Installation
Overview
With this upgrade the radio is kept almost exactly as specified by Ten-Tec. The alignment procedure is exactly the same. There is just one soldered on component that must be modified on the main board from what is supplied by Ten-Tec. There is an optional additional LED that can be installed in an existing, but unused location on the display board. And there is a new processor with totally new firmware mounted on a carrier daughter board that snaps into the PIC processor socket on the main board. From the new daughter board there are a few new wire connections, besides those already on the socket, to the main board, top and bottom, and to a new rear aluminum panel.
1254 Upgrade Kit Contents
To build or modify the radio with this upgrade follow all the original Ten-Tec assembly instructions except where as noted in this documentation.
Main Board Component Change
The main board Diode D5 must be modified. The silicon switching diode used here is part of the battery backup circuit to the original PIC processor. The diode is in series with the 5 volt supply to the processor, and it is used to block the battery current to everything other than the processor when the external power is off. The diode has a forward voltage drop of .7 Volts that reduces the supply voltage to the processor from 5 to 4.3 Volts. The new Cypress processor used in the kit can not run all it's features at this lower voltage. The voltage to the 28 pin socket passed up to the new daughter board must be restored.
There are a few ways to increase the voltage. The first option is to remove the diode altogether and replace it with jumper. (A cut end of a resistor or capacitor wire can be used to make the jumper.) The full 5 volts is then available to the new processor. The new processor has non-volatile FLASH memory used for both program and data storage. No battery backup is required, and the battery should not be installed while using the upgrade kit.
Another option with a kit that is already assembled is to "tack" thin jumper wire carefully on the ends of the existing D5 diode, shorting it out. The wire can then be removed and the battery replaced for returning to operation with the PIC processor.
Location of D5 Jumper (Outlined in Blue)
Display Circuit Board Auxiliary LED
This step is optional. Two green LEDs, D5 and D6, are provided with the Ten- Tec kit to indicate the receiver mode, either AM or SSB. The stock display board has three positions for LEDs though, with an unused and unmarked location available for a LED between the two designated for use in the kit's instructions. The upgrade makes use of this unused board mounting location. Take the provided new LED and place it in the two holes of the unused position. Mount it with the same polarity orientation as the other two, and at the same height off the circuit board. The firmware controls the illumination of this LED if present to provide additional information about the state for the radio.
Daughter Board Installation
The Cypress processor daughter board is pre-assembled and ready to snap in place on the main circuit board. All that is required is to carefully remove the PIC processor if installed then line up the pins 1 to 1 from the main board's processor socket to the daughter board header and press the new board in place.
Daugher Board Cable Connections
The processor daughter board has five male .100" headers, two of which are used to wire to the radio main board, and two to the rear panel. One is not connected and used only for reprogramming the processor.
- JP3 AGC Two Pin, one wire, input from the top of the main radio board.
- JP1 IN Two Pin, shielded two wire, audio input from the bottom of main radio board.
- JP4 CAT Four Pin, four wire, computer control cable to the rear panel.
- JP2 LINE Three Pin, two wires used for the line output to the audio jack on the rear panel.
- JP5 ISSP Five Pin header used for processor FLASH firmware updates.
AGC Tie In Point
The AGC tie in voltage is used to determine the signal strength read over the
computer control interface. Use the yellow wire with the two pin female MOLEX connector. Plug
one end into JP3 on the daughter board. The connector goes in only one way. (The
unused pin on the connector is ground.) Cut, strip and solder the other end of
the wire to resistor R66, either side. Leave enough wire length so the connector
can reach to the daughter board and be easily attached and removed.
Audio Tie In Point
The audio input to the processor is picked up from the input of the main board's
audio power amplifier. To access this point the shielded audio cable must be
plugged into JP1 on the daughter board and threaded past and through the board
opening around the tuning encoder and then to the bottom side of the board.
There is a row of what looks like 10 pins where the amp is soldered to the
board. Note only 9 of these pads go to the pins of the amp. Observe the picture
of the bottom of the board around the speaker connector and the notch for the
tuning encoder. Pin 8 is the solder point for the signal, center conductor, of
the sheilded cable. Pin 9 is the ground tie point. It is easier to get to this
ground point on the trace off of pin 9. Once soldered be careful not to put any
stress on the cable's connections to the circuit board.
Computer Control Interface Cable
The four wire cable used for the computer interface has a MOLEX connector on each end. One end connects to a DB9/Level Shifter. The DB9 assembly will be attached to the new rear panel. The other end connects to JP4 on the daughter board. The cable's wires must be run around the side of the main circuit board to get to it's other side. If the radio is already assembled the rear panel must be removed. It will be replaced with the new panel. The side rail of the case assembly must be loosened to pass the wires and connector between the case and board. Keep the panel off and the case side loose for the next step.
Audio Line Output Cable
The two wire twisted pair cable has a three position MOLEX connector on one end and an audio jack on the other. The jack will be attached to the new rear panel with it's nut. The twisted pair is routed next to the computer control cable between the circuit board and the side of the radio case. The MOLEX connector plugs into JP2 on the daughter board. The side of the case can now be reset.
Note: The connector JP2 has a third pin whitch ties to the radio's +5V power supply. This pin is not normally used.
Rear Panel
The new aluminum rear panel has two extra openings for the DB9 and line output jack connectors. Unscrew the two mounting posts on the DB9 connector and mount it to the panel so the pins on the board it's tied to are facing upward. Place the audio jack in the panel and use the nut to fix it in place. Screw on the new panel.
This completes the upgrade.
