Project

BXF Azimuth Rotator Controller

I decided to build a new rotator controller to replace my Yaesu G400RC controller (but my design was made to work with virtually any rotator) to give me additional futures beyond the sole analogue position feedback of the G-400RC. I wanted the new design to be digital, have integrated PC control, hands off operation (pick your direction and then sit back) and have different modes of operation depending upon current operation style. I had previously built a rotator PC interface but not a full blown rotator controller, however my original code covered most of what I wanted to do except the LCD hardware and user inputs. This is a development in progress, since making it I’ve found I use the rotator controller differently to how I envisaged but I’ll cover that at the end.

I built the rotator controller around the PICAXE-20X2 chip which is far the best chip in Revolution Educations range and can be used in almost any design. It supports almost all PICAXE BASIC commands and has 16 hardware inputs/outputs, it also has loads of registers and code space. After using the PICAXE-20X2 chip on other projects I got my head round some of the advanced commands and my own limitations from when I done my original rotator PC interface on the PICAXE-28X1 chip.

My original premise was to split the rotator controller into modes, mainly to test how I would use each one and after using it I redesigned the code to make it an all in one but the modes were:

Manual; standard control were the buttons change direction LEFT or RIGHT.

Fast; this is like manual but the LEFT and RIGHT buttons move the desired heading faster than the physical rate of rotation and the antenna catches up.

Preset; uses a dial (potentiometer) on the front panel to set a desired heading and the antennas track to that heading.

PC Control, heading feedback to the PC works on all modes but setting the heading only works in Manual mode. PC control also supports L for LEFT, R for RIGHT and S for STOP – this can be used also to interface to additional non PC [other BXF project] controllers.

The PC protocol is based on Yaesu GS-232 and I’ve included support for AZ only (GS-232A) or AZ+EL (GS-232B), in the GS-232B all EL commands are ignored or answered with 0 degrees.

After deciding what I wanted from the new code I set about looking for a suitable rotator controller, or box, to house it into which I found in Friedricshafen in the guise of a KR-400 control box for EUR 30. It had a nice big south stop analogue meter in it but that didn’t worry me as I planned to use a 4×20 LCD (which I had bought off eBay). I cheated slightly by using a Wulfgang K107 LCD interface board (tech doc .pdf) to drive the LCD, this was for 2 reasons;

It allows me to use serial to update the LCD instead of connecting all the parallel pins to the PIC so simplified the design, and
The K107 LCD interface supports large character mode (as seen in the pictures) so allows me to use the full height of the LCD better (easier).

The final code doesn’t have modes but instead allows any input to move the rotator, I did drop the FAST mode as it was redundant and I didn’t use it much. The use now is you press LEFT or RIGHT to move in the desired direction, spin the preset to take you to the preset direction or press PARK* to take you to a pre-defined heading. Pressing LEFT, RIGHT or PARK at any point cancels the current movement and start the new one, so if I set the preset to 200 degrees and pressed PARK (which say was set to 120 degrees) then the rotator would cancel heading to 200 degrees and head to 120 degrees. The same is for the PC input, any PC input to goto a direction would override any current movement and head to the new heading set by the PC input. The PC can read the antenna direction at any time which does not effect the antenna movement.

* At present there is only one input used as a predefined heading, which I call PARK and have set to 120 degree, Europe from my QTH. The PICAXE-20X2 has 5 additional spare inputs in this project so it’s more than capable of having extra switches attached to these inputs and assigning them to additional presets in the code.

Outside The Case

There was not much modification required to the KR-400 box. I added an extra button on the front for PARK, originally for changing mode and on the back a 9-way D-type connector which I use for my rotator wiring as it’s much easier to disconnect, also all my other rotators use the same plug so they are all interchangeable. I also added a USB-B port on the back for PC interfacing, internally this goes to a USB<>Serial interface. Inside is where the main changes are.

Inside The Case

The original circuit and meter in the box was of little use so the first thing I done was to remove both. I left the transformer in along with the capacitor over the motor outputs which was also original, after that it was a new PCB with all the required circuitry and that was about it!

Calibration

The rotator controller needs calibrated. This is done in a simple way by either powering on the rotator controller holding the PARK button or if the MINOffset or DirCorrect EEPROM values are 0 (no values stored in EEPROM would be the case after programming). When in calibration mode the user is presented with step by step text based commands on the LCD to follow for calibration. You only need to do the calibration once after which MINOffset and DirCorrect values are stored on EEPROM and recalled on each power up.

The steps for calibration require the rotator to be moved fully LEFT (CCW) to 0 degrees (north) so the feedback pot in the bell housing reports its minimum value (MINOffset).

Pressing the PARK button saves this ADC value in EEPROM (MINOffset) which is then subtracted from ADC reads in the main code.

We then go RIGHT to 360 degrees (north) and save this ADC value (DirCorrect) which is used for the correction factor.

The ADC value is again saved in EEPROM when the PARK button is pressed.

Let me explain using my values. On my rotator 0 degrees (north) returns an ADC value of 22, this ADC value is subtracted from all other ADC reads in the code, the reason is 22 is 0 degrees so an ADC value of 32 would be 10 degrees (it’s not quite that linear but you get the idea). We then goto 360 degree (north) which in my case is ADC 953. ADC 953 is actually not yet right as we need to subtract the MINOffset value for the correct ADC for 0 to 360, we then need to convert to a correction factor.

To get the most accurate heading I sample the ADC value in the code 64 times. I use 64 [times] as this then fills a 16 bit register when sampling the ADC at 10 bits without the chance of it overflowing. The maximum ADC value at 10 bits is 1024 so 1024 * 64 = 65636.

As my max ADC value is 953 (remember my minimum value of 22) I need to subtracted this off so the real ADC value is 953 – MINOffset or 931. It’s the value of 931 which is loaded into the register 64 times meaning the register value is stored as 931 * 64 = 59584. I then divide this by 360 to get the correction factor. 59584/360 = 165.5. In PIC code we can only divide by full numbers so I take into account if the decimal is greater than 0.5 and if so I add a number to the correction factor to make it closer to the real value, if my result was 165.4 I would then use 165 but as it is 165.5 I instead use 166.

This means if I have an ADC value from the rotator of 546, I first subtract 22 (MINOffset) from it, leaving me with 524 which is sampled 64 times giving a register value of 33536 (in reality the ADC value of 546 could vary slightly on each of the 64 reads, one of the reason we average so many). I then divide 33536 by 166 (DirCorrect) and I get a heading of 202 degrees.

Did you follow?

Schematic

Download the schematic (uses ExpressSCH)

Pictures

Code

Download the code

Old Design (PICAXE-28X1)

A long time back I decided I wanted PC control of my antennas, mainly for point and shoot, click on a heading in some PC software and start CQ’ing so that I wouldn’t have to think both about calling and antenna direction. For this I ordered an LVB Tracker from AMSAT UK but before it arrived I thought I’d have a go at making one myself using PICAXE, it worked but it was crude!

I have a Yaesu G-400RC rotator which is the one with a round controller for the display and uses a comparator circuit to ‘match’ the heading of the controller display with that of the rotator itself, the problem is the comparator swings from –15v to +15v and is non-linear. This meant interfacing to a PIC chip was possible (using an opamp) but as the voltage was non-linear it would not work so well.

My first attempt was using a PICAXE-28X1 chip which as good as a design it was I didn’t know PICAXE programming as much back then so didn’t fully utilise the chip, or code. Instead of using the hardware serial (hserin) inputs, which allows serial reception in the background while the code executes, I used the normal ones and had to set a serial buffer timeout which would expire if no serial data was received, during this time all the code execution stopped. Also due to my lack of familiarity of PICAXE code back then the code wasn’t really optimised, an example was lack of subroutines (Gosub) meaning there was lots of code repeated. There was no calibration routine so working out the actual heading was left to the user to calculate and enter the correction values, for the ADC value, direct into the code. I’ve not reproduced the code here as it’s in my mind redundant and outdated. But some of it was salvaged for this project. What I did end up doing though was to take some of the ideas and features from this code and turned it into my LVB Extender design, an add-on for the LVB Tracker, which could send serial commands to the LVB Tracker giving added extra features and automation to rotator system without the need for a PC.

PICAXE-18M & MXD2125 Based Elevation Module

Jul 24th, 2011

by m1bxf.

2 comments

One of the aspects of amateur radio I enjoy is EME. When I was active on 2m (144MHz) EME I built my own elevation system using a jack-arm but I then needed a way to feedback the angle. I tried many ways in the past such as potentiometers then Sam G4DDK introduced me to the MXD2125 dual axis accelerometer device.

This can be used, along with gravity, to measure tilt, the angle vs down. Comparing both X & Y axis outputs the resolution can be very small, smaller than is required. Up until now the way I got the angle back was from one of the axis digital outputs by converting it to an analogue voltage by using an RC circuit which my elevation controller could work with, but not very well. The main problem is the analogue voltage is not pure DC and I have in the past observed inaccurate readings and sometimes it just fails to work, but this maybe wiring also. To cure this headache I set out to make the system as fully digital as possible so I decided to measure the digital pulses from both X and Y axis’s directly with the PICAXE-18M and then either convert that to a voltage with a DAC/digital pot or send it to the shack by serial and process it there by either re-designing the elevation controller to work with serial feedback or converting the serial to analogue there.

When I searched for info on this idea I came across a webpage by Frederic, F1OAT who has already used a PICAXE-08M with an MXD2125 – info about his circuit is here and at the bottom of this page here. I also came access some code which uses a PICAXE-18M to control a Maxim DS1803 digital potover I2C, which I have some samples of, so in the end my solution uses that. I built a test circuit using a PICAXE-08M and with the help of Frederics code proved I could get it all to work.

The finished project uses a MXD2125, a PICAXE-18M, and a DS1803 and provides a fully ‘digital’ means of reporting the angle by converting it to a voltage. I found at 0 degrees I get a voltage of ~0.2v and at 90 degrees ~4.3v out of the DS1803 which is about 0.045v per degree. The digital pot has a resolution of 0.0195v per bit when fed from 5v. No calibration is needed at the sensor end, only as much ‘swing’ as possible between 0 degrees and 90 degrees. As the output is linear the LVB Tracker is calibrated for 0 degree voltage and 90 degrees voltage and so knows what the angle is based on these to stored values, being digital it shouldn’t drift over time, something I think is happening with the RC circuit…

Code:

 ' 'The code relating to MXD2125 is 'taken from example code by F1OAT (frible@teaser.fr) Nov 2006. Symbol pin_x = 7 ; pin #5 <= MXD2125 X output Symbol pin_y = 0 ; pin #3 <= MXD2125 Y output ' CORDIC section variables definition Symbol x = w2 Symbol y = w3 Symbol ang = w4 Symbol ang_l = b8 Symbol ang_h = b9 Symbol dx = w5 Symbol dy = w6 Symbol i = b0 Symbol d = b1 Symbol neg = b2 Symbol tmp = b3 'The code relating to I2C or DS1803 is 'taken from example code by Peter H. Anderson, Elmore, VT, Aug, '04. ' Define IO Terminals Symbol SCL = 0 Symbol SDAIn = Pin1 Symbol SDAOut = 1 Symbol DevAdr = B0 Symbol PotNum = B1 Symbol PotSetting0 = B2 Symbol PotSetting1 = B3 ' Used in I2C Routines Symbol OByte = B4 Symbol IByte = B4 Symbol Ack = B5 Symbol N = B6 Symbol MSBit = B7 setfreq m8 ' increases the sample rate START: p_cordic: ; CORDIC section to guage the XY values (i.e. angle) x = 0 dx = 0 y = 0 dy = 0 ; Cumulate several pulses measurement to enhance accuracy for i=1 to 16 pulsin pin_x,1,ang ; high level pulse duration x = x + ang pulsin pin_x,0,ang ; low level pulse duration dx = dx + ang pulsin pin_y,1,ang ; high level pulse duration y = y + ang pulsin pin_y,0,ang ; low level pulse duration dy = dy + ang next i neg = 0 ; Put vector in proper 90° quadrant if x >= dx then qx1 x = dx - x ang = 2048 ; 180° neg = 1 - neg goto qx2 qx1: x = x - dx ang = 4096 ; 360° qx2: if y >= dy then qy1 y = dy - y neg = 1 - neg goto qy2 qy1: y = y - dy qy2: d = 1 ; CORDIC iterations for i=0 to 9 if y <= 32767 then pos y = 65535 - y neg = 1-neg pos: dx = x / d dy = y / d x = x + dy y = y - dx lookup i, (512,302,159,81,40,20,10,5,2,1), dx ; ATAN table for ang_premult=1024/90 if neg=1 then sub ang = ang + dx goto nextstep sub: ang = ang - dx nextstep: d = d*2 next i 'convert the angle to a value which can be used by the I2C routine. 'In this case it coverts it to numbers close to 0-255 for 0-90 degrees 'which makes it suitable to write this direct to the DS1803 ang = ang - 1965 ang = ang * 2 ang = ang / 10 Top: DevAdr = 0 'debug ang PotNum = 0 PotSetting0 = ang 'write angle to Pot0. 'PotSetting0 = 255 GoSub DS1803WritePot ' PotNum = 1 'Un-comment this code if you wish to use Pot1. 'PotSetting1 = 64 'Gosub DS1803WritePot 'Gosub DS1803ReadPots 'SerTxD (#PotSetting0, " ", #PotSetting1, 13, 10) 'debug PotSetting0 goto start DS1803WritePot: Branch PotNum, (WritePot0, WritePot1) WritePot0: Gosub I2CStart OByte = 2 * DevAdr + $50 Gosub I2COutByte OByte = $A9 GoSub I2COutByte OByte = PotSetting0 GoSub I2COutByte Gosub I2CStop Goto DS1803WritePotDone WritePot1: Gosub I2CStart OByte = 2 * DevAdr + $50 Gosub I2COutByte OByte = $AA GoSub I2COutByte OByte = PotSetting1 GoSub I2COutByte Gosub I2CStop Goto DS1803WritePotDone DS1803WritePotDone: Return DS1803ReadPots: Gosub I2CStart OByte = 2 * DevAdr + $51 Gosub I2COutByte Ack = 1 ' master is to ACK after receipt of byte Gosub I2CInByte PotSetting0 = IByte Ack = 0 ' no ACK as this is the last byte prior to the stop Gosub I2CInByte PotSetting1 = IByte Return I2CStart: High SDAOut High SCL Low SDAOut ' bring SDA low while SCL is high Low SCL Return I2CStop: High SCL High SDAOut ' bring SDA high while SCL is high Return I2COutByte: For N = 1 to 8 ' for eight bits MSBit = OByte / 128 ' beginning with the MSB If MSBit = 1 Then I2COutByte_1 ' most sig bit Low SDAOut GoTo I2COutByte_2 I2COutByte_1: High SDAOut I2COutByte_2: High SCL Low SCL OByte = OByte * 2 ' shift byte such that next bit is in most sig bit position Next High SDAOut ' null clock pulse to allow for slave to acknowledge High SCL Low SCL Low SDAOut Return I2CInByte: ' receives a byte, most sig byte first. ' result returned in I_BYTE High SDAOut For N=1 to 8 ' for eight bits High SCL IByte = IByte * 2 + SDAIn Low SCL Next Branch Ack, (NoAck, YesAck) NoAck: High SDAOut ' high Z on 9th clock pulse Goto I2CInByte1 YesAck: Low SDAOut ' logic zero on 9th clock pulse I2CInByte1: High SCL Low SCL Low SDAOut Return

Images:

Revision:

240711 – Project posted to web.

LVB [Tracker] Extender

Jul 24th, 2011

by m1bxf.

No comments yet

I started using an LVB Tracker by G6LVB (also of FunCube Dongle fame) to control my Yeasu G400RC and KR-5400 rotators which have my directional antennas on them – The G400RC + homebrew jack-arm elevation was mainly for EME and the KR5400 was for satellite work. I had to built an elevation feedback circuit, I chose a MXD5125 for this but I found I still lacked some of the features of more advanced rotators and with the LVB Tracker being controlled by serial using the GS-232 protocol I found this would be easy to remedy using a PIC.

The main features I wanted to add were the ability to input a wanted heading and then leave the rotator to goto that heading instead of having to hold any button down as the rotator can be slow and my attention span is short. I wanted to have a button for ‘park’ to put the antenna in it’s ‘resting’ direction and an easy way to just rotate 45 degrees or 180 degrees (flip) at a time, I also added a button to toggle a relay which was used to switch the satellite antennas from RH to LH circular polarization and back again.

This shows how I interfaced the LVB extender (in yellow) with the LVB Tracker (in blue)…

In the end I used a PICAXE-28X1 chip as I needed a bit of program memory and lots of input pins. The input buttons consist of UP, DOWN, CW & CCW plus LH/RH, Park, +45 degrees and +180 degrees. The serial from both the LVB Tracker PIC and PICAXE-28X1 are TTL so I connected the serial to the LVB Tracker between the PIC and the MAX232 chip used for RS-232 level conversion.

Whenever UP, DOWN, CW, CCW, +45 degrees or +180 degrees button are pressed the first thing my LVB Extender has to do is read the current positions using the GS-232 “C2″ command which prompt the LVB Tracker to output both current azimuth and elevation positions which I read and store. From these positions the code works out what needs done with them. If it is UP, DOWN, CW or CCW then it runs a loop to increment or decrement the original position for the duration of the button being pressed with increasing speed over time. It writes the value back to the LVB Tracker on every loop. If the +45 degree or +180 degree buttons are pressed the LVB Extender again reads the current positions using a “C2″ command and either adds 45 degrees or 180 degrees to the value and writes it back to the LVB Extender ensuring the write command has the originally read elevation value to this is not effected. The Park button sends a stored position, from my old QTH in JO02ab the best heading for me was 127 degrees azimuth and 0 degrees elevation (best for monitoring 144.300 into Europe). The Park heading is programmable only in the code, I made no provision to set it on the fly, main because I didn’t know how when I created this, I do now and will add it if requested.

The LH/RH button only toggles a relay to switch a voltage to the antennas. If azimuth value reaches 360 degrees the code converts it to 0 degrees and if it reaches 0 degrees it converts to 360, both are able to be set if you like to go over the limits a little. On elevation the counting is limited to between 0 and 90 degrees.

Code:

'Very few comments in this code, it's old and moldy... 'This code is used to extent the use of the LVB tracker http://www.g6lvb.com/Articles/LVBTracker/ 'an azimuth and elevation controller now available from AMSAT. There is lots of information 'available on the web about this unit. The extended features are to allow press and hold of the 'manual controls to the desired azimuth or elevation and adding presets and 180 degree swap. 'Definitions here: 'INPUTS > 76543210 'Usage Logic HW Dec 'Serial in from LVB In7 18 256 'Park In7 18 256 'North In6 17 64 '180 deg switch In5 16 32 'RH/LH Porolization In4 15 16 'CCW In3 14 8 'CW In2 13 4 'Down In1 12 2 'Up In0 11 1 'OUTPUTS 'Usage Logic HW 'CCW signal to LVB Out0 21 'CW signal to LVB Out1 22 'Down signal to LVB Out2 23 'Up signal to LVB Out3 24 'UNUSED Out4 25 'LHC LED Out5 26 'RH/LH control + RH LED Out6 27 'Serial out to LVB Out7 28 'Registers 'W11 = Azimuth Value (Decimal) 'W12 = Elevation Value (Decimal) 'W13 = Counter 'B9 = Delay Value 'B1>B4 = Azimuth 'B6>B9 = Elevation 'B10 = RESERVED 'B11 = 45 degree count (segment) 'B12 = Release Counter 'B13 = loop 'State constance - SYMBOLS are globals and makes changes easier in the future. SYMBOL park_azi = 0127 SYMBOL park_ele = 0000 SYMBOL north_azi = 0000 SYMBOL north_ele = 0000 SYMBOL delay = B11 SYMBOL segment = B12 SYMBOL amount = B13 SYMBOL Azu_val = W11 SYMBOL Ele_val = W12 SYMBOL fast = 40 'Delay after holding switched down. SYMBOL slow = 150 'Original delay SYMBOL Release = W13 'Define Inputs SYMBOL CCW_Val = %11110111 SYMBOL CW_Val = %11111011 SYMBOL Down_Val = %11111101 SYMBOL Up_Val = %11111110 SYMBOL Park_Val = %01111111 SYMBOL North_Val = %10111111 SYMBOL Sw_45_Val = %11011111 SYMBOL RHLH_Val = %11101111 'Do all power-up settings here: Set: high 6 'Sets the LHC LED on. low 1 low 2 low 3 low 4 delay = slow 'setfreq m8 Pause 2000 gosub lvb_read gosub lvb_write_azi Start: Release = 1000 Start_1: if Release = 0 then else dec Release endif If PINS = North_Val then goto north If PINS = Park_Val then goto park If PINS = RHLH_Val then goto switchpol If PINS <> %11111111 then goto PINCHECK 'Reset anything that has changed back to defualt states. low 1 low 2 low 3 low 4 delay = slow goto start_1 'Add this line here so it's the last state to check. This means when the up/down/left/right buttons are release 'the pins are set low again. PINCHECK: If Release = 0 then gosub lvb_read else endif If PINS = CW_Val then goto CW If PINS = CCW_Val then goto CCW If PINS = Up_Val then goto up If PINS = Down_Val then goto down If PINS = Sw_45_Val then goto switch45 goto start CCW: high 0 'debug Azu_val for amount = 0 to 20 If PINS=%11111111 then goto start if Azu_val =< 0 then Azu_val = 359 else endif Dec Azu_val gosub lvb_write_azi pause delay next delay = fast goto CCW CW: high 1 'debug Azu_val for amount = 0 to 20 If PINS=%11111111 then goto start if Azu_val => 360 then Azu_Val = 0 else endif Inc Azu_val gosub lvb_write_azi pause delay next delay = fast goto CW Down: high 2 for amount = 0 to 10 'debug Ele_val If PINS=%11111111 then goto start Dec Ele_val if Ele_val =< 0 then goto down if Ele_val > 200 then Ele_val = 0 else endif gosub lvb_write pause delay next delay = fast goto down Up: high 3 for amount = 0 to 10 'debug Ele_val If PINS=%11111111 then goto start Inc Ele_val if Ele_val => 90 then goto up gosub lvb_write pause delay next delay = fast goto up Switch45: gosub lvb_read if B0 = "-" then Azu_val = 360 - Azu_Val else endif Segment=Azu_val/45 Segment=Segment+1 Azu_val=Segment*45 If Azu_val > 360 then Azu_val=Azu_val-360 else endif gosub lvb_write_azi pause 300 for amount = 0 to 10 If PINS=%11111111 then goto start inc Segment Azu_val=Segment*45 If Azu_val => 360 then Azu_val=Azu_val-360 else endif gosub lvb_write_azi pause 400 Next amount goto start North: if B0 = "-" then Azu_val = 360 - Azu_Val else endif Azu_val = Azu_val + 180 if Azu_val => 360 then Azu_val = Azu_val - 360 else endif gosub lvb_write_azi pause 300 'if B0 = "-" then 'Azu_val = 360 - Azu_Val 'else 'endif 'Segment=Azu_val/180 'for amount = 0 to 1 ' If PINS=%11111111 then goto start ' pause delay ' inc Segment ' Azu_val=Segment*180 ' If Azu_val => 360 then ' Azu_val=Azu_val-360 ' else ' endif 'gosub lvb_write_azi 'Next amount goto start Park: Azu_val = park_azi Ele_val = park_ele gosub lvb_write goto start switchpol: toggle 5 'Swap the state of PIN 5 (RH/LH control + RH LED) toggle 6 'Swap the state of PIN 4 (LHC LED) pause 200 goto start lvb_write_azi: 'Convert Azimuth into hundreds, tens and units. B2=Azu_val/100 Azu_val=Azu_val//100 B3=Azu_val/10 Azu_val=Azu_val//10 B4=Azu_val 'debug b2 'debug b3 'debug b4 'debug b7 'debug b8 'debug b9 setfreq m8 serout 7,N9600_8,("W",#B2,#B3,#B4,13) setfreq m4 'Re-calculate current azimuth due to dividing it. Azu_val=b2*100 b3=b3*10 Azu_val=Azu_val+b3 Azu_val=Azu_val+b4 return lvb_write: 'Convert Azimuth into hundreds, tens and units. B2=Azu_val/100 Azu_val=Azu_val//100 B3=Azu_val/10 Azu_val=Azu_val//10 B4=Azu_val 'Convert elevation into hundreds, tens and units. B7=0 B8=Ele_val/10 Ele_val=Ele_val//10 B9=Ele_val 'debug b2 'debug b3 'debug b4 'debug b7 'debug b8 'debug b9 setfreq m8 serout 7,N9600_8,("W",#B2,#B3,#B4," ",#B7,#B8,#B9,13) setfreq m4 'Re-calculate current azimuth due to dividing it. Azu_val=b2*100 b3=b3*10 Azu_val=Azu_val+b3 Azu_val=Azu_val+b4 'Re-calculate current elevation due to dividing it. Ele_val=b7*100 b8=b8*10 Ele_val=Ele_val+b8 Ele_val=Ele_val+b9 return lvb_read: setfreq m8 serout 7,N9600_8,("C2",13) 'C2 requests current azimuth and eleavtion from LVB. serin 7,T9600_8,B0,B1,B2,B3,B4,B5,B6,B7,B8,B9,B10 'Store the response in to B0>B9 registers. 'serin 7,T9600_8,B0,B1,B2,B3,B4,B5 setfreq m4 ' for some reason all numbers appears to be $70 too large! subtract $70 from all numbers b2=b2-$30 b3=b3-$30 b3=b3*10 b4=b4-$30 B7=B7-$30 B8=B8-$30 B8=B8*10 B9=B9-$30 'debug b2 'debug b3 'debug b4 'debug b7 'debug b8 'debug b9 'calculate current azimuth into decimal Azu_val=B2 * 100 Azu_val=Azu_val + B3 Azu_val=Azu_val + B4 'calculate current elevation into decimal Ele_val=B7 * 100 Ele_val=Ele_val + B8 Ele_val=Ele_val + B9 return goto Start

Revision:

240711 – Project posted to web.

Icom (CI-V or band Data) to Yaesu BCD Band Data Converter

Jul 23rd, 2011

by m1bxf.

10 comments

After the 2011 Camb-Hams DX’Pedition to Arran and using the Discovery 64 on 6m and making some good contacts on it I decided to bite the bullet and go buy a decent 6m Amplifier.

I have been thinking of getting an amplifier for HF and 6m for a while but didn’t want to have 2 extra amplifiers in the shack, one for HF and one for 6m (50MHz). There are a few options about for a combined HF + 6m amplifier and luckily a Yaesu VL-1000 Quadra (1KW HF and 500w on 6m) recently came available second hand at Martin Lynch and Sons so while standing out in the single spot in the garden at the Arran DX site where I could get decent and reliable Vodafone coverage I gave them a call, agreed a price and had it shipped, bullseye!

The Quadra needs to switch bands for bandpass switching which can be achieved by sniffing RF from the exciter or via Yeasu’s 4 bit Band Data interface which most Yaesu radios support. However my exciter is an Icom IC-756pro3 and Icom do external band switching by varying a voltage on a single pin between 0v and 8v depending upon the band selected (note WARC bands are not individually identified), I could also use the CI-V frequency data (with CI-V Transceive set to ON):

L = Low / 0v, H = High / 5v

The Project

So what I need to do is build an interface which takes the Icom Band Voltage from the Icom IC-756pro3 ACC2 port and converts it to Yaesu 4 bit Band Data. If I wanted to use just CI-V I could use a PICAXE-08M (8 PIN) which support 4 output pins, Yaesu Band A to D and one serial in PIN used for CI-V but the SERIN support for the 08M is limited. I decided to go for a PICAXE-20X2 as it has a hardware serial pin, supports 19200 baud, the fastest the IC-756pro3 manages and gave me plenty of spare pins. My final spec sheet was:

Auto switching between CI-V and Icom analogue band data as source input.
4 pins outputting Yaesu Band Data to the Quadra VL-1000.
8 additional user configurable pins, i.e. selected pin go high on selected band to drive external equipment like coax relays.
Support remote (on/off) switching of the Quadra VL-1000 by providing 13.8v to the Quadra when the IC-756pro3 is switched on.
Have the PTT line integrated within the interface connections, it is not connected nor needed for the PIC.

NOTE: I found the VL-1000 manual is close to useless with regards to the Pinout diagrams – it has a picture with pins numbered but has a list next to it in in letters A,B,C etc… I also blew the 5A fuse inside my IC-756pro3 and damaged a track later on by not getting the 13.8v on the correct pin, i.e. following the manual so be warned.

The PICAXE code:

#PICAXE-20X2

#REM
v1.2 released 010911
Added funcionality for the 5B4AGN BPF on PinsC.

v1.1 released 230711
Improved CI-V string searching
Additional checks in Band Data routine to ensure we didn't get there by mistake

v1.0 released 130611
Initial release

#endrem

SYMBOL m160 = $01 '%00000001
SYMBOL  m80 = $02 '%00000010
SYMBOL  m60 = $03 '%00000011
SYMBOL  m40 = $03 '%00000011
SYMBOL  m30 = $04 '%00000100
SYMBOL  m20 = $05 '%00000101
SYMBOL  m17 = $06 '%00000110
SYMBOL  m15 = $07 '%00000111
SYMBOL  m12 = $08 '%00001000
SYMBOL  m10 = $09 '%00001001
SYMBOL   m6 = $0A '%00001010

'All these symbols are shifted one bit due to pin C.0 being blocked by HSEROUT.
SYMBOL m160c = $02 '%00000010
SYMBOL  m80c = $05 '%00000100
SYMBOL  m60c = $1E '%00000000
SYMBOL  m40c = $06 '%00000110
SYMBOL  m30c = $1E '%00000000
SYMBOL  m20c = $0A '%00001010
SYMBOL  m17c = $1E '%00000000
SYMBOL  m15c = $0E '%00001110
SYMBOL  m12c = $1E '%00000000
SYMBOL  m10c = $12 '%00010010
SYMBOL   m6c = $1E '%00000000

SYMBOL CIVinbaud  = B19200_64	'Change this to CI-V serial rate
SYMBOL CIVinPIN	= PinB.6
Symbol CIVorADC	= PinB.7
Symbol Band_ADC	= 6	'ADC6

SYMBOL Freq	  = W0 'B0, B1
SYMBOL CHSM1  = B2 'General register used in many places for calculations
SYMBOL CHSM2  = B3 'General register used in many places for calculations
SYMBOL MHZ	  = B4 'MHz register
SYMBOL KHZ	  = B5 'KHz register
SYMBOL MClear = B6 'Used to count the loop for clearing the serial memory
SYMBOL Search = B6 'Used to count where the CI-V identifier will be
SYMBOL Search2= B7 'Used to count where the CI-V checkbit will be
SYMBOL Lookfor= B8 'Used to substitute hSerPtr so we have a fixed upper limit when looping
SYMBOL Band	  = B9 'Used to save which band we are on, *reserved for future use

SETFREQ M64		'Run the code at 64MHz!!!

let DirsA = %00000000
let DirsB = %00001111
let DirsC = %00011110

HSERSETUP CIVinbaud,%001

Start:

IF CIVinPIN = 1 or CIVorADC = 0 then 'CI-V Code
IF hSerPtr  = 0 then goto start 'No seral data, no need to run the code.
Pause 1000 'wait a while to let the serial buffer to fill.

Lookfor = hSerPtr 'Transfer hSerPtr value to Lookfor as hSerPtr can still increase as we loop below

FOR Search = 0 to Lookfor 	'Loop to the value of Lookfor
 Search2 = Search + 6		'Search2 looks for the check bit $FD which is 6 places ahead of the CI-V identifier
 GET Search, CHSM1   'for each position in turn load the buffer into CHSM1
 GET Search2,CHSM2   'for each position in turn look 6 places ahead and load into CHSM2
 If CHSM1 = $05 and CHSM2 = $FD then goto LoadFreq 'Set frequency ($05) identifier and checkbit ($FD) found
 If CHSM1 = $03 and CHSM2 = $FD then goto LoadFreq 'Read operating frequency ($03) identifier and checkbit ($FD) found
 If CHSM1 = $00 and CHSM2 = $FD then goto LoadFreq 'Set frequency ($00) identifier and checkbit ($FD) found
Next 					'Go back to the start of the loop or finish

Goto ClearhSerPtr	'If we get here then we didn't find valid $00, $03 or $05 so clear the serial buffer

LoadFreq:			'We found valid serial data so process it and output the band data
CHSM1 = Search + 4		'Set where to look for MHZ value
CHSM2 = Search + 3		'Set where to look for KHZ value

GET CHSM1, MHZ		'Read the CHSM1 location into register MHZ, this is need formatting
GET CHSM2, KHZ		'Read the CHSM2 location into register KHZ, this is need formatting

BcdTOASCII MHZ,CHSM1,CHSM2	'Extract the MHZ serial value to individual registers
CHSM1 = CHSM1 - 48		'Format to decimal
CHSM2 = CHSM2 - 48
MHZ  = CHSM1 * 10 + CHSM2	'Add them back together

BCDTOASCII KHZ,CHSM1,CHSM2	'Extract the KHZ serial value to individual registers
KHZ = CHSM1 - 48			'Format to decimal (only need the first value in KHZ case)

Freq  = MHZ * 10 		'Combine the MHZ and KHZ value into one register
Freq  = Freq + KHZ
Select Case Freq			'Go find a match
	Case 10 to 29
		PinsB = m160	'Set PinsB to %00000001
		PinsC = m160c	'Set PinsC to the value required
		Band  = 160

	Case 30 to 49
		PinsB = m80 	'Set PinsB to %00000010
		PinsC = m80c	'Set PinsC to the value required
		Band  = 80

	Case 50 to 69
		PinsB = m60 	'Set PinsB to %00000011
		PinsC = m60c	'Set PinsC to the value required
		Band  = 60

	Case 70 to 99
		PinsB = m40 	'Set PinsB to %00000011
		PinsC = m40c	'Set PinsC to the value required
		Band  = 40

	Case 100 to 129
		PinsB = m30 	'Set PinsB to %00000100
		PinsC = m30c	'Set PinsC to the value required
		Band  = 30

	Case 130 to 169
		PinsB = m20	'Set PinsB to %00000101
		PinsC = m20c	'Set PinsC to the value required
		Band  = 20

	Case 170 to 199
		PinsB = m17 	'Set PinsB to %00000110
		PinsC = m17c	'Set PinsC to the value required
		Band  = 17

	Case 200 to 229
		PinsB = m15 	'Set PinsB to %00000111
		PinsC = m15c	'Set PinsC to the value required
		Band  = 15

	Case 230 to 269
		PinsB = m12	'Set PinsB to %00001000
		PinsC = m12c	'Set PinsC to the value required
		Band  = 12

	Case 270 to 479
		PinsB = m10	'Set PinsB to %00001001
		PinsC = m10c	'Set PinsC to the value required
		Band  = 10

	Case 480 to 540
		PinsB = m6	'Set PinsB to %00001010
		PinsC = m6c	'Set PinsC to the value required
		Band  = 6
Else				'No matcxh found, out of bounds
		PinsB = $FF	'Set PinsB to 0
		PinsC = $FF	'Set PinsC to 0
		Band  = 0
EndSelect
'debug
Goto ClearhSerPtr
'#REM
Else				'Band Voltage Code
Pause 100
IF hSerPtr  > 0 then goto start 'No seral data, no need to run the code.
ReadADC10 Band_ADC,Freq
Select Case Freq
	Case 860 to 983 '160m
		PinsB = m160	'Set PinsB to %00000001
		PinsC = m160c	'Set PinsC to the value required
		Band  = 160

	Case 700 to 799 '80m
		PinsB = m80 	'Set PinsB to %00000010
		PinsC = m80c	'Set PinsC to the value required
		Band  = 80

'	Case 575 to 676 '60m
'		PinsB = m60 	'Set PinsB to %00000011
'		PinsC = %00000100	'Set PinsC to the value required
'		Band  = 60

	Case 575 to 676
		PinsB = m40 	'Set PinsB to %00000011
		PinsC = m40c	'Set PinsC to the value required
		Band  = 40

	Case 010 to 147
		PinsB = m30 	'Set PinsB to %00000100
		PinsC = m30c	'Set PinsC to the value required
		Band  = 30

	Case 450 to 553
		PinsB = m20	'Set PinsB to %00000101
		PinsC = m20c	'Set PinsC to the value required
		Band  = 20

	Case 369 to 430
		PinsB = m17 	'Set PinsB to %00000110
		PinsC = m17c	'Set PinsC to the value required
		Band  = 17

	Case 369 to 430
		PinsB = m15 	'Set PinsB to %00000111
		PinsC = m15c	'Set PinsC to the value required
		Band  = 15

	Case 246 to 307
		PinsB = m12	'Set PinsB to %00001000
		PinsC = m12c	'Set PinsC to the value required
		Band  = 12

	Case 246 to 307
		PinsB = m10	'Set PinsB to %00001001
		PinsC = m10c	'Set PinsC to the value required
		Band  = 10

	Case 147 to 245
		PinsB = m6	'Set PinsB to %00001010
		PinsC = m6c	'Set PinsC to the value required
		Band  = 6

	Case 000 to 009	'ADC registered too low a voltage to be valid

Else				'No matcxh found, out of bounds
		PinsB = $FF	'Set PinsB to 0
		PinsC = 0	'Set PinsC to 0
		Band  = 0
 EndSelect

EndIf
'debug
'#endrem

ClearhSerPtr:		'Routine to clear the serial buffer
FOR MClear = 0 to hSerPtr
 PUT MClear , 0
NEXT

hSerPtr = 0		'Reset the HSERPTR pointer to 0

CHSM1   = 0
CHSM2   = 0
MClear  = 0
Lookfor = 0
Goto start

Download the code, schematics and PCB layout here.

The code is split into 2 sections based on whether the CI-V is connected. If the CI-V is connected by default it is high which can be detected by the PIC which is what the line in the code equalling ‘IF CIVinPIN = 1 or CIVorADC = 0 then’ does. If there is CI-V then the PICAXE runs the CI-V routine to decode the frequency and works out the MHZ and 100KHz, i.e 14.123MHz becomes decimal 141. If there is no CI-V connected (the CI-V input to the PICAXE chip will be 0v) then the PICAXE uses a routine to look at the band data voltage using ADC to determine the band, first you need to make sure you don’t put more than 5v into the PIC, so you divide it with a couple of resistors R1/R2 so the voltage is 0.6 that of its original (i.e. 8v becomes 4.8v to the PIC). You then simply read the voltage as a function of ADC, 4.8v is 96% of 5v (we are using READADC10 which is 10bit value and the max ADC value is therefore 1024) so 4.8v = 96% of 1024 the [max] ADC value is 983. All we now do is for each band give a lower and upper limit for each ADC value (accounting for rig variance) and if the ADC value falls within a range then the appropriate band is chosen and BCD pins set accordingly.

If the band voltage is say 6.2v out the radio what band are we on? Reduced first by R1/R2 the voltage becomes 3.72v into the PIC, this has an ADC value (3.72/5v * 1024) of about 762 which rightly falls into the 80m band range. 80m has a lower ADC limit of 700 and an upper ADC limit of 799.

Remember the PIC code is split in 2, the top half is for CI-V decoding and the bottom half band voltage decoding.

When the radio is switched on 13.8v is taken from ACC2 on the IC-756pro3 which powers the PICAXE and also goes to the VL-1000 to switch it on, ensure the remote switch on the back of the VL-1000 is set to ON.

Updates:

230711 – Version 1.1 released:

Improved CI-V string searching
Additonal checks in Band Data routine to ensure we didn’t get there by mistake

Code now works fine with HRD controlling the radio over CI-V and all band switching works independent of whether the radio or HRD initiates a band switch.

170711 – I received an email from Jack Brindle, W6FB who commented “There is one change I would suggest in the output table, though. The BCD code 0×0 is not defined, but is used by some manufacturers. For example Elecraft uses it in the K3 for 60 meters. However, 0xF (all ones) _is_ defined as a no-band selector.” So with that in mind I’ve changed the code so ‘no band selected’ is now all 1’s (0xF) – which turns out to be 70MHz, see my post about that.

150711- I received a comment from Barry GM3YEH who uses the Icom to Yaesu BCD Band Data Converter on his radio with N1MM contest logging software and a 5B4AGN BPF and found the rig stays in sync with N1MM software but the BPF only changes to the correct band temporarily then drops into a ‘no band selected’ state after a second or two. Barry suggested it might be down to N1MM polling the radio which the interface sees as 0v on the CI-V line which makes the code execute the Band Data Voltage code for which there is no band voltage data so it defaults to 0, ‘no band selected’. On 230711 I reworked the code so it now has a much better CI-V ‘search’ string so it doesn’t get false values and also added an extra check in the Band Voltage code as there were times, as mentioned above, that the code would move there even if it was receiving CI-V data.

/END UPDATE:

SCAM12 Installation

Jul 11th, 2011

by m1bxf.

4 comments

So I was convinced for my new mast I would use a SCAM12 after seeing G4ERO’s installation (picture on his QRZ page). I had done some antenna work round at Colins QTH and seeing how simple it was to erect (BINGO!) and take down. The mast is approx 3m when down (with antennas on) and the top of the SCAM12 is 12m when up. The SCAM12 is pneumatic and requires about 22PSI of pressure when fully up and mine stays up for days. The SCAM12 is fully rotate-able and sits within a swivel base/mount but I use a rotator at the top which you can see below the 6m/4m antenna so you can work out and see the SCAM12 is low when down. I do plan to move this to the bottom when I get round to working out how best to do it.

And when up:

Mounting the SCAM12 I again took advice from Colin G4ERO and dug a hole about 100cm x 30cm x 30cm, bought a 2.5m long 178mm x 102mm x 19mm universal beam, modified it, (see below) put it in the hole and aligned it for vertical. I then concreted the bottom 50cm of it, let it set and filled and packed the rest with mud.

As the SCAM12 is able to rotate, there is a bearing in the bottom of the mast so it is not a good idea to mount it direct onto the ground. So I welded a bracket on the bottom to hold the SCAM12 off the ground. I then used threaded bar and some angle iron to hold it against the universal beam with some wood between both to tighten against. Since these pictures were taken I’ve repainted the universal beam Hamerite ‘Highland Green’ which is more similar to the SCAM12 colour.

As the mast is pneumatic I got a small compressor for 30EUR at a Dutch Radio Rally which take 2 minutes 40 seconds to put the mast fully up. I’ve fitted it with a remote control and pressure switch to it automatically switched off when at the correct pressure. The SCAM12 comes with a key to allow the air out and it takes a minute to come down.

There are guying points for 4 guy ropes on a slip ring but so far I have not guyed the mast at home and it’ has been up in quite strong winds, if I’m worried about the wind I only put a few sections up. The sections can also be locked off if the SCAM12 is planned to be up for an extended period of time.

SmallWonder Labs PSK-20 Mod to 20m WSPR

Jun 18th, 2011

by m1bxf.

1 comment

I bought a Small Wonder Labs PSK-20 kit a few years ago when I was dabbling with HF data modes. The PSK-20 is, from the PSK-20 manual “[a] transceiver on a single PC-board design measuring 4.6" x 5.27" (12 x 13.4 cm). It is functionally a crystal-controlled SSB transceiver with slightly wider than normal IF passband characteristics. It covers the range of 14.070 to 14.074 Mhz.”. It comes in kit form and unfortunately is no longer available, however a note on the Small Wonder Labs webpage states “[there] will be a successor- schedule is uncertain”.

I built my PSK-20 then never used it. It sat in a drawer until recently I thought I could use it for something other than PSK. With the relatively low TX output, mine gives 2w out, it would be ideal for WSPR. I was hoping I would be able to re-tune it from the designed 14.073MHz to 14.0956MHz but the pull on the crystals was too much and it wouldn’t do it. The design of the PSK-20 is based on a 9MHz IF and a 5.07MHz LO. The LO is just a 5.0668MHz crystal and the 9MHz is a 9MHz crystal and an additional eight 9MHz crystals used in crystal ladder filters, four in the RX path and four in the TX path. As the design is a simple mixer it was easy to decide that changing the crystals would get me onto 14.0965MHz so I purchased 10 x 10MHz crystals and 1 x 4.096MHz which would mix to give me the desired 14.0965MHz which is used for WSPR on 20m. The RS part numbers for the crystals are 6936952 for a bag of ten 10MHz crystals and 2261572 for the 4.096MHz crystal, total price for both was £11.08.

I fitted the new crystals and aligned the PSK-20 onto 14.0965MHz as seen on my frequency counter and started using it with WSPR but nothing was decoding and nobody was decoding me. I checked I had TX output and then found out the PSK-20 is natively LSB, this meant I was on the ‘wrong’ frequency and also as WSPR is an FSK type mode, the tones were inverted. I’m not 100% sure if WSPR is tolerant of which mode it is on but PSK31 is for which the kit was designed – in PSK you change the phase not not tone to signal information.

So the problem I had now was to get the PSK-20 onto USB and although I found lots of people asking how to do this on various internet forums there was no answer on how to do it. So I emailed Dave Benson, K1SWL, the kit designer and proprietor of Small Wonder Labs asking how he would suggest I mod the PSK-20 to USB. I got an answer 40 minutes later, although I had gone to bed, fantastic support!!!

Dave suggested I put a 10uH inductor in series between the 10MHz IF crystal and the C38 trimmer to pull is below 10MHz, to about 9.998MHz. First I had to cut the track between Y6 (the 10MHz IF crystal) and C38 on the underside of the PCB. I then fitted a 10uF inductor so that it was in series between Y6 and C38. I didn’t have a surface mount inductor so it is obvious how and where I mounted it in the picture below.

So I switched the PSK-20 on, connected some headphones to the AF OUT connector (watch as the volume it very high) and tuned my IC-756pro3 to 14.0965MHz USB and sent some audio, tuning both C38 and C42 (the trimmer for the LO) I was able to resolve USB! Bullseye!

I then connected up the PSK-20 to WSPR and let rip. I get about 2w output but at first I run using just 0.5w with fantastic results. Here is a 12 hour plot of where I’ve been heard. I use a 1/4 vertical on 20m with the feedpoint 1.5m above ground and 8 radials which act like guy ropes.

If you would like more information or details on how I achieved this then contact me using the Feedback option on the site.

Masthead + PA + Radio Sequencer

Jun 18th, 2011

by m1bxf.

No comments yet

My 2m station includes a masthead preamp, a 2 x 4cx250 linear and the IC-910. In order not to blow up the preamp I needed to get a sequencer, me being me I decided to design and build one, total cost with the box was around £10. This is a very simple design and uses a PICAXE-08M for the control as it supports 5 input/outputs. All I needed was 1 input (PTT) and 3 outputs, preamp, TX Amp and radio. The preamp, TX Amp and radio outputs are driven by relays so can be configured for NO or NC when the sequencer is not active, the non sequenced state can also be set in the software too.

The delay on TX is 100ms between the preamp going off and the TX amp coming on and then a further 50ms for the radio to move into TX. On un-keying the radio is moved into RX, 50ms later the TX amp is removed then 100ms later the preamp comes back on. My initial design used 4 LEDs, a green one for power, one red/green for TX/RX, a green one to indicate preamp on/off and a red one for indicating the TX has come on. You may decide to omit some of them.

Updated to v1.2

I’ve done some updates to the design based on feedback from users. The main update was to add a means of adjusting the timing sequence manually so I added a potentiometer to one of the inputs and read the ADC voltage on it. The ADC value is then added to the default value giving an additional delay meaning the sequence delay can be set between 100ms to about 1 second.

The update also allowed me to clean up the code by adding comments and symbols. this should allow whoever builds it better understand how to customise the outputs and give a better overall understanding of the PICAXE code if they are new to it.

NOTE: If this design is to be used with a radio which goes into transmit when the PTT line is grounded then you can omit D3 and REL3 and connect the PTT line of the radio directly to the collector of Q3.

Download v1.3 of the code directly.

#PICAXE-08M

'Sequencer v1.3 © Gavin Nesbitt, M1BXF - July 2010

#rem
This code is used to sequence 3 outputs when the input pin is grounded. The design purpose is for an amateur
radio station which has a preamp, TX amplifer and radio which for saftey reasons require them to be switched
on and off in a set order. 

The output pins can be modified in the Symbol code below, PTT_PIN, TXAmp_PIN & Preamp_PIN.  The minimal delay
between the Preamp switching off and the amp being switched on plus the minimum delay between the TX amp
switching on and the TX being activated can be set in Symbols TX_amp_delay & TX_delay.

#endrem

'Define Symbols
Symbol TX_Amp_Delay	= 100	'The minimum delay between the Preamp switching off and the amp being switched on
Symbol PTT_TX_Delay	= 75 'The minimum delay between the TX amp switching on and the Radio PTT being activated
Symbol User_Delay		= B0	'Variable to store the ADC value
Symbol PTT_TX_Delay2 	= W1	'Variables W1 and W2  to store the final TX Delay, these are word values
Symbol TX_Amp_Delay2	= W2	'to cope with values >256.

Symbol PTT_PIN		= 0	'Define the PIN which drives the PTT line
Symbol TXAmp_PIN		= 1	'Define the PIN which drives the TX Amplifer
Symbol Preamp_PIN		= 2	'Define the PIN which drives the Preamplifer
Symbol Timer_POT		= 4	'Define the PIN which the ADC is read on
Symbol PTT_IN_PIN		= PIN3'Define the PIN which the PTT is driven from
Symbol PTT_STATE		= 0	'Define the level which activates the PTT

'Main Code
pause 1000

Pre_On:
		IF PTT_IN_PIN=PTT_STATE then Pre_Off	'In normal state PIN3 will be high (1) unless the PTT is pressed
		high Preamp_PIN		'Switch ON the Preamp
		goto Pre_On			'Loop here waiting for the PTT (PTT_PIN = ground) to be pressed

Pre_Off:
		low Preamp_PIN		'Switch OFF the Preamp
		gosub TIME_DELAY		'Chech the added delay after switching the pre-amp off
		if PTT_IN_PIN=PTT_STATE then Amp_on	'Check incase the PTT has been releases and if not goto Amp_On
		goto Pre_On			'If the PTT has been released goto Pre_On

Amp_On:
		pause TX_amp_delay2	'Delay the time between the Preamp being switched OFF and the Amp being switched ON
		high TXAmp_PIN 		'Switch ON the TX_Amp
		if PTT_IN_PIN=PTT_STATE then TX_on	'Check incase the PTT has been releases and if not goto TX_On
		goto Amp_Off		'If the PTT has been released goto Amp_Off

TX_On:
		pause TX_Amp_delay2		'Delay the time between the Amp being switched ON and the TX being switched ON
		high PTT_PIN		'Switch ON the TX
		if PTT_IN_PIN=PTT_STATE then TX_on	'Check incase the PTT has been releases and if not goto TX_On (loop)
		goto TX_Off			'If the PTT has been released goto TX_Off

TX_Off:
		low PTT_PIN			'Switch OFF the TX
		pause TX_Amp_delay2		'Delay the time between the TX being switched OFF and the Amp being switched OFF
		if PTT_IN_PIN=PTT_STATE then TX_on	'Check incase the PTT has been re-pressed and if so goto TX_On

Amp_Off:
		low TXAmp_PIN		'Switch OFF the Amp
		pause TX_amp_delay2	'Delay the time between the Amp being switched OFF and the Preamp being switched ON
		if PTT_IN_PIN=PTT_STATE then Amp_on	'Check incase the PTT has been re-pressed and if so goto Amp_On
		goto Pre_On			'Goto the start

TIME_DELAY:
		READADC Timer_POT,User_Delay		'Read the ADC value on the Timer_POT pin into varable User_Delay
		User_Delay = User_Delay * 2			'Double the max delay range from 256 TO 512
		TX_amp_delay2 = User_Delay + TX_Amp_Delay	'Add the user range to the default value
		PTT_TX_Delay2 = PTT_TX_Delay + User_Delay	'Add the user range to the default value
		RETURN						'Return to the code above

40m 1/4 Vertical [Epic] Antenna

Jun 5th, 2011

by m1bxf.

3 comments

So the antenna farm at M1BXF QTH just got larger with the addition of a 40m 1/4 vertical. I’d been thinking about this antenna for while as verticals are good for DX, more in this in a moment, and require little space to erect, but does need space for radials.

The antenna is based on a 10m fiberglass pole for the vertical element support, 17 radials and a clothes line ground screw to hold it up. I ended up with 17 radials as I cut one for length then made a ‘jig’ which allowed me to make 4 at a time after, so I made 3 x 4 in the jig + the one I had… I put screws in at each joint of the 10m pole also so there was no chance in it falling down into itself.

As you can see I erected it near some trees, this is mainly to make it less noticeable in the direction of the house which is through the trees as it were. To help make it blend in further I painted the pole Hamerite ‘highland green’.

The radials all connect to a circular copper bar I made which goes round the base of the antenna with a short wire going to the ground of the feed-point. The radiating element ends in a circular crimp, another is also soldered to the SO-239 centre pin so the method of connecting the vertical radiator to the feedpoint is with a nut and bolt, click to enlarge.

Once all was connected up I felt like tuning it, this only took 2 attempts to get it to VSWR 1.07 @ 7.1MHz as you can see in the first plot, the second plot shows the other resonances upto 60MHz so it is usable on 15m (21MHz) also, albeit with an ATU as the VSWR minimum is outside the 15m band. At first the VSWR @ 7.1MHz was 1.2:1, getting it lower was me being picky.

So why is this antenna epic? Well 5 minutes after connecting it up and tuning through 40m I heard VK7AC working a pileup, 3 calls later and we managed 58/57 either way so the first QSO on the antenna was with Australia (Tasmania) @ 17255km, EPIC!!!

Using Power Point for Project Decaling

May 30th, 2011

by m1bxf.

3 comments

So I build loads of project which in the end require labelling, but how to do it so it seems professional? In the past I used to just make lines of text which was more or less the project name and my callsign, printed it and stuck it to the box, not very professional!

Well while looking at some projects on the net over the weekend I found a Cumbria Designs Minicounter frequency counter built by Matti Niskanen, OH2CF which looked like a real professional product, the decaling was superb. Reading details of the project Matti explained he uses Microsoft Power Point to make the panel designs, it suddenly hit me that it was such a simple way to do it. I guess Visio would also do but MS Power Point comes with Office 2007 which I have installed and creating shapes, text, lines, you name it and then positioning them would be simple.

I thought I would give it a go on my External Voice Keyer which I’ve just connected up and started to use. At the start the front panel is all based on handwriting, which works but it just doesn’t look professional.

I then thought instead of measuring where all the holes, LEDs and switches where I would take a photo of it, load it into Power Point and then use it as a template, here is a moc up of what that looked like, this is the finished and tweaked overlay put back onto the photo for this article but it does show the picture (perspective) wasn’t quite right but it did save loads of time measuring.

You can see the design on the screen with the photo removed, then printed and then with the holes where the LEDs, switches and variable pot go.

After the design was prepared with the various holes cut out, it was glued using pva glue to the metal front panel. The finished design makes the Voice Keyer look much better than it did before.

This is rev 1, you can see the one fitted to the Voice Keyer has my callsign and project name in handwriting on it whereas the designs above have it added within Power Point. I’m going to add a few additional switches to the Voice Keyer in the week as it supports 4 voice memories which will be handy to switch between so I will add a ‘next memory’ button and an erase button so the design will change to accommodate them.

Update 020611:

I’ve now added the extra switches and re-arranged the front panel including a new colourful decal…

And updated my SO3R shack controller to look very similar…

Now onto other projects…

4m Transverter

Apr 23rd, 2011

by m1bxf.

4 comments

A band I’m interested in is 4m which in the UK we are allowed 70MHz to 70.5MHz. I’m mainly interested in the MS and ‘E’ capability of this band but very few commercial SSB radios have 4m built in so the easiest way is to transvert, usually from 28MHz with a 42MHz oscillator to get 70MHz. For those unfamiliar with transverting this mixing will produce 2 frequencies, one 42MHz above and one 42MHz below, if we take 70.2MHz this means an unwanted one at 112.2MHz and the wanted one at 28.2MHz. All we do is put the IF through a 28MHz filter to remove the unwanted frequency.

Although there are few commercial radios there are many commercial 4m transverters available. The one I chose was Bo’s OZ2M which has a single 28MHz IF transceive port and separate 70MHz RX and TX ports. TX output is adjustable on the board for a maximum output of about 150mW and the RX path has about 15dB gain. My first 4m system consisted of a boxed OZ2M transverter with a Spectrum Comms TA4S4 4m amplifier providing 45w for the 150mW drive in the TX path.

The original M1BXF transverter project

This worked well and it required an RF relay to combine the 70MHz RX and TX lines after the amplifier which meant it made the setup a little more complicated than I would have liked but it worked. I used it on Camb-Hams DX’Peditions to Mull in 2008 and Harris in 2009 with good results, about 33 QSOs in total. 45w was fine but in the UK we are allowed 160w so for VHF NFD 2009 and the Camb-Hams DX’Pedition to Harris in 2010 I decided to make a better PA. This started with buying a Bremi BRL-200 CB amplifier which can be modified to 4m. I had little success at this and could barely get 60w out when the mod quotes over 100w.

I had a spare Bremi case, not the one which I used for the 4m amplifier, it was from a CB amp which died years ago, when the transformer failed, and a large heatsink so decided to look into make something a little more powerful and compact. I found a 300w PA covering 70MHz on eBay which used the MRF-151G transistor, this required about 5w drive for 300w out. The MRF-151G is a 48v part so my next task was to get a decent 48v PSU. eBay again helped and a 48v 20amp PSU was bought.

I managed to get the 48v PSU in the Bremi box but due to the height of the caps on the PSU board I couldn’t get the amp in. In the end I had to invert the heatsink and have the amp sitting external to the box. This worked but it meant it was exposed and the box was rather empty, not what I had wanted. The other point was generating the 5w drive. The transverters output was 150mW which wasn’t enough and the Spectrum amp was 45w which was too much. Thankfully as the TX line was separate to the RX line I was able to add some attenuators on the TX path between the OZ2M and Spectrum amp so it would only generate 5w. Again this worked but lets look I now had a boxed transverter with the 70MHz transmit leg going to a 30dB attenuator then into the Spectrum amp then into the MRF-151G amp then to a coax relay. All rather messy. I used this for a while but it wasn’t good. If I wanted to do crossband between 4m and 6m there was an additional coax relay.

I liked the Bremi box and I knew the system worked with the OZ2M transverter performing well and the MRF-151G producing a stable output – but it was a mess and nearly required a diagram to connect up! I decided to stay with OZ2M transverter but I didn’t want to dismantle my original one as it was quite well constructed so I bought a second one to save the first from destruction I also removed the 48v PSU from the box to make space for the amp, transverter and other bits such as the coax relays, logic and other bits.

Final [Current] Design

Another thing I needed to overcome was the 5w drive for the MRF-151G amp. I found a design online by GI0GDP using a single 12v device.

This was mounted on the heatsink with the MRF-151G amp so that 150mW from the OZ2M transverter would easily produce 300w out the MRF-151G amp.

Some of the other changes were bringing the coax relays into the box. I use a YU7EF duoband 6m/4m dual band antenna so I need to bring a 6m feed out to the 6m radio. The antennas comes into the box on a CX-140N coax relay which when the transverter is off (or x-band is enabled) bypasses the transverter to an N-Type on the rear and when energised connects the antenna to another coax relay switching between 4m RX and TX.

One new addition was the addition of an 4×20 LCD to show the status of the amp. I monitor the heatsink temperature, the 12v and 48v lines and also which state the system is in, RX or TX. The logic is based on a PICAXE-20X2 which controls which relays are energised and when the fan on the heatsink should be on, based on transmit state and temperature. There is a 4pin DIN on the back which is used for PTT and outputs 12v when the transverter is on, this is for my Icom IC-756pro3 which needs 12v on one of the accessory jack pins to enable transverter mode.

Now that the project is finished I now have a single box (rather cluttered) containing my 4m transverter, the amplifiers and RF switching. I can connect my 6m/4m antenna to it and take the 6m side to my IC-756pro3. I added support for crossband on the transverter, like my original version, so I’m able to operate with the transverter used for 4m transmit with receive on 6m (the input relay de-energised) or receive on 4m and transmit is on 6m. The output power can be adjusted from 2w out to 280w, the RF meter is calibrated for full scale being 160w, the UK limit

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