CUSTCHK.TXT Calibration Checklist for PSA-65C(E) EDITED 11-3-03 by Scott R. Kelly EQUIPMENT NEEDED... A tuneable RF Calibrated Signal Source with a 60dB by 10dB step attenuator. Adjustable 50 watt, 12V DC power supply, Ext. DC plug, (mate for DC jack). PRELIMINARY SETTINGS and OBSERVATIONS..... STBY LED should be lit whenever unit is plugged in and in the off position. Verify the 2dB/10dB toggle SWITCH is in the 10dB/Division position. Turn the DETENT SPAN SWITCH to 125 MHz/DIV. INTENSITY postioned 12 o'clock. Turn VARIABLE SPAN (VAR-SPAN) full clock-wise. REF LEVEL to 0 dBm position. > Check INT/EXT Power source input & POWER SWITCH, in BATT position. Select EXTernal DC Power input with rear panel INT\EXT switch. Apply external variable DC power via EXT. DC jack (center pin positive). External variable voltage set at 12.0 VDC nominal. Check for normal oper. Maximum allowable dropout voltage is 11.70 volts at the EXT DC input. DC Fuse should be AGC-4, 4 Amp or equivalent. > ( at turn-on ) Check SIGN-ON, LCD BACKLIGHTING, and LCD CONTRAST... Watch 2-line LIQUID CRYSTAL DISPLAY (LCD), & flash of LOCK LED A dark bar appears across top row first, with the entire LCD backlit. Then, (example) "PSA-65C ver. 2.1" above, "(c) 2000 AVCOM" below. Then the CENTER FREQUENCY (CF) and SPAN are displayed on the top line, and the START and STOP frequencies are displayed below, if the span is narrow. The CF "tenths" come on when the CF is stable. Typically blank when tuning. The FREQUENCY LOCK LED should also flash on momentarily. (depends on Span) Check that the DISPLAY CONTRAST varies the darkness of writing on the LCD. Also check that LCD is backlit with a green glow. > FRONT PANEL CONTROLS... Baseline trace should be visable on the CRT screen. Turn VERTICAL CONTROL to move the baseline around the -65dBm tic-marks. Turn the CENTER FREQUENCY TUNING CONTROL (CF TUNE), to position the ZERO SPIKE into the viewable area. Verify normal operation of the SWEEP RATE CONTROL (SWEEP). Fast sweep rate in clock-wise position and visa versa. > INTERNAL BATTERY LOAD TEST..... Disconnect external supply, and slide switch to INTernal position. (Unit should have gone off when external plug was pulled, and back on again when switch was put in INTernal position.) Read Battery voltage with BATT CHG switch ON, unit unplugged from line. Reading = 12.0 volts nominal. ( readout is seen on the LCD display ) > BATTERY CHARGING..... Plug into AC line power and turn unit ON in LINE position. Check Battery Charging circuit, when BATT CHG switch is turned on. An increasing voltage should be seen on LCD, nominally 12 to 14 volts. Verify normal ON-OFF operation of BATT CHG switch & LED. > Check INTENSITY CONTROL, clock-wise rotation increases intensity, visa-versa > Check HORIZONTAL ( 13 division ) OVERSWEEP... Turn CF TUNING to set ZERO SPIKE, 6 & 1\2 divisions from both ends of trace. (Use HORIZ to move alternate trace ends into view.) Next turn HORIZ (not CF TUNING) to move ZERO SPIKE to center of graticule. > Checking HORIZONTAL CALIBRATION of GRATICULE..... Turn REFERENCE LEVEL SWITCH (REF LEVEL) to 0dBm. Turn SPAN to 50MHz / Division. CF tune to about 250 MHz. Turn VAR-SPAN to the CAL position. (Full span is clock-wise, CAL position.) Connect the RF source to the RF INPUT, and set a 500 MHz signal for, -30dbm. Check that the ZERO SPIKE and 500 MHz signal are 10 divisions apart. Turn CF TUNING, to move ZERO SPIKE, and signal into viewable area. Toggle ZERO SPAN SWITCH to (ZERO SPAN) AUDIO position. Observe LCD (Digital Display) increase, while turning CF TUNING clock-wise. Stop at reading around 770 MHz. Toggle ZERO SPAN SWITCH to NORMal position. Turn CF TUNING to move the 500MHz signal to the start of the graticule. Verify RF input signal change, to 1000MHz(1Ghz),shows signal at last div. Due to non-linearity the begining 500MHz is typically less than 10 divs. This is OK since the VAR-SPAN can widen the displayed frequencies. Turn the DETENT SPAN SWITCH to 125 MHz/DIV. Inject a 1250 MHz RF signal. Check that the ZERO SPIKE and 1250 MHz signal are 10 divisions apart. Turn CF TUNING as required to keep ZERO SPIKE, and signal in viewable area. NOTE-last 250MHz is typically streached out, 8div @ 50MHz/div. ACCEPTABLE. > DIGITAL LCD and FREQUENCY COUNTER..... (Battery charging OFF) Turn (detent) SPAN to 50MHz / Division. Turn VAR-SPAN to 20 MHz/div. Continue to tune, up to upper extream, while watching counters for smooth operation, and that there are no LCD segements missing. Continue increasing CF TUNING, LCD readings, to the stop of CF TUNING range. Typ. reading is over 1280MHz, watch for STOP freq.reading to cease at 1260. Reverse CF TUNING direction, continue down to 0 MHz. > Check FREQUENCY readout / LEFT - CENTER - RIGHT ... Verify readouts ( below 27 MHz/div ) seem correct. No LCD display 10MHz over/under range is normal, for start/stop readings. Continue CF TUNING in downward direction toward zero MHz. Typical LCD readings update regularly and end stop is greater than -70MHz. Some wrap-around counting below zero has typically been seen. > ABSOLUTE AMPLITUDES..... ( spec. = plus/minus 2dB typical ) Turn VERT to the 12 O'Clock position, turn VAR SPAN to 1 MHz mark. ( VERT, is set between tic marks at 0 REF. and 1.0 MHz/div. DETENT SPAN ) Set the SWEEP RATE to mark, to avoid Deflection loss. Inject RF test signal of 98 MHz, -40dBm. (Use 60dB step attenuator.) (or any calibrated signal between 2 and 1000 MHz) CF TUNE to the test signal. The signal's "Absolute Amplitude", should agree with the Calibrated RF Signal Source. Switch external signal attenuator one position at a time, ( a 10dB step). The displayed signal steps one division per attenuator step, at 10dB/div. Switch REF LEVEL back and fourth between +20dBm, 0dBm, -20dBm, and -40dBm. For each REF LEVEL change, a two Division change of signal peak occurs. ie; a -40dBm signal's peak shows up on the -40 dBm line of the pre-numbered GRATICULE when the 0 REF LEVEL is selected. With the +20 dBm REF LEVEL selected, a -40 dBm signal barely comes up out of the noise floor. REF is switched to the -20 dBm REF LEVEL, the signal is displayed taller. The signal's power hasn't changed, but the instrument sensitivity did. The signal's peak is now at the second line down (marked -20dBm). It's two divisions down from the REFERENCE LINE, (now set to equal -20 dBm, by the REF LEVEL switch ). So the REF LINE = -20 dBm, the Scale is 10dB/div, two divisions = 20 dB, therefore the signal is 20 dB down from -20 dBm... The signal's power is again read as being -40 dBm. At a REF LEVEL of -40 dBm, the signal's peak reaches the REFERENCE LINE. The REF LINE ( top of GRATICULE )is -40 dBm, and the signal is still -40dBm. NOTE: The noise floor moves up when switched to the -40 dBm REF LEVEL. This jump is normal, it is the instruments maximum sensitivity level. Maximum sensitivity is typically -95 dBm at 0.2 MHz / div. DO NOT RE-ADJUST VERTICAL POSITION when switching REF LEVEL. The maximum sensitivity depends on the SPAN, and REF. LEVEL. Smaller DETENT SPAN settings are quieter or more sensitive because the resolution bandwidth is smaller, which allows less noise thru the IF. The -40 dBm REF LEVEL at .2 and 1 MHz / div settings are the most sensitive. > CHECK ABSOLUTE AMPLITUDES AT OTHER DETENT SPANS... All amplitude levels should match from one DETENT SPAN setting to the next. > RESOLUTION BANDWIDTH.... This measurement is the distance between two points on the signal, -3 dB down ( left and right ) from the signal's peak. Typical values below; 125 MHz / div = 3 MHz wide, 50 MHz / div = 1 MHz wide, 10 MHz / div = 300 KHz wide, 5 MHz / div = 150 KHz wide, 1 MHz / div = 75 KHz wide, * .2 MHz / div = 75 KHz wide, * Resolution Bandwidth of 0.2 MHz/div changes when 10 KHz option is installed. > CHARACTERIZE FLATNESS with a input RF frequency sweep from 1 to 1250 MHz. VERT POSITION at 12 o'clock, baseline between the tic-marks.(at 1 MHz/div) Change SPAN to 125 MHz/Div, VAR SPAN at CAL position. Retune CF TUNING near 700MHz, now sweep entire RF range for flatness. Vary input RF Signal Source from 0 to 1250MHz, at some viewable amplitude. (Allow for Sweep and Deflection losses.) Use a relatively slow SWEEP RATE. (If questionable then check signal amplitude with CF TUNING and VAR SPAN.) > ZERO CAL..... Turn SPAN to .2MHz / Division. Turn the VAR SPAN (left) to near ZERO SPAN. Turn CF TUNING to read 0.0MHz on LCD, use FINE TUNING CONTROL for fine adjust (Typical flat line near top of screen is the peak of the ZERO SPIKE.) Adjust the (Zero Cal) adjustment thru the top cover, to maximize the ZERO SPIKE amplitude on the CRT graticule. ie; to move ZERO SPIKE peak to the center of the CRT graticule. > 2MHz SPAN..... Turn VAR SPAN to CAL position, full clock-wise direction. Turn CF TUNING and/or FINE TUNE to obtain a LCD reading of 1.0 MHz, to move the ZERO SPIKE to the begining first line of the graticule. Input a 2 MHz RF Signal. It should show up at the last Graticule division. (This set the span of the .2MHz/Div to 2.0MHz from left to right.) Verify by FINE TUNING the ZERO SPIKE from one edge to the other while, getting an instant LCD reading at each edge with ZERO SPAN MOMentary Switch. (Plus 1.0MHz reading on one side, a minus 1.0MHz reading on the other side.) > CENTER OF EXPANSION ..... Toggle ZERO SPAN SWITCH to MOMentary position and hold. ( at .2 MHz/Div ) FINE TUNE for LCD reading = 0.0MHz! ( The ZERO SPIKE should be fine tuned for maximum ZERO SPAN amplitude.) Release ZERO SPAN SWITCH to NORMal. Turn SPAN to 50 MHz / Division. Adjust HORIZ Pot, to move the ZERO SPIKE to the center of the graticule. > CHECK VARIABLE SPAN..... Center frequency reading shouldn't change much from full span to zero span. > CHECK LCD AUX JACK..... Pins are counted from the lower right, counter-clockwise. Pin 8 is the center pin, and is the ground return. Pin 6 is accessory power out, nominal +12.5 volts dc. Pins 1 thru 5 are special program pins for offsetting Frequency Readouts. Avcom's Frequency Extenders, down-converters, are hard wired to obtain the proper frequency readings on the LCD COUNTER. If an Extender is avail- able, plug it in to the AUX jack. The LCD reading should agree with the Extender's converted frequency. > FREQUENCY LOCK..... Check at 250 MHz CF, fast sweep, 1 MHz / div SPAN, VAR SPAN about 3/4 of the way CCW, toward ZERO span. FINE TUNE a 250 MHz input signal. Depress ZERO SPAN Switch to the MOMentary position and release. A quick flashing of the FREQ LOCK LED should have been noticed while in MOMentary position. Followed by a stepping motion of the signal, after the ZERO SPAN Switch was released ( steps are about 20 KHz each ). The FREQ LOCK LED may then flash slower while aquiring a new center freq. A slight CW turn of the FINE TUNE control, should have the signal stepping to the right to get back toward the center of the screen. Turn the SPAN up to 50 MHz / div. Slowly turn the VAR SPAN up CW. The FREQ LOCK LED should flash some and then go off around 18 MHz / div. ( as read off the top right portion of the LCD Counter ) Continue turning VAR SPAN up, beyond 27 MHz / div. the START & STOP frequencies quit being displayed. The FREQ LOCK resumes normal operation below 15 MHz / div. Check the FREQ LOCK PUSH-BUTTON operation, the FREQ LOCK LED should go off with a momentary hold and release of the FREQ LOCK PUSH-BUTTON. Normal operation continues when FREQ LOCK PUSH-BUTTON is used again. NOTE; unit always tries to come on in the FREQ LOCK mode, momentary flashing of FREQ LOCK LED is normal. Depending on the MHz / div, it will either stay on, or go out if span is too great for lock. > VERTICAL POSITION..... Is always set prior to making any amplitude readings of consiquence. SPAN must be at the 1 MHz / div position, REF LEVEL at 0 dBm position, and VERTICAL SENSITIVITY in the 10 dB / div position. Baseline noise is then set between the tic-marks, at -65 dBm. No further adjustment is required for other REF LEVELS or SPANS. > 2dB/DIVISION..... Is a relative scale. It is NOT an absolute scale, unless some known input signal amplitude is used for a reference. A five division movement of RF amplitude will be seen on the Graticule, for every 10dB change of RF input signal. That is five divisions X the 2 dB / div. = 10dB. Tollerance is a full division, 2 dB. There is typically some compression down near the baseline noise, and usually an excessive step up near 0 dBm. > AM & FM DEMOD..... The type of demodulation is selected with the AM / FM TOGGLE SWITCH. AM operation is available anytime the AUDIO DEMOD volume switch is ON and loud enough to here. Ticking on the speaker will be heard for every spike displayed on the swept display. If the signal is at Center Frequency and near or at zero span, as set with either VAR SPAN or the ZERO SPAN TOGGLE switch, what ever is seen in the swept display will be heard. FM on the other hand, can only demodulate frequency modulated signals. Tune in a local FM radio station to check. Attach an antenna(88-108 MHz) The ZERO SPAN TOGGLE switch must be in AUDIO or MOMentary position, and the AUDIO DEMOD volume switch is ON and loud enough to here. > CHECK HARDWARE All hardware on the instruments case should be checked for tightness. This completes the PSA-65C, SPECTRUM ANALYZER's, operations verification.