Field Modification FM Upgrade for XL12 Transmitters to IBOC/DRM DAB Compatibility. Original Issue 19 December 2005

Transcription

1 Field Modification Upgrade for XL12 Transmitters to IBOC/DRM DAB Compatibility Original Issue 19 December 2005 Nautel Limited Peggy's Cove Road, Hackett's Cove, NS, Canada B3Z 3J4 T F U.S. customers please contact: Nautel Maine, Inc. 201 Target Industrial Circle, Bangor ME T F Copyright 2005 NAUTEL. All rights reserved.

2 Upgrade for XL12 Transmitters to IBOC/DRM DAB Compatibility FIELD MODIFICATION 1 GENERAL INFORMATION This document provides instructions for the customer to modify the subject equipment in the field. 1.1 Reason for Modification This modification upgrades an XL12 Transmitter to allow for compatibility with IBOC/DRM DAB. 1.2 Equipment Affected This modification affects XL12 transmitters with serial numbers H101 or B101 and greater that have RF drive tuning PWB NAPI59, NAPI60 or NAPI62. Units affected include transmitters equipped with single or dual exciters, NAPM06 through NAPM06H/02 Interphase PDM Driver PWB, and NAPE58 RF Drive PWB. 1.3 Responsibility for Implementation of Modification This modification should be implemented by qualified transmitter maintenance personnel. 1.4 Scheduling Implement this modification at the convenience of station maintenance personnel. 1.5 Manpower Requirements This modification requires approximately four man hours. It is necessary for the transmitter to be placed in an off-air status for the duration of this procedure. 1.6 Special Tools/Test Equipment An oscilloscope, digital multimeter, and frequency counter are required to complete the procedure. Tools consist of standard electronic hand tools. Static precautions should be observed when working on any solid state equipment. 1.7 Materials The materials required to complete this modification are identified in Table 1. (see Table 1) *. The number of RF power modules required depends on the transmitter type and the number of spares owned. The correct quantity will be determined by Nautel Customer Service when the order is placed. ** The number of RF Synthesizer PWBs and interphase PDM driver PWBs required depends on single or dual exciters. The correct quantities will be determined by Nautel Customer Service when the order is placed. Table 1: Materials Qty Description Part # 1 Documentation, XL12 IBOC/DRM Upgrade * Power Module Assembly Upgraded Power Module ** RF Synthesizer PWB NAPE70B ** Interphase PDM Driver PWB Assembly NAPM06H/03 1 NAPM06H/03 Interphase PDM Driver Manual - 1 NAPE70B RF Synthesizer Manual - 1 Upgraded Power Module Manual - Field Modification Page 1 of 8 Issue 1.0

3 Table 2: Changes to Transmitter Manual Parts List Ref Des Name Of Part And Description Nautel s Part # Jan/Mil/OEM Part No. OEM Code A1 RF Synthesizer PWB NAPE70B See NAPE70B Booklet A4 RF Synthesizer PWB NAPE70B See NAPE70B Booklet A5 Interphase PDM Driver NAPM06H/03 See NAPM06H/02 Booklet A6 Interphase PDM Driver NAPM06H/03 See NAPM06M/02 Booklet Publications Affected This upgrade affects the transmitter s documentation. Changes to affected pages should be made using pen and ink to ensure permanence. The following sections of the transmitter manual will be changed: Figure Family Tree: Change the nomenclature and description of the existing RF drive PWB, to NAPE70B RF Synthesizer PWB. Change the nomenclature of the existing interphase PDM driver PWB to NAPM06H/03. Table 7-5 Ref Des Index - Exciter Interface PWB: Change line items referenced in Table 2. Service Instruction Manuals (in Appendices binder): Replace existing RF Power Module manual with replacement variation. Replace existing NAPM06 Interphase PDM Driver PWB manual with the NAPM06H/03 variation. Replace existing NAPE58 RF Drive PWB manual with the NAPE70B RF Synthesizer PWB manual. 2 MODIFICATION INSTRUCTIONS For single exciter transmitters, disregard references 'A1A4' and 'A1A6' on the exciter panel. 2.1 Preparing the Transmitter for Modification The transmitter must be shut down while performing this modification. Set the control switch to LOCAL Press the RF POWER increase and decrease simultaneously to set output power to 0 W. Press RF OFF and switch off the ac to the transmitter at the main disconnect. 2.2 Interphase PDM Driver PWB Gain access to the exciter panel (NAE74) located behind the control/monitor panel Locate the interphase PDM driver PWBs (A1A5 and A1A6) on the exciter panel (see Figure 1) Remove and retain the four sets of hardware securing each PWB to the chassis. Remove the PWBs Obtain the upgrade interphase PDM driver PWBs (NAPM06H/03). Using retained hardware, secure the upgrade PWBs to the chassis where the removed PWBs were located. Page 2 of 8 Issue 1.0 Field Modification

4 2.3 RF Drive PWB Locate the RF drive PWBs (A1A1 and A1A4) on the exciter panel (see Figure 1) Remove and retain the four sets of hardware securing each PWB to the chassis. Remove the PWBs Obtain the upgrade RF synthesizer PWBs (NAPE70B). Using retained hardware, secure the upgrade PWBs to the chassis where the removed PWBs were located. 2.4 RF Power Module Locate the two (2) RF power module cover panels found below each row of RF power modules. Remove the cover panels by turning the quick release latches, or removing the two screws from each panel. Retain the two (2) panels. Refer to Figure MD-1 in the transmitter manual as a locating aid Starting with the RF power module in the top left corner, unscrew the thumbscrews on the connector connected to J1 of the module. Remove the connector from the module by pulling down on the connector Loosen the self retaining screw at the bottom front of the module. Carefully pull the module forward and lift it out of the transmitter Repeat steps and for the seven (7) remaining RF power modules in the transmitter. Do not over tighten the self retaining screw located behind connector J1. The screw is part of the RF power module's mechanical interlock and only needs to be hand tightened Starting at the top left corner place one (1) of the upgrade RF power modules into the transmitter. Ensure the module is pushed firmly into place. Tighten the screw located at the bottom front of the module. Reconnect the connector to J1 on the module, and tighten the two (2) thumbscrews on the connector Repeat step for six (6) of remaining RF power modules, leaving the position of RF power module D (A6) empty. Refer to MD-1 in the transmitter manual as a locating aid Replace any existing spare RF power modules that have been supplied with the modified parts. Retain all packing materials to return all replaced PWBs and RF power modules to Nautel in good working condition for credit. 3 TESTING The setup of the PWBs is for normal analog broadcasting. The setup for IBOC/DRM broadcasting is contained in a separate document. 3.1 Confirmation of PWB Setup Locate the interphase PDM driver PWBs (NAPM06H/03, A1A5 and A1A6) on the exciter panel. Ensure that jumpers E1 through E5 are set for NORM. Set AUDIO FILTER DIP switch S1 to the same positions as the PWB removed in section Locate the RF synthesizer PWBs (NAPE70B, A1A1 and A1A4) on the exciter panel. Ensure that jumpers are set as follows: - E1, E2 and E4 are set for INT. - E3 is set to HIGH. - E5 is set to position D. - E6 is set to ENABLE. Field Modification Page 3 of 8 Issue 1.0

5 J Ensure that the selector switches (S1 through S4) on the RF synthesizer PWB are set to the carrier frequency in khz and S5 is set to Set selector switch S6 according to Table A-1 in the NAPE70B Service Instructions manual for the desired carrier frequency. 3.2 RF Synthesizer PWB Setup Connect an oscilloscope probe between TP7 and TP4 (ground) on the exciter A RF synthesizer PWB (A1A1) Turn on the ac to the transmitter. Press RF ON and confirm that exciter A is selected The oscilloscope indication should be a symmetrical (50% duty cycle) square wave at the carrier frequency, with a nominal peak-to-peak amplitude of 15 V If the indication is not a 50% duty cycle adjust the SYMMETRY potentiometer (R32) until a 50% duty cycle is achieved Monitor TP2 with a frequency counter. It should read the desired 2ƒc/N frequency, between 240 khz and 280 khz Connect the oscilloscope probe between TP7 and TP4 (ground) on the exciter B RF synthesizer PWB (A1A4). Select exciter B on the front panel. Repeat steps through Select EXCITER A. Turn off the ac to the transmitter Disconnect the oscilloscope probe from the PWB. Figure 1: Exciter Panel Page 4 of 8 Issue 1.0 Field Modification

6 Q8 Q6 Q7 Q5 PA Top View (as mounted) Gate Lead RF AMPLIFIER Ground A2A1 RF AMPLIFIER A2A2 MODULATOR A2A3 Figure 2 - PA Voltage Monitoring Point 3.3 RF Power Module Tuning On the remaining upgraded RF power module, remove and retain the seven (7) screws that secure its cover. Remove the cover. Connect an oscilloscope probe to the gate lead of FET Q6 in RF amplifier A2A2 (see Figure 2). Carefully install the RF power module back into the transmitter in position D (A6) as outlined in step 2.4.5, ensuring not to damage the oscilloscope probe. Step and apply only to transmitters equipped with dual exciters (A and B) For transmitters equipped with the NAPC103B through NAPC103G System Control PWB (on the rear of the control panel door), record the position of selector switch S19, then move the selector switch to the AUTO XFR INHIBIT position. Power Module Right Side View For transmitters equipped with the NAPC103 or NAPC103A System Control PWB (on the rear of the control panel door), record the position of selector switch S19. Set the switch on the system control PWB to the Exciter A position and install the jumper on the pins at E2 (CHANGEOVER INHIBIT), recording its original position Remove and retain the cover from the RF drive section located at the bottom front of the transmitter. It is held in place by four (4) quick release latches or four (4) cross-head screws. Refer to MD-1 in the transmitter manual as a locating aid Switch on the ac to the transmitter. Press RF POWER increase and decrease simultaneously to set the power to 0 W. Verify exciter A is selected, and press RF ON. Ignore the RF DRIVE alarm if it is present. Field Modification Page 5 of 8 Issue 1.0

7 3.3.6 Monitor the RF drive level on the oscilloscope and adjust potentiometer R3 on exciter A s regulated power supply PWB (see Figure MD-8 in the transmitter manual) until the level on the oscilloscope is 23 V pk to pk. Press SYSTEM RESET. The RF DRIVE alarm should now be off Locate the RF drive tuning PWB (on the RF drive panel; see Figures MD-1 and MD-8 in the transmitter manual) Connect the positive lead of a digital multimeter (set to read dc voltage) to TP5 (RF power module A) on the RF drive tuning PWB and the negative lead of the meter to TP13 (ground). Take care when inserting the multimeter leads into the test points on the RF drive tuning PWB. The tip of the multimeter lead can be pushed through the PWB and short the test point to the chassis (ground). This will make tuning impossible Select FORWARD POWER on the power meter and increase the output power to 1000 W Using the beryllium copper screwdriver (Nautel Part # HAZ79), from the ancillary kit that was shipped with the transmitter, adjust the tuning inductor that is accessible through the front panel of the Power Module A (A3), for a low voltage reading on the digital multimeter. When you are tuned to the correct level, turning the inductor clockwise or counter clockwise will cause the voltage at the test point to increase. The correct tuned point is a low voltage between two peaks. The beryllium copper screw driver must be removed from the tuning inductor to get an accurate voltage measurement Repeat step for the remaining seven power modules using Table 3 as a guide for connecting the positive multi-meter lead Repeat Step Select EXCITER B. Monitor the level on the oscilloscope and adjust potentiometer R3 on exciter B s regulated power supply PWB (see MD-8 in the transmitter manual) to obtain a level that is 23 V peak to peak Any spare upgraded RF power module(s) should fine tuned. Install the spare power module into position C and monitor TP7 (C) on the RF drive tuning PWB while tuning Press RF POWER increase and decrease simultaneously to set power to 0 W. Select RF OFF. Table 3: Tuning Guide RF Power Module Location (Ref Des) Test Point (RF Tuning PWB) A A3 5 - A B A4 6 - B C A5 7 - C D A6 8 - D E A7 9 - E F A F G A G H A H Page 6 of 8 Issue 1.0 Field Modification

8 3.4 Gain Trim Adjustment Select EXCITER A and press RF ON. Set the output power level to 5 kw with no audio applied. Select PA VOLTS to be displayed on the control panel. Record the PA voltage and transmitter output power Switch to EXCITER B and monitor the PA voltage and transmitter output power. If the values monitored from exciter B are not the same as those recorded with exciter A, adjust the GAIN TRIM potentiometer (R51) on exciter B s interphase PDM driver PWB (A1A6 on the exciter panel) until the values are approximately the same Press RF POWER increase and decrease simultaneously to set the power to 0 W. Press RF OFF. 3.5 RF Symmetry Adjustment Monitor the RF drive at K1-1 on the RF drive panel with an oscilloscope Select EXCITER A. Press RF ON and slowly increase to 10,000 W. On the exciter A RF synthesizer PWB (A1A1), adjust the RF DRIVE SYMMETRY potentiometer (R32) until the oscilloscope signal s duty cycle is 50% Select EXCITER B. On the exciter B RF synthesizer PWB (A1A4), adjust the RF DRIVE SYMMETRY potentiometer (R32) until the oscilloscope signal s duty cycle is 50% Press RF OFF, set power to 0 W and turn ac mains off. Remove the oscilloscope from the RF power module and replace the side cover. Reinstall the module back into the transmitter. 3.6 Audio Gain Adjustment Locate the remote interface PWB (A4 on the rear of the control panel). Disconnect the audio feed from inputs TB2-7, TB2-8, and TB2-9, recording where each connects. If there is a second audio connection, disconnect it from TB2-10, TB2-11, and TB2-12, recording where each connects Connect a signal generator to the remote interface PWB, connecting the ground to TB2-7, the positive to TB2-8, and the negative to TB2-9. If the signal generator has an unbalanced output, connect the positive to TB2-8 and the ground to TB Locate AUDIO SOURCE switch S1 on the exciter interface PWB (A1 on the exciter panel, see Figure 1). Record the position of the switch, then set the switch to the SINGLE position Set the signal generator for a 1000 Hz tone with a level of 10 dbm Connect a modulation monitor to the RF MONITOR BNC connector (J2) on the remote interface PWB Turn the ac mains on. Select EXCITER A and press RF ON. Increase the transmitter s output power to 10 kw. Apply the 1 khz tone and adjust the AUDIO GAIN potentiometer (R31) on exciter A s interphase PDM driver PWB (A1A5 on the exciter panel, see Figure 1) for a 95% peak modulation level Switch to EXCITER B and adjust the AUDIO GAIN potentiometer (R31) on exciter B s interphase PDM driver PWB (A1A6 on the exciter panel, see Figure 1) for a 95% peak modulation level. Field Modification Page 7 of 8 Issue 1.0

9 3.6.8 Press RF POWER increase and decrease simultaneously to set the power to 0 W. Press RF OFF Remove the modulation monitor and the signal generator and replace the audio feed(s) to their original connections as recorded in step Return AUDIO SOURCE switch S1 on the exciter interface PWB to its original position as recorded in step COMPLETION OF TESTING The transmitter may now be returned to its on air status. Page 8 of 8 Issue 1.0 Field Modification