10s 0.1 Hz HOLD or RESET, because each of these actions initiates a MHz 0.01s 1 kHz new measurement. Measurement delays for each mode are discussed here. MHz 0.1s 100 Hz MHz 1.0s 10 Hz Frequency MHz 10s 1 Hz In frequency measurements, each GATE setting establishes CH B 0.0256s 10 kHz a set time during which the measurement is made and results CHB 0.256s 1 kHz in a different display resolution. Gate Times settings for kHz, CHB 256s 100 Hz MHz. and CH B (PRESCALE). Frequency modes and their re- sulting display resolutions are as follows: CHB 25.6s 10 Hz Table 4. Gate time and measurement resolution in Frequency mode.OPERATING INSTRUCTIONS As observed in the table, smaller GATE Times result in lower resolutions. They are useful when quicker updates are desired, for example, while tuning an oscillator. Better resolutions require longer update intervals. Period Period measurements are made by averaging over a set number of cycles. That number is determined by the GATE switch as follows: GATE Number of Setting cycles averaged 0.0256/0.01s 1 0.256/0.1s 10 2.56/1.0s 100 25.6/10s 1000 The time required for a period measurement to be completed can be found by the formula: Number of Average Time = cycles x cycle averaged length Where time units are same (seconds, milliseconds, etc.) on both sides. For a constant input frequency this is: . Number of cycles averaged Time = Input frequency (Hz) Note that two GATE switch settings select 100 and 1000 cycle averaging. Because of this, significant delays may occur between display updates at low frequencies. Inter-Measurement Interval The inter-Measurement interval is fixed at 200 milliseconds in all modes except CH B (PRESCALE) and TOTALize. In CH B mode it is 640 ms, and in TOTALize, counting is continuous. This fixed interval is independent of gate time, number of cycles, or input frequency. GENERAL CONSIDERATIONS Use of Attenuator Probes Channel A input resistance (1M) and input capacitance (40 pF max) are independent of the x10 Attenuator switch. To decrease loading, a high- impedance oscilloscope probe may be used with Channel A. ~24-Note: When using a 10:1 probe make certain that the signal amplitude is large enough to provide at least the minimum required signal to the counter after probe attenuation (see "Channel A Sensitivity" in "SPECIFICATIONS). Note: Do not use a 10:1 probe with the CH B (PRESCALE) input. The probe is designed for 10:1 attenuation with a counter input resistance of 1 MQ). The 50 Q termination of the CH B jack would result in unacceptably high (180,001/1) attenuation. Cable Considerations Accuracy of radio frequency measurements can be affected by connections between signal source and counter. Main con- siderations are standing waves and shunt cable capacitance. Standing waves are usually present due to reflections when a transission line is not terminated in its characteristic impedance. These standing waves may cause damage to the signal source or produce inaccurate measurements, and their effects increase as cable length reaches onefourth of the wave- OPERATING INSTRUCTIONS length for the frequency being measured. Standing waves can be minimized by keeping cable lengths shout, and, more importantly, providing a proper termination. The cable's characteristic impedance and the terminating impedance should match the source impedance. For example, for a source impedance of 50 ohms, use 50 ohm coaxial cable terminated with a 50 ohm resistive load. Use a de blocking capacitor in situations where bias voltage or other dc voltages could be affected by the termination resistor. Shunt cable capacitance, which can cause undesirable sig- nal attenuation, increases with increased cable length. It is recommended that for radio frequency measurements, the ca- ble be no longer than three feet (90 cm), to keep shunt capac- itance within acceptable limits. in 50 systems the internal 50 Q) input terminzation of the CH B (PRESCALE) jack minimizes reflections and the resulting standing waves. Thus, the need for an external termination is eliminated. Also, shunt capacitance has a much lesser effect at this jack then at the Channei A input, and the above restriction on cable tength is reduced. However, CH B measurements must always be taken from a 50 point in the circuit under test.OPERATING INSTRUCTIONS FUNCtion or GATE Time Changes When switching gate times or function modes, note that such a change initiates a new measurement; the display is not updated until the new measurement is completed. Even though the decimal point and leading zeroes are adjusted im- mediately, appearance of the correct value may be significantly delayed depending on measurement interval (see "Display In- terpretation - Measurement Delays"). Line Frequency Measurement WARNING Use caution in measuring the line frequency of an ac outlet. Using the probe tip only, measure both sides of the line. The ground side will give a zero reading and the hot side will provide the desired measurement. Do not use the ground lead of the probe. Remember that the chassis of the counter and the ground lead of the probe are already at earth ground (via the 3- wire power cord of the instrument). Touching the ground" lead to the "hot" side of the line would place a direct short on the power line through the probe cablbe, resulting in possible injury and damage to the probe cable. Use of the attenuator, filter, and/or a x10 probe is advisable when measuring line frequency, because of the high amplitude signal, and because noise is usually present and can cause mis-counting. CHECK (SELF TEST) The CHECK mode provides a quick, general self test of in- strument operation. 1, Engage the CHECK Mode with the FUNCtion switch (13). This connects the counter input internally to the time base oscillator. 2. Engage each GATE Time Mode with the GATE switch (14) and check that the results match the following: GATE Ddisplay setting* reads 0.01s 10000.0 kHz 0.1s 10000.00 kHz 1.0s 10000.000 kHz 10s 0000.0000 kHz, OVERFLOW litOPERATING INSTRUCTIONS 3. Pressing the HOLD switch (12) should hold the display value and keep the GATE indicator off for as long as the button is pushed in. When HOLD is disengaged, GATE should resume flashing. (If a new GATE Time has been selected, the display is updated to its proper value after the first GATE interval. 4. Pressing the RESET switch (11) should clear the display. The GATE indicator should stay off as long as RESET is pushed. Upon release of the button, GATE should resume flashing and the display should be updated at the end of the first GATE interval. *GATE indicator lights during this interval; time between measurement is 200 ms.Section VIII A WARNING The follwing instructions are for use by qualified personnel only. To avoid elec- trical shock, do not perform any servic- ing other than contained in the operating instructions unless you are qualified to do so. FUSE REPLACEMENT If the primary line fuse FS5 blows, the display and the FUNCtion or GATE LED indicators will not light and the counter will not operate. The fuse should not normally open unless a problem has developed in the unit. Try to determine and correct the cause of the blown fuse, then replace only with a fuse of the correct rating. For 100 or 120 V operation a 0.2 A, 250 V, 3AG fuse should be used and for 220 or 240 V operation a 0.1A, 250 V, 3AG fuse shouid be used. The prima- ry line fuse, FS5, is located on the rear panel (see Fig. 2). lf replacement of the primary line fuse does not alleviate the problem, then one of the four transformer secondary fuses, FS1/FS2/FS3/FS4, may be open. The four fuses are located MAINTENANCE AND CALIBRATION on the main circuit board (see Fig. 11). Replace only with a 0.5A, 125 V or 250 V 5x20 mm for each. LINE VOLTAGE CONVERSION The primary winding of the power trnasformer is tapped to permit operation from 100, 120, 220, or 240 VAC, 50/60 Hz line voltage. Conversion from one line voltage to another is done by simply replacing the fuse holder with voltage selector located on the rear panel (see Fig. 2-12). To convent to a different line voltage, perform the following procedure: 1. Make sure the power cord is unplugged. 2. Reset the Fuse holder with voltage selector for the desired line voltage as shown on the rear panel. 3. A change in line voltage may also require a corresponding change of fuse value. Install the correct fuse value as list- ed in the FUSE REPLACEMENT section.MAINTENANCE ADJUSTMENTS This unit was accurately adjusted at the factory before shipment. Readjustement is recommended only if repairs have been made in a circuit affecting adjustment accuracy, or if you have a reason to believe the unit is out of adjustment. However, adjustments should be attempted only if the follwing equipment is available: 1. 10MHz Standard with an accuracy of at least + 0.1 PPM (1 x 107) and an output level of at least 100 mV rms. 2. RF Generator (Wavetek 3001 or equivalent). 3. RF Millivoltmeter (Booton 92BD or equivalent). The following adjustments require the removal of the case top; unplug the power cord, turn the unit over and remove the four Phillips screws, two holding the rear rubber feet and the two next to the front rubber feet. Locations of the electrical adjustments are shown in Fig. 11. ADJUSTMENT FUNCTION OF ADJUSTMENT SVR1 Channel A Sensitivity SVR2 Totalize Sensitivity . Sj Sa So FS3 @svr2- U2 SVR1 POWER SWITCH S7 we ZS Figure 11 Main board Adjustments, Component SideTime Base Adjustment This adjustment should be performed after a one hour warmup with the top case on but not screwed down, allowing the heat rise inside the unit to stablize. The top case is then lifted off and the adjustment made. 1. 2. Set the unit for KHz mode with the FUNC switch and 1.0s Gate Time with the GATE switch. Connect the 10 MHz standard frequency source to Channel A Input. . Using a small non-metallic slotted screwdriver, adjudt the trimmer SC1 for a reading of 10000.000 + 1 Hz on the unit display. . Set the unit for CH.B mode with the FUNC switch and 2.56s Gate Time with the GATE switch. . Connect the 1000MHz standard frequency source to channel B input. . Using a small non-metallic soltted screwdriver, adjust the trimmer SC2 for a reading of 1000;0000 + 100Hz on the unit display. Channel A Sensitivity Adjustments 1. Set the unit to MHz mode with the FUNC switch and 0.01s Gate time with the GATE switch. . Connect the RF Generator and the RF Millivoltmeter with a BNC Tee to the Channel A Input. Set the RF Generator frequency output to read 100.000 MHz and set its level for a reading of 50 mV rms on the RF Millivoltmeter. The counter display should read 100.000 + 1 count. . Slowly decrease the RF Generator output level until the counters least significant digit varies by more than 3 counts. The counter will typically start to read lower. . Adjust the Channel A Sensitivity Trimmer SVR1 (through the hole in the metal sheild) so that the counter display reads 100.000 MHz + 1 count. . Repeat steps 3 and 4 until trimmer SVR1 no longer can give a stable 100.000 MHz + 1 count on the display. The typical range of the RF level required would be approximately 20 mV to 30 mV rms. TOTALIZE Adjustments 1. Set the unit for TOTAL mode with the FUNC switch. 2. Connect the RF Generator and RF Millivoltmeter with a BNC Tee to the Channel A Input. Set the RF Generator frequency output to 10.000 MHz and its level for a reading of 35 mV rms on the RF Millivoltmeter. 3. Adjust Trimmer SVR2 until the display just starts to change the second digit from the left. MAINTENANCE AND CALIBRATIONSection IX The following troubleshooting steps provide a logical proce- dure for fault isolation. If the procedure cannot, of course, guarantee to pinpoint every possible problem, it will in most cases localize the problem to a certain area. Most of these troubleshooting steps require removal of the top cover as described previously. General Fault Isolation 1. Performance test Test each operating mode by applying an appropriate signal to Channel A and Channel B as di- rected in Table 4. Frequency accuracy of the signal isnt critical, but amplitude should be adequate to produce sta- ble readings (use caution not to exceed the maximum Channel B input ratings). On Channel A, the filter, and/or attenuator may be used to stabilize the reading. 2. Fault Isolation Proceed as follows according to the re- sults of the test: a. if no display can be obtained at all, follow the proce- dure for "No Display. b. If display shows abnormalities such as missing decimal points or unlit segments or digits, follow the procedure for Abnormal Display". . If display appears nomal, but value is incorrect or un- stable (in Channel B, Channel A, or both), follow the procedure for Incorrect or Unstable Display Value". . !f problem is not adequately described by any of the above, start at "No Display" and proceed through each step until the difficulty is isolated.TROUBLESHOOTING Table 5 Operational Test Input wperation RESOLU- normal (Ideal) Input Operation |RESOLU- | Normal (Ideal) Frequency ; Mode splay Frequency | Mode TION Display 10 kHz FREQUENCY) 100 Hz io Less than 0001 #SEC | over lit *** kHz 10 Hz 10.00 100 H PERlod 1 Hz 10.000 00 Hz Hz 10.0000 ** To KAZ FREQUENCY| 1 KHz 010 NOTE: MHz 100 Hz .0100 * ;Measurement delay of 10 seconds. 10 Hz -01000 . ** :Measurement delay of 25.6 seconds. 1 Hz 010000 *** :Measurement delay of at least ten seconds. 100 MHz FREQUENCY] 10 kHz 100.00 CH B 1 kHz 400.000 100 Hz 100.0000 10 Hz 100.00000 ** 10 kHz PERiod 1 HSEC 100.0 01 HSEC 100.00 001 HSEC 100.000 0001 HSEC | 100.0000 10 kHz TOTALize not Display a accumu- : applicable. lates, with fifth digit from right changing at approximately 1 Hz. not 100 Hz 10000.0 required CHECK 10 Hz 10000.00 input 1 Hz 10000.000 Hz 0000.0000* over litTROUBLESHOOTING NO Display. 1. Check supply voltage at U2 pin 25 for approximately 3. +5 volts. If this voltage isnt present, check ac input, fuse and + 5V (VA) power supply circuit (D17, D18, C31,UP1)}. Otherwise proceed to Abnormal Display. Abnormal Display. 4. 1. Digit Strobes and time base Set the unit to any operating mode and check for the digit strobe waveforms of page 8 at U2 pins 22-24 and 26-30. If 9. these are normal, proceed to step 2. If not, check the output of the time base oscillator at pin 38 for a waveform of frequency 10 MHz and peaks of 0 and 2.4 V. if normal, check U2 and display digits; if no output is obtained, check oscillator components, U2 and + 5V (VCC) power supply (D19, D20, C35, UP2). 2. Display test Enable display self-test by connect U2 pins 1 and 22 to each other via a 1ss355 diode { anode to pin 22 ). Display should be all eights with all decimal points and OVERFLOW indicator on. If not, 7 check displays and U2 segment driver pins 8-11 and 13 - 16. Waveform at each of these pins should approximate a dc level of about 1.0 V, with negative spikes of about 4 kHz. Waveforms shown are with display digits connected. Decimal points If the problem involves decimal points in MHz or Channel B modes, check the mode selection logic as in step 5 of Incorrect or Unstable Display Value. MHz or kHz/ SEC indicators For problems involving these (D24, D25), check the mode selection logic as in Incorrect or Unstable Display Value, step 5. GATE indicator If the GATE indicator, D26, does not function properly, check D26, Display U7 and U2 pin 3. D26 is connected via Display U7 to pin 3, which goes low whenever a measurement is being taken. (If this pin shows no activity, check for proper mode selection as in Incorrect or Unstable Display Value, step 5). Function indicator If the Function indicators kHz, MHz, CH B, PER, TOTALize, and CHECK square LEDs, does not function properly, check LED1-LED6, U5 and U2. . Gate time indicator lf the Gate time indicator .01/ 0.0256s, .1/0.256s, 1/2.56s, and 10/25.6s square LEDs does not function properly, check LED7-LED10, U11 and U12.incorrect or Unstable Display Value. 1. Half-splitting: Channel A Apply an appropriate signal to Channel A and check the waveform at the collector of Q4. Waveform should be a square wave (0-2.8V) of same frequency and polarity as the Channel A input signal. If the waveform is normal, proceed step 3; otherwise, check for a problem in the Channel A analog circuitry; see the next step. . Channel A analog circuits Table gives waveforms for the Channel A input buffer and signal shaping circuits, along with input conditions required for obtaining them. The order of table entries is from input to output, permitting either sequential or half-splitting trouble- shooting techniques, as desired by the user. . Half-splitting: Channel B Apply an appropriate signal to the Channel A jack. Check the output of the ECL-to- TTL converter, collector of Q7.A TTL level waveform should be observed; its frequency should be 1/320 of input frequency. Note that because of the high frequency, shape irregularities in this waveform can be expected, If the waveform is correct, proceed to step 5. If not, check the Channel B circuits. 4. Channel B input amplifier With signal still applied at the Channel! B input, check for presence of signal at the input of IC4, and the output of Q7 and Q8. If not detected, check IC5A, IC5, A IC4 and associated TROUBLESHOOTING components. Table 6 Channel a analog circuit waveform Test Point Waveform (See Note 1 next page) A. Gate of Q1. Identical to input. B. Gate of Q1, but with 1/10 amplitude of input. ATTEN set to x10. C. Source of Q1 Connect- |1Vp-p, 10 kHz sine wave ion point of C7, C9, C10, |centered at + 1.3V.(see Note 2 R8. next page) D. U1 pin 10. 1Vp-p, 10 kHz sine wave centered at + 3.8V. E. U1 ping, 11. DC level of + 3.8V. F. U1 pin 4 or 7. 1Vp-p, 10 kHz rounded square wave centered at + 3.8V. G. U1 pin 5 or 6. Same as F, but inverted. H. U1 pin 3 or 12. Same as F, with squarer edges. 1. U1 pin 2. Same as H, but inverted. J. U1 pin 13. 0.7Vp-p, 10 kHz square wave centered at + 3.8V. K. U1 pin 15, or base of Q3.|1Vp-p, 10 kHz square wave centered at + 3.8V. L. U1 pin 14, or base of Q4.|Same as K, but inverted.TROUBLESHOOTING 7. Channel A/Channel B Select a. See table 8 for reference. 8. Reset Check that all readings are cleared to zero when RESET switch is pushed. If not, check $4. Table 8 Check of Function Logic Function Engaged] Test Points | Waveform PERiod U2 pin 4 U2 strobe D8 (pin 22). U7 pin 11,12 |Logic high. D25 Lit. U10 pin 7 Logic high. TOTALize U2 pin 4 U2 strobe D4 (pin 27). U7 pin6 U10 pin 10 [Logic high. CHECK U2 pin 4 U2 strobe D3 (pin 28). U7 pin13 JLogic high. U10 pin 1 Logic high. Either U7 pin6 Logic high. Frequency MHz or |D24 Lit. Frequency CHB__|U14 pin6 Logic high. Function Engaged |Test Points | Waveform Frequency kHz U2 pin 4 U2 strobe D1 (pin 30). U7 pin 1,3 Logic high. D25 Lit. U10 pin 3 Logic high. Frequency MHz U2 pin 4 U2 strobe D1 (pin 30). U14 pin 5 Logic high. U14 pin 3 Same as U9 pin 4 (U2 digit U2 pin 20 strobe selected by Gate switch, see Tabie 3). U7 pin4 Logic high. U10 pin 2 Logic high(see other entries for U7 pin 6). Frequency CH B U2 pin 4 U2 strobe D1 (pin 30). U14 pin 12,13 |Logic high. U14 pin 2 Same as U14 pin 1 (u2 U2 pin 20 digit strobe selected by Gate switch, see Tabie 3). U14 pin 9,10 |See last entry in this table. U7 pind Logic high. U7 pin6 Logic high (see other entries for U7 pin 6). U10 pin 4 Logic high.Section X FUSE REPLACEMENT AND VOLTAGE SELECTION This instrument is the universal line voltage operation; 100V, 3. 120V, 220V and 240V. The below is explaining the user how to replace fuse. 1. Extract the fuse drawer from the AC socket with the aid of a screwdriver (The extra safe fuse drawer can only be extract. 4. ed with the aid of a tool. Eg. screwdriver.) 2. Only then the fuse holder with voltage selector can be re- moved from the fuse holder. \ J (A) AC. Socket. Figrue 12-1. Fuse replacement and voltage selection Pull out the fuse link from the fuse holder with voltage selec- tor and then replace a new fuse rated voltage in accordance with specific required fuse or select the voltage according to the user's local line source. When finish the replacement, install the equipments follow up as figured steps D,C and B. The equipments can be eas- ily installed by hands. a (D) Fuse link op (C) Fuse Holder with voltage selector (B) Fuse drawer Figure 12-2. Fuse replacement and voltage selectionLIST OF FIGURES AND TABLES Resolution in Frequency mode. ....5ee Page23 See Page32 Curve. (Channel A !nput).......... See Page13 Table 6. Channel A analog circuit waveform ..See Page34 See Page35 See Page36 Figure 1. Front Panel ..............0.:0c0ee sees See Page 4 Table 4. Gate time and Measurement Figure 2. Rear Panel .............:.:cceceeee ees See Page 7 Figure 3. Maximum Input Protection Derating Table 5. Operational test Figure 4. Samples of Various Display....... See Page21 Table 7. Check of different gate time Figure 11.Main board Adjustments, Component Table 8. Check of Function logic Side View. occ ceeceseeeeeeeee ee ees See Page29 Figure 12-1,12-2. Fuse Replacement and Voltage selection................00. See Page37 Table 1. Number of Significant Digit Displayed for Typical Frequencies for Channel A Input and kHz or MHz Frequency Mode ......... 0c ccc ceee eset eee eee ne ees See Page9 Table 2. Number of Significant Digits Displayed for Typical Frequencies for Channel! B (PRESCALE) Input and CH B Frequency Mode. ...........:eeeeeee See Page10 Table 3. Number of Significant Digits Displayed For Typical Periods. .............06.- See Page11