DEC-001 Installation Instructions Skill Level: The installation of this assembly requires a medium level of expertise in working with modern electronic equipment. The use of appropriate tools, correct soldering techniques and advanced workmanship skills are necessary to achieve a high quality result. ESD Warning: All work must be performed at an ESD safe work station. Wear a personal grounding strap whenever handling the open SWR Analyzer or the DEC-001 board. Additional Items Required: Soldering Iron, 25-30 Watts with a small tip Solder for use on printed circuit boards Wire strippers for 22 to 28 for gauge wire Solder wick Medium strength locktite Phillips screwdriver, #1 Nut driver, 1/4 inch Test load resistors, 12.5 Ohm, 75 Ohm, 100 Ohm, 200 Ohm Shrink sleeving, 1/8", 2 one inch pieces Before You Start: Your SWR Analyzer must be fully functional. Do not proceed with this installation if there is an electrical or operational problem with your unit. You must get the unit repaired prior to beginning the installation. Note: The Vectronics SWR-584B is identical to the MFJ-259B. The Vectronics SWR-584C is identical to the MFJ-259C. Lets et Started: Remove the 4 screws (8 total) on each side of the SWR Analyzer, remove the cover and set these aside. Remove 2 batteries from each end of the battery holder. Remove the 2 screws in the bottom of the battery holder that are towards the outside edge. Refer to Figure 1: Battery Holder Removal. The battery holder wires are routed through a hole in the main board. Refer to Figure 2: Battery Holder Wires. These wires must be re-routed to free up the hole to mount the DEC-001 board. Cut the wires approximately 3 inches from each battery holder terminal and set the battery holder aside. The wires will be spliced during reassembly. An alternate method is to unsolder the wire from the points where they are soldered to the PC board, reroute them around the side of the main board and resolder them to their original locations. Familiarize yourself with the exposed side of the main board. Test points are silk screened on this side and you will be making connections to 7 points on the board. Refer to Figures 3 through 6 for examples of the silk screened test points. Test point numbers are identical, T1, T2, T3, T4, T21 but are located in different places on the boards for different models. Power will be connected to T18 for all models.
round will be connected to R73 or R53 (ground leg) for all models. The test points are thru holes on the main board and are 0.025" in diameter. If a hole has solder in it, use solder wick to open up the holes for T1, T2, T3, T4, T18 and T21. Refer to Figure 7: Wiring Harness Installation for the following wire installation. Remember that T1, T2, T3, T4, T18 and T21 are located in different places on the board for different model analyzers. Locate the supplied 8 pin connector/wire assembly supplied with the DEC-001. Note the location of pin 1 on the connector. Note that pin 2 is blocked for connector keying. Identify the wire connected to pin 1 and solder it to a ND connection on the main board. You can use one of the ground leads of R73 or R53 for this connection. Identify the wire connected to pin 3 and solder it to T4 on the main board. This is the VZ voltage. Identify the wire connected to pin 4 and solder it to T3 on the main board. This is the VS voltage. Identify the wire connected to pin 5 and solder it to T18. This is switched +12 VDC on the main board. Identify the wire connected to pin 6 and solder it to T21 on the main board. This is the frequency sample from the prescaler on the main board. Identify the wire connected to pin 7 and solder it to T2 on the main board. This is the VR voltage. Identify the wire connected to pin 8 and solder it to T1 on the main board. This is the VF voltage. Dress the wiring harness to position the connector at the lower left of the SWR Analyzer as viewed from the back. A wire tie or lacing cord may be used to dress the wires if desired. Refer to Figure 7: Wiring Harness Installation. Inspect your workmanship, look for: Correct pin number to main board connections. No solder shorts. All wires have adequate clearance and are not stressed or pinched. Remove the 6-32 screw and washer at the lower left of the main board. Save it for reuse later. Install a 6-32 threaded 1/4" long spacer where the screw and washer were removed. Refer to Figure 8: Hex Post Installation Install a 6-32 threaded 1/4" long spacer in the hole of the main board where the battery holder wires were removed. Use a small pattern nut and apply a small amount of locktite to the threads. Mount the DEC-001 board to the two new hex posts. Reuse the 6-32 screw and washer removed above and install one new 6-32 screw and washer to secure the DEC-001 board in place. Refer to Figure 9: DEC-001 Board Installation and to drawing Offset Spacer Installation at the end of this document. Note that the MFJ-259C, MFJ-269 and MFJ-269C require the use of an offset spacer to be installed at the connector end of the DEC-001 board. Refer to the Offset Spacer Installation drawing at the end of this document.
Mate the 8 pin connector to the 8 pin header on the DEC-001 board. Observe connector keying and note that there are two header connections, a 4 pin on top and an 8 pin next to the board. Locate the DB-9 connector wiring assembly supplied with the DEC-001. It will be necessary to mount the DB-9 connector in the side of the rear cover of the unit. Refer to Figure 10: DB-9 Installation. Cut out the template you want to use from the drawing and tape it to the right side of the cover. (Side opposite the battery holder.) Cut out goes near the bottom towards the back side. Refer to the DB-9 Hole Cutout drawing at the end of this document. Put masking tape on the opposite side of the cover to prevent scratches while working to make the DB- 9 cut out. Spot punch the hole locations. Then start with a small drill bit and work up to the final hole size. Final cut out is completed using a nibbling tool and or small file. De-burr all sharp edges. Take your time and make trial fits of the DB-9 connector periodically. Install the DB-9 connector wiring assembly in the cutout of the cover using the hardware supplied. Note that the DB-9 connector is mounted from the outside. Apply a small amount of locktite to the threads of the hex posts. Mate the 4 pin connector to the 4 pin header on the DEC-001 board. Observe connector keying. The 4 pin connector will now be lying on top of the 8 pin connector. You are now ready to re-connect the battery holder wires. If will be necessary to splice the red and black wires that were cut earlier. Use a short piece of shrink sleeving to insulate the splices. Apply power to the analyzer and check for normal operation. Correct installation will not affect the normal operation of the analyzer. If the software has not been installed, do so now. Launch the program. Connect a serial cable between the analyzer and the computer. A USB to serial adapter may be used if a serial port is not available. Select the Port and then click on the Power button. The analyzer information should appear on the computer screen. Click on the Antenna ICON to display the Control Panel. Click the Calibration button and follow the steps to calibrate the analyzer. Re-mount the battery holder using the screws and washers previously removed. Use caution not to pinch any wires where the battery holder contacts the hex stand offs. You analyzer should now look like Figure 11: Final Installation. Re-install the cover and secure with the 8 screws previously removed.
Installation Figures Figure 1: Battery Holder Removal Figure 2: Battery Holder Wires
Figure 3 MFJ-269 Test Point Locations Figure 4 MFJ-269C Test Point Locations
Figure 5 MFJ-259B Test Point Locations Figure 6 MFJ-259C Test Point Locations
Figure 7: Wiring Harness Installation
Figure 8: Hex Post Installation Fig ure 9: DEC-001 Board Installation
Figure 10: DB-9 Installation Figure 11: Final Installation
Troubleshooting Operation 1. Make sure your SWR Analyzer is operating correctly by its self. Correct wiring to the DEC-001 will have no effect on the normal operation of the SWR Analyzer. If the SWR Analyzer does not operate correctly and is not correctly calibrated, the DEC-001 will not provide reliable data to the remote computer. 2. Disconnect the MFJ Header connector. This will completely isolate the DEC-001 circuit board from the SWR Analyzer. If the SWR Analyzer still does not operate correctly, look for solder shorts at the wire connections added to the main circuit board. Also check for the possibility of any pinched wires that may have occurred. 3. Connect a 50 ohm load to the SWR Analyzer Antenna connector and set the Frequency Switch to the 4-10 MHz range. The LCD should indicate: The correct frequency R should be approximately 50 X should be approximately 0 SWR should be approximately 1.0 DEC-001 Operation 3. With the MFJ Header connection restored and the 50 ohm load connected in step 3 above, check the DC voltages on the three terminal regulator, U3. Input voltage should be >10 VDC and output voltage should be 4.8 to 5.2 VDC. 4. Check that the Heart Beat LED is flashing. Flashing at approximately once per second indicates the program in U2 is running and that the crystal oscillator is operating. The actual rate of flashing is not critical and may vary slightly. 5. Measure the voltage on pin 5 of U2. It should be approximately 2.50 VDC. 6. Measure the voltage on pin 7 of U2. It should be approximately 0.00 VDC. 7. Measure the voltage on pin 3 of U2. It should be approximately 1.25 VDC. 8. Measure the voltage on pin 2 of U2. It should be approximately 1.25 VDC. 9. Measure the voltage on pin 2 of U1. It should be approximately +8.5 VDC. 10. Measure the voltage on pin 6 of U1. It should be approximately -8.5 VDC. RS-232 Operation 11. Disconnect the RS-232 cable to the remote computer from the DB-9 connector on the SWR Analyzer cover. Measure the voltage on pin 3 of the DB-9 connector on the SWR Analyzer cover. It should be approximately 0 VDC. (Same as pin 13 of U1).
12. Measure the voltage on pin 4 of the DB-9 connector on the SWR Analyzer cover. It should be approximately -8.5 VDC. (Same as pin 14 of U1). 13. Measure the resistance between pin 5 of the DB-9 connector on the SWR Analyzer cover and ground at the DEC-001 circuit board. It should be <3 ohms. 14. Be sure you have a straight through RS-232 cable to the remote computer. A null modem cable will reverse the RX and TX data lines. 15. Check your RS-232 cable for continuity. Only the following 3 connections are used. Pin 5 to pin 5 Pin 3 to pin 3 Pin 2 to pin 2 Faulty Bridge Diode 16. A very common failure mode for these instruments is the 4 diodes in the RF bridge circuit. These diodes are HSMS 2820 Schottky diodes and are available from various sources such as Digi-Key. They are surface mount parts and have a minimum breakdown voltage of only 15 volts. It does not take much more than this to damage one or more of them. To make matters worse, two of them are connected directly to the RF connector and the other two only have a 50 ohm resistor between them and the antenna connector. Connecting an antenna with a static charge to the instrument is likely to cause damage. You should always discharge anything before making a connection to your analyzer. Often the damage is not readily apparent. The instrument will still read SWR, R and X but the accuracy will be very poor and the instrument can not be calibrated without first being repaired. If after installing the DEC-001 you cannot get the calibration pots to adjust correctly, you most likely have a bad diode(s). The telltale sign is not being able to set the high values for VS, VZ and VR using the calibration pots on the main board of the analyzer. They will have lower than normal readings due to low output from a leaky diode(s). Microcontroller Software Version 17. The micro-controller software version can be read by sending a?. The DEC-001 will respond with Version X.X where the X.X is a number such 1.3.
RS-232 Serial Data Communication The DEC-001 will communicate with a RS-232 terminal program such as RealTerm or other equivalent programs. The terminal program should be configured for 57,600 Baud, No Parity, 8 Data Bits and One Stop Bit. Sending the r character (lower case r for Read) will get a response with 7 lines of data as shown below. The first line is the A to D count for VZ. The second line is the A to D count for VS. The third line is the A to D count for VR. The fourth line is the A to D count for VF. The fifth line is the Frequency High Byte. Multiply this number by 65,536 for the decimal value. The sixth line is the Frequency Middle Byte. Multiply this number by 256 for the decimal value. The seventh line is the Frequency Low Byte. Multiply this number by 1 for the decimal value. The sum of these three frequency bytes in decimal form represents the frequency counter reading from the micro-controller. This sum should be multiplied by 8 or 4 (there is a prescaler in the SWR Analyzer) to get the actual counter numbers.
The frequency in the example above is calculated as follows: 0 * 65536 = 0 35 * 256 = 8,960 16 * 1 = 16 The sum is 0 + 8,960 + 16 = 8,976 8,976 * 8 = 71,808 The time base used by the counter is 10 ms. Therefore, multiply the number by 100 to get the frequency in Hz. 71,808 * 100 = 7,180,800 Hz or 7.1808 MHz Note: The example above is with a SWR Analyzer prescaler operating as divide by 8. Some SWR Analyzers use a divide by 4 prescaler.