Q10 Frequency Change Procedure IS05001 Original Issue 22 February 2005 Nautel Limited 10089 Peggy's Cove Road, Hackett's Cove, NS, Canada B3Z 3J4 T.+1.902.823.2233 F.+1.902.823.3183 info@nautel.com U.S. customers please contact: Nautel Maine, Inc. 201 Target Industrial Circle, Bangor ME 04401 T.+1.207.947.8200 F.+1.207.947.3693 info@nautel.com e-mail: support@nautel.com www.nautel.com Copyright 2005 NAUTEL. All rights reserved.
IS05001 Q10 Frequency Change Procedure INFORMATION SHEET 1 INTRODUCTION The Nautel Q10 transmitter is a tuned transmitter with power amplifiers, a final combinerfilter, protectionmonitoring circuitry and interconnecting coaxial cables that must be adjusted for the desired operating frequency. The selection of frequency sensitive components and adjustment of tuned circuits is normally carried out at the factory for the transmitter's assigned carrier frequency. In the event that a carrier frequency change is required, the following procedures provide the information to change the carrier frequency and realign the appropriate frequency sensitive components. NOTE This procedure should only be attempted by competent personnel with the required test equipment available. Improper tuning at the new frequency can result in a degradation of transmitter specifications and could result in failure of power amplifiers. 1.1 Equipment Affected: This frequency change procedure is written for the Q10 transmitter. 1.2 Responsibility for Implementation of Procedure: Implementation of this procedure is to be carried out by suitably qualified station maintenance personnel. 1.3 Scheduling: This procedure may be implemented at the convenience of station maintenance personnel. 1.4 Manpower Requirements: It is estimated that implementation of this modification will require eight (8) hours to complete. Note that it is necessary for the transmitter to be placed in an off-air status for the duration of this procedure. 1.6 Special ToolsTest Equipment: Table 1 lists the test equipment that is required to complete this procedure. The required equipment is also identified in each section: Table 1 - Required Test Equipment Qty Description 1 Tuning tool supplied with transmitter 1 13 mm Torque Wrench (110 inch pound setting) 1 5.5 mm wrench or nut driver 1 7 mm wrench or nut driver 1 Adjustable wrench 1 short # 1 cross head screwdriver 1 standard # 1 cross head screwdriver 1 ¾ inch deep socket and ratchet 1 FM Exciter (35 watts minimum) Nautel M50, NE50, NE30, or equivalent 2 Inline Wattmeter - Bird Model 43 (with N connectors) and elements for each 500 W, 100 W, and 25 W 1 External Inline Wattmeter - Bird Model 4610-000 (with 3-⅛ EIA flanges) with 15 kw and 5 kw elements 1 N Plug to BNC Plug adapter Amphenol #5225 or equivalent 3 N Plug to BNC Jack adapter Amphenol #31-216 or equivalent 1 Dummy load - 15,000 Watts, VSWR less than 1.05:1 1 Dummy Load - 500 Watts, VSWR less than 1.05:1 1 FM Modulation Monitor 1 Digital Multi-meter (DMM) Fluke 179 1 Clamp Current Meter (>70A) Fluke 36 Q10 Frequency Change Procedure Page 1 of 25 IS05001 Issue 1.0
1.7 Materials Required: Materials required consist of the frequency dependant parts of the transmitter. These parts are listed in Table 2 and will vary depending on the new carrier frequency. Table 2 Parts Required Qty Part Description Number 8 193-8098-xx See Table 5 Power Module Input Cable 1 193-6007-01 87.9 to 91.9 MHz Hardware Kit 1 193-6007-02 92 to 97.9 MHz Hardware Kit 1 193-6007-03 98 to 103.9 MHz Hardware Kit 1 193-6007-04 104to 107.9 MHz Hardware Kit 1 193-8298-01 IPA select on test cable set (W47- W48) 1 193-8299 IPA replacement cable set (W44) 2 INSTRUCTIONS: 2.1 Transmitter Shutdown: Before a frequency change can take place, the transmitter must be turned on for one last measurement before it is decommissioned. 2.1.1 Ensure that there is an external wattmeter on the output of the transmitter. 2.1.2 On the control interface PWB: Disable the HIGH SWR MONITOR circuit by adding a jumper across A36R55 (located below U14). Disable the COMBINER MATCHING alarm by adding a jumper across A36R18 (located to the left of U39). 2.1.3 At the original frequency, turn the transmitter on and set the transmitter forward power to 10 kw on the transmitter front panel RF KILOWATTS power meter A35M1. Measure and record the voltage at A36J6-11 (IPA FWD PWR ADJ). 2.1.4 Set the transmitter forward power to 1 kw (you will have to turn off a few power supplies in order to achieve a 1 kw power level see Q10 Technical Instruction Manual Section 5.15 Low Power Operation for Antenna Maintenance for more information) on the controlmonitor panel RF KILOWATTS power meter A35A1M1. 2.1.5 Remove the two combiner skirts located on the top of the transmitter. These are held in place with two crosshead screws each and are located to the left and right of the power probe. Disconnect plug P43 forward power sample connector from output power probe A34A2J1. Disconnect plug P44 reflected power sample connector from output power probe A34A2J2 and reconnect it to A34A2J1. See MD-10 in the transmitter manual. 2.1.6 Press Meter Scale Select for RF KILOWATTS meter A35A1M1 on the controlmonitor panel until REFLECTED POWER is viewed (REFLECTED POWER amber LED should be on). Record the indicated power level. Press RF OFF. Recorded Power Level:. 2.1.7 Return plug P43 to A34A2J2 and plug P44 to A34A2J1. Remove jumpers from step 2.1.2. 2.2 Before proceeding with the frequency change procedure the transmitter MUST be shut down. 2.2.1 Set the RF output power levels to minimum by selecting pre-set level 1 and then press the power increase ( ) and power decrease ( ) buttons at the same time. Then select pre-set level 2 and then press the power increase ( ) and power decrease ( ) buttons at the same time. 2.2.2 Press RF OFF. Select exciter A and IPA module A for transmitters with dual configurations. Then switch off the AC power source to the transmitter at the service entrance. Page 2 of 25 Issue 1.0 Q10 Frequency Change Procedure IS05001
2.3 Frequency Sensitive Assemblies: The following assemblies in the Q10 transmitter contain components that are sensitive to the carrier frequency. A copy of the Q10 technical instruction manual including the module service instruction appendices should be available to aid in locating components and assemblies. A34 - RF CombinerFilter Assembly A18 - RF Drive Changeover Assembly A25 - IPA Splitter Assembly RF Power Module Input Cables IPA Select On Test Cables 2.4 CombinerFilter Assembly: The combinerfilter assembly (NAF109) is used to combine the outputs of the eight RF power modules and is tuned to a customer specific frequency. Contained within the filter section are the 2 nd and 3 rd harmonic notches. The components used to assemble the notches and the location within the filter section is determined by the carrier frequency. A replacement combinerfilter may be obtained from Nautel, and will be supplied with the NAFP94 power probe attached. See Section 2.4.2 for details on tuning the combinerfilter assembly. NOTE All hardware and parts that are removed during the disassembly of the transmitter must be retained for reassembly. Some additional hardware is available in the transmitter s ancillary kit, but all dropped hardware must be located. Lost hardware can drop into high voltage areas and cause damage when the AC power is restored. 2.4.1 CombinerFilter Removal: Refer to Tables 3 and 4 to determine if the combiner needs to be re-tuned. If the new frequency is in the same band as the old frequency listed in Tables 3 and 4 and is within 2 MHz of the old frequency, then no changes are required. Proceed to step 2.4.4. If changes are required then the combiner output filter must be removed for tuning andor exchange. 2.4.1.1 Remove the front and rear air blockers that cover the front and rear of the combiner. The air blockers are be held in place with two ¼ turn crosshead fasteners. Place the air blockers to one side. 2.4.1.2 Remove the 3 18 inch rigid or coax feeder from the transmitter s output. Wrenches will be required to remove the hardware. 2.4.1.3 Disconnect and remove the thirtytwo (32) power module output cables that connect the power module outputs to the combineroutput filter (W1 through W32), noting that all cable terminations are indicated on both ends. 2.4.1.4 Disconnect the B+ supply plugs, RF drive BNC connectors, and control ribbon cables from all of the power modules and IPA module(s), noting that there may be an optional backup IPA installed in the A21 location at the rear of the transmitter. 2.4.1.5 Mark the IPA module(s), so that they can be returned to their original locations (they should already be labelled as IPA modules), and then remove all of the power modules and the IPA module(s) from the transmitter and place to one side. 2.4.1.6 Disconnect plugs P43 and P44 from the power probe located at the top of the combineroutput filter. 2.4.1.7 Disconnect the safety ground wires (# 457 & # 458) from the power probe located on top of the combiner. 2.4.1.8 Remove the RF changeover assembly, A18, (see MD-2 in the transmitter manual) from the rear of the combiner. It is not necessary to completely remove this assembly from the transmitter so it may be left hanging on its cables once it has been un-bolted. Remove the two sets of hardware that secure the bottom of the changeover assembly to the combiner. Then remove the four sets of hardware that secure the top of the changeover assembly to the rack, noting that there are two screws on each side. Q10 Frequency Change Procedure Page 3 of 25 IS05001 Issue 1.0
2.4.1.9 Remove and retain the ten crosshead screws that secure the top of the combiner to the rack. Five screws are accessible from both the left and the right hand sides of the combiner. Also remove the four crosshead screws that secure the combiner to the mounting angles (two on each side). See Figure 1. WARNING The combinerfilter assembly is heavy and awkward to handle. It is recommended to have at least two people available when removing this assembly. Five screws on each side Two sets of hardware on each side 2.4.1.11 If a pre-tuned combineroutput filter assembly has been supplied by Nautel please go to section 2.4.4. 2.4.2 Combiner Tuning: Extreme care must be taken to ensure there are no foreign materials left inside the combiner. 2.4.2.1 Remove the cover from the front of the combiner by removing the sixteen crosshead screws, noting that the cover has all of the combiner cable information listed. 2.4.2.2 Using Table 3 as a guide determine if changes to the second harmonic notch are required. If the new frequency is within the same listed band then no change is required. Go to step 2.4.2.5. 2.4.2.3 Set the appropriate links for the second harmonic notch filter according to Table 3. Refer to Figure 2 for the proper link locations, noting that there are four possible links in total and that depending on the carrier frequency there will be between one and four links installed. Figure 2 shows one link set to position 2 and three links set to position 3. Position 0 Position 1 Position 2 Position 3 Position 4 Position 5 Position 6 LINK LINK Figure 1 - Combiner Front View 2.4.1.10 Carefully remove the combiner through the front of the transmitter. It will have to be lifted slightly, then the bottom of the combiner angled towards the front of the transmitter, while lowering it out of the rack. Place the combiner on a suitable clean work surface. Position 6 Position 5 Position 4 Position 3 Position 2 Position 1 Position 0 Figure 2 Second Harmonic Notch Filter 2.4.2.4 Use a 5.5 mm wrench or nut driver to removeinstall the link hardware. Page 4 of 25 Issue 1.0 Q10 Frequency Change Procedure IS05001
Table 3 Second Harmonic Notch Filter Link Combinations Table 4 Third Harmonic Notch Filter Inductor and Capacitor Selection Carrier Frequency Link Position Total Links Installed for Frequency Range 0 1 2 3 4 5 6 87.9-88.4 3 1 -- -- -- -- -- 88.5-89.4 2 2 -- -- -- -- -- 89.5-90.4 1 3 -- -- -- -- -- 90.5-91.3 -- 4 -- -- -- -- -- 91.4-92.1 -- 3 1 -- -- -- -- 92.2-92.8 -- 2 2 -- -- -- -- 92.9-93.6 -- 1 3 -- -- -- -- 93.7-94.3 -- -- 4 -- -- -- -- 94.4-95.1 -- -- 3 1 -- -- -- 95.2-95.8 -- -- 2 2 -- -- -- 95.9-96.6 -- -- 1 3 -- -- -- 96.7-97.4 -- -- -- 4 -- -- -- 97.5-98.4 -- -- -- 3 1 -- -- 98.5-99.4 -- -- -- 2 2 -- -- 99.5-100.4 -- -- -- 1 3 -- -- 100.5-101.4 -- -- -- -- 4 -- -- 101.5-102.4 -- -- -- -- 3 1 -- 102.5-103.4 -- -- -- -- 2 2 -- 103.5-104.4 -- -- -- -- 1 3 -- 104.5-105.4 -- -- -- -- -- 4 -- 105.5-106.4 -- -- -- -- -- 3 1 106.5-107.4 -- -- -- -- -- 2 2 107.5-107.9 -- -- -- -- -- 1 3 ( -- Means No Link Installed ) 2.4.2.5 Using Table 4 as a guide, determine if a change to the third harmonic notch is required. If the new frequency is within the same listed band then no change is required. Go to step 2.4.3. Frequency Range (MHz) 87.9-91.9 ** 92-97.9 Inductor Plate (Qty 1) 98-103.9 193-6082 104-107.9 Capacitor Plate (Qty 2) 193-6082- 02 193-6080- 05 193-6082- 01 193-6080- 07 193-6080- 09 193-6082- 02 193-6080- 08 Position of 3 RD Notch See Figure 3 See Figure 4 See Figure 5 See Figure 6 ** One capacitor strap, PN 193-6098, will be supplied if your frequency change kit uses the PN 193-6080-05 capacitor plates. This capacitor strap is used to securely hold the capacitor plates together (see Figure 3). 2.4.2.6 If change is required then remove the existing third harmonic notch components and install the components listed in Table 4. Refer to Figures 3 through 6 for the proper configuration of the third harmonic notch. Use the new hardware that is provided in the supplied hardware kit to secure the third harmonic notch components. 2.4.2.7 Ensure the Teflon sleeve that covers the centre shaft is secured in place. If it is loose on the shaft it must be secured with a small amount of silicon adhesive (RTV). Q10 Frequency Change Procedure Page 5 of 25 IS05001 Issue 1.0
Figure 3 Third Harmonic Notch for 87.9 to 91.9 MHz Mount Inductor Plate to upper holes Inductor Plate 193-6082-02 Use three HMSP22 screws, HMW33 split washers, and HMW03 flat washers. Two Capacitor Plates 193-6080-05 Use six HA17 screws, HAB23 star washers, and HL02 hex nuts. Mount Inductor Plate to upper holes Capacitor Strap 193-6098 Use two HMSP09 screws and HMW10 washers. Page 6 of 25 Issue 1.0 Q10 Frequency Change Procedure IS05001
Figure 4 Third Harmonic Notch for 2 to 97.9 MHz Mount Inductor Plate to lower holes Inductor Plate 193-6082-01 Use two HMSP22 screws, HMW33 split washers, and HMW03 flat washers. Two Capacitor Plates 193-6080-07 Use six HA14 screws, HAB23 star washers, and HAV52 cap nuts. Mount Inductor Plate to lower holes Q10 Frequency Change Procedure Page 7 of 25 IS05001 Issue 1.0
Figure 5 Third Harmonic Notch for 98 to 103.9 MHz Inductor Plate 193-6082 Use two HMSP22 screws, HMW33 split washers, and HMW03 flat washers. Two Capacitor Plates 193-6080-09 Use six HA11 screws, HAB23 star washers, and HAV52 cap nuts. Page 8 of 25 Issue 1.0 Q10 Frequency Change Procedure IS05001
Figure 6 Third Harmonic Notch for 104 to 107.9 MHz Inductor Plate 193-6082-02 Use three HMSP22 screws, HMW33 split washers, and HMW03 flat washers. Two Capacitor Plates 193-6080-08 Use six HA14 screws, HAB23 star washers, and HL02 hex nuts. Q10 Frequency Change Procedure Page 9 of 25 IS05001 Issue 1.0
2.4.3 If the change in frequency is more than 2 MHz then the capacitor C3 will also have to be adjusted. This will have to be done before the combiner is installed back into the transmitter. Refer to Figures 8 and 9 for the layout of the C3 capacitor. 2.4.3.1 In order to adjust the C3 capacitor the top part of the combiner must be removed from the lower body. To remove the top part of the combiner, remove the small access cover (held in place with two nuts & washers) from the back of the combiner and the four thumb screws that secure the ground plate. See Figure 7. Access cover Four thumb screws, two on each side 2.4.3.5 Next remove the ground plate by turning the four ground plate adjusters counter clockwise. These four thumb screws, which screw into the bottom of the ground palte, must all be turned equally to prevent warping the ground plate or cross threading the screws. Once the four thumb screws are clear of the ground plate remove the ground plate, noting that the thumb screws remain fixed to the lower body. 2.4.3.6 There may be as offset in the setting of the C3 capacitor due to the tolerance of machined parts in the lower combiner body. To check for an offset use a straight edge (ruler) determine and record the present setting of the C3 capacitor by lining up the straight edge as shown in Figure 8. If the capacitor setting is different from the old carrier frequency then there is an offset (+ or -). This offset must be considered when re-setting the C3 capacitor. 2.4.3.7 Offset Example: If the old carrier frequency was 97.1 MHz and the measured setting of capacitor C3 was 97.4 MHz then the offset is + 0.3 MHz. Therefore 0.3 MHz will have to be added to the new frequency for the setting of C3. Figure 7 - Combiner Rear View 2.4.3.2 Using a cross-head screwdriver remove the four screws that secure the centre shaft of the upper body to the centre shaft of the lower body. Two screws can be accessed through the front of the combiner and the other two can be accessed through the rear access opening. 2.4.3.3 Remove the four thumb screws, two on each side, that secure the ground plate in position. 2.4.3.4 Once the ground plate and centre shaft have been released then remove and retain the fourteen sets of hardware that secure the upper body to the lower body. Then carefully lift the upper body off of the lower body taking care not to damage the Teflon sleeve that covers the lower shaft. Place the upper body on a clean surface. Page 10 of 25 Issue 1.0 Figure 8 C3 Frequency Setting 2.4.3.8 Using a 13 mm wrench loosen the hex nut that secures the puck to the top of the C3 capacitor. Then using a cross-head screwdriver loosen, but do not remove, the six M5 screws that secure the top plate to the lower body. Do not loosen the cross head screws near the shaft. Q10 Frequency Change Procedure IS05001
Loosen These Screws Loosen These Screws Puck Hex Nut Figure 9 C3 Capacitor Hardware Loosen These Screws 2.4.3.9 Calculate the new setting for the C3 capacitor by adding the offset that was determined in step 2.4.3.5 to the new carrier frequency. For example: New carrier frequency 104.3 MHz and offset of + 0.3 MHz (104.3 + 0.3 = 104.6) the new setting for C3 would be 104.6 MHz. Keep in mind that if the offset was negative then the offset is subtracted from the new carrier frequency. 2.4.3.10 To adjust the C3 capacitor grasp the metal plate (butterfly wing shape) and with a turning motion, move it to the correct calculated position. 2.4.3.11 Once the C3 capacitor is set to the new carrier frequency tighten the six M5 screws. Align the screw holes in the puck so that one set points to the front of the combiner and the other set points to the back of the combiner. With the puck properly aligned tighten the nut with a 13 mm torque wrench set to 110 inch pounds. The puck must not be allowed to turn when the nut is tightened or the shaft in the upper body will not align properly. 2.4.3.12 Install the ground plate and turn each of the thumb screws an equal amount of turns to prevent the screws from cross threading or the plate from warping. Turn the screws only one or two turns at a time and turn all screws equally until the ground plate is close to the mid point on the screw threads. upper body. Install a few of the fourteen sets of hardware to hold the upper body to the lower body. Check the alignment of the holes in the upper body shaft and the puck. If the holes are properly aligned install the four cross-head screws that secure the shaft to the puck and tighten them securely. If the holes are not properly aligned the upper body must be removed and the puck loosened, repositioned, and then torqued to 110 inch pounds before trying to assemble the upper body to the lower body. 2.4.3.14 Once the shaft in the upper body has been properly secured to the puck in the lower body then the remaining sets of hardware that secure the two bodies together can be installed and securely tightened. 2.4.3.15 Install the four thumb screws that secure the ground plate in position. These are the thumb screws that were removed in step 2.4.3.3. 2.4.3.16 Install the small access cover on the rear of the combiner using the two nuts and washers that were removed in step 2.4.3.1. 2.4.3.17 Check all hardware on the second and third harmonic filters as well as the hardware that secure the upper body to the lower body. Ensure that the inside of the combiner is free from any foreign material and install the cover on the combiner using the sixteen sets of hardware that were removed in step 2.4.2.1. 2.4.3.18 Carefully re-install the combiner into the transmitter through the front of the transmitter, noting that at least two persons are required to install the combiner. The cover on the combiner with the silk screen printing must face towards the front of the transmitter. Angle the combiner slightly and insert the top (power probe section) of the combiner up through the opening in the top of the transmitter. 2.4.3.13 Carefully install the upper body on the lower body taking care to align the puck on the lower body into the shaft in the Q10 Frequency Change Procedure Page 11 of 25 IS05001 Issue 1.0
2.4.3.19 The combiner must be inserted far enough so that it can be brought straight down to rest on the angle supports. With the combiner sitting on the two angle brackets install the ten cross-head screws that secure the top of the combiner to the rack. Then install the four sets of hardware that secures the combiner to the angle brackets. Tighten all mounting hardware. 2.4.3.20 Reconnect the safety ground wires (# 457 & # 458) to the power probe (A34A2) located on top of the combiner. 2.4.3.21 Connect plug P43 to J1 on the combiner s power probe (A34A2) and P44 to J2 on the power probe Power module input cable assembly cables Remove the black covered coax cables from the bulkhead connectors of the module input cables 2.4.3.22 Secure the RF changeover assembly to the rear of the combiner that was unbolted in step 2.4.1.8. Install the four sets of hardware that secure the top of the RF changeover assembly to the rack and then the two sets of hardware that secures the bottom of the assembly to the combiner. Once all of the hardware is installed ensure it is all securely tightened. 2.4.4 Module Input Cables: Refer to Table 5 to determine if the power module input cables (Nautel part number 193-8098-xx) must be changed. The cables are numbered W33 through W40. If new cables are required they will be supplied from Nautel as part of the frequency change parts. See Figure 10. 2.4.4.1 If new input cables are required disconnect the black covered coax cables (marked A25W1P2 through A25W8P2) from the back side of the power module input cable assemblies. DO NOT attempt to remove the P1 end of the black covered coax cables from the IPA splitter (A25) to avoid damaging the IPA splitter. 2.4.4.2 Once the black coax cables have been disconnected use a ¾ inch deep socket and ratchet wrench to remove the hardware from the back of the bulkhead connector that secures the power module input cables to the rack. It is recommended to remove all eight power module input cables before starting to install the replacement cables. Page 12 of 25 Issue 1.0 Figure 10 - Power Module Input Cables Table 5 Power Module Input Cables Frequency Part Number Range (MHz) 87.9 to 94.7 193-8098-04 94.8 to 101.3 193-8098-05 101.4 to 107.9 193-8098-06 2.4.4.3 Obtain the eight replacement power module input cables from the frequency change parts kit and install them in the rack using the ¾ inch deep socket and ratchet wrench. Securely tighten the hardware that holds the bulkhead connectors to the rack. 2.4.4.4 When all of the power module input cables are in place reconnect the black covered coax cables (A25W1 through A25W8) to the bulkhead connectors. Ensure that the fittings are not cross threaded and that they are fully engaged and tight. Use a rule to measure the distance from the rack to the back of the type N connector on the black covered coax to ensure all of the connectors are fully engaged. Q10 Frequency Change Procedure IS05001
2.4.5 Install the eight RF power modules and the IPA module(s), noting that the IPA module(s) should have been identified when they were removed. 2.4.5.1 Connect the power module output cables (four for each power module) from the power module output BNC connectors (J1 through J4) to the combiner (J1 through J32), noting that all cables are identified as to their location and termination points. 2.4.5.2 Connect the remaining B+ supply plugs, RF drive BNC connectors, and control ribbon cables to all of the power modules and IPA module(s), noting that there may be an optional backup IPA installed in the A21 location at the rear of the transmitter. 3 TESTING: The following procedures detail the method for tuning the various transmitter subassemblies and bringing the transmitter up to power at the new carrier frequency. WARNING All steps must be preformed in the order they are written. In order to avoid major damage to the transmitter it is important to correctly calibrate all of the protection circuits correctly. Failure to follow these instructions can result in major damage to the transmitter. Please consult the factory if there are any difficulties with the calibration procedures. 3.1 Preliminary Settings: The transmitter contains many solid state devices which may be damaged if the preliminary settings are not followed. The precautionary information in the operating instructions of section 2 of the Q10 manual must be read and fully understood prior to turning on the transmitter and must also be observed during operation. 3.1.1 Verify that the AC power to the transmitter is switched to the OFF position. 3.1.2 Terminate the transmitter s output into a precision 50 Ohm dummy load via an external Bird Watt meter (or equivalent). A 15 kw and a 5 kw element will be required for the Watt meter. The dummy load must be rated for at least 15 kw. If a 15 kw dummy load is not available then the system antenna may be used provided it is 50 Ohms +- j zero or the matching is better than 1.01:1. Matching between 1.01: and 1.05:1 will result in degraded performance from the transmitter and matching greater than 1.05:1 is not suitable as a test load. 3.1.3 Ensure all interlocks are closed or on the controlinterface PWB (A36) install a temporary jumper wire between TB1-15 and TB1-16. WARNING If a jumper is installed between TB1-15 and TB1-16 on the controlinterface PWB safety features provided by the external interlock will be disabled. It is highly recommended that a fail safe method of alerting personnel to this danger be posted at all normally interlocked locations. Voltages that are dangerous to life will be present on the RF output stages and the antenna system if the transmitter is turned on. 3.1.4 Verify that all RF power module and IPA module(s) connections are completed and that all of the proper cables have been installed for the new carrier frequency. 3.1.5 Switch off all of the switching power supplies (IPA module supply(s) and RF power module supplies) by moving the switch on the front of each power supply to the OFF position. 3.1.6 On the controlmonitor PWB (A36) adjust potentiometer R19 (FWD PWR) fully clockwise (four turns minimum). Also adjust potentiometers R97 (IPA VOLTS), R121 (IPA REFLD PWR), and R147 (IPA OUTPUT) fully counter clockwise (four turns minimum). 3.1.7 Verify that the exciter has been set to the new carrier frequency. If this has not been done refer to the exciter s manual to change the carrier frequency to the new frequency. Q10 Frequency Change Procedure Page 13 of 25 IS05001 Issue 1.0
3.1.7.1 If the exciter provided is not a Nautel M50 or NE50 exciter then a Bird Watt meter with a 100 Watt element will have to be installed between the exciter s output connector and the exciter output cable (W41P1) to monitor reflected power. 3.1.8 Record the present setting of switches S5-1 through S5-4 and S15-1 through S15-4 on the display PWB (A35A1A1). 3.1.8.1 Record the positions of switches S5-1 to S5-4 and S15-2 to S15-4. Set S5-1 to OPEN and set S5-2 through S5-4 to the CLOSED position. Set switches S15-2 through S15-4 to the OPEN position. 3.1.9 Remove coax cable W44 and install a Bird Watt meter with a 500 Watt element and coax cable set 193-8299 in its place. Two type N to BNC adaptors must be installed on the Bird meter for this test. W44 is an IPA power module output cable that is connected from A20J4 (IPA in the A location) to A22J2 on the IPA A (SWR) power probe, NAFP95. See MD-2 in the transmitter manual for the probe location. 3.1.10 When using an NE30 exciter install a Bird Watt meter between the exciter s output connector and the exciter output cable. Use a 100 Watt element in the Bird Watt meter. 3.1.11 Replace the two coax cables, numbered W47 and W48, that connect to A24A1J1 and A24A1J2 of the IPA combiner (A24) with the two coax cables A18J7 and A18J8 (shortest cables: 30 inches in length) from the 193-8298-01 IPA select on test cable set assembly that was provided with the frequency change parts. 3.2 IPA InputOutput Tuning: The following steps provide instructions for tuning the IPA input and output sections of the RF drive circuit: 3.2.1 Remove the cover from the RF drive changeover assembly (A18) noting it is located on the back of the combiner. See MD-2 and MD-4 in the transmitter manual. 3.2.1.1 Then disconnect the connector from A18A3J2 (the A18A3 assembly is the IPA input power probe). This connector will be identified as P28 on single IPA systems and as P4 on dual IPA systems. Also disconnect the connector from A18A3J1 (identified as P3) and connect it to A18A3J2. 3.2.1.2 Connect a 500 Watt 50 Ohm load to A18A3J1 using a suitable piece of coax cable terminated with BNC connectors. 3.2.1.3 Apply AC power to the transmitter and press RF ON. The exciter should no longer be muted and the IPA MODULE INPUT alarm should be on. 3.2.1.4 Set the M50 or NE50 exciter for an output power of 25 Watts or the NE30 exciter for an output power of 25 Watts, as displayed on the exciter s power meter. 3.2.1.5 Null (make as small as possible) the DC voltage at A18A3A1E1 by adjusting capacitor C2 (RATIO ADJ) on the IPA input power probe and record the level. E1 must be left connected for this calibration. It may be easier to measure the voltage at A18J17 pin 5. 3.2.1.6 Press RF OFF and ensure that the exciter in muted. Remove the 500 Watt load from A18A3J1. 3.2.1.7 Disconnect connector P3 from A18A3J2 and reconnect P3 to A18A3J1. Reconnect the connector, P28 for single IPA systems or P4 on dual IPA systems, that was originally removed from A18A3J2. 3.2.2 IPA Input Matching: The following procedure is for tuning the IPA input matching assembly (A18A2). See MD-4 in the transmitter manual. 3.2.2.1 For dual exciter andor IPA systems ensure that exciter A and IPA A are both selected. Also ensure the exciter is on and muted, and that all power module power supplies and IPA module power supply(s) are turned OFF. Page 14 of 25 Issue 1.0 Q10 Frequency Change Procedure IS05001
3.2.2.2 For systems with the NE50 exciter use a DMM to monitor the exciter s reflected power level (REFLD PWR LEVEL) at A16A10TB1-9, on the rear of the exciter. For systems with the M50 monitor the reflected power level with a DMM on pin 36 of the REMOTE INTERFACE connector on the back of the M50 exciter (pin 37 is the ground). For systems with the NE30 exciter monitor the reflected power on the Bird Watt meter that is installed between the NE30 s output connector and the exciter s output coax cable. Press RF ON. If the DMM monitoring the M50 s or NE50 s reflected power displays close to 1.26 VDC then exciter is SWR limiting due to poor matching. You will have to reduce the exciter s output power until the displayed voltage is less than 1.26 VDC. 3.2.2.3 For single IPA equipped systems only ensure that the TUNE 4, TUNE 5, and TUNE 6 capacitors of the IPA input tuning assembly are turned fully clockwise (maximum capacitance). 3.2.2.4 Adjust the TUNE 1, TUNE 2, and TUNE 3 capacitors of the IPA input tuning assembly (A18A2) until the reflected power is at a minimum. If the exciter s output power was reduced to allow for proper tuning it will have to be increased to the proper level. For the M50 or NE50 the required output power is 25 Watts and for the NE30 the required output power is 25 Watts. The reflected power as indicated on the M50 or NE50 should be 0.0 Watts and should be less than one Watt for the NE30. 3.2.2.4.1 For dual IPA equipped systems switch to IPA B on the transmitter s front panel and adjust the TUNE 4, TUNE 5, and TUNE 6 capacitors of the IPA input tuning assembly (A18A2) until the reflected power is at a minimum. If the exciter s output power was reduced to allow for proper tuning it will have to be increased to the proper level. For the M50 or NE50 the required output power is 25 Watts and for the NE30 the required output power is 25 Watts. The reflected power as indicated on the M50 or NE50 should be 0.0 Watts and should be less than one Watt for the NE30. 3.2.2.5 Select IPA A on the transmitter s front panel and verify that it is still tuned. 3.2.2.6 Adjust potentiometer A36R195 (EXCITER FWD PWR) on the controlmonitor PWB clockwise until the voltage at A36TB2-21 is equal to 4.75 VDC for the M50 or NE50 equipped systems or 4.19 VDC for the NE30 equipped system. 3.2.2.7 Press the PROTECT RESET and then the ALARM RESET button and the IPA MODULE INPUT alarm should turn off. The IPA MODULE OUTPUT alarm should still be on. 3.2.3 IPA Splitter Tuning: 3.2.3.1 Turn on the IPA A power supply (A2) and the IPA B power supply (A3), if the transmitter is equipped with dual IPA modules. See MD-1 and MD-2 in the transmitter manual for the IPA power supply locations. 3.2.3.2 While monitoring the reflected power on the IPA output Bird Watt meter (100 Watt element installed) slowly adjust A36R97 (IPA VOLTS) on the controlinterface PWB clockwise until the forward power displayed on the Bird meter is 40 Watts. Adjust capacitors C1 and C2 of the IPA splitter assembly (A25) until the reflected power on the IPA Bird output Watt meter is at a null (minimum). See MD-2 in the transmitter manual for the location of the IPA splitter. 3.2.3.3 Recheck the exciter reflected power and attempt of further minimize the reflected power by very carefully adjusting the TUNE 1, TUNE 2, and TUNE 3 capacitors of the IPA input tuning assembly (A18A2) for IPA A then switch to IPA B and adjust the TUNE 4, TUNE 5, and TUNE 6 capacitors of the IPA input tuning assembly (A18A2). The reflected power as indicated on the M50 or NE50 should be 0.0 Watts and should be less than one Watt for the NE30. Switch back to IPA A when the exciter s reflected power has been minimized (dual IPA systems only). Q10 Frequency Change Procedure Page 15 of 25 IS05001 Issue 1.0
3.2.3.4 Continue adjusting potentiometer A36R97 (IPA VOLTS) clockwise until the forward power level in Table 6 is achieved on the IPA output Bird Watt meter (500 Watt element installed) while monitoring the reflected power (25 Watt element installed) and tuning capacitors C1 and C2 of the IPA splitter assembly (A25). 3.2.3.5 Recheck the exciter reflected power to ensure it is minimized by adjusting the TUNE 1, TUNE 2, and TUNE 3 capacitors of the IPA input tuning assembly (A18A2) once the IPA is at its rated output power according to Table 6. If the system is equipped with dual IPA modules switch to IPA B and recheck the exciter s reflected power by adjusting the TUNE 4, TUNE 5, and TUNE 6 capacitors of the IPA input tuning assembly (A18A2). Table 6 IPA Output Power Verses Frequency at 10 kw Carrier Frequency (MHz) IPA Output (Watts) Carrier Frequency (MHz) IPA Output (Watts) 88-89 120 98-99 175 89-90 130 99-100 175 90-91 135 100-101 180 91-92 135 101-102 190 92-93 145 102-103 195 93-94 150 103-104 195 94-95 155 104-105 205 95-96 160 105-106 210 96-97 160 106-107 215 97-98 170 107-108 220 3.2.3.6 Record the voltage at A39TP IPA VOLTS on the power supply distribution PWB. Adjust potentiometer A36R147 (IPA FWD PWR) on the controlinterface PWB until the voltage at A36TP5 is 1.25 times the voltage A36TP8 (nominal level is 9.375 VDC +- 5 %). Record the voltage at A36TP5. Recorded Voltage Level:. 3.2.3.7 Press ALARM RESET and the IPA MODULE OUTPUT alarm should turn OFF. 3.2.3.8 Turn the exciter output power down to 15 Watts and verify that the IPA remains on. Then reduce the exciter s output power to 12 Watts. 3.2.3.9 Readjust potentiometer A36R159 (EXCITER FWD PWR) on the controlinterface PWB until the IPA MODULE INPUT alarm just turns on. Increase the exciter output power to 25 Watts and verify that the IPA resumes operation. Press ALARM RESET and the IPA MODULE INPUT alarm should go out. For systems equipped with the M50 or NE50 exciter return the exciter s output power to 25 Watts. 3.2.3.10 If the transmitter is equipped with dual IPA modules switch to IPA B on the transmitter s controlmonitor panel and check the voltage level at A36TP5 on the controlinterface PWB. Adjust potentiometer A36R192 (IPA B FWD PWR TRIM) on the controlinterface PWB so that the voltage at A36TP5 is the same as was recorded in step 3.2.3.6. 3.2.3.11 Press RF OFF and ensure IPA A is selected on the transmitter s control panel. If a Bird Watt meter was installed in the exciter s output it can now be removed. 3.2.4 IPA Output SWR Calibration: The following procedure calibrates the IPA output SWR threshold circuits: 3.2.4.1 On the IPA power probe (A22) swap the forward and reflected power samples. Move plug P45 to A22J10 and plug P46 to A22J9. For systems equipped with dual IPA modules also move plug P47 to A23J10 and plug P48 to A23J9 on the IPA B power probe. Adjust potentiometer A36R97 (IPA VOLTS) on the control interface PWB fully counter-clockwise (four turns minimum). 3.2.4.2 Press RF ON and the IPA MODULE OUTPUT alarm should turn on. 3.2.4.3 Adjust potentiometer A36R97 (IPA VOLTS) clockwise until the IPA output Bird Watt meter reads 75 Watts (100 Watt element installed). Record the voltage at A39TP IPA VOLTS. Adjust potentiometer A36R121 (IPA REFLD PWR) on the Page 16 of 25 Issue 1.0 Q10 Frequency Change Procedure IS05001
controlinterface PWB clockwise until the IPA MODULE SWR alarm just turns on. The IPA output should be inhibited. Recorded IPA VOLTS:. 3.2.4.4 Adjust A36R97 (IPA VOLTS) one turn counter-clockwise, then press the PROTECT RESET and ALARM RESET buttons. The IPA MODULE SWR alarm should turn off and the IPA output should no longer be inhibited. 3.2.4.5 For dual systems with dual IPA modules, switch to IPA B. While monitoring A39TP IPA VOLTS on the power supply distribution PWB (A39) slowly increase potentiometer A36R97 (IPA VOLTS) clockwise until the IPA MODULE SWR alarm just comes on and the IPA volts are inhibited. The IPA volts reading should have been the same as the recorded level from step 3.2.4.3 just before the IPA was inhibited. 3.2.4.6 Press RF OFF and then reconnect plug P45 to A22J9 and plug P46 to A22J10 on the IPA power probe (A22). For systems with dual IPA modules also reconnect plug P47 to A23J9 and plug P48 to A23J10 on the IPA power probe (A23). 3.2.4.7 Press RF ON and then press the PROTECT RESET and ALARM RESET buttons. The IPA MODULE SWR alarm should go out and the IPA module should no longer be inhibited. Switch back to IPA A on the transmitter s controlmonitor panel and readjust the IPA to the level that was recorded in step 3.2.3.6. Press ALARM RESET and then RF OFF. 3.2.5 IPA Monitor Adjust and Power Output Calibration: The following procedure calibrates the final combined output stage for optimizing IPA and transmitter performance. 3.2.5.1 Connect a jumper from A36CR30 cathode to ground, to cause an RF POWER MODULE PA FAIL alarm, and inhibit the ALC circuit. Then adjust A36R95 (PA VOLTS) on the controlmonitor panel clockwise until the voltage at A36U30 pin 7 is 3.5 VDC. 3.2.5.2 To ensure the output power is zero press select power pre-set 2 and press the power increase ( ) and power decrease ( ) buttons on the transmitter s control panel at the same time. Then select power pre-set 1 and press the power increase ( ) and power decrease ( ) buttons on the transmitter s control panel at the same time. 3.2.5.3 Switch on all module power supplies (A4 through A11). Press RF ON and then press the PROTECT RESET and MODULE RESET buttons at the same time. Then press the ALARM RESET button. Next press the power increase ( ) and power decrease ( ) buttons at the same time to reset the processor. The transmitter should now be operating at minimum power. 3.2.5.4 Using a DMM check the PA VOLTS at TP A through TP H on the power supply distribution PWB (A39). All voltages should be + 15.5 VDC +- 2.5 V. See MD-1 in the transmitter manual for the location of the PWB. 3.2.5.5 Using a DMM check the INTERMEDIATE RF LEVELS at TP A through TP H on the power module distribution PWB (A38). See MD-1 in the transmitter manual for the location of the PWB. All voltages should be + 5 VDC +- 1 V. If the voltages are not + 5 VDC +- 1 V then retune the IPA splitter capacitors A25C1 and A25C2 for a null (minimum) in IPA reflected power. Also ensure that the IPA forward power is the same as is listed in Table 6 for the selected carrier frequency. If necessary adjust A36R97 (IPA VOLTS) on the controlinterface PWB to set the power to the correct level. 3.2.5.6 Using a clip-on DC current meterprobe measure the DC current for all power modules (A26 through A33). Clip the DC current meter over the two white wires that go to pins 1 and 2 of the plug that terminates at J1 in each RF power module. The current in both white wires is to be measured at the same time. It should be 16 Amps +- 4 Amps. Press RF OFF. Q10 Frequency Change Procedure Page 17 of 25 IS05001 Issue 1.0
WARNING Do not exceed 49 volts on the PA VOLTS meter (M2) when adjusting for 11.5 kw in the following steps. NOTE If an IPA MODULE SWR alarm or IPA MODULE OUTPUT alarm occurs during the following steps the IPA splitter capacitors, A25C1 and A25C2 will have to be adjusted to minimize the IPA reflected power. 3.2.5.7 Press RF ON. While monitoring the external Bird Watt meter (15 kw element installed) press and hold the power increase button on the transmitter s controlmonitor panel until the power indicated on the external Watt meter is 5 kw. Check the IPA reflected power and carefully re-tune the IPA splitter capacitors A25C1 and A25C2 until the reflected power for the IPA is less than 6 Watts (25 Watt element installed). Readjust the IPA output power level (A36R97) if required, according to the level indicated in Table 6 for the assigned carrier frequency. If required adjust the output power for exactly 5 kw. 3.2.5.8 Using the formula below calculate the PA voltage required to achieve 11 kw based on the voltage measured at A39TP PA VOLTS. If the calculated PA voltage required to achieve 11 kw is 47 VDC +1-2 V then go to step 3.2.5.10. If the voltage is not in the range of 46 to 48 VDC then the trimmer ground plate in the combinerfilter (A34) will have to be adjusted. Proceed to step 3.2.5.9 to avoid transmitter damage. Calculated PA volts = X *1.483 where X = measured PA volts at 10 kw 3.2.5.9 Set the output power to zero by pressing the power increase ( ) and power decrease ( ) buttons at the same time. Then press RF OFF. WARNING Never adjust the trimmer ground plate with the transmitter in operation. This could result in catastrophic failure of the RF combinerfilter andor the power Page 18 of 25 Issue 1.0 amplifiers. Always press RF OFF and reduce the output to minimum before making any adjustments. Ensure that the ground plate is level by observing the location of the thumb screws on the RF combinerfilter chassis. 3.2.5.9.1 Loosen the thumb screws on the sides of the RF combinerfilter and using the ground plate adjusters elevate or drop the ground plate by turning all four adjusters an equal amount in the same direction. Note the direction the adjustors were turned and how far they were turned. Tighten the thumb screws to secure the ground plate. This is a trial and error process that may have to be repeated to determine the proper direction of travel and required distance to move the ground plate. Return to step 3.2.5.7. See Figure 11. Four thumb screws Four ground plate adjusters Figure 11 - Ground Plate Adjustment Screws 3.2.5.10 Select forward power to be displayed on the transmitter s power meter, A35M1. Press and hold power increase ( ) until the PA voltage (A39TP PA VOLTS) increases to its maximum value, noting that potentiometer A36R19 (FWD PWR) on the controlinterface PWB may have to be adjusted counter-clockwise while holding the power increase ( ) button to ensure the transmitter s power meter (M1) does not pin. While holding the power increase ( ) button adjust A36R95 (PA VOLTS) on the controlinterface PWB until the external Bird Watt meter (15 kw element installed) displays 11.5 kw. Q10 Frequency Change Procedure IS05001
3.2.5.11 Press power decrease ( ) until 10 kw is displayed on the external Bird Watt meter. Adjust A36R19 (FWD PWR) on the controlinterface PWB until the voltage at A36TP2 is + 11 VDC. Then adjust A35A1R53 (POWER METER) on the controldisplay PWB until the power that is displayed on the power meter (M1) is 10 kw. 3.2.5.12 With the transmitter operating at 10 kw: Check the IPA output reflected power and carefully adjust A25C1 and A25C2 for minimum if the reflected power is greater than 6 Watts. Check and adjust A36R147 (IPA FWD PWR) on the controlinterface PWB until the voltage at A36TP5 is equal to the voltage at A36TP8 times 1.25 (A36TP5 = A36TP8 * 1.25). Also check the exciter reflected power and carefully adjust the TUNE 1, TUNE 2, and TUNE 3 capacitors of the IPA input tuning assembly (A18A2) to minimize the reflected power for IPA A selected, if required and for systems with dual IPA modules adjust the TUNE 4, TUNE 5, and TUNE 6 capacitors of the IPA input tuning assembly (A18A2) to minimize the reflected power for IPA B selected, if required. 3.2.6 IPA Select On Test Cable Selection: The following procedure ensures that the IPA select on test cable set is selected properly for optimal performance of the IPA module(s) and the transmitter. The installed cables must meet the following parameters in the order that they are listed. Only check and record the data if the previous step was successful. Once a cable set has passed all of the steps the measurements must then be checked and met for the other low voltage power supply (LVPS B ) as well as for the other IPA power module (power module B ) in systems with dual IPA power modules. NOTE: When repeating the test for low voltage power supply B do not adjust any potentiometers. NOTE Only one or two cable lengths will meet all of the requirements laid out in section 3.2.6 and Table 7. Start with the shortest cable length (30 inches) and proceed until steps 3.2.6.1 through 3.2.6.12 can all be completed. Both cables, W47 and W48, must be the same length for all tests and the final result. 3.2.6.1 Before recording the results on each IPA cable set ensure that the transmitter is setup as follows: 1) The power on the IPA output Bird Wattmeter (500 Watt element installed) is correct based on the information in Table 6 according to the selected carrier frequency. 2) The reflected power on the IPA output Bird Watt meter (25 Watt element installed) is less than 6 Watts. 3) The transmitter s output power is at 10 kw according to the external Bird Watt meter (15 kw element installed). 4) A36R147 is adjusted so that the voltage at A36TP5 = A36TP8 * 1.25 (This should be approximately 9.375). NOTE If step 3.2.6.1 cannot be achieved with the installed IPA Select On Test Cable Set at the assigned IPA output power level (according to Table 6) then the IPA output power level may be increased to a maximum of fifteen percent more than the Table 6 value for the assigned carrier frequency. 3.2.6.2 The following conditions must be met in the order that they are listed before recording the data in Table 7. Any cable set that does not meet these minimum conditions is not suitable for consideration. Condition # 1: The transmitter s synchronous noise must be -50 db or lower with the transmitter operating at full power and at half power. Condition # 2: The minimum power results must be between zero and twenty percent less than the full power results. Condition # 3: There must be a check mark in all three TX offon columns indicating that the transmitter can be turned RF OFF and RF ON with all power modules installed, with one power module removed, and with two power modules removed. Q10 Frequency Change Procedure Page 19 of 25 IS05001 Issue 1.0
3.2.6.3 Before proceeding with the test ensure POWER PRESET # 1 is set for 10 kw output power and that POWER PRESET # 2 is set for minimum power. To set POWER PRESET # 2 to minimum power press and release the POWER PRESET # 2 button, then press both the power increase ( ) and the power decrease ( ) at the same time. 3.2.6.4 Measure the transmitter s synchronous and asynchronous noise levels with the output power set to 10 kw and 5 kw. Record the results in Table 7. 3.2.6.5 With the transmitter operating at 10 kw measure the voltage at A36TP5 on the controlinterface PWB. It should be greater than 7.8 VDC. Record the A36TP5 voltage in Table 7 with the transmitter operating at full power then press RF OFF and then press RF ON. Note if the transmitter returns to the previous power level when RF ON is pressed. Then select POWER PRESET # 2 (set for minimum power) and record the A36TP5 voltage in Table 7 with the transmitter operating at minimum power. Next press RF OFF and RF ON. Note if the transmitter returns to the previous low power setting. If the transmitter returned to the proper power level for both the full power and the minimum power test place a check mark in the TX UP Less 0 cubes column of Table 7 and continue with the test. 3.2.6.6 Select POWER PRESET # 1. With the transmitter operating at 10 kw remove power module A (A26) by switching OFF the associated power supply (A4), then disconnect the power modules output coax connectors (W1P2, W2P2, W3P2, and W4P2) from the RF combiner (A34) at the combiner end. DO NOT remove the coax cables from the power module end. Then disconnect the RF drive cable to power module A by disconnecting W33P1 from the module s J1 connector. Ensure that the IPA MODULE OUTPUT alarm is not on. 3.2.6.7 With power module A disconnected from the RF drive and the combiner measure the voltage at A36TP5. It should be greater than 7.8 VDC. Record the A36TP5 voltage in Table 7 with the transmitter operating at full power (this will be less than 10 kw with the one power module removed) then press RF OFF and then press RF ON. Note if the transmitter returns to the previous power level when RF ON is pressed. Then select POWER PRESET # 2 (set for minimum power) and record the A36TP5 voltage in Table 7 with the transmitter operating at minimum power. Next press RF OFF and RF ON. Note if the transmitter returns to the previous low power setting. If the transmitter returned to the proper power level for both the full power and the minimum power test place a check mark in the TX UP Less 1 cube column of Table 7 and continue with the test. 3.2.6.8 Select POWER PRESET # 1. With the transmitter operating at slightly less than 10 kw remove power module B (A27) by switching OFF the associated power supply (A5), then disconnect the power modules output coax connectors (W5P2, W6P2, W7P2, and W8P2) from the RF combiner (A34) at the combiner end. DO NOT remove the coax cables from the power module end. Then disconnect the RF drive cable to power module B by removing W34P1 from the module s J1 connector. Ensure that the IPA MODULE OUTPUT alarm is not on. 3.2.6.9 With power modules A and B disconnected from the RF drive and the combiner measure the voltage at A36TP5. It should be greater than 7.8 VDC. Record the A36TP5 voltage in Table 7 with the transmitter operating at full power (this will be less than 10 kw with the two power modules removed) then press RF OFF and then press RF ON. Note if the transmitter returns to the previous power level when RF ON is pressed. Then select POWER PRESET # 2 (set for minimum power) and record the A36TP5 voltage in Table 7 with the transmitter operating at minimum power. Next press RF OFF and RF ON. Note if the transmitter returns to the previous low power setting. If the transmitter returned to the proper power level for both the full power and the Page 20 of 25 Issue 1.0 Q10 Frequency Change Procedure IS05001