Codan_8525B_8528_sch.pdf
TRANSCEIVER OPTION F DRG 15-10339-001 ISS 3 SHT 1 OF 2 ORIG OS DATE 11/4/89 CHKDDATE 13/4/89 APPD CM DATE 11/5/93 FITTING INSTRUCTIONS TRANSCEIVER - OPTION F (PA ASSEMBLY 08-03743 SERIES) 1. Obtain unfinished PA from current production batch and proceed to fit fan option as follows. 2. Secure existing resistor MTG PCB to top of O/P transformer heatsink with silastic and terminate 2 wires from T4 to PCB. 3. Drill out blind holes beneath T4 in PA heatsink 3.0 (through PCB) and remove all swarf. 4. Apply heatsink compound to fully line inside surface of O/P transformer heatsink (3). 5. Fit O/P transformer (5) T4 to heatsink (3), with MTG base on underside of s/assy. 6. Place O/P transformer s/assy in position and trim wires to suit ensuring centre wire is long enough to just go through PA PCB and doesn t touch PA heatsink. 7. Remove s/assy and apply heatsink compound to base and secure to PA heatsink with screw (8). 8. Terminate wires to PA PCB and terminate 2 wire from T4 to resistor PCB. 9. Remove diode D15 for 100 watt CW operation (60 watts CW when fitted) 10. Apply heatsink compound to top of driver heatsink bracket (4). 11. Fit driver heatsink bracket (4) using screw and nut (7) and (9) ensuring bracket is placed squarely and firmly on top of T3. 12. Drill hole 8.0 in rear panel as shown and fit grommet. 13. Fit fan/cover assembly (2) to top of PA heatsink using screw (6) and folding tabs over heatsink flange. Fit grommet to screen. 14. Fit cable through rear panel and screen. 15. Fit cable clamp and route cable as shown, fit cable tie, remove connector (leaving long leads) and solder ends as shown. HF SSB Transceiver 8525B/8528 series Technical Service Manual12-50055 Issue 1, Page 1 Addendum The following sections are added to the HF SSB transceiver 8525B/8528 series Technical Service Manual, Codan part number 15-02036 Issue 6, November 1995. This information is provided in addition to that existing in Chapter 4, Local Oscillators. It explains the operation of the new synthesisers. Drawings associated with this addendum are: RF Mixer and Dual Synthesiser Circuit Diagram04-03120 RF Mixer and Dual Synthesiser PCB Assembly08-05295 Local Oscillators (04-03120) Two synthesised oscillators are used to drive the first and second mixers. The first oscillator operates between 45.250 MHz and 75 MHz in 2 kHz steps. It converts the 250 kHz to 30 MHz receive signal to 45 MHz for the first IF. The second oscillator operates between 43.350 MHz and 43.352 MHz in 10 Hz steps. It converts the 45 MHz first IF to 1650 kHz second IF. Each oscillator consists of a: voltage controlled oscillator phase/frequency detector loop amplifier filter reference crystal oscillator (common) The division ratios required are provided in serial data form by the microprocessor from data stored in the memory. The reference frequency crystal Z2 (6600 kHz) is held at a constant temperature by a power PTC thermistor (R100) or by a high stability temperature controlled oven (08-05235). The crystal oscillator provides the reference frequency for the two synthesisers. The reference, after being divided by four (1650 kHz), provides the local oscillator drive to the modulator/demodulator for USB operation. A 1647 kHz (Z3) crystal oscillator drives the modulator/demodulator stages for LSB operation. Addendum Page 2, 12-50055 Issue 1HF SSB Transceiver 8525B/8528 series Technical Service Manual Voltage Controlled Oscillator (VCO) As VCO1 and VCO2 are very similar, only VCO1 will be described in detail. The differences between the two VCOs are detailed in the table below. VCO1VCO2 VaricapsD17 to D20D46 and D47 VCO output to synthesiser input pin 4 Via buffer V41 and coupling capacitor C144 Via R45 and C155 Division ratioDivides to 2 kHz1.1 kHz to 2 kHz in 10 Hz steps Filter componentsC127, C129, C181, R79, R99 and C123 C179, R166 and C180 Reference frequencyReference crystal oscillator (6600 kHz) 6600 kHz obtained from IC2 pin 3 and applied to IC3 pin 1 FET V2 operates as a Hartley oscillator tuned by four varicaps D17 to D20. The output level is kept near constant frequency by a negative bias voltage applied to the V2 gate. This voltage is generated from schottky diode D21 charging capacitor C44. Unity gain feedback amplifier V3 and V4 provides a buffer between the oscillator and the cascade connected amplifier V5 and V6. The second amplifier provides +7 dBm drive to the ring diode mixer D13. The VCO output is buffered by V41, before being applied to synthesiser IC2 pin 4. Synthesiser for VCO1 Synthesiser IC2 generates a DC control voltage via the phase/frequency detector and control amplifier. This is applied to the varicaps to lock the VCO1 to the nominated frequency. The 6600 kHz oscillator, part of IC2, is divided down to a 2 kHz reference frequency. The VCO signal applied to pin 4 of IC2 is also divided to produce 2 kHz when VCO1 is at the nominated frequency. Both of these signals are applied to the phase/frequency detector in IC2. The phase/frequency detector (IC2) provides two outputs. Pin 14 provides a go down pulse. Pin 15 provides a go up pulse. These outputs are high (+5 V) when locked, except for a very narrow negative going pulse that occurs simultaneously on both outputs. V29 and V30 provide a 3 mA discharging current pulse when pin 14 is low. V28, V31 and V32 provide a 3 mA charging current pulse when pin 15 is low. Addendum HF SSB Transceiver 8525B/8528 series Technical Service Manual12-50055 Issue 1, Page 3 These current pulses accumulate in the loop filter (C127, C129, C181 and R79). The resulting voltage is applied to the varicaps (D17 - D20) via a filter (R99 and C123). This filter removes any reference components from the control voltage. Codan Pty LtdPO Box 96Telephone ACN 007 590 605CampbelltownNational (08) 8305 0311 81 Graves StreetSouth AustraliaInternatl +61 8 8305 0311 Newton5074Facsimile (08) 8305 0411 South Australia Service bulletinPage 1 of 2 17-00107ISSUE 1October 1991 9103 Automatic Antenna Tuner - Serial Nos A1312 - A1342 Symptom The 9103 tuner has recently incorporated a revised Printed Circuit Board (PCB) Artwork to include components necessary for scanning when used with Coda 85. series transceivers. An error has been discovered on the PCB silkscreen whereby Capacitor C88 (2.2F) may have been inserted incorrectly. The silkscreen identifies the +ve terminal of C88 closest to capacitor C87 and is incorrect. The +ve terminal should be located closest to Resistor R64. On units with Serial Nos greater then A1342 the error has been rectified and the incorrect identifier on the PCB removed however, the possibility exists for some units in the Serial No. range A1312 - A1342 to have had the capacitor wrongly inserted. Whilst this may not be apparent from tuner operation, the capacitor may break down over a long period of time resulting in poor scan operation. Remedy Owners of Tuners with Serial Nos in the above range are advised to check the orientation of capacitor C88 and replace it where incorrect. This can be accomplished by the following: I. Remove 10 screws securing the Tuner lid II. Remove 4 screws securing the shielding plate III. Check the orientation of Capacitor C88 as per the attached Fig 1 and if incorrect - (a)Remove 4 screws securing the PCB, desolder Capacitor C88 and replace it with one correctly oriented. (b)Carefully scratch off the + sign on the PCB adjacent to C88 to avoid future confusion; (c)Replace the PCB IV.Re-assemble the Tuner The Tuner should then be checked for correct operation. Replacement capacitors can be made available from Codans Service Department. 2 of 2 Ensure C88 has +ve terminal closest to R64 IC9 R66 R67 C87 C88 + D6 R64 R41 R11 + R65 C32 R63 R8 D15 D14 R7 R61 IC15 D10 + IC5 R48 C30 Figure 1. Part of 9103 Tuner Assembly
