Daniels VT-4R150 Instruction Manual
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Contents
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DEDANIELSELECTRONICS3-4 VT-4R150 VHF Project 25 Digital Transmitter Instruction Manualthe transmitter should be connected to a service monitor set to monitor the deviation of the carriersignal generated by the transmitter. Key the transmitter by moving the front panel power switch tothe “KEY” position and adjust pot R11 to achieve a deviation of 3 kHz (for a 25 kHz widechannel) or 1.5 kHz (for a 12.5 kHz wide channel).Next, de-key the transmitter and remove the audio signal generator. Connect the signal generatorto microphone connector MIC1-2. Key the transmitter by moving the front panel power switch tothe “KEY” position. Adjust pot R9 to achieve a deviation of 3 kHz kHz (for a 25 kHz widechannel) or 1.5 kHz (for a 12.5 kHz wide channel). This completes the audio level alignmentprocedure.3.4.7 Amplifier AlignmentThe RF power output of the amplifier is set to its rated value of 2.0 Watts or 8.0 Watts at thefactory. This should not require adjustment under normal circumstances. However, should it benecessary to correct the output power, the 'Output Power Adjustment’, which is described in theAmplifier Manual, can be adjusted accordingly. Power adjustment may also be required when thetransmitter's operating frequency is changed. When a large frequency change has beenprogrammed into the transmitter, the amplifier should be aligned at the new frequency according tothe Amplifier Manual.3.5 Recommended Test Equipment ListAlignment of the transmitter requires the following test equipment or its equivalent.Dual Power Supply: Regulated +9.5 Vdc at 2 A.Regulated +13.8 Vdc at 2 A - Topward TPS-4000Oscilloscope / Multimeter: Fluke 97 ScopemeterCurrent Meter: Fluke 75 multimeterRadio communications test set: Marconi Instruments 2955R (analog only)Motorola R2670 with Project 25 optionAlignment Tool: Johanson 4192It is recommended that the radio communications test set be frequency locked to an externalreference (WWVH, GPS, Loran C) so that the high stability oscillator may be accurately set towithin its ±1 ppm frequency tolerance.3.6 Repair NoteThe transmitter is mainly made up of surface mount devices, which should not be removed orreplaced using an ordinary soldering iron. Removal and replacement of surface mountcomponents should be performed only with specifically designed surface mount rework and repairstations complete with ElectroStatic Discharge (ESD) protection.When removing Surface Mount Solder Jumpers, it is recommended to use solder braid in place ofmanual vacuum type desoldering tools when removing jumpers. This will help prevent damage tothe circuit boards. |
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