DISCLAIMER: THIS CONTENT IS PROVIDED TO INTERESTED PEOPLE "AS IS" FOR NON COMERCIAL PURPOSE ONLY. UNDER NO CIRCUMSTANCES I AM RESPONSIBLE FOR ANY DAMAGES TO YOUR RADIO, PC OR OTHER EQUIPMENT. THIS DEVICE WAS TESTED UNDER DIFFERENT CONDITIONS AND UNTIL NOW IT WORKS WITHOUT PROBLEMS.
QuickTune consists of a 12C5xx PIC using the internal 4 MHz oscilliator, a push button switch which starts the tuning process, a LED as activity/error indicator and serial RS232 in- and outputs to the FT-817.
QuickTune can be powered in 2 ways:
When direct powerd, QuickTune always draws little power from the FT-817 (even if it is turned off). In this case there is no need for C2 and you can jumper SW1b with a piece of wire.
Demand powered means that QuickTune is only powered during the tuning process. This is accomplished by SW1b and C2. When SW1a and SW1b are pressed the same time C2 is first loaded and then the PIC starts operating. Because of SW1a which is also pressed it starts the tuning process immediately. When SW1a and SW1b are released the process ends and also the power to QuickTune is cut. In oder to set back the FT-817 to the state as it was before pressing SW1 it is now powered from C2. The power from C2 should be enough for the PIC to do this and then shut itself off.
The software within the PIC handles the communication to the FT-817 via the RS232 level converters T1 and T2 using CAT commands at a speed of 9600 baud. When you press SW1 the PIC first tries to accuire the current mode of the FT-817. If this fails (eg. no connection, wrong baud rate etc.) then LED D1 starts blinking and QuickTune again tries to figure out the current mode as long as it succeeds or SW1 is released. If the mode could be read it is saved in the PIC. Next the mode of the FT-817 is set to CW. You could use other modes for tuning. This must be configured within the assembler source. Then the FT-817 is locked and PTT is set to ON. As long as you press SW1 PTT stays on and a carrier for the tuner is generated. After releasing SW1 PTT is set to off, the FT-817 is unlocked and the saved mode is restored so that the FT-817 is in the same state as before pressing SW1.
By using a PIC of the 12C5xx series you must also pay attention to the oscilliator callibration value which could be different for every PIC. It is placed during production into the last memorylocation. By using it you can fine tune the internal 4 MHz R/C oscilliator. This is important because the 9600 baud RS232 communication routines need accurate timing. For more informations on this see the Microchip PIC12Cxx release notes.
You can also use a PIC of the 84 series (16C84, F84, F84A). Just set the type within MPLAB and the source should compile for a 84 without problems. By using the 84 there will also some space for additional functionality like a direct frequency input using a number keypad. I may add this later.
Image 2: The PCB
Image 3: Component positions
You can download a PDF File with the schematic and the PCB here.
If you dont have the Adobe Acrobat Reader installed on your machine you can find it here
Image 3: The etched PCB
Image 4: The finished PCB with all components
NOTE: THE POWER REDUCTION FEATURE USES UNDOCUMENTED CAT COMMANDS FOR THE FT-817 (WRITING AND READING EEPROM ADDRESSES DIRECTLY). USING THIS ON OTHER RADIOS MAY DAMAGE THEM. THIS FEATURE IS IN THE CURRENT VERSION ONLY INTENDED FOR THE FT-817 AND WORKS WITH MY FT-817 WITHOUT PROBLEMS. THIS DOES NOT MEAN THAT IT WILL WORK WITH OTHER RADIOS OR EVEN WITH OTHER FT-817 WITH OTHER FIRMWARE VERSIONS THAN MINE. USE IT WITH CAUTION. I AM NOT RESPONSIBLE FOR ANY DAMAGE TO YOUR RADIO. YOU HAVE BEEN WARNED!
Also the same Note as above applies to this!!
|This paper can also be found in the german HAM Radio Magazine
"Funkamateur" at www.funkamateur.de, Issue 11 / 2003, Page 1135,
Title: "QuickTune für den FT-817"