K40 RTTY Module Guide
Contents
1. K1EL RTTY Filter Board Kit K 40FILT Introduction K40FILT is an accessory board for the K40 CW Keyboard Kit that allows the K40 to send and receive RTTY Audio from a receiver is fed to the K40FILT where it is filtered and then processed by a PIC processor running at 5 MIPS The processed data is demodulated and fed over to the K40 for Baudot to ASCII conversion and display on the LCD Letters typed on the K40 side are converted to ASCII and then output either as FSK or AFSK though a sine wave tone generator on the K40FILT board The K40FILT has an LED array that is used to tune RTTY stations in quickly and accurately Features e Audio preamp filter e 4 Pole SCAF Bandpass Filter e DSP demodulator e AFSK Tone generator e PIC16F684 PIC Processor e LED tuning display on board Assembly Instructions An accurate DVM or VOM is a requirement for this project There are a large number of precision 1 resistors that MUST be installed correctly to insure proper operation The color codes on these resistors can be confusing and an ohmmeter is the most reliable way to insure correct resistor placement Other than that the assembly of the K40FILT is very easy all you need is a low wattage soldering iron some solder a few pieces of hook up wire a good pair of wire cutters and small pliers You will need an assembled working K40 board to test and check out the K40FILT board These instructions will take you through a step by2. RTTY Indicator LEDs The LED display will blank when a signal is very far out of tune or no signal is present This is an aid for tuning since the display will stay off until you are close to a station At that point the display will turn on and you can tune in easily The right mode LED corresponds to Mark while left most LED corresponds to Space If RX is set to reverse the LED positions are reversed You will find that you can successfully tune in very weak stations that only light one or two LEDs each side of center Contests add an extra challenge since stations can be right next to one another K40FILT does a good job with its built in band pass filter but find a narrow IF filter in the receiver set to RTTY mode will improve the K40 copy particularly with strong adjacent signals Turning AGC off can help reduce this interference also Transmitting There are three K40 outputs used for transmitting PTT KEY and FO The K40 PTT output is used to key your transceiver and switches to ground when active This usually goes to the key input but check your transceiver s manual to be sure The K40 KEY output is used to frequency shift key your transceiver in FSK mode If your transceiver has a direct FSK input it s the easiest way to go Use Table 1 1 to determine what your transmitter requires and set the K40 to either TX or TX mode ALT F9 If your transceiver does not support FSK you will need to run in USB AFSK mode In this case connect the K
3. 10 K40 to K40 FILT Interconnect K 40FILT User s Manual rev2 2 20 2007 Page 19 KIEL RTTY Filter Board Kit K 40FILT 2 Pole Bandpass Filter with 14 dB Gain fe 047uf Ree Bandpass nput Switching ik 4 7K Sheet 3 DIGI FS AFSK Output Switching Sheet 2 CTRL 170 CD4866 ost Sheet 3 Sheet 2 AGND AFSK Output Buffer amp Level Control Ral LMC6482 VA cr zeg E BluF ia K KIEL Systems Input Bandpass amp Switch re en tore K40FILT User s Manual 2 20 2007 Page 20 K1EL K40FILT RTTY Filter Board Manual Bandpass and Mark Space Filters AtSu Sheet 1 2125 Hz IARKOUT Sheet 3 2295 Hz SPACEOUT Sheet 3 19 LTC1 68 Sheet 3 FILTCLK Sheet 1 KIEL Systems Bandpass amp Tone Filters ri ii K 40FILT User s Manual rev2 2 20 2007 Page 21 K1EL K40FILT RTTY Filter Board Manual Sheet 2 YDD Sheet 2 Sheet 1 Ragzana RALZANL 2 RA2 AN2 2 lt CED_PuM Sheet 4 RA3 MCLR RA4 TIG RASZTICKI Sheet 1 vss 16F694 Sheet 1 Sheet 2 KIEL Systems Microcontroller Bee ANO K 40FILT User s Manual rev2 2 20 2007 Page 22 K1EL K40FILT RTTY Filter Board Manual von gt No Mo GP2 T CKI GP4 0SC2 Sheet 3 GP3 MCLR GPS 0SC1 vss PIC12F508 KIEL Systems LED Level Indicat
4. 2 20 2007 Page 2 K1EL RTTY Filter Board Kit K 40FILT Theory of Operation The following block diagram shows the basic sections of the K40 filter board Audio from the receiver is amplified and filtered through an initial active filter stage This stage provides 16dB gain for low level audio input and also provides some out of band signal rejection This stage also isolates and protects the SCAF from the input The LMC6482 handles large input amplitudes well and clips very cleanly The first narrow bandpass filter is made up of two sections of an LTC1068 switched capacitor filter It provides a filter bandwidth of about 800Hz with a center frequency of 2210 Hz The output of the bandpass filter is then fed into a pair of tone filters made up of the remaining two sections of the LTC1068 These filters are set to 2125 and 2295 Hz respectively The filtered tones are then fed directly into the PIC processor where they are rectified filtered and sliced to produce a digital Baudot serial output Additionally the PIC provides a signal gate to squelch output and the LED display if no signal is tuned in A PWM signal is sent to a second PIC to drive an LED tuning bar display The LED bar also indicates mark space activity on transmit In AFSK transmit mode the PIC generates square waves at either the mark or space frequency as determined by the FSK input from the K40 The square waves are fed through the bandpass filter which filters the harmonic con
5. A note about lead in and tail you will notice when working other RTTY stations that it is common practice to key the transmitter without modulation for a second or two before starting to send data Again there may also be a similar delay at the end of the transmission This can be duplicated on the K40 through the use of the lead in and tail delay settings They specify the amount of time after PTT is asserted before FSK starts and how long to hold PTT after FSK is finished K 40FILT User s Manual rev2 2 20 2007 Page 6 K1EL K40FILT RTTY Filter Board Manual Note that the CW paddles and speed control are inoperative in RTTY mode Also CW specific command keys are disabled in RTTY mode Command Description by Key Several K40 commands operate differently in RTTY mode and some commands are not supported at all In the command descriptions below a double star indicates an RTTY mode command SHIFT F2 lt 45 gt should really be entered as SHIFT F2 4 5 A message key press is denoted by lt Fx gt where x is the message key number lt F1 gt lt F2 gt lt F10 gt The Shift command keys setup K40 RTTY operating modes Remember to use the SHIFT F1 P command to save these settings in EEPROM if you want them to be held so that they will be loaded next time you power up F1 through F12 Send Message To make message access easy they are assigned to the twelve function keys Hitting one of these keys will cause a message to be queued up an
6. digital 1 and 0 serial data stream Audio is taken either from the transceiver high impedance line output or across the speaker The K40 FILT input has an impedance of about 1K ohms so an impedance transformer is helpful to match a receiver s low impedance speaker output to the K40FILT input Once it is decoded the serial data stream is passed over to the Keyer PIC on the K40 PCB where Baudot to ASCII conversion takes place with resulting letters and numbers displayed on the LCD In an effort to make K40 RTTY operation easy to use the basic operational mode is fixed That means 60 WPM 45 45 baud Baudot coding 5 data bits with 2 stop bits at 2125 2295 Hz shift Automatic threshold correction is always enabled during receive as well as automatic unshift on space The user has control of transmit diddle and mark space reversal in both transmit and receive To enable RTTY mode simply press ALT F1 and the K40 will change to RTTY mode and RTTY ON will be displayed momentarily on the LCD To change back to CW mode just press ALT F1 again and the LCD will display RTTY OFF placing the K40 back in CW mode When switching to RTTY mode the K40 will automatically be set to receive with the receive buffer displayed Receiving Find a RTTY station that is transmitting and attempt to tune it in This takes practice and a bit of patience at first But after a while you will learn how to watch the LEDs and tune carefully to get the widest spread in cadence with
7. resistor placement or missing components Oscilloscope Measurements An oscilloscope will provide a more accurate way of measuring the filter levels The table below shows peak to peak values for various filter settings They taken in tune mode SHIFT F8 in TX and TX mode ALT F9 U1 PintO U1 Pin3 U1 Pin15 U1 Pin21 2 8V PtP 3 0V PtP 1 4V PtP 3 2V PtP 1 7V PtP 3 0V PtP 3 2V PtP 1 4V PtP Table 2 K 40FILT User s Manual rev2 2 20 2007 Page 13 K1EL K40FILT RTTY Filter Board Manual Immediate Commands Key noma Shit ALT Table 3 Buffered Commands ID I Seialg1 Im i seat TM Load Loop Count Insert CR Play Serial DECSZ Loop Table 4 EH K 40FILT User s Manual rev2 2 20 2007 Page 14 K1EL K40FILT RTTY Filter Board Manual Bill of Materials K40FILT PCB K40 Filter Printed Circuit Card PC Board LTC 1068 Switch Cap Filter IC 24 pin SDIP aq fun K40FILT PCB ERR LNCG462 Dual Op Amp Brinde 03 PiCi6r684 RITY Controller id Pin DIE roa eb4066 cmos switoh______ 14 Pin DIP ros PIc1aF508 Display Controller 6 Pin DIN ros LED Display ia E maza 270 0 5 Resistor n R1 R6 R9 R14 10K 1 Resistor 1 4 W Blue e al 49 9K 1 Resistor 1 4 W Blue Do 24 3K 1 Resistor ra w Blue 78 7K 1 Resistor 1 4 W Blue e TISK 1 Resistor 71 uw Blue PR7 RIS iier 18 Resistor 1 4 WB PRI0 R17 61 9K 18 Re
8. running RTTY on a separate transmitter and receiver is accurately tuning your receiver to the frequency you are transmitting on When running AFSK with a transceiver this is not usually an issue since the tone pair frequencies transmitted are the same as those received The spot command provides a way synchronize a transmitter and receiver running FSK Spot is enabled and disabled by SHIFT F4 When in spot mode the K40FILT board is held in receive during transmit This allows you to tune your transmitted FSK on your receiver and tune using the LEDs on the K40FILT board The filter board will demodulate the signal and pass decoded Baudot over to the K40 Since the K40 can transmit and receive simultaneously the data stream will be displayed in the receive window This is a valuable tool for setting up your RX RX and TX TX settings It s not unusual in FSK setups to run receive shift differently than transmit shift i e RX TX or RX TX it s mainly a function on how the transmitter FSK input works If you want to transmit with Diddle on use the ALT F3 command to turn it on or off When diddle is on the K40 will continually send the LTRS characters when there are no characters queued up to send This fills transmit with a continuous stream of frequency shift transitions which help the demodulator on the receive side stay in sync with your transmission and will reduces errors When you use the insert key to change from receive to transmit th
9. sure you get them placed correctly start with R1 and go all the way through to R24 Note that 10K resistor R21 is a 5 value OO 00 0000 Next install the DIP sockets Align the notch in the socket with the silkscreen Note that the socket for U1 is made up of three 8 pin sockets Carefully line these up before soldering It s easy to bridge adjacent socket pins when soldering so take your time Install and solder the capacitors Two caps C2 and C11 have polarity markers that must be observed On both caps the long lead is the positive lead and should be installed closest to the silkscreen legend The square pad is the positive side Install the ceramic resonator X1 orientation does not matter The last item to install is the trimpot VR1 this part can be installed in either orientation install it so that the Screw Adjust is closest to U4 K40FILT User s Manual 2 20 2007 Page 1 K1EL K40FILT RTTY Filter Board Manual 9 10 11 12 lt 13 14 Now wire the K40FILT board to the K40 board as shown in Fig 9 on Page 19 If you purchased the K40 enclosure follow the detailed wiring harness instructions Note that there are three signal connections 5V and two grounds After this step but before installing any ICs turn the K40 power on and measure the voltage on U4 pins 14 and 7 Pin14 should be 5V with respect to pin 7 Turn power off and install U3 Power on again and measur
10. 40FILT FO output AFSK on the enclosure to your transceiver audio input Sometimes you can drive the microphone input directly in other cases there may be a phone patch or line input jack that you may want to use instead again consult your transceiver manual When running AFSK mode you will have to set the input level appropriately to prevent over modulation There are two adjustments that control this the output level control on the K40FILT board and the Mic level on your transceiver Set the K40 to RTTY mode ALT F1 and then hit the insert key if everything is hooked up correctly this will key your rig It s best to start both level controls near minimum K40FILT pot fully clockwise and gradually increase both together to a point where you just start to see an RF output Monitoring ALC advance the mic to a point where either you reach your desired power output or the ALC stops increasing with increasing Mic level It is always a good idea to monitor your signal after the adjustments are complete to make sure it is clean Both FSK and AFSK are produced simultaneously by the K40FILT board choose the one you want to use and ignore the other Both KEY and PTT outputs are open collector and can key up to 50 V have found most modern transceivers present a voltage in the range of 5 to 12 volts which must be pulled low to assert It is imperative that you check this carefully to be sure that it is within the range the K40 can control One problem in
11. CQ CQ CQ TEST DE KIEL KIEL PSE K K You can then fire it off just by pressing a single message key Note that the message starts with two CRLF sequences that s what the two M do In other words use M to insert a CR LF Unfortunately you can t use the enter key since that will end message entry mode There are two rules to follow when using K 1 Always put a K at the beginning and end of the message 2 Don t use the Insert key while transmitting a message with a K in it the transmit state of the console PIC can get out of sync with the keyer PIC If you want to stop a message please use ESC If you do send a K message without the trailing K it s not a big deal but you will have to hit Insert twice to get back in sync again A nice K40 feature is fast callsign entry Pressing the END key will open up a small window in the upper left corner of the display where you can enter a callsign When you hit return the callsign will be copied into the F12 message slot This is great for contest exchanges Try entering a message formatted like this KAM 4C lt F12 gt DE KIEL 5NN SNN NH NH QSL C lt F12 gt DE KIEL QSL M K Now you can quickly enter different callsigns into the F12 slot using the END key and reuse the above message over and over again Note that the CALL token C is used to call the message in F12 and then return If you did not include the C the message would jump to the F12 slot and stop when that message finished
12. RTTY frequency shift keying heard If you have a wide LED swing but garbage is printing there are two possibilities it may not be an RTTY station or you need to reverse mark and space Generally if you set your transceiver to USB or RTTY mode the K40 should be set to RX This is not a standard for example the Drake R8 receiver set to RTTY mode runs in LSB mode requiring RX ALT F8 is the command used to change between RX and RX The spread of the LED display will change as a signal fades in and out and as selective fading causes mark and space to have different amplitudes The K40FILT automatically compensates for both conditions and no retuning is necessary With very deep fades the K40 may print an erroneous character or get out of sync for a couple of characters This is normal for HF RTTY operation Some higher end DSP demodulators can follow weak signals and extreme noise better than the K40FILT can with its meager 5 MIPS PIC Baudot coding uses FIGS and LTRS codes to shift between an upper and lower character set If one of these codes is missed due to noise the K40 will print in the wrong case until the next space carriage return FIGS or LTRS code If this happens you may see a string of numbers or punctuation in the middle of a sentence K 40FILT User s Manual rev2 2 20 2007 Page 4 K1EL K40FILT RTTY Filter Board Manual DODODO MARK LEDs normal SPACE LEDs reverse SPACE LEDs normal MARK LEDs reverse Fig 2
13. Se the K40 manual for a discussion of buffered commands F1 F12 Jump to message As mentioned previously message keys are buffered commands which are sent as they are taken out of the FIFO buffer The ability to jump from one message to another is very useful Here s a simple example Load Slot F1 with CQ CQ lt F3 gt Load Slot F2 with QRZ QRZ lt F3 gt Load Slot F3 with DE KIEL K Message F1 will be sent as CQ CQ DE KIEL K Message F2 will be sent as QRZ QRZ DE KIEL K Jump can be used to make a message loop here s how Load Slot F1 with co CQ CQ CQ DE KIEL KIEL KIEL lt F1 gt After sending CQ CQ CQ CQ DE KIEL KIEL KIEL we loop back to the beginning and send it again This will repeat forever until the ESC key is pressed CTL C lt F1 F12 gt Call a message The call command will jump to the specified message send that message and after the message completes the stream will return to where it was called It is more flexible than a jump to message An example of this command is Load slot F1 with C lt F2 gt C lt F2 gt de C lt F3 gt C lt F3 gt BTU OM KN Load slot F2 with WA1LABC Load Slot F3 with KIEL Message F1 will play as WALABC WAIABC DE K1EL KIEL BTU OM KN This illustrates a powerful feature you can build up complicated messages that can be reused by substituting different callsigns in a called slot In this example the complicated message is in slot F1 and the called slots are F2 and F3 Even thou
14. but you may need a higher level If you are using a receiver turn on calibrate or tune in a carrier signal to get a beat note If you are using a signal generator set it to 2000 Hz Tune up and down slowly until you see some activity on the LED display You may have to play with the audio level some As you tune you will first see LEDs light on one side continue tuning and you will see the LEDs sequence across from one side to the other The left most LED corresponds to a 2295 Hz tone 15 16 17 while the right most is 2125 Hz If your audio level is too low you may only see one or two LEDs light each side of center as you tune Try increasing the gain by hitting the ALT F2 command If you are having problems read the section on filter verification Now let s try to tune in some RTTY stations Connect AF IN to your receiver s audio output Make sure you are still in RTTY mode ALT F1 Look on 20 meters around 14 080 14 090MHz that s usually a good place When no station is tuned in the LEDs should be out As you approach proper tuning you will see one LED side light up and then both LED banks will alternate back and forth in cadence with the RTTY signal A properly tuned signal will show the LEDs on each end the brightest with an occasional LED flash in between As soon as you are tuned in the print gate will open and letters will appear on the K40 display If you are printing garbage it s possible that you need to rever
15. d sent after the current contents of the FIFO buffer have been sent in other words they are buffered commands There is no way to send a message immediately except to clear the FIFO buffer with the ESC key and then send the message If you hit the message key of an empty slot nothing will happen See below for instructions on how to load a message Copied from the K40 manual SHIFT F1 Save Something in Memory The K40 has the ability to store messages and other items in non volatile memory Non volatile means that the memory contents are preserved even if power is turned off Recording begins by pressing the SHIFT F1 key the following chart shows all available recording options SHIFT F1 followed by F1 F12 Record a message P Store current settings as the power on default Message Recording Message recording is easy let s say you want to put a new message in slot F4 first press SHIFT F1 then press F4 The CAPS light will come on to let you know that you are in record mode and you can then enter your message If you make a mistake you can back up using the BACKSPACE key At any time you can abort by pressing the ESC key Any alphanumeric key or prosign can be put into a message as well as any buffered command The message slots are fixed in size when you get to within 8 entries of the slot being full the SCROLL LOCK light will turn on When you reach the end of the slot Slot FULL the SCROLL LOCK light will flash When you are all finished and
16. e LCD display is automatically toggled to show the transmit window The transmit buffer is identified by an underline cursor which indicates the text K 40FILT User s Manual rev2 2 20 2007 Page 5 K1EL K40FILT RTTY Filter Board Manual entry point When going back to receive the LCD is toggled back to the receive window and the cursor is turned off The user can toggle between receive and transmit windows manually by using the TAB key Scrolling PGUP PGDN is also supported and hitting the HOME key returns the buffer back to the active line However don t hit END that key is used for fast callsign entry While receiving the K40 supports type ahead so you can enter a response message while reading an incoming message You can quickly toggle to the Tx buffer with the TAB key to check a spelling or see where you are Hit TAB again to get back to the incoming display The Caps Lock light on the keyboard will flash when there are characters in queue waiting to be sent The transmit monitor command Shift F4 is useful in some cases It allows you to monitor real time transmit progress in the receive window and will show messages fully expanded instead of message token letters When TX monitor is on the transmit stream is printed in lower case in the Rx window The LCD window is not toggled back and forth with transmit receive in this mode since everything can be seen in one window You still can toggle the display manually with the TAB key TX m
17. e the voltage on U3 pin 5 you should see about 2 5 volts this is the filter clock which can be viewed with an oscilloscope if you have one it should be a 200 KHz square wave If you don t see 2 5 volts carefully check the soldering connections on U3 and X1 Turn power off again and install U1 power up again and you should see 2 5 volts on pin 6 This is the analog reference Again if you don t see 2 5 volts check the connections on U1 particularly the power pins and bypass caps Remove power after testing Now install U2 and U4 Power up and hit ALT F1 on the K40 keyboard You should see RTTY ON show on the display Monitor the voltage on U3 pin 6 on U3 with a voltmeter Hit the Insert key on the K40 keyboard Pin 6 will toggle between 5V and OV each time you press Insert Check that Pin 7 toggles also and is the complement of pin 6 when 6 is high 7 is low and vice versa Turn power off and install U5 Power up and watch the LED display you should see a power up LED test in which each LED is turned on and off in a sequence Make sure all LEDs light one at a time When the test is over all LEDS will turn off If not check the connections on the LEDs and U5 Now it s time to check out the K40FILT filters Connect an audio frequency generator or receiver audio output to the AF input on the K40FILT board The level needs to be around 1V peak to peak preferably a high impedance output 6000 You can use speaker audio out
18. ed sequence into a message M MCQ CQ CQ DE KIEL KIEL K M The above message will send two CR LFs followed by the message and then send another CR LF CTL N Send Serial Number The four digit serial number is sent in Morse A leading zero is suppressed so 0047 is sent as 047 CTL S NULL Command In RTTY mode the S command has no effect and is ignored It will be displayed on the LCD input window but will not be acted upon CTL W lt NN gt Wait for NN Seconds NN 01 99 This command is used to insert a fixed pause into a message it s well suited for building a beacon message Load Message Slot F1 with BCON DE KIEL wen lt F1 gt When you press F1 BCON DE K1EL will be sent followed by a pause of 60 seconds after which the whole thing will be repeated This beacon will repeat until you hit the ESC key Longer delays than 99 seconds can be derived by looping a wait command in a DECSZ loop an example is given in the CTL Z command description CTL Z lt F1 F12 gt Decrement Loop Count and Skip Message if Zero This command allows you to control looping in a message The structure of the command consists of the CTL Z command followed by a message key F1 F12 There must be a load loop command in the message stream somewhere ahead of the CTL Z command When the CTL Z command is encountered the loop count is decremented by one and if the result is not zero the message is jumped to If it is zero the message is skipped The
19. es will be honored It is called persistent because if power is lost and then restored the beacon will continue to cycle The beacon is ended by hitting the ESC escape key CTL ALT DEL Clear EEPROM and Restart This causes the K40 to clear all of EEPROM and reload the factory settings Be careful when using this because it will erase all of your messages Since the factory default is CW mode RTTY mode will be cancelled See the K40 manual for the default settings Known bug only one of the two delete keys on the keyboard will work for CTL ALT DEL HOME Return Display to Home Position The current display line is set to the current active position In receive this means the current line new data is being added to In transmit this means the line the input cursor is on END Quick Message Load This command allows message F12 to be loaded very quickly It is intended to be used to load a callsign that would be called from other messages This is very useful during contests For example let s say that the following message was loaded in F1 K C lt F12 gt DE KIEL KIEL K K When a station is heard that you want to call hit END and then quickly type in the callsign followed by ENTER Then when you hit F1 the callsign is inserted and sent W1XYZ DE KIEL KIEL K Another message can be loaded into F2 AK C lt F12 gt 599 NH QSL BK K Which plays as W1XYZ 599 NH OSL TAB Toggle Receive Transmit Display Window Either incoming or outgoin
20. esting the ability to send and keep track of a serial number is indispensable This command allows you to preset the serial number to any 4 digit number from 0000 to 9999 Just hit ALT F4 and enter four numbers If you make a mistake hit ESC to cancel and re enter the number in other words backspace won t work on this guy Any non numeric entered will cause the K40 to simply ignore the command and not change the serial number Once the serial number is set you can increment decrement and send the serial number using buffered commands CTL I CTL D and CTL N respectively The right and left arrow keys can also be used to increment the serial number ALT F8 Set Rx Reverse Mode This sets the sense of the serial receive data When pressed a display will shows the mode it is changing to For example if the display shows RX receive is reversed mark lo space hi RX signifies normal receive sense mark hi space lo ALT F9 Set Tx Reverse Mode This sets the sense of the serial transmit data When pressed a display will shows the mode it is changing to For example if the display shows TX transmit is reversed mark lo space hi TX signifies normal transmit sense mark hi space lo ALT F12 Start Persistent Beacon When this command is issued the K40 will send the message in slot 1 F1 repetitively A jump to message F1 command is not required at the end of the message The message can contain any valid command Calls or jumps to other messag
21. first time the ZL command is encountered the count is loaded and subsequent CTL L commands are ignored until the loop count expires this allows a loop count load and loop count test to reside in one message The best way to describe the command further is with a couple of examples Load Message Slot F1 with L02 CQ CQ DE K1EL Z lt F1 gt SK Results when F1 is pressed CQ CQ DE K1EL CQ CQ DE KIEL SK What happens is this When CTL L is processed the K40 loads the count and stores it then it outputs the message The CTL Z command tells the K40 to decrement the loop count and test to see if it is zero if it K 40FILT User s Manual rev2 2 20 2007 Page 11 K1EL K40FILT RTTY Filter Board Manual isn t zero the K40 jumps back to the beginning of F1 If however the count is zero the K40 skips over the jump and just outputs the SK Remember that the CTL L command is ignored after the initial load Longer delay example Load Message Slot F1 with BCON DE KIEL lt F3 gt Load Message Slot F3 with L10 W60 Z lt F3 gt lt F1 gt Results when F1 is pressed BCON DE K1EL will be repeated every 10 minutes In this example the message is sent followed by a jump to F3 which waits for 60 seconds 10 times which gives us 10 minutes After the 10 minute wait we will jump back to F1 and do it all over again Additional Key Assignments These are the key assignments that are treated just like letters and are buffered ismappedto QRZ 1 i
22. g streams can be displayed The TAB key selects which A blinking cursor is shown in the transmit outgoing window K 40FILT User s Manual rev2 2 20 2007 Page 9 K1EL K40FILT RTTY Filter Board Manual SHIFT TAB Clear Displays Clears both receive and transmit display windows ESC Abort Clear Buffer ESC can be pressed at any time to abort a message abort a command or to clear the type ahead buffer If you press ESC while entering a message the message buffer will be cleared and you effectively can start over at the beginning Note You need to press ENTER to exit message entry mode ESC just clears what you have entered and starts you over INSERT Receive Transmit Control This will toggle the K40 receive and transmit mode When first starting out the K40 is set to receive mode The receive display is shown and the K40 Filter board is set to receive mode Pressing the insert key will toggle to transmit mode the PTT line is asserted and the K40 Filter board is placed in transmit mode A fast way to tell if transmit is in force is to look for the blinking cursor on the display If the display is in home position then the blinking cursor is visible In receive mode no cursor is displayed This is a toggle command each press will advance from transmit gt receive or receive gt transmit plus Increment Serial Number minus Decrement Serial Number Buffered Commands The K40 supports the following buffered commands
23. gh F2 and F3 are called by F1 they can still be sent individually CTL D Decrement Serial Number The four digit serial number is decremented by one If equal to zero the serial number is not decremented K 40FILT User s Manual rev2 2 20 2007 Page 10 K1EL K40FILT RTTY Filter Board Manual CTL I Increment Serial Number The four digit serial number is incremented If equal to 9999 it is not incremented CTL K lt nn gt Toggle RTTY Receive Transmit This is used to build a message that will automatically change to transmit mode when the message key is pressed This allows the user to send a message with one keystroke Normally the insert key would have to be pressed followed by the message key A CTL K command should be placed at the end of a message to return the K40 to receive mode after the message is sent KCQ CQ CQ DE KIEL KIEL KK The above message sent with the K40 in Rx mode will change to transmit send the message and then change back to receive mode If the message were sent while the K40 was already in transmit the K commands are ignored CTL L lt nn gt Load Loop Count nn 01 gt 99 This command works in conjunction with the CTL Z command A loop count is entered with this command The CTL Z command will decrement this loop count and will repeat a message until the loop count reaches zero See the CTL Z description for more info CTL M Insert a CRLF Sequence This inserts a Carriage Return Line Fe
24. hat you have the K40 wired correctly to the K40 FILT and that you have a keyboard attached to the K40 Values given are ballpark values and may vary plus or minus 10 The key thing to look for is that there is a difference in voltages on U1 pin 15 and pin 22 when changing from mark tone to space tone Pin 22 should be higher than pin 15 during mark and vice versa during space The high and low voltage levels on each should match closely 7 With power applied enter CTL ALT DEL to reset the K40 and K40FILT Measure pin 9 of U3 to ground you should see 0 volts Pins 3 10 15 and 22 of U1 and pin 7 of U2 should be at 2 5V DC Press SHIFT F8 to enter tune mode a 2125Hz mark tone will be generated You should now see approximately 2 VAC between pin 9 of U3 and AGND Pin 6 of U1 1 0 VAC between pin 10 of U4 and AGND 7 VAC between pin 10 of U1 and AGND 1 0 VAC between pin 3 of U1 and AGND 1 0 VAC on pin 22 of U1 and pin 13 of U3 2125Hz to AGND 3 VAC on pin 15 of U1 and pin 12 of U3 2295Hz to AGND Press ALT F9 to generate a 2295 Hz space tone You should now see approximately 2 VAC between pin 9 of U3 and AGND 7 VAC between pin 10 of U1 and AGND 1 0 VAC between pin 3 of U1 and AGND 3 VAC on pin 22 of U1 and pin 13 of U3 2125Hz to AGND 1 0 VAC on pin 15 of U1 and pin 12 of U3 2295Hz to AGND That completes the tests if you encounter differences look in the related circuitry for shorts unsoldered connections incorrect
25. mand to enable or disable diddle on transmit SHIFT F4 Spot Toggle When operating the K40 RTTY in FSK with a separate transmitter and receiver this command provides a means to exactly tune your receiver to your transmitter frequency When spot is enabled the K40 board is set to transmit while the K40 filter board is left in receive mode This allows the receiver to be tuned into the transmitted RTTY stream using the K40 filter boards tuning LEDs In addition since the K40 can transmit and receive simultaneously the transmitted data once tuned in on the filter board will be displayed in the K40 s LCD receive window SHIFT F6 Tx Monitor Toggle Use this command to control the Tx monitor mode When enabled on transmitted characters will be printed in the Receive window in lower case SHIFT F8 Tune Toggle Test FSK The PTT output is turned on The sense of the FSK output can be toggled by using the ALT F9 command This allows either mark or space to be sent continuously to tune filters or test keying Be sure to leave transmit sense in the state you started with ALT Commands The ALT command keys setup K40 RTTY operating preferences In most cases you ll set these once save them to memory and not think about them again Remember to use the SHIFT F1 P command to save these settings in EEPROM so that they will be loaded next time you power up ALT F1 Set RTTY CW Mode This is the way you put the K40 into RTTY mode The mode will
26. onitor can produce quite a cluttered display and only use it to verify that messages are being sent the way expect It s useful in contests when you are using the fast callsign entry feature and want to be sure you entered callsigns correctly Since the 16 by 2 line LCD display does not give you an accurate view of what your output looks like the K40 implements an automatic carriage return feature You can just type without regard to where the line end should be When the line reaches a length longer than 40 characters the next space entered will auto matically generate a carriage return line feed sequence You can enter carriage return if you like and it s supported but not required Hitting the Enter key or M will generate a carriage return sequence It s displayed as a right arrow gt on the LCD Sorry but the line wrap point is fixed at 40 letters and cannot be changed Most of the message features of the K40 in CW mode are supported for RTTY mode except for CW only features like prosigns and speed changes Only buffered commands available in RTTY mode are covered in this manual The K token is redefined in RTTY mode K toggles between receive and transmit This allows you to build a message that will automatically set the K40 to transmit mode before sending the message A AK at the end of the message returns the K40 back to receive after the message has been sent This is great for contests since you can build a message like MKAMAM
27. ors Bebe EEE K 40FILT User s Manual rev2 2 20 2007 Page 23 KIEL RTTY Filter Board Kit K 40FILT K40 to IC703 Interface It is a simple procedure to connect the K40 to an IC 703 for RTTY operation Reference IC 703 Manual page 38 Connect as follows IC 703 Connector K40 Connection MSEND Pin 3 PTT K40 PCB Table 6 On K40 Enable GAINX2 SHIFT F2 Set RX and TX sense to K40 Transceiver Space Low FSK Input Low True Enable Transmit Ground 5V PtP max Receiver Audio Figure 11 Typical FSK Interconnect Product Information The K 40FILT is fully guaranteed and if you are not satisfied please return the kit for a full refund Any questions will be handled by snail mail or e mail via these addresses Steven T Elliott KIEL or e mail KIEL k1el com 43 Meadowcrest Drive Bedford NH 03110 USA Watch the KIEL Website for latest updates and new products http www k1el com While best efforts have been made to insure the K40FILT design is as complete and reliable as possible it is still possible to cause equipment damage or incur personal injury if the K40FILT kit is not used as intended is connected incorrectly or modified in any way K1EL can not be held responsible in these events K40FILT User s Manual 2 20 2007 Page 24
28. rwise QSOs will be difficult if not impossible The K40 follows this convention In normal transmit mode TX the KEY output will be off for mark and on for space This is compatible with most transceivers that support FSK In normal receive mode the lower frequency 2125Hz of the tone pair is interpreted as a mark while the higher tone 2295Hz is interpreted as a space This is in line with most transceivers set to RTTY mode This also corresponds to upper sideband mode USB AFSK Tx tones follow the same scheme as receive as shown in the table below Mark Space Mark Mark Frequency Frequency Key Out Key Out Normal RX TX 2125 Hz 2295Hz Normal TX Off On Reverse Rx TX 2295 Hz 2125Hz Reversetx On of Table 1 As mentioned previously there are two ways to generate FSK transmissions the first is by AFSK whereby a transmitter is run in USB mode and audio tones are fed into the Mic input The second is by direct FSK where the frequency of the transmitter s VFO is pulled up or down by switching extra capacitance across the VFO tank circuit or heterodyne crystal In newer rigs that use digital synthesis FSK is applied to a digital frequency synthesizer and the frequency shifting is done in the digital domain Purists will say that AFSK or digital FSK results in less phase distortion and narrowest bandwidth but both can be used successfully In RTTY receive the K40 filter board simply converts the two audio tones back into a
29. se the mark and space tones This can be done in one of two ways First is using the Rx reverse command on the K40 Hit ALT F8 and the K40 will reverse receive mark and space Second is by changing the receiver to the opposite sideband and retune Now test the FSK transmit mode you ll need an ohmmeter for this Press the SHIFT F8 key to turn RTTY Tune on The open collector PTT output will turn on and show continuity to ground The KEY output will remain off The rightmost tuning LED will be lit Press the ALT F9 key and now the left most LED will light and the KEY output will show continuity to ground Measure with the red meter test lead on the KEY or PTT output pad black on ground To test AFSK leave the K40 in tune mode and with an oscilloscope look at the FO pad on the K40FILT Adjust VR1 CCW to increase the output level to something you can trigger on Now press ALT F9 and you will see the tone switch between 2125 and 2295 Hz When the LCD display shows TX the tone should be 2125 Hz and 2295 on TX Hit Shift F8 to leave tune mode Hit Shift F3 to enable diddle and then press INSERT to turn on transmit You should see mark space activity on both the KEY and FO outputs If you don t have a scope you can listen to the tones at FO with HiZ cans Hit Insert when done That s it After reading through the theory of operations it s on to the command section to learn about the K40 command set K 40FILT User s Manual rev2
30. sistor ECH blue K 1 Resistor 1 4 W Blue Ys 31 6K 1 Resistor 1 4 W Blue 105K 1 Resistor 1 4 W Blue ei Ri6 Ra 7K 5 Resistor MAN rie 64K 18 Resisto i wie 2 26K 1 Resistor 1 4 W Blue oo iis 5h ee E ron pe capacitor es c2 2 2 uf capacitor Jtantalum space c5 0047 pF mylar capacitor Dipped radial __ c4 027 uF mylar capacitor Dipped radial GT Ceramic Resonator 3 iea VR1 10 K Potentiometer Vertical eet oo ee BP DIP socket N A 2 14pin 14P DIP EE RS Table 5 K 40FILT User s Manual rev2 2 20 2007 Page 15 K1EL K40FILT RTTY Filter Board Manual Fig 4 K40FILT PCB Checkplot K 40FILT User s Manual rev2 2 20 2007 Page 16 K1EL K40FILT RTTY Filter Board Manual ei TI RO TR G TR o L di PIC16F 684 O E Dia P K40 RTTY FILTER CD4066 ua ia wuw klelcom cio US i u2 q DCE LTC1068 Fig 8 K40FILT PCB Component Values K 40FILT User s Manual rev2 2 20 2007 Page 18 K1EL K40FILT RTTY Filter Board Manual TR RO G TI 5V Audio Input KEY is pulled low gt on Mark if if TX Set s G on Space if TX Set Audio Input impedance is approx 1K ohms 5 volts PtP maximum from Receiver KEY and PTT are both open collector transistor outputs 50 VDC 100ma max to ground K40 FILT PTT is pulled low on transmit AFSK Audio Output to Transceiver Mic Input Audio level is adjustable on the K40FILT board Fig
31. smappedto QSL ismappedto BELL K40FILT Specifications RTTY Receive Tone Pairs Mark Space Input Level Data Rate Data Format Unshift on Space Threshold Control Autostart Tuning Indication Gain Boost RTTY Transmit Output Modes Data Rate Data Format Tone Pairs Mark Space FSK Level AFSK Tone Format AFSK Tone Level Figures Control Diddle FSK Spot Automatic CR LF Line Length 2125 2295Hz 2295 2125Hz reverse 1V nominal 5V max peak to peak 45 45 Baud 60 WPM fixed 5 accuracy Five level Baudot 1 start 2 stop bits Standard always on Automatic always on Standard fixed level Six LEDs frequency bar graph auto squelch User selectable 2X gain Audio Frequency Keying Frequency Shift by level 45 45 Baud 60 WPM fixed 5 accuracy Five level Baudot 1 start 2 stop bits 2125 2295Hz 2295 2125Hz reverse AFSK only Mark high Space Low Mark Low Space High reverse Sine wave 1 accuracy spurious response at least 50 db below fundamental 100 mV to 2 5V peak to peak on board pot adjust Automatic fig space generation User selectable User selectable 40 characters nominal with automatic word wrap K 40FILT User s Manual rev2 2 20 2007 Page 12 K1EL K40FILT RTTY Filter Board Manual Filter Verification Procedure The on board ASFK tone generator can be used to verify the operation of the front end filter You can use either an oscilloscope or an AC voltmeter to do the checks It is assumed t
32. step process that will test portions as you go This will make debugging much easier since if a problem arises you will be able to locate the source right away First inventory and identify all parts before you start This will allow the assembly to proceed smoothly The Bill of Materials can be found on Page 12 Use your ohmmeter to sort the resistors by value Email us about any shortages and we ll send them to you 2 After inventory carefully inspect the PCB for any solder shorts or other obvious defects it s easier to find them before placing parts 3 Start with the six LEDs the easiest way to do this is to install one of the center ones first Align the LED carefully to be in the center of the silkscreen with front edge flush with the front edge of the PCB Carefully solder in place One by one install the remaining five LEDs insuring that each LED is spaced evenly and is flush with the front edge solder one lead first so can go back and individually tweak them before soldering PIC12F508 LED controller Transmit Receive Switching Single 5 volt supply requirement Board dimension 2 25 by 3 0 inches Diddle UOS ATC Autostart Current Draw lt 10 ma the second lead It s important to do a good job so that the LEDs fit correctly through the front panel of the enclosure Next install the watt resistors Verify each value with the Bill of Materials on Page 13 and Fig 7 on page 18 Double check to make
33. tent resulting in a clean sine wave output Frequency change is made at zero crossing so that there is no phase discontinuity in the signal In FSK transmit mode the K40 KEY output is fed to the transmitter FSK input The K40 PTT is connected to the transmitter key input In other words KEY controls frequency shift and PTT controls transmitter keying with Rx Tx changeover timing controlled by settings in the K40 DigiFSK Ny NL Mark 1 2 LMC6482 era Analog Audio Input gt Er 1 4 LTC1068 Input gt Bandpass AV AF amp Gain av 1 2 LTC1068 Space 2295Hz Analog 1 4 LTC1068 AFSK Buffer FO Analog o Q Gain 1 Gnd PIC16F684 1 2 LMC6482 0 Mark Analog gt LED o i Tunin Space Analog gt Driver 5 LEDs g PIC12C508 2 Signal 20 MHz _ Detect Rx Out RO U UU Rx nTx TR D Tx Rx DigiFSK DigiFSK TxData TI Switching Generate Fig 1 K40 Filter Board Block Diagram K40FILT User s Manual 2 20 2007 Page 3 K1EL K40FILT RTTY Filter Board Manual Using the K40 in RTTY Mode On the amateur bands RTTY is commonly transmitted by frequency shift keying Information is sent by switching between two tones most often 170 Hz apart One tone idle is called mark while the other is called space The most common tone orientation is for the space tone to be higher in frequency than the mark frequency It is important for a station to be set up with the same mark space relationship as other stations on the band othe
34. toggle each time this command is pressed A message on the display will tell you what mode it is changing to ALT F2 PTT Lead In Delay Time The K40 provides a transmitter PTT output that is used to switch a transmitter over to transmit mode in advance of actual FSK transmit A default time of 800 milliseconds is built in but you can extend it using this command The time delay specifies the time between when PTT is asserted and when FSK keying will start The format for the command is ALT F2 lt nn gt where nn is a two digit number calling out the delay in 10 s of milliseconds nn 26 selects 260 800 milliseconds The maximum delay that can be set is 99 or 990 800 1 8 seconds Note that a default delay of 600 mSec is used if Lead In is left at zero It is essential to have a period of unmodulated signal before FSK starts to insure the receiving station locks to your signal in advance ALT F3 PTT Tail Delay Time Like Lead In delay the time between the end of FSK modulation and PTT deassertion is programmed in units of 10 mSecs A default time of 800 ms is built in The syntax is the same as ALT F2 A tail delay helps transmissions to end cleanly and can help prevent stray characters at transmission end Lead in Delay Tail Delay PTT lt gt lt gt Key Fig 3 Lead and Tail Illustration K 40FILT User s Manual rev2 2 20 2007 Page 8 K1EL K40FILT RTTY Filter Board Manual ALT F4 Set Serial Number For cont
35. want to save the message press the ENTER key and the CAPS LOCK light will go out If you want to review your message without actually sending it hit the Transmit Mute key SHIFT F7 followed by the desired message key and your message will be played in sidetone only Don t forget to turn off transmit mute when you are ready to go live again The following chart shows the sizes of the 12 message buffers in letters commands F1 192 F4 192 F7 192 F10 112 F2 192 F5 192 F8 112 F11 32 F3 192 F6 192 F9 112 F12 32 Preserving Settings The basic settings of the K40 are preserved when power is shut off When the K40 is powered on for the first time a default set of values are loaded into EEPROM You can customize these defaults very easily When you have the K40 setup the way you like it just press SHIFT F1 followed by the letter P and current settings for the following items will be saved in EEPROM memory Only the RTTY related items are shown below Lead In Delay Tail Delay Tx Reverse Rx Reverse RTTY On Off Serial Number Diddle Gain K 40FILT User s Manual rev2 2 20 2007 Page 7 K1EL K40FILT RTTY Filter Board Manual SHIFT F2 Gain 2x Multiplier Toggle Use this command to enable of disable additional gain in the receive channel Turn 2X gain off for receive input levels in the range of 500mV to 2V of peak to peak audio Turn 2X gain for receive levels from 100 to 500 mV SHIFT F3 Diddle Toggle Use this com
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