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transmitter tuning procedure in SECTION II, Installation/Initial
turn on, for additional information.

6.31

Other Troubleshooting Techniques

6.31.1

Handling MOSFET’s

Due to the fragile nature of the gate of a MOSFET, special care
in their handling is required. The gate junction may be destroyed
if static electricity is allowed to discharge through the MOSFET.
For example, a static charge could build up on a person as they
walk across a carpet and discharge across the MOSFET if it is
not protected by antistatic packaging.

NOTE

MOSFET transistors which are in circuit are immune to this
damage.

The MOSFET transistors are shipped in antistatic packaging.
The transistors should remain in this packaging until they are to
be used or tested. Proper precautions should be observed to
ground any potential static charge before handling the MOS-
FETS.

6.31.2

Testing MOSFET’s

The MOSFET’s will have to be removed from the circuit in
order to perform the following test.

Observe the precautions in the paragraph entitled “Handling
MOSFET’S” in this section.

The MOSFET’s used in the DX-25U transmitter may be
checked with an ohmmeter. However, there is a requirement
which restricts the use of some ohmmeters. If the battery voltage
is too low (under 3V) or too high (over 20V) the ohmmeter
cannot be used. A battery voltage less than 3V will not give an
operational check of the transistor and a battery voltage greater
than 20V may result in damage to the transistor under test. A
Simpson 260, which uses a 9V battery on the Rx10K scale
works quite well.

This test will show how a MOSFET can be switched “ON” and
“OFF” by charging and discharging the gate of the MOSFET.

Connect the positive lead of the ohmmeter to the drain or case
of the transistor. Connect the negative lead to source. Alternately
touch a jumper from gate to source and then from gate to drain.
The ohmmeter should read towards infinity or at least 2 me-
gOhms when the MOSFET is switched “OFF” and less than 90k
Ohms when the MOSFET is switched “ON.” When doing this
test, lay the MOSFET on a flat surface or hold sides of the case.
The resistance of your finger tips and skin will effect the
readings when you touch the leads.

6.31.3

Finding A Missing Step

It is possible to have a failed PA Module without the Fault LED
being illuminated. It should be possible to see this problem on
the detected audio waveform. If a “Big Step” PA Module is not
operating properly, an error in the demodulated audio waveform
will be present as seen in Figure 6-1. This kind of error is

apparent only with triangle (linear ramp) tone modulation. If a
PA Module failure is suspected, operate the transmitter at 30
kW at full modulation. Display the demodulated audio output
of a modulation monitor on a dual trace scope. If a big step
amplifier is not working, an error will be noticeable on the
display. To determine which amplifier is at fault, connect the
second channel of the scope to a probe and look at the output of
the Modulation Encoder for each big step until the transition
from 0 to 5VDC occurs at the same point in time as the error on
the wave form. See Figure 6-1.

Because there are 58 “Big Steps”, it helps to know where to start
to look on the modulation encoder. A good rule is that the higher
the positive peak level where the error occurs, the higher the
step number. A 100% modulated signal at 30 kW is NOT using
all the big steps — steps RF48 through RF58 are only ON during
positive peaks. To check these steps, a non-symmetrical audio
waveform should be used in order to modulate the transmitter
with a steady state tone at 125% positive peak without causing
overmodulation, and carrier shift, on the negative peaks.

Figure 6-2 shows a non-symmetrical ramp modulating to 125%
positive peak and only 50% negative peak. An error is also
shown near the top of the positive peak indicating a big step
failure at approximately “Big Step” RF55. The Modulation
Encoder waveform is also shown for that step. Once the step
causing the error is located, the PA Module can be changed. If
substituting the PA Module does not remove the error, then the
problem may exist on the Modulation Encoder.

6.31.4

Using FlexPatch™ for Bypassing a Failed
PA Module

FlexPatch™ is a Harris feature to allow the engineer to patch a
failed RF amplifier from an active step position, such as step
RF6, to a step position that is only used for positive peak
modulation, such as step RF90. Module RF90 will now operate
as module RF6. This patching is done at a “TTL” level basis
and can be done while the transmitter is on the air.

Because approximately 47 RF amplifiers are used to create 50
kW carrier, a failed module in the RF6 position will result in a
power output drop of approximately 2% and a slight THD
increase. The transmitter will operate with no other problems in
this condition. However, FlexPatch™ will allow the transmitter
to resume operation at full power and optimum modulation
clarity with only a slight loss of positive peak capability.

Refer to Figure 6-8 for the following procedure. To use the
FlexPatch™ feature to bypass a failed PA Module:

a. On the Modulation Encoder controlling the failed RF

amplifier, locate and remove the gold jumper for the failed
RF amplifier to be patched.

b. Locate and remove the gold jumper for step RF90 on

Modulation Encoder A37. Step RF90 is selected because
it would only be ON during the highest positive peaks.

c. Locate and remove one of the FlexPatch™ jumpers and

connect one end to the OUTPUT signal side from where
the jumper plug was removed for the failed amplifier.

DX-25U

6-18

888-2297-002

Rev. R: 11-11-96

WARNING: Disconnect primary power prior to servicing.

Содержание DX 25U

Страница 1: ...I Operation IV Theory V Maintenance VI Troubleshooting VII Parts List Subsections VIII RF Oscillator Buffer Amplifier RF Amplifier Modules Driver Combiner Motherboard Driver Supply Regulator RF Multim...

Страница 2: ......

Страница 3: ...cing For Stereo 2 13 Bandpass Tuning 2C1 2 13 Remote Control Connections 2 13 Control Inputs 2 13 Analog Monitoring Outputs 2 13 Status Monitoring Outputs 2 13 Section III Operators Guide Introduction...

Страница 4: ...on one or more ColorStat panel indicators are illuminated RED 6 7 Possible Causes 6 7 Symptom Transmitter will turn ON but immediately turns OFF one or more ColorStat panel indica tors illuminate RED...

Страница 5: ...is Red but transmitter operation is normal A 3 Section B Buffer Amplifier A16 Introduction B 1 Principles of Operation B 1 Circuit Description B 1 Buffer Amplifier Supply Voltage B 1 First RF Amplifi...

Страница 6: ...Steps Not Continuously J 4 Symptom 15 VDC or 15 VDC faults J 4 Section K Analog To Digital Converter A34 Introduction K 1 Principles of Operation K 1 Circuit Description K 1 Converting a PA Sample to...

Страница 7: ...ata P 9 Up Down Counter Control Gates U1 U2 U14 U26 P 11 Data Strobe Gates U1 3 8 11 and U13 8 P 11 Up Down Counter Inhibit Circuits P 11 Multiplex and Output Buffers For BCD Power Data U9 U11 U21 U23...

Страница 8: ...ntrol R 1 Multimeter Circuit M1 R 1 Supply Current Meter Circuit M2 R 1 Power Meter Circuit M3 R 1 Maintenance R 2 Adjustments R 2 Troubleshooting R 2 Symptom Incorrect Meter Indications R 2 Section S...

Страница 9: ...07 31 96 41404 41390 Title Page MRH 1 MRH 2 and pages 7 15 to 7 18 7 21 to 7 23 002 P1 10 09 96 40242 Title Page MRH 1 MRH 2 and pages 7 24 to 7 26 002 P2 10 14 96 41282 Title Page MRH 1 MRH 2 and pa...

Страница 10: ......

Страница 11: ...for individual transmitter modules and the overall transmitter h SECTION VIII Diagrams i The following sections provide principles of operation for boards and modules in the DX 25U TRANSMITTER Sectio...

Страница 12: ...Figure 1 1 DX 25U Front View with Doors Closed Figure 1 2 DX 25U Rear View with Doors Closed DX 25U 1 2 888 2297 002 Rev R 11 11 96 WARNING Disconnect primary power prior to servicing...

Страница 13: ...acement AND IN WHAT OR DER EQUIPMENT SHOULD BE SET IN PLACE If possible lay out equipment location with lines marked on the floor HANGING HARDWARE Ensure that all pipe hangers conduit hangers threaded...

Страница 14: ...and remove the bar and Neutralization Board Once the PA Cabinet is in position it will be necessary to put the Combiner bar back in place When tightening the hex head bolts torque to 80 inch pounds A...

Страница 15: ...is used static pressure in the duct must be neutral or slightly negative Static pressure for air intake at the rear of the transmitter must be neutral or slightly positive The exhaust grill opening o...

Страница 16: ...from no load to full load tap T1 down to the next voltage combi nation to avoid unnecessary tripping of the Over Voltage Over load during initial turn on 2 9 Component Installation Some components hav...

Страница 17: ...various interface connections 2 12 1 Audio Input Use a shielded pair audio cable for connection between process ing equipment and Audio Input terminal TB3 on the External Interface The External Inter...

Страница 18: ...ernal 50 Ohm termination a 50 Ohm 3 to 5 Watt termina tion should be placed across the Modulation Monitor input terminals Do not connect the coaxial cable to the monitor until instructed to do so duri...

Страница 19: ...al turn on procedure provides checks or adjustments in the following sequence a Low Voltage Power Supply test b Underdrive overload test c PA Power Supply check d Fan rotation check e Driver operation...

Страница 20: ...s that will be detected by the Underdrive Overload circuit that are not RF related failures i e a short across the PA Power Supply during the step start sequence Refer to Section IV Overall System The...

Страница 21: ...a Remove the clip lead between TP8 and GND on the LED Board if used in checking out the PA Power Supply b The PA OFF switch S2 on the Controller should be OFF up c Apply single phase and three phase...

Страница 22: ...NG control adjusts the PA Supply Current and power output With a PA Power Supply voltage of 230 VDC PA Supply Current should be between 110 and 115 Amps d The TUNE control is adjusted for a PEAK in po...

Страница 23: ...Table 2 4 Minimum Recommended Control and Status Functions for Remote Control Section II Installation Rev AA 8 9 2000 888 2297 002 2 11 WARNING Disconnect primary power prior to servicing...

Страница 24: ...e transmitter can accommodate reference levels from 10 dBm to 10 dBm at 600 Ohms b Switch the transmitter to MEDIUM power Set the output level from the audio generator to the station s reference value...

Страница 25: ...installation The Customer Interface for remote control metering and status monitoring is compatible with nearly all remote control systems If the remote control system does not have enough channels a...

Страница 26: ...is provided at the LOW MEDIUM or HIGH terminals on TB1 If the transmitter is already ON providing another of these inputs will change power level without interrupting RF output e RAISE LOWER inputs c...

Страница 27: ...Table 2 5 Initial Turn On Meter Readings Section II Installation Rev AA 8 9 2000 888 2297 002 2 15 WARNING Disconnect primary power prior to servicing...

Страница 28: ......

Страница 29: ...pushed and released If any indicators are still red after operating the RESET do not attempt to turn on the transmitter and contact qualified maintenance personnel 3 4 Transmitter Turn On Procedure W...

Страница 30: ...f AC power failures greater than approximately 2 hours occur and no Battery Backup has been installed the transmitter will remain OFF after AC power returns and operator action will be required to tur...

Страница 31: ...put will be slightly reduced The fault indication can not be RESET The fault must be corrected to clear the fault indication Continue normal operation and contact qualified maintenance personnel Secti...

Страница 32: ......

Страница 33: ...itter impedance 3 Switch Board Meter Panel See Table 3A 2 and Figure 3A 2 4 ColorStat Panel See Table 3A 3 and Figure 3A 3 5 Driver Control Compartment 6 Center Control Compartment 7 Left Control Comp...

Страница 34: ...d 7 RAISE pushbutton Used to adjust power level When the transmitter is in the LOW MEDIUM or HIGH power mode depress to RAISE power output and hold until desired power is reached IN DICATOR illuminate...

Страница 35: ...ly on the audio input board GREEN indicates normal operation RED indicates 15 Volt supply fault 6 OSCILLATOR RF output status indicator Bicolor LED indicator Indicates oscillator board RF output statu...

Страница 36: ...R DRIVE status indica tor RED indicates low RF drive level to the Power Amplifier GREEN indicates drive level above the preset threshold Red can also indicate a short in the PA power supply 18 SUPPLY...

Страница 37: ...status of 15 Volt supply on the A D Converter board GREEN indicates normal operation RED indicates 15 Volt supply fault 30 A D CONVERTER CONVER SION ERROR status indicator Bicolor LED indicator GREEN...

Страница 38: ...3A 4 Boards Listed in Alphabetical Order A5 thru A7 Main Combiner Motherboard A8 Binary Combiner Motherboard A14 Driver Combiner Motherboard A15 RF Drive Splitter A16 Buffer Amplifier A17 Oscillator A...

Страница 39: ...Figure 3A 4 Left Control Compartment Front View 839 7855 117 Section IIIA Controls and Indicators Rev AA 8 9 2000 888 2297 002 3A 7 WARNING Disconnect primary power prior to servicing...

Страница 40: ...Figure 3A 5 Center Control Compartment Front View 839 7855 118 DX 25U 3A 8 888 2297 002 Rev AA 8 9 2000 WARNING Disconnect primary power prior to servicing...

Страница 41: ...Figure 3A 6 Driver Compartment Front View 839 7855 119 Section IIIA Controls and Indicators Rev AA 8 9 2000 888 2297 002 3A 9 WARNING Disconnect primary power prior to servicing...

Страница 42: ...Figure 3A 7 Driver Compartment Rear View 839 7855 126 DX 25U 3A 10 888 2297 002 Rev AA 8 9 2000 WARNING Disconnect primary power prior to servicing...

Страница 43: ...Figure 3A 8 Left Center Control Compartments Rear View 839 7855 121 modified Section IIIA Controls and Indicators Rev AA 8 9 2000 888 2297 002 3A 11 WARNING Disconnect primary power prior to servicing...

Страница 44: ...Figure 3A 9 Output Network Compartment Rear View 839 7855 120 DX 25U 3A 12 888 2297 002 Rev AA 8 9 2000 WARNING Disconnect primary power prior to servicing...

Страница 45: ...Figure 3A 10 Step Start Panel Unit 3 839 7855 139 Section IIIA Controls and Indicators Rev AA 8 9 2000 888 2297 002 3A 13 WARNING Disconnect primary power prior to servicing...

Страница 46: ......

Страница 47: ...thepower amplifier An RFSense feedbacksignal from the RF splitter controls the regulator output voltage to control the Driver stage output 4 2 1 6 Driver Encoder Temp Sense Board The Driver Encoder Te...

Страница 48: ...ifier modules in the Power Amplifier stage which varies the turn on turn off times of the modules to optimize distortion and noise performance 4 2 3 Controller Section The Controller section consists...

Страница 49: ...Figure 4 1 DX 25U Block Diagram Section IV Overall System Theory Rev AA 8 9 00 888 2297 002 4 3 WARNING Disconnect primary power prior to servicing...

Страница 50: ...a 30 Volt K2 has closed logic signal to the turn on turn off logic Approximately one half second later step start contactor K1 de energizes 4 4 2 PA Supply Discharge Circuit Crowbar This circuit is co...

Страница 51: ...e A DC power supply compensation signal for circuitry on the Analog Input Board comes from R22 R23 R24 R27 and C3 Refer to SECTION J Analog Input Board for the circuit de scription 4 4 12 2 Driver Sup...

Страница 52: ...d the DX 25U Overall Schematic 839 7855 151 in the Drawing Package 4 6 1 Door Interlock Circuit The door interlock circuit turns the transmitter OFF if any of the three interlocked RF Amp Compartment...

Страница 53: ...er 47 RF amplifiers are ON With a carrier power of 30kW a 125 positive peak requires a peak output power of 151 9 303 8kW and additional RF amplifiers are turned ON SUMMARY The more steps or RF amplif...

Страница 54: ...t to the front of the transmitter as the TUNE control The TUNE control is adjusted for a peak in output power The combiner output impedance is low approxi mately 8 Ohms and is matched to approximately...

Страница 55: ...umber of quantities that may be represented by that word including zero For example if a digital word has 6 bits it may represent 26 64 quantities If a digital word has 12 bits it may represent 212 40...

Страница 56: ...amplifiers are switched OFF As the audio signal changes from instant to instant the number of RF amplifiers that are ON changes a For carrier only no modulation only enough RF amplifi ers to produce t...

Страница 57: ...Modulator uses new technology which produces a very high quality low distortion amplitude modulated signal for AM broadcasters OverallAC to RFefficiency oftheDX 25Uis veryhigh because the digital mod...

Страница 58: ......

Страница 59: ...loration bulg ing of parts and peculiar odors 2 Oxidation 3 Dirt corrosion rust mildew and fungus growth FEEL By checking for overheating lack of proper venti lation or other defects can be detected a...

Страница 60: ...of the power supply discharge switches S9 S10 and S12 located in the inter locked RF Amplifier and Driver Compartments 5 2 3 7 Indicators and Front Panel Switches Preventive maintenance of indicator...

Страница 61: ...opening the interlocked RF Amp Compartment door inside the Center or Left Control Compart ment Remove the defective RF amplifier by pulling it out and then insert the replacement RF amplifier The inne...

Страница 62: ...nk DO NOT TRY TO PRY THE HEATSINK AWAY FROM THE PC BOARD WITH TRANSISTORS STUCK TO THE HEATSINK OR THE PC BOARD MAY BE DAMAGED AND THE HEATSINK MAY DISTORT Sometimes the transistor pad will tear when...

Страница 63: ...river Combiner motherboard the secondary rod will have to be removed through the top of the transmitter If top removal is not possible because of an overhead clearance problem remove the RF Drive Spli...

Страница 64: ...ate with a 100Hz tone at 95 b Operate the transmitter at 5 0 kW and measure the percent of modulation If it is within 1 of the level noted at 25 kW no further adjustment of the Offset control is neces...

Страница 65: ...ortion of the waveform d Adjust R43 maximum counterclockwise At this point it should be possible to see some of the individual Digital Modulation voltage steps It may be possible to see the steps bett...

Страница 66: ...ircuit board and are mounted on the heat sink using screws compression washers and insulator pads To remove the printed circuit board the seal between the transis tors and the insulator pads will have...

Страница 67: ...switch S8 to the Normal position and release momentary pushbutton switch S5 Make sure that the vertical sensitivity of both channels of the scope are the same i Connect both scope probes to TP6 to en...

Страница 68: ...tmeter or a dc coupled oscilloscope and adjust for minimum voltage at TP8 and TP9 with reference to ground 5 6 6 4 Trip Threshold Adjustment The overload settings for the Antenna and Bandpass circuit...

Страница 69: ...er set the following test point voltages to match those recorded on the Factory Test Data sheets 1 TP6 R42 Average Current Overload 2 TP5 R41 Overdrive Overload 3 TP7 R68 Peak Current Overload 4 TP8 R...

Страница 70: ...Vp p a To adjust the Overdrive overload place switch S1 on the Driver Supply Regulator in the OPEN LOOP position and note the voltage of D8A and D8B on the RF MULTIME TER b Adjust R2 on the Driver Sup...

Страница 71: ...ational measure the following Test Point voltages on the original board and adjust the new board to the same voltages TP1 R17 Driver Threshold Reset TP2 R19 Driver Threshold ON TP3 R49 Temp Cal TP4 R5...

Страница 72: ...S WHERE AC OR RF POWER HAS BEEN APPLIED BEFORE PROCEEDING WITH THE FOLLOWING PRO CEDURE q Remove the left rear access panel from the OutputNetwork Compartment to expose the four cooling fans Replace t...

Страница 73: ...ng hardware straps plates etc are all listed on the parts list When installing these components make sure all connections are tight Use specialcare when handling vacuum capacitors 5 7 3 Frequency Dete...

Страница 74: ...cy NOTE Recheck the frequency after 30 minutes This must be repeated for both crystals 5 7 5 2 Buffer Output A16 a Turn off the low voltage to the transmitter at CB1 and CB2 b Locate the Predriver in...

Страница 75: ...t on the DRIVER IDC position h The Driver Combiner is now adjusted for resonance Reso nance is indicated by a peak in the drive amplitude and the DRIVER IDC reading on the RF MULTIMETER 1 Resonance is...

Страница 76: ...ccess panels from the Driver Compart ment and the left rear RF Amp Compartment and replace the following PA Power Supply fuses 1 A25 F1 F8 2 A24 F1 F9 3 F20 on top of T1 b Apply primary AC power to th...

Страница 77: ...sic performance of the transmitter 5 7 9 1 Binary RF Amplifier Phase Alignment Binary RF amplifier phase alignment is performed to achieve optimum stereo performance This alignment is performed by mea...

Страница 78: ...ons between big steps will be smooth If for instance the 1 2 Step B7 amplitude is too low you will see a transition approximately halfway between Step 37 and Step 38 This is the half step transition Y...

Страница 79: ...p p per division Figure 5 4 RF Drive Waveform at RF Amplifier Gate of Q3 anode of CR3 RF AMplifier turned ON 5Vp p per division Figure 5 5 Antenna VSWR Detector voltage and current samples as meas ure...

Страница 80: ...ion with 100 Hz 100 modulation 1V per division 0 0 Vdc at top line Figure 5 8 Modulated B waveform at DC Regulator A30TP30 25kW op eration with 100 Hz 100 modulaltion Figure 5 9 Oscillator sync sample...

Страница 81: ...Demodulated Audio Bottom Trace Modulation Encoder waveform of Step 6 Good binary alignment shown Figure 5 12 Demodulated audio Transmitter operaeting at 5kW with 100 Hz approximately 10 triangle modul...

Страница 82: ......

Страница 83: ...Signal 6 6 240 VAC Coil Voltage 6 6 Open Contactor Coil On K1 or K2 6 6 Symptom Transmitter will not turn on one or more ColorStat panel indicators are illuminated RED 6 7 Possible Causes 6 7 Symptom...

Страница 84: ...Failure 6 11 Driver Supply Regulator Loop Select 6 11 Defective Driver Encoder Signals 6 11 Severe Driver Mistuning 6 11 ColorStat panel Overdrive Fault 6 11 Possible Causes 6 11 High AC Line Voltage...

Страница 85: ...Power Supply Voltage Low 6 16 Audio Processor Equipment Defective or Incorrectly Set 6 16 Incorrect Transmitter Tuning 6 16 Transmitter Operated In FlexPatch Mode 6 16 Failed RF Amplifier 6 16 Sympto...

Страница 86: ...for Bypassing a Failed PA Module 6 18 Using FlexPatch for Isolating Modulation Encoder RF Amplifier Problems 6 19 Measuring Drive Level 6 19 Measuring Drive Phasing 6 19 Excessive Drive Phase Differen...

Страница 87: ...cles back on or repeats within 2 4 seconds after the transmitter cycles back on it becomes a Type 1 fault and will require a manual restart TYPE 3 LOWER POWER OUTPUT BANDPASS VSWR Output Monitor detec...

Страница 88: ...LTAGE AT THE MAIN BREAKER OR FUSE PANEL THEN REMOVE THE STEP START PANEL COVER AND ATTACH YOUR MEASURING DEVICE TO THE TERMINALS LISTED 6 3 1 3 Contactor Drive Circuitry Measure the 15 VDC on 3TB1 8 i...

Страница 89: ...tal Converter conversion error fault circuit and will also produce a PA Turn Off command If any of these fault indicators are illuminated on the ColorStat panel refer to the Troubleshooting ColorStat...

Страница 90: ...e control signal is at the appropriate Encoder output Refer to SECTION L Modulation Encoders for additional information 6 9 1 4 Open fuses on Fuse Boards A24 or A25 If a fuse has opened there will be...

Страница 91: ...and before the PA Power Supply capacitors had fully charged could cause an Overcurrent overload on turn on Turn the PA OFF switch to the OFF up position on the Controller If the transmitter turns ON r...

Страница 92: ...modulation levels with frequencies from 90 140Hz could be sensed as a fault This condition should normally not occur if the three phase line voltages are well balanced If the balance is marginal then...

Страница 93: ...tion This switch is set through the cover over the Driver Supply Regulator in the Driver Compartment If the transmitter will operates the problem is in the Closed Loop regulator section of the Driver...

Страница 94: ...uses 6 18 1 1 Fans Not Operating Properly Failed Running Backward The transmitter will turn ON for approximately 20 seconds with NO air flow Press the LOW power button and open the Center Control Comp...

Страница 95: ...Voltage at CB1 and CB2 for approxi mately 1 minute to allow the power supply to discharge Reap ply Low Voltage and note if the regulator is now reset 6 24 ColorStat panel Analog to Digital Converter...

Страница 96: ...t the supply has failed The transmitter will turn OFF and will not be able to be turned ON until the fault is cleared With the Low Voltage on measure the voltage on both sides of F1 on the DC Regulato...

Страница 97: ...source to keep it going b TRANSIENTS or other signal pickup fed back into the transmitter output from the antenna system c COMPONENT FAILURES causing a change in load impedance at the transmitter out...

Страница 98: ...e if any are illuminated 6 29 Symptom Higher Than Normal Audio Distortion 6 29 1 Possible Causes 6 29 1 1 Failed RF Amplifier s If audible distortion is heard on the air and the problem is not in the...

Страница 99: ...MOSFET transistors or a defective RF amplifier output toroid An RF amplifier that fails from phasing problems will operate for a short time before failure During this condition the module will operate...

Страница 100: ...ation monitor on a dual trace scope If a big step amplifier is not working an error will be noticeable on the display To determine which amplifier is at fault connect the second channel of the scope t...

Страница 101: ...mproper drive level WARNING ENSURE ALL AC PRIMARY POWER IS REMOVED FROM TRANSMITTER AND THAT THE GROUNDING STICK HAS BEEN USED TO DISCHARGE ANY RESIDUAL POTENTIAL WHERE POWER HAS BEEN APPLIED BEFORE P...

Страница 102: ...a specific module problem The drain phasing of the Binary Amplifiers can be adjusted Refer to SECTION V Maintenance for this procedure RF amplifier drain phasing should be within 4 degrees of each ot...

Страница 103: ...les in P8 1 and 2 P8 is located next to the RF amplifier TEST SWITCH S2 on the Modulation Encoder c Insert one end of a FlexPatch cable into P8 1 Connect the other end of the jumper to the hole closes...

Страница 104: ...lation Encoder signal for missing step 10 Figure 6 2 Upper Trace Demodulated audio at 100Hz 125 peak ramp modulation at 10kW showing missing step 56 Lower Trace Modulation Encoder signal for step 56 F...

Страница 105: ...n of Q3 TP1 RF Amp turned ON Shows zero crossing reference phase and measured phase approximately 4 degrees lagging 2Vp p per division X10 Magnification Figure 6 7 RF Drain Waveform as seen at RF Amp...

Страница 106: ...Figure 6 8 FlexPatch Operation DX 25U 6 24 888 2297 002 Rev R 11 11 96 WARNING Disconnect primary power prior to servicing...

Страница 107: ...SSY 938 4203 020 7 32 Table 7 19 PWA IPA PWR SPLITTER ESD SAFE 992 5889 002 7 32 Table 7 20 MULTIMETER W O PROBE 992 6752 004 7 32 Table 7 21 PWA DX SWITCH 992 6784 002 7 32 Table 7 22 PWA PWR DISTRIB...

Страница 108: ...4 504 0448 000 CAP 16 000PF 5KV 5 293 0 0 EA 1C3 504 0449 000 CAP 18 000PF 5KV 5 293 0 0 EA 1C3 504 0496 000 CAP 4700PF 10KV 5 293 0 0 EA 2C1B 504 0497 000 CAP 6200PF 10KV 5 293 0 0 EA 1C4 504 0509 00...

Страница 109: ...IS P N DESCRIPTION QTY UM REF SYMBOLS EXPLANATIONS 252 0002 000 WIRE STRD 22AWG GRN 1 50 FT 296 0260 000 TUBING SHRINK 3 32 WHITE 0 30 FT 296 0263 000 TUBING SHRINK 3 8 WHITE 0 20 FT 354 0287 000 LUG...

Страница 110: ...CAP 1UF 600V 5 1 0 EA C008 516 0419 000 CAP 05 UF 500V 2 0 EA C003 C004 516 0453 000 CAP 1UF 100V 20 X7R 1 0 EA C014 540 1491 000 RES 10 OHM 1 2W 2 4 0 EA R010 R011 R012 R013 540 1600 017 RES 4 7 OHM...

Страница 111: ...4732A 4 7V ESD 1 0 EA CR010 398 0019 000 FUSE FAST CART 2A 250V 3 0 EA F001 F002 F003 402 0129 000 CLIP 1 4 DIA FUSE 6 0 EA 2 XF001 2 XF002 2 XF003 404 0509 000 SOCKET IC 28 PIN 1 0 EA XU001 404 0513...

Страница 112: ...00 168 RES 49 9 OHM 1 2W 1 1 0 EA R012 548 2400 230 RES 200 OHM 1 2W 1 1 0 EA R019 548 2400 264 RES 453 OHM 1 2W 1 1 0 EA R072 548 2400 268 RES 499 OHM 1 2W 1 1 0 EA R079 548 2400 269 RES 511 OHM 1 2W...

Страница 113: ...D 4 0 EA U062 U063 U064 U065 382 0560 000 IC 74LS27 ESD 1 0 EA U053 382 0580 000 IC 74LS32 ESD 2 0 EA U060 U061 382 0622 000 IC 74LS14N ESD 3 0 EA U054 U055 U057 382 0637 000 IC 74LS30 ESD 2 0 EA U066...

Страница 114: ...100 C101 C102 C103 C104 C105 C106 C107 C108 C109 C110 C111 C112 C113 C114 C115 516 0815 000 CAP NETWORK 001UF 10 16 0 EA C099 C116 C117 C118 C119 C120 C121 C122 C123 C124 C125 C126 C127 C128 C129 C130...

Страница 115: ...ROW VERTICAL 1 0 EA J017 610 0999 000 HDR 10 PIN PC BD 1 0 EA J019 610 1027 000 HEADER MALE 12 PIN 1 0 EA J018 612 0904 000 JACK PC MT GOLD PLATED 10 0 EA P010 P011 P012 P015 3 J020 3J021 612 1176 000...

Страница 116: ...EA R011 548 2400 501 RES 100K OHM 1 2W 1 3 0 EA R004 R025 R034 548 2400 542 RES 267K OHM 1 2W 1 2 0 EA R041 R042 548 2400 566 RES 475K OHM 1 2W 1 2 0 EA R019 R024 548 2400 601 RES 1MEG OHM 1 2W 1 13 0...

Страница 117: ...FER AMP 1 0 EA 929 9009 198 XFMR 1 0 EA T001 Table 7 8 DRIVER ENC TEMP 992 8048 001 HARRIS P N DESCRIPTION QTY UM REF SYMBOLS EXPLANATIONS 354 0309 000 TERM SOLDER 14 0 EA TP001 TP002 TP003 TP004 TP00...

Страница 118: ...M 1 2W 1 1 0 EA R083 548 2400 185 RES 75 OHM 1 2W 1 2 0 EA R093 R096 548 2400 201 RES 100 OHM 1 2W 1 2 0 EA R044 R045 548 2400 209 RES 121 OHM 1 2W 1 18 0 EA R001 R002 R003 R004 R005 R006 R007 R008 R0...

Страница 119: ...ALOG SWITCH SPDT ESD 1 0 EA U004 384 0205 000 DIODE SILICON 1N914 4148 ESD 7 0 EA CR002 CR003 CR006 CR007 CR008 CR009 CR010 384 0431 000 RECT 1N4001 ESD 1 0 EA CR005 386 0082 000 ZENER 1N4744A 15V 1W...

Страница 120: ...R021 R033 R043 R045 548 2400 426 RES 18 2K OHM 1 2W 1 1 0 EA R002 548 2400 430 RES 20K OHM 1 2W 1 1 0 EA R014 548 2400 458 RES 39 2K OHM 1 2W 1 1 0 EA R001 548 2400 501 RES 100K OHM 1 2W 1 1 0 EA R046...

Страница 121: ...N ESD 1 0 EA U037 382 1098 000 IC 74LS126AN ESD 9 0 EA U009 U010 U011 U021 U022 U023 U033 U034 U035 384 0205 000 DIODE SILICON 1N914 4148 ESD 6 0 EA CR012 CR013 CR015 CR016 CR017 CR018 384 0321 000 DI...

Страница 122: ...0 EA C126 C127 526 0314 000 CAP 33UF 10V 20 1 0 EA C072 526 0333 000 CAP 15UF 20V 20 1 0 EA C071 526 0374 000 CAP 1 0F 5 5V 1 0 EA C044 540 1356 000 RES NETWORK 10K OHM 2 2 0 EA R080 R081 540 1377 000...

Страница 123: ...0 HDR 20C 2ROW RT ANG 1 0 EA J005 610 0986 000 HDR 40C 2ROW RT ANG 3 0 EA J002 J007 J008 610 0987 000 HDR 40C 2 ROW STRAIGHT 2 0 EA J001 J003 610 0999 000 HDR 10 PIN PC BD 2 0 EA J004 J006 610 1112 00...

Страница 124: ...404 0673 000 SOCKET 8 PIN DIP DL 1 0 EA U043 404 0674 000 SOCKET 14 PIN DIP D L 57 0 EA U001 U002 U003 U004 U005 U006 U007 U008 U009 U015 U016 U017 U018 U019 U020 U021 U022 U023 U024 U025 U026 U027 U0...

Страница 125: ...OHM 2 2 0 EA R100 R147 540 1444 000 RES NETWORK 150 OHM 2 6 0 EA R098 R120 R122 R148 R160 R163 540 1457 000 RES NETWORK 330 OHM 2 1 0 EA R154 540 1484 000 RES NETWORK 15K OHM 2 1 0 EA R185 540 1600 2...

Страница 126: ...548 2400 485 RES 75K OHM 1 2W 1 2 0 EA R066 R082 548 2400 487 RES 78 7K OHM 1 2W 1 1 0 EA R114 548 2400 493 RES 90 9K OHM 1 2W 1 1 0 EA R146 548 2400 501 RES 100K OHM 1 2W 1 9 0 EA R004 R008 R012 R024...

Страница 127: ...404 0303 000 SOCKET IC 10 PIN 1 0 EA XU010 404 0507 000 SOCKET IC 18 PIN 1 0 EA XU008 404 0673 000 SOCKET 8 PIN DIP DL 9 0 EA XU003 XU004 XU005 XU006 XU007 XU009 XU011 XU012 XU019 404 0674 000 SOCKET...

Страница 128: ...38 548 2400 330 RES 2K OHM 1 2W 1 6 0 EA R032 R036 R037 R040 R065 R078 548 2400 342 RES 2 67K OHM 1 2W 1 3 0 EA R011 R012 R089 548 2400 347 RES 3 01K OHM 1 2W 1 1 0 EA R076 548 2400 354 RES 3 57K OHM...

Страница 129: ...R011 R012 R013 R014 R015 R016 R017 610 0679 000 PLUG SHORTING 25 CTRS 2 0 EA P001 P002 610 0980 000 HDR 20C 2ROW RT ANG 1 0 EA J001 612 1012 000 JACK PC MT 040 PINS 6 0 EA 3 P001 3 P002 620 1677 000 R...

Страница 130: ...5 XU008 XU009 XU014 XU016 404 0675 000 SOCKET IC 16 CONT 5 0 EA XU002 XU003 XU006 XU013 XU015 404 0738 000 SOCKET 20 PIN SINGLE ROW 2 0 EA XLCD001 404 0767 000 SOCKET 20 PIN DIP DL 1 0 EA XU007 404 07...

Страница 131: ...2W 1 1 0 EA R064 548 2400 358 RES 3 92K OHM 1 2W 1 2 0 EA R037 R076 548 2400 368 RES 4 99K OHM 1 2W 1 2 0 EA R002 R057 548 2400 382 RES 6 98K OHM 1 2W 1 1 0 EA R023 548 2400 384 RES 7 32K OHM 1 2W 1...

Страница 132: ...1 000 RECT 1N4001 ESD 4 0 EA CR014 CR015 CR021 CR022 384 0612 000 DIODE 1N3070 ESD 13 0 EA CR005 CR006 CR007 CR009 CR010 CR011 CR012 CR016 CR018 CR019 CR023 CR028 CR033 384 0719 000 TRANSZORB 1N6373 5...

Страница 133: ...1 0 EA R004 548 2400 230 RES 200 OHM 1 2W 1 1 0 EA R010 548 2400 242 RES 267 OHM 1 2W 1 2 0 EA R027 R043 548 2400 247 RES 301 OHM 1 2W 1 1 0 EA R009 548 2400 269 RES 511 OHM 1 2W 1 1 0 EA R003 548 24...

Страница 134: ...0 EA 302 0693 000 SCREW 1 4 28 X 625 11 0 EA 328 0073 000 WASHER RETAINER 40 0 EA 335 0252 000 WASHER TEFLON 6 0 EA CR017 CR019 CR021 354 0760 000 TAB ADAPTOR 250 SERIES 4 0 EA 356 0208 000 CLAMP FLAT...

Страница 135: ...0 EA 464 0169 000 TOOL TRIMMER ADJUSTMENT 1 0 EA 472 1660 000 XFMR PWR 1 0 EA T001 472 1666 000 XFMR INTERPHASE 1 0 EA T003 472 1668 000 XFMR PWR 817 2099 009 1 0 EA T002 476 0416 000 CHOKE FLTR 10MHY...

Страница 136: ...EA 817 1335 119 PLATE GROUNDING 2 0 EA 817 2099 062 RUNNING LIST PA CABINET DX25 0 0 EA 822 0922 033 FRT DOOR HINGE PLATE 3 0 EA 822 0922 153 STRAPS 1 0 EA 822 0922 158 DRIVE CABLE SUPPORT RING 1 0 E...

Страница 137: ...PLY REGULATOR 1 0 EA A022 992 8007 001 PWA FUSE 1 ESD SAFE 1 0 EA A024 992 8007 002 PWA FUSE 2 ESD SAFE 1 0 EA A025 992 8038 001 PWA BUFFER AMP 1 0 EA A016 992 8048 001 DRIVER ENC TEMP 1 0 EA A019 992...

Страница 138: ...0 EA CR001 516 0530 000 CAP 01UF 10 100V X7R 1 0 EA C003 516 0555 000 CAP 047UF 10 100V X7R 1 0 EA C001 548 2400 401 RES 10K OHM 1 2W 1 1 0 EA R004 548 2400 446 RES 29 4K OHM 1 2W 1 1 0 EA R005 548 24...

Страница 139: ...1 0 EA C022 516 0792 000 CAP NETWORK 1UF 10 2 0 EA C031 C032 516 0907 000 CAP 0 330UF 10 50V 1 0 EA C025 522 0548 000 CAP 10UF 50V 20 6 0 EA C001 C005 C006 C009 C026 C033 522 0569 000 CAP 100UF 50V 2...

Страница 140: ...DIODE 1N3070 ESD 2 0 EA CR001 CR003 386 0083 000 ZENER 1N4742A 12V ESD 1 0 EA CR002 386 0138 000 ZENER 1N4750A 27V ESD 1 0 EA CR004 516 0453 000 CAP 1UF 100V 20 X7R 2 0 EA C005 C006 522 0628 000 CAP 2...

Страница 141: ...4 0 EA 822 0922 026 RF COND SUPPORT 2 0 EA 822 0922 053 COMBINER COVER SUPPORT 2 0 EA 822 0922 109 STDOFF 25 X 5 35 X 4 40 2 0 EA 839 7855 094 SCHEM COMBINER MB MAIN 0 0 EA 843 5100 030 PWB COMBINER M...

Страница 142: ...150 OHM 5 20W 9 0 EA R001 R002 R003 R004 R005 R006 R007 R008 R010 548 2400 401 RES 10K OHM 1 2W 1 1 0 EA R024 548 2400 466 RES 47 5K OHM 1 2W 1 2 0 EA R022 R023 548 2400 547 RES 301K OHM 1 2W 1 1 0 EA...

Страница 143: ...CR009 CR010 CR011 CR012 CR013 CR014 CR015 CR016 CR017 CR018 CR019 CR020 CR021 CR022 CR023 CR024 CR025 CR026 CR027 CR028 CR029 CR030 384 0743 000 DIODE ARRAY DUAL 8 ESD 5 0 EA CR001 CR002 CR003 CR004 C...

Страница 144: ...131 000 RECEPTACLE 25 POS D 1 0 EA J001 614 0715 000 TERM BD 4 TERM 1 0 EA TB003 620 1677 000 RECEPTACLE PC MT BNC 2 0 EA J007 J008 839 7855 090 SCHEM EXTERNAL INTERFACE 0 0 EA 843 5100 063 PWB EXTERN...

Страница 145: ...07 2 J008 2 J009 2 J010 2 J011 2 J012 2 J013 2 J014 2 J015 2 J016 494 0345 000 CHOKE RF 1 2 UH 1 0 EA L017 522 0628 000 CAP 220UF 400V 20 6 0 EA C001 C002 C003 C004 C005 C006 540 1600 422 RES 75K OHM...

Страница 146: ...WEAR 23 0 EA 328 0073 000 WASHER RETAINER 23 0 EA 358 0437 000 BUSHING PANEL 252 ID 2 0 EA 358 2635 000 CABLE TIE PUSH MOUNT SNAP IN 12 0 EA 358 3131 000 STUD BRS 1 4 20 X 1 1 0 EA J002 GND 358 3172...

Страница 147: ...A 822 0922 128 STUD 1 4 20 X 1 9 1 0 EA 2E2 822 0922 129 SHAFT 5 1 0 EA 822 0922 130 SHAFT 14 1 0 EA 822 0922 133 SPARK BRKT 1 0 EA 822 0922 134 SPARK BRKT 1 0 EA 822 0922 138 STRAP 1 0 EA C4 STDOFF 8...

Страница 148: ...5 RES 3 9 OHM 3W 5 2 0 EA 542 1006 000 RES 5 4 OHM 766W 10 3 0 EA R001 R002 R003 560 0049 000 MOV 4500A 75J 275VAC 2 0 EA 560 0077 000 VARISTOR 275VRMS 30KA 8 0 EA RV001 RV002 RV003 RV004 RV005 RV006...

Страница 149: ...Schematic Analog Input Board 839 7855 100 DX50 Cabinet Outline 839 7855 152 FD Chart DX25 839 7855 138 Tuning Chart DX25 839 7855 142 Schematic Output Monitor 843 5400 101 Schematic DC Regulator 839...

Страница 150: ......

Страница 151: ...requency Divider Integrated circuits U1 and U2 are dual J K flip flops used as frequency dividers Each IC section is connected as a divide by two circuit The signal at P2 2 is one fourth the crystal f...

Страница 152: ...A 5 1 2 1 CMOS switch U4 Observe the DC voltage at U4 6 while depressing S4 on the LED Board The voltage should change from LOW to HIGH If the DC voltage changes from LOW to HIGH but there is no RF ou...

Страница 153: ...ymptom Output At Incorrect Frequency A 5 4 1 Possible Cause Frequency Divider Jumper Plug P2 Check the position of the P2 The crystal frequency will be divided by four if P2 is from 1 2 and will be di...

Страница 154: ...oscillator jumper 1 3 or external oscillator jumper 1 2 C1 P4 For normal operation jumper 2 3 For combined transmitter operation jumper 1 2 F2 P5 Selects a 50 Ohm input impedance for external oscillat...

Страница 155: ...d Q4 The two RF drive signals to the MOSFET gates are 180 out of phase note the dots indicating phase of each secondary winding on T1 Transistors Q3 and Q4 switch between ground and the DC supply Diod...

Страница 156: ...ial Cable or Connector Fault With all power removed from the transmitter you can remove P4 from the Oscillator Board and check for a 50 Ohm resistance into P4 8 and 9 this indicates that the coaxial c...

Страница 157: ...ndicates open fuse A16F3 D3 A16F1 Pre driver Section A FUSE Protects the 30 or 60 Volt supply from faults in the pre driver C3 A16F2 Pre driver Section B FUSE Protects the 30 or 60 Volt supply from fa...

Страница 158: ......

Страница 159: ...nd about zero Volts and the positive supply voltage at an RF rate Amplifier efficiency is high because each MOSFET switches between cutoff and saturation in a very short time Dissipation is lowin both...

Страница 160: ...d Diagram 817 2099 031 Figure C 2 RF Amplifier Operation Half Quad Configuration 817 2099 032 Figure C 3 RF Amplifier Operation Full Quad Configuration 817 2099 033 DX 25U C 2 888 2297 002 WARNING Dis...

Страница 161: ...an arc which can crack the toroid The quad amplifier configuration and reverse diodes in the MOSFETs provide an RF current path as described in the next paragraphs This explanation is based on simpli...

Страница 162: ...bands the input circuit so that no component changes are required for operation at any frequency in the broadcast band For T1 this network consists of L3 R3 R22 and L6 for T2 the network consists of L...

Страница 163: ...TSINK MAY DISTORT Remove all the screws from heatsinks and transistors In most cases the transistor will stick to the heatsink because of the seal created by the transistor pad This seal will have to...

Страница 164: ...mplifier is put back in place and the transmitter is turned back on For example Are the A and the B halves of the amplifier receiving the proper drive Is the amplifier receiving a proper ON OFF contro...

Страница 165: ...is a short circuit failure or when the power MOSFETs try to conduct supply voltage when the amplifier is switched ON C7 DS3 Indicator LED Illuminates when module receives ON command for Modulation En...

Страница 166: ......

Страница 167: ...odules The Predriver supply voltage from the 60 VDC supply goes through rheostat R1 and enters the board at J28 2 The supply is fed through metering circuits R9 R10 R11 and R12 and then to J1 where it...

Страница 168: ...ransformer T10 is a torroidal transformer located between the Driver Combiner Motherboard and the RF Drive Splitter DX 25U D 2 888 2297 002 12 12 94 WARNING Disconnect primary power prior to servicing...

Страница 169: ...the regulator section from the Open Loop Adjust control through a voltage follower or from the output of a differential amplifier with inputs from the Closed Loop Adjust control and from the RF drive...

Страница 170: ...ain and Q3 Q4 Q7 source The voltage DIFFERENCE between Q2 s drain voltage and regulator output voltage A is divided by the voltage divider consisting of R22 R24 and R25 As Q2 drain becomes more positi...

Страница 171: ...and R3C and the voltage drop across the resistor is measured Resistors R44 and R45 are voltmeter multiplier resistors E 4 8 4 Driver Amplifier D8 Voltages DRIVER 8A VDC and DRIVER 8B VDC The Driver Su...

Страница 172: ...ossible short circuits to ground in the 115 VDC supply components cabling and on the Driver Supply Regulator If F10 is good check for loose connector or other open circuit between the 115 VDC supply o...

Страница 173: ...S1 is in the Open Loop position R2 adjusts RF drive level to the power ampli fier by varying supply voltages to driver sections 8A and 8B D6 R12 When S1 is in the Closed Loop position R12 adjusts RF...

Страница 174: ......

Страница 175: ...Volt DC ranges the multimeter is a 10 000 Ohm per Volt meter For current ranges the meter acts as a voltmeter measuring the voltage drop across a resistor in the DC current path One side of the meter...

Страница 176: ......

Страница 177: ...ules The current at that instant is this total voltage divided by the combiner load impedance approximately 8 Ohms At25kWcarrierpower theRFcurrentinthecombinerisnominally 40 Amperes At a 100 positive...

Страница 178: ...ller there are more turns in the combiner transformer primary windings In addition four of the Binary steps 1 2 1 4 1 8 and 1 16 have tapped transformer primary windings for fine adjustments in step a...

Страница 179: ...nitor H 2 2 Output Monitor The Output Monitor contains circuits to detect a VSWR condi tion when arcs faults or impedance changes occur in the trans mitter bandpass filter output network or in the ant...

Страница 180: ...urrent sample from T9 enters the board at J3 6 is fed to parallel resonant circuit L5 through L8 and C12 C39 and C47 Switch S7 is used to select coarse values of inductance and capacitance The voltage...

Страница 181: ...2 2 9 Directional Coupler Circuit Description A voltage proportional to RF current from the Output Sample Board enters the board at J1 3 and J1 5 and is fed to the anodes of CR28 and CR33 The voltages...

Страница 182: ...the MEDIUM power sample A logic HIGH signal at J2 7 will turn on Q3 and Q4 through CR18 This will energize both K1 and K2 for the HIGH power sample H 2 2 12 5 VDC And 5 VDC Regulators DC supplyinputst...

Страница 183: ...ing Reflected Power meter P2 Directional Coupler Reflected Balance Coarse adjustment Jumper plug is set according to Frequency Determined Components Chart R23 Adjusts Bandpass Trip sensitivity R24 Adj...

Страница 184: ...ent TP10 Bandpass Filter phase angle detector current sample used during phase angle detector adjustment TP7 5 Volt regulator output test point TP2 5 Volt regulator output test point TP4 Antenna Thres...

Страница 185: ...er than the input impedance some overshoot will result If the source impedance is less than the input impedance high frequency response will change slightly J 2 3 Instrumentation Amplifier U6 U9 An In...

Страница 186: ...hen the transmitter is switched between HIGH MEDIUM and LOW power levels The audio signal will also change proportionally with the DC com ponent J 2 7 1 BCD Logic Input To U8 The BCD power control sig...

Страница 187: ...erator differential amplifier U19 J 2 9 1 1 Square Wave Generator U19 Differential amplifier U19 operates open loop so its gain is very high Assuming no Big Step Sync input inverting input U19 2 is at...

Страница 188: ...s including a BCD Binary Coded Decimal Control Signal from Con troller A38 is Zero With the transmitter ON use an oscil loscope or voltmeter to check Power Control Lines at inputs to U17 and U18 If th...

Страница 189: ...git Binary Number Decimal Number Binary Number 0 0000 5 0101 1 0001 6 0110 2 0010 7 0111 3 0011 8 1000 4 0100 9 1001 Table J 1 Decimal to Binary Power Level Decimal BCD Binary Coded Decimal Maximum Po...

Страница 190: ...rd A35 Controls and Indicators LOCATION COMPONENT FUNCTION DESCRIPTION C3 TP1 Audio sample output of input amplifier about 1 5 Vp p audio at 100 modulation no DC component C3 TP2 Ground D4 TP3 Max Pwr...

Страница 191: ...g of wide band toroidal RF transformer T1 Resistor R18 and an L C network with components selected by section of DIP switch S1 provide adjust able frequency determined phase shift refer to the Tuning...

Страница 192: ...ive pulse from DL1 goes to the input of U7 pin 1 and is the signal DATA STROBE L on J6 26 The signals on the J6 connector go to the Modulation Encoder board The rising edge of the DATA STROBE L is use...

Страница 193: ...signal K 3 7 2 Amplifier Stage U24 U25 U26 The output of the A D converter is amplified by U24 and U25 The gain of the amplifier stage is slightly over 5 U24 is an operational amplifier and U25 is a c...

Страница 194: ...s a CONVER SION ERROR on the LED Board the problem is in the indicator circuits Check DS1 on the Analog to Digital Converter If the ColorStat panel Conversion Error indicator is RED but A34DS1 is GREE...

Страница 195: ...lts JP10 Selects division ratio for A D sample divide by 1 2 or 3 Refer to schematic diagram or Frequency Determined Components chart JP11 Enables RF sample phase correction circuit when in position 1...

Страница 196: ......

Страница 197: ...rectly by the individual bit If the bit is a logic HIGH then the associated RF amplifier is turned ON If the bit is a logic LOW then the associated RF amp is turned OFF a B7 1 2 Step b B8 1 4 Step c B...

Страница 198: ...of the DS0026 driver is taken from two internal transistors The collector of the pull up current source transistor is connected to the B supply 5 75 VDC and the emitter of the pull down current sink...

Страница 199: ...the A37 Modulation Encoder at J18 8 Inverter U56 4 goes to a logic HIGH which drives U53 8 to logic LOW This forces U59 2 to logic LOW and produces the PAOff L signal The Cable Intrlk Fault triggers...

Страница 200: ...by simply holding all Binary Steps ON if excessive audio input causes the A D converter to attempt to turn ON a Big Step that does not exist A CLIP patch cable is used to jumper P15 to the first unus...

Страница 201: ...on the Modulation Encoder will be traced back to PA Off signals from other printed circuit boards Failure of logic gates inverters or drivers can also cause a PA Off indication and a logic probe or a...

Страница 202: ...Figure L 2 Mod Encoders Interconnect Diagram Figure L 3 DX 25U L 6 888 2297 002 Rev T2 06 27 97 WARNING Disconnect primary power prior to servicing...

Страница 203: ...Figure L 4 Cable Interlock RF Amp Fault Indicator Section L Modulation Encoder A37 Rev T2 06 27 97 888 2297 002 L 7 WARNING Disconnect primary power prior to servicing...

Страница 204: ...inted circuit board fault or con nector damage These are unlikely but careful visual inspection could show a printed circuit board fault short damaged pc board trace poor solder joint or a damaged con...

Страница 205: ...ION COMPONENT FUNCTION DESCRIPTION A1 TP1 Test Point for Modulated B voltage C1 TP2 Test Point for 5 Volt regulator output C2 TP3 Test point for DATA STROBE logic signal logic HIGH pulses D1 TP4 Test...

Страница 206: ......

Страница 207: ...n on board regulated supplies on other printed circuit boards in the transmitter Additional regulated supplies using this IC are a Analog to Digital Converter A34 1 15 Volt supply 2 15 Volt supply 3 5...

Страница 208: ...U3 Q1 The output voltage is determined by the reference voltage at pin 8 Vref and the voltage sample divider R16 and R19 The regulator controls the output voltage so that the reference voltage at pin...

Страница 209: ...the setting of adjustable resistor R51 in the output voltage sample divider The error amplifier in U6 com pares the pre distorted reference voltage at pin 9 and a sample of the supply output voltage...

Страница 210: ...3 of U4 establishes the over voltage threshold at approximately 3 7 VDC and Pin 4 TP16 of U4 establishes the under voltage threshold at approximately 3 0 VDC M 2 11 3 5V Detector The 5 VDC detector mo...

Страница 211: ...lock circuitry should be inspected for a short circuit or evidence of discoloration due to overheating M 3 1 2 MOD ENC 5V Fault The 5 VDC is derived from the B voltage on the Modulation Encoder A37 an...

Страница 212: ......

Страница 213: ...ver Compartment door Each TYPE of interface circuit is described in the following paragraphs Sheet three of the schematic diagram provides a summary of information for each type of interface circuit i...

Страница 214: ...Figure N 2 External Interface Typical Control Input Circuits 817 1280 087 Figure N 3 Equivalent Circuits For Calculating Effect of Circuit Loading on Monitor Voltage Outputs 817 1280 088 DX 25U N 2 8...

Страница 215: ...urce resistance for each voltage divider output are given on sheet 3 of the schematic diagram if you are not familiar with Thevenin equivalent circuits see Figure N 3 N 3 3 2 Operational Amplifier Buf...

Страница 216: ...xternal Inputs Missing If the 15 VDC from TB1 11 or the 15 VDC from TB1 12 is used check for presence of this voltage If the voltage is missing check voltage regulator U6 for 15 VDC at its output and...

Страница 217: ...rface transistors are in DIP integrated circuit packages pin outs are shown on the External Interface sche matic diagram Check for a transistor emitter collector short by removing primary power from t...

Страница 218: ......

Страница 219: ...F The transmitter has no filaments to warm up so a TURN ON REQUEST from the power control logic immediately energizes K1 to start the PA Power Supply step start sequence Primary AC is initially applie...

Страница 220: ...ON h At this time approximately 1 2 seconds has elapsed since the TURN ON REQUEST and the transmitter is ON The 1 6 second K1 TURN ON pulse will continue to remain HIGH for approximately 0 4 seconds t...

Страница 221: ...Figure P 1 Block Diagram Turn On Rurn Off Control Logic Section P Controller A38 Rev S 05 02 97 888 2297 002 P 3 WARNING Disconnect primary power prior to servicing...

Страница 222: ...e latch is clocked by the Power Level Change pulse g INHIBIT GATES The inhibit gates prevent the LOW MEDIUM or HIGH command from generating a TURN ON REQUEST signal if there is FAULT present The comma...

Страница 223: ...ked into Power Level Latch U40 c Clears the Power Latch circuits on the Analog Input Board This brings the power control data lines to zero d Clears the turn on one shot IC U56A 13 This prevents gener...

Страница 224: ...the Underdrive Inhibit B signal which resets the Underdrive Fault detector Refer to Section Q LED Board for a description of Underdrive Fault circuits The output of U59 6 also drives the 0 3 second d...

Страница 225: ...EMOTEinputturns the opto isolatorON and pulls the collector line to ground unless the LOCAL RE MOTE switch is in the LOCAL position The opto isolator output is paralleled with the corresponding Local...

Страница 226: ...erates a delayed pulse to strobe the Power Level Data latches on the Analog Input Board P 6 3 1 6 Inverters U41 2 4 6 8 10 12 All six Decoder outputs are inverted by the six sections of Hex Inverter U...

Страница 227: ...s then happen simultaneously 1 The Step start sequence begins 2 The Oscillator output is switched ON 3 The DC Regulator circuits are enabled 4 The Driver Encoder Temp Sense Board turns the Driver Modu...

Страница 228: ...Figure P 3 Block Diagram Power Control Section DX 25U P 10 888 2297 002 Rev S 05 02 97 WARNING Disconnect primary power prior to servicing...

Страница 229: ...ate are a CLOCK pulse b RAISE H or LOWER H logic signal c HIGH MEDIUM or LOW power level select signal d INHIBIT signal The clock pulse train alternates between HIGH and LOW states Clock pulses will a...

Страница 230: ...through H12 H1 is the Most significant bit H12 is the least significant bit H1 through H4 represent the first decimal digit H5 through H8 the second and H9 through H12 the third Examples Decimal BCD B...

Страница 231: ...Schematic 843 5400 091 on the left side of the sheet Status indicator drive outputs are a RAISE LOWER HIGH MEDIUM LOW status Logic HIGH inputs illuminate indicator lamps in the buttons on the transmit...

Страница 232: ...doors are open 30 Vdc is applied to the Door Interlock input on the Controller through a resistor on the DC Regulator The InterlockString circuitappliesalogicHIGHfromthe 30Vdc supply for the interlock...

Страница 233: ...Figure P 7 Controller Board Interlock Status Logic Simplified Diagram 817 2099 026 Section P Controller A38 Rev S 05 02 97 888 2297 002 P 15 WARNING Disconnect primary power prior to servicing...

Страница 234: ...and U60 1 is HIGH P 7 5 Door Interlock Normal Operation When the Door Interlock is closed no fault present Q9 2 is grounded logic LOW and the transistor is OFF The collector goes HIGH and charges C81...

Страница 235: ...15 seconds a Door Interlock Fault output is generated P 7 8 3 Inhibit Transistor Q9 7 Transistor Q9 7 prevents an Interlock String fault caused by de energizing External Interlock relay K3 from gener...

Страница 236: ...E Do not install back up batteries unless C44 is charged 5B voltage at TP6 is greater than 4 5 Volts Current drain from the batteries into C44 will shorten battery life P 9 3 1 Replacing Batteries Bec...

Страница 237: ...Failure When primary AC is restored after a power failure the transmit ter will automatically recycle ON at the same power level and operating condition as before the power failure unless the power f...

Страница 238: ...BT3 Battery holders for three 1 5 Volt AA cells for optional long term battery back up for 5B supply DO NOT USE RECHARGEABLE BATTERIES DS1 Red LED illuminates if one or more voltage regulators provide...

Страница 239: ...r condition the OVER TEMP LED on the Driver Encoder Temp Sense Board will latch RED to indicate power reduction has occurred A single VSWR trip does not lower transmitter power but generates a Type 4...

Страница 240: ...r B Regulator Fault 5V Output Monitor 5V on board Regulator Fault 15V Output Monitor 15V on board Regulator Fault REPEATING TYPE 2 FAULT See NOTE below TYPE 2 TURNS PA POWER SUPPLY OFF Recycles Back O...

Страница 241: ...Figure Q 1 LED Board Block Diagram Section Q LED Board A32 Rev R 11 11 96 888 2297 002 Q 3 WARNING Disconnect primary power prior to servicing...

Страница 242: ...ollows a RF Drive Switch over signal Refer to SECTION A Os cillator b VSWR Induced Lower Refer to SECTION P Controller The VSWR Self Test circuit checks the VSWR Fault logic by simulating a VSWR signa...

Страница 243: ...HIGH When Reset B goes HIGH the Retrigger Gate output also goes HIGH and triggers the latch again Q 4 8 3 Latch Outputs The following description refers to Figure Q 3 Latched Fault Status Indications...

Страница 244: ...Figure Q 2 Reset Circuit Simplified Diagram 817 1280 101 A DX 25U Q 6 888 2297 002 Rev R 11 11 96 WARNING Disconnect primary power prior to servicing...

Страница 245: ...Q 5 2 1 Type 1 Fault Logic Type 1 Fault logic on the LED Board is shown on sheet 1 of the LEDBoard schematic 839 7855 184 atgridlocationsC1through C3 Type 1 Fault logic includes OR gate U32 OR gate U...

Страница 246: ...Q 5 2 3 4 Inhibit Air Interlock Status Indication Gates U62 pins 8 and 11 When the transmitteris firstturned ON and the Overdrive Inhibit is released the Inhibit logic in the Air Flow circuit generate...

Страница 247: ...on the LED Board The inverting input of the comparator is a fixed reference voltage derived from the 15 VDC regulated supply Normally the sample is lower than the reference voltage and the comparator...

Страница 248: ...ly temporary or transient conditions such as current overloads caused by overmodulation Turning the PA Power Supply OFF may correct the condition so Type 2 Faults cycle the transmitter OFF then back O...

Страница 249: ...between the negative side of the PA Power Supply and ground and is also the shunt for the 100 Ampere supply current meter Voltages at the differential amplifier input are small 50 millivolts across t...

Страница 250: ...Both the RED and GREEN sections of the bicolor LED are ON OFF Occurs during the 2 4 second timeout period RED Occurs if the Type 2 Fault is detected again before the 2 4 second timeout Q 5 4 Type 3 F...

Страница 251: ...ault is detected during the 0 5 second pulse output the output pulse will be extended another 0 5 second The one shots are inhibited by the Supply Fault L signal from the Controller during turn on whe...

Страница 252: ...OR ed by U38 11 then inverted by U38 3 to provide the VSWR H output A single VSWR hit will send a 0 5 second logic HIGH pulse to the External Interface and a latched VSWR output will remain HIGH unti...

Страница 253: ...de a VSWR Self Test Indicate output Q 5 4 6 1 Manual VSWR Self Test Inputs Depressing the Manual Test switch S2 on the ColorStat panel will ground U25 9 and the output pin 8 will go LOW The other inpu...

Страница 254: ...t pulse to the Output Monitor is detected the D input pin 2 of U42A will be HIGH when the latch is clocked and outputs and indication circuit conditions will be as follows a Q Output HIGH Invertor U26...

Страница 255: ...Figure Q 5 VSWR Logic Simplified Diagram 817 2099 037 Section Q LED Board A32 Rev R 11 11 96 888 2297 002 Q 17 WARNING Disconnect primary power prior to servicing...

Страница 256: ...Conversion Error logic signal from the Conversion Error circuit on the Analog to Digital Converter at U25 pin 1 When the OVERDRIVE INHIBIT L signal is present the output of the gate will be LOW no ma...

Страница 257: ...Figure Q 6 VSWR Self Test Logic Simplified Diagram 817 1280 106 Section Q LED Board A32 Rev R 11 11 96 888 2297 002 Q 19 WARNING Disconnect primary power prior to servicing...

Страница 258: ...rtor output is LOW the outputs of AND gates U6 3 and U6 8 are forced LOW no matter what the other gate inputs are The LOW output of gate U6 8 also forces gate U6 11 output LOW The Buffer and Predriver...

Страница 259: ...Figure Q 7 Regulated Supply Fault Sensing Circuits 817 1280 107 Section Q LED Board A32 Rev R 11 11 96 888 2297 002 Q 21 WARNING Disconnect primary power prior to servicing...

Страница 260: ...Figure Q 8 RF Sense Circuits Simplified Diagram 817 1280 099 DX 25U Q 22 888 2297 002 Rev R 11 11 96 WARNING Disconnect primary power prior to servicing...

Страница 261: ...cates RED when a VSWR occurs because of an antenna system load fault or mistuning of the transmitter Tee matching network Tune and Load controls DS5 Indicates RED when a 15 Volt regulator fault occurs...

Страница 262: ...V Power Supply Peak Current overload circuit reference voltage comparator inverting input TP6 HV Power Supply Average Current overload circuit reference voltage comparator inverting input TP12 HV Powe...

Страница 263: ...ly by demulti plexer U8 which selects the appropriate LED to illuminate corresponding to the selection made with the front panel switch The LED s are connected to the 15vdc bus via resistors then thro...

Страница 264: ...s on which various meter ing circuits are located b Metering Circuit Fault Again refer to the paragraphs on Principles of Operation above for location of metering circuits Possible faults include 1 Op...

Страница 265: ...oling fans the AIR FLOW REDUCED LED DS7 will illuminate The AIR LED on the ColorStat panel will change from GREEN to AMBER 2 If the air flow is further reduced because of restricted filters or the fai...

Страница 266: ...gulator will reduce the B voltage to D8A and D8B to keep the RF drive within the correct range The Driver Supply Regulator will then continue to regulate the RF drive level by adjusting the voltage to...

Страница 267: ...tiometer R51 buffered by operational amplifier U9 and ampli LOCATION COMPONENT FUNCTION DESCRIPTION D5 DS1 DRVR illuminates when D7 is turned on D6 DS2 OVER TEMP illuminates when power reduction sign...

Страница 268: ...tion is in process At this point NAND gate U8 9 is held HIGH by U11 13 while U8 10 toggles from HIGH to LOW Each time U12 12 goes LOW output U8 8 will go HIGH This HIGH pulse to the Controller will sl...

Страница 269: ...rcuit is established between J1 9 and J1 19 from Driver Modules D8 through D14 and between J2 9 and J2 19 from Driver Modules D1 through D7 Both interlock circuits are identical Therefore only the int...

Страница 270: ......

Страница 271: ...enclosed in an RF free space d Electromagnetic pulse EMP This is a interfering signal pulse that enters the system by magnetic coupling trans former Generally caused by lightning Lightning from cloud...

Страница 272: ...surges on the lines followed by a surge protector The surge protector must be connected to the building ground system by short direct connections A surge protector is a solid state device that is a h...

Страница 273: ...urrent flowing in the shield but does not affect the signal currents a 5 Conclusion The 1 chance of a major lightning strike probably can not be protected against but the other 99 can be controlled an...

Страница 274: ...Figure a 6 Basic Elements of a Properly Designed Antenna System Figure a 7 Surge Protectors and Ferrite Choke a 4 WARNING Disconnect primary power prior to servicing...

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