Minicounter v3.0 - Cumbria Designs
Contents
1. Minicounter User Manual CONTENTS 1 INTRODUCTION 2 2 PREPARATION 2 3 CIRCUIT DESCRIPTION 3 4 ASSEMBLY 5 5 TESTING 9 6 USER SET UP 10 7 USE 12 APPENDIX A Troubleshooting cumbria The Steading designs Stainton PENRITH Cumbria CA11 OES UK www cumbriadesigns co uk 1 Introduction Thank you for purchasing the Cumbria Designs Minicounter Module We hope that you enjoy constructing this kit and find many uses for this feature rich design This manual describes the assembly and operation of the Minicounter even if you are a seasoned constructor we respectfully ask that you read this manual and familiarise yourself with the instructions and kit contents before commencing construction If assembled carefully this unit will provide many years of reliable service The Cumbria Designs Team 2 Preparation 2 1 Tools We recommend that the following tools are used during assembly and testing 25W fine tipped soldering 60 40 Rosin cored solder 5 or smaller diagonal side cutters Small pointed nosed pliers Solder sucker just in case Multimeter 2 2 Conventions The following symbols are used within the assembly instructions to draw attention to critical steps such as component orientation and anti static precautions The associated narrative describes the action required D Critical Step Static Sensitive 23 Assembly The production of a successful finished working kit is dependent upon care2. common groups Groups A to F each of which contain the following functions Display Mode Radio Counter Display Format GHz MHz MHz kHz IF Offset 0 to 999 999 99 Multiplier 1 to 255 This allows 6 different configurations to be programmed and applied immediately by the PL2 control pins The 2 common groups allow the Tx to Rx hang delay to be programmed and as a last resort the default settings to be restored Minicounter v3 0 PCB1 1 Version 1 8 The set up buttons use control inputs 1 2 and 3 For correct operation in set up mode it is essential that these pins are not grounded by external switches Either remove the PL2 connector or set user controls such that these pins are all high open To enter set up mode follow these simple steps e Ensure unit is powered off e Power unit on e When the Cumbria Designs Message appears press SEL The SET UP message will be displayed for a couple of seconds after which the unit goes into the GROUP A screen To navigate through the menu structure the three push buttons are used The Up and Down buttons are used to move between groups and to change values the Select button is used to set a value and move onto the next function within a group The action is intuitive and is illustrated in the Group Programming Functions diagram 6 3 Group Menus At the Group level in the menu use the UP DN buttons to move between groups and briefly press the SEL b
3. should be fitted to the regulator to keep the operating temperature at an acceptable level 7 3 RF Input The RF input presents a high impedance 2M2 at low and MF frequencies This will allow direct low capacitance cable connection to a signal source with minimal loading At these frequencies an RMS drive level of a few tens of millivolts Minicounter v3 0 PCB1 1 Version 1 8 should be adequate to allow reliable frequency measurement At higher frequencies the input capacitance of the JFET causes the input impedance to fall to typically several hundred Ohms at 100MHz To avoid undesirable loading on the source this reduced impedance must be accounted for with a buffer stage or impedance matching At the upper VHF measurement range a drive level of about 1volt RMS will be necessary to support reliable operation 7 4 Controls The control inputs can be wired together to personalise the Minicounter for a specific application For example consider a simple CW transceiver where direct frequency measurement might be required on transmit and an IF offset is needed during receive for a high local oscillator There are several possibilities one option is to configure Offset A to the IF frequency set Offset B to 0 00kHz ground the Sum Diff pin on PL2 to select the difference The Tx Rx control on PL2 is connected to the GROUP B pin on PL2 and the key circuit On receive GROUP A is active and Offset A will be applied The d
4. 2 3 RF Checks Connect a signal source between the RF input pin and ground a grid dip oscillator loosely coupled to the input with a 2 or three turn loop of wire is ideal Note the comments in Section 3 regarding input Page 9 of 16 Cumbria Designs impedance The display will now show the frequency of the source Grounding the GROUP B pin PL2 pin 1 will add the pre programmed 455 kHz offset to the measured frequency Similarly grounding any of the other offset control pins will add the associated offset to the input frequency By grounding the Sum Diff pin PL2 pin 6 the difference between the source frequency and the selected IF offset will be displayed This concludes the unit testing 6 USER SET UP 6 1 Frequency Calibration Before calibrating the frequency display allow the temperature of the Minicounter to stabilise to that of the environment it will be used in Apply a signal of a few hundred millivolts at a known accurate frequency to the RF input The display should now register a frequency close to the source frequency With a non metallic trimming tool adjust TC1 to bring the display frequency to the same value as the calibration source The frequency calibration is now complete 6 2 Set Up Mode In Set Up mode the IF Offsets display formats multipliers and Tx to Rx Hang Delay can be changed The set up variables are configured in groups there are 6 groups associated with the PL2 pins and 2
5. d CMOS in the gating and pre counter circuits provide an upper operating capability in excess of 100MHz The PIC Processor internal prescaler is programmed to act as a divide by 2 When combined with the divide by 6 action of IC2 this provides a divide by 8 action the 8 bit count jointly held in the pre counter and prescaler represent the binary Least Significant value of the measured frequency Two further 8 bit counters internal to the PIC Processor provide a binary 24 bit frequency count for each gate sample This is processed by the PIC Processor to factor in any offset or multiplier values converted to Binary Coded Decimal BCD and passed to the LCD for display normally held high by pull up resistors grounding an input activates the associated function The function of each pin is given in Table 1 below PL2 Function High or Open Low Ground Pin 1 GROUP B Use GROUP B settings 2 GROUP C All inputs High or Open Use GROUP C settings 3 GROUPD applies GROUP A settings Use GROUP D settings 4 GROUP E Use GROUP E settings 5 GROUP F Use GROUP F settings 6 Offset Sum Difference Offset Sum Offset Difference 7 Delta RIT Normal Measurement Show difference 8 TX Rx Rx Tx Tx Rx and RIT operation are only available in Radio Mode Table 1 Minicounter v3 0 PCB1 1 PL2 Control input functions Version 1 8 Page 4 of 16 Cumbria Designs 4 Assembly Th
6. during component handling Minicounter v3 0 PCB1 1 Version 1 8 placement and good soldering Don t be tempted to rush the construction even though this is a relatively simple kit a wrongly placed component can provide hours of frustrating fault finding Also as this kit uses a double sided Printed Circuit Board PCB with through plating removal of a wrongly soldered part can be difficult Follow the assembly instructions carefully to avoid mistakes 2 4 Component Identification All parts carry a coded identity to describe their values It is important to be able to recognise these during assembly Capacitors have their value printed numerically e g 104 100nF 103 10nF etc Resistors have their values represented by coloured bands To simplify component identification the parts list carries the identities of each component as it appears on the device For resistors the colour coding is given This should be referred to during assembly to ensure the right parts are placed in their respective positions on the PCB 2 5 Component Leads Many of the passive components will require their leads to be formed to align with the holes on the PCB This mainly applies to the axial parts such as resistors and diodes Forming component leads is easily done with a pair of pointed nose pliers and using the hole spacing on the PCB as a Page 2 of 16 Cumbria Designs measure Alternatively small formers made from scrap
7. e control and arithmetic actions needed to carry out measurements and communicate with the LCD Page 3 of 16 Cumbria Designs 3 2 Frequency Measurement The Minicounter frequency range spans from a few kHz to over 120MHz The signal to be measured is applied to the two pin RF input connector input ground A J FET buffer Q1 provides a high impedance interface for frequencies up to about 30MHz This allows direct connection to circuitry with minimum loading Beyond 30MHz the input capacitance of the J FET progressively reduces the input impedance At these frequencies depending upon the application care may be needed to select a measurement point capable of driving an impedance of several hundred Ohms A bipolar transistor Q2 provides the gain needed to drive IC1A and IC1B the gate shaping circuit IC1D is the counter gate This is opened and closed by IC3 the PIC Processor IC1C is used to clock out any residual stored count in IC2 the pre counter IC2 is a dual 4 bit binary counter 3 3 Control Inputs 8 diode protected control inputs are presented on PL2 These allow the user to select the various functions of the Minicounter The inputs are configured as a 6 bit counter This is a high speed CMOS device capable of operating at much higher frequencies than the internal prescaler of the PIC Processor which has rated upper frequency limit of 50MHz The combination of the input amplifier and the use of high spee
8. e following assembly sequence is recommended This allows most of the smaller parts to be held in place with the board turned over whilst soldering the underside All components are mounted on the top silk screen side of the board 4 1 4 2 4 3 4 4 4 5 4 6 Resistors Broad tolerance band shown in capitals R3 10R Brown Black Black BROWN R4 2M2 Red Red Black Yellow BROWN R5 220R Red Red Black Black BROWN R6 68K Blue Grey Black Red BROWN R7 470R Yellow Mauve Black Black BROWN R1 10K Brown Black Black Red BROWN R2 470R Yellow Mauve Black Black BROWN R8 15R Brown Green Black GOLD IC Sockets Ensure correct orientation Match index cut out on socket to board printing Tip solder one pin only then check positioning before continuing Heat solder and reposition if necessary a Fit the 18 pin microcontroller socket for IC3 b Fit 14 pin sockets for IC1 IC2 C Fit the 16 pin socket for IC4 Crystal Fit X1 the 20MHz crystal This is heat sensitive and is easily damaged if overheated It is recommended that a gap of about 2mm is left between the crystal and the PCB This will provide a little extra thermal isolation during soldering Resistor Network The resistor network has a common pin marked by a spot at one end For correct operation of the controls the common pin must be aligned to pin 1 on the board print This is adjacent to C8 Fit RN1 8x10K Contro
9. e mounted inside a transceiver or used as a versatile stand alone frequency counter If it is to be installed in its own case for stand alone use the control buttons can be extended to the front panel from PL2 No modification of the circuit board is necessary Refer to the circuit diagram for wiring details The four 2 54 mm countersunk screws and the spacers provide a convenient method of installing the Minicounter module into an enclosure or host equipment Remember to include the short 3mm spacers to ensure adequate clearance between the top side tracks of the LCD and the rear of the mounting surface 7 2 Backlight The two BL pads are provided to give users the option to either permanently enable the back light by soldering a wire link between the two pads or to extend control to a front panel switch to save power in battery operated equipment By linking the two BL pads on the main PCB the circuit is completed illuminating the LCD A value of 15 Ohms was chosen for R8 the backlight current limiting resistor to provide sufficient brightness for reading the display in dim or dark conditions without drawing excessive current This keeps the regulator at a comfortable temperature and conserves power under battery operation The backlight is capable of being run at a much higher current to produce more light by reducing the value of R8 However we recommend a lower limit for R8 of 10 Ohms At this value some form of heatsink
10. g time and DOWN to decrease hang time Press SEL for 2 seconds to return to top Minicounter v3 0 PCB1 1 SEL 2 secs DOWN RESTORE DEFAULTS Restart with new settings RESTORE DEFAULTS PRESS SEL TO CONFIRM Defaults restored SEL 2 secs Press SEL for 2 seconds To overwrite settings with default values and return to the top To exit Default function without change press UP to return to Hang Delay function or DOWN to exit and re start Version 1 8 Cumbria Designs Page 13 of 16 Minicounter v3 0 PCB1 1 MINICOUNTER PCB VERSION 1 1 PARTS LIST Capacitors C2 C3 10n Ceramic Capacitor C4 C5 100n Ceramic Capacitor C6 C7 C8 C10 C1 22p Ceramic Capacitor C9 C11 10u Electrolytic Capacitor TC1 22p Trimmer Capacitor Resistors R1 10K 1 MRS25 R2 R7 470R R3 10R R4 2M2 R5 220R R6 68K R8 15R RN1 8x10K SIL Resistor VR1 10K Potentiometer Switches S1 Push Switch S2 Push Switch S3 Push Switch Semiconductors Q1 J310 JFET Q2 MPSH 10 Transistor IC1 74VHCOON Quad 2 input NAND gate IC2 74VHC393N Dual 4 bit binary Counter IC3 PIC16F628 Microcontroller IC4 74HCT151N Data Selector Multiplexer ICH 7805 Regulator D9 1N4004 Diode D1 D8 1N4148 Diode x1 20MHz Crystal LCD 16x 2 Way Backlit LCD Module Version 1 8 Cumbria Designs Connectors and IC Sockets 1 x 18 Pin DIL Socket 1 x 16 Pin DIL Socket 2x 14 Pin DIL Socket PL1a 1X16 SIL Socket Strip PL1b 1x16 SIL P
11. he Push Switches by pressing them into mounting holes until they snap into position Observe orientation set by hole layouts Fit push button switches S1 S2 and S3 Minicounter v3 0 PCB1 1 Version 1 8 Page 6 of 16 Cumbria Designs 4 12 Electrolytic Capacitors ES C9 and C11 are polarised Capacitors the short lead marked goes to ground a Fit C9 10uF Adjacent to IC1 b Fit C11 1OuF Adjacent to the power connector 4 13 Connectors Recommended Pin Header Connector orientation is with rear locking tab facing into the centre of the board a Fit the two 2 way pin headers 12V Power and RF RF input b Fit the 8 way pin header PL2 Control inputs 4 14 Semiconductors Static sensitive parts Discharge yourself to ground before handling Avoid wearing static generating clothing e g wool man made fibres etc during assembly gently formed for correct alignment before insertion into sockets IC pins can be pushed inwards by placing the device on its side on a firm surface and gently pressing the body down against the pins When inserting parts take care to check pin alignment ES Orientation is critical Observe correct alignment of IC pins which will need to be Fit IC 74VHCOO0 Fit IC2 74VHC393 Fit IC3 PIC16F628 Processor Fit ICA 74HC151 4 15 LCD Backlight Option If the LCD backlight is required it is now a convenient point to insert the associated wiring For a permanent backlight bridge the pads
12. in Strip PL2 8Way Pin Header Power 2Way Pin Header RF 2Way Pin Header 2 x 2 Way Shells 1 x 8 Way Shell 12x Crimp Pins PCB Minicounter v1 1 Hardware Pack 4 x 8mm Nylon Spacers 4 x 3mm Nylon Spacers 4 x M2 5 x 20mm C S Screws 4 x M2 5 Nuts 4 x M2 5 Washers Nylon 4 x M2 5 Washers Steel Page 14 of 16 Ic ter Schemat Inicoun dez zHWOZ dzz LOL Se NOOSHArL NEGEDHAPL Q z E AS x o d ao e uU ONG a 2 x d Qr E S Oz OF Oy ala 16 aj Qc OT OF Oc Op AS Qh Zh O Ot Q OFT O E si Ost QNO qN QNS AS NMOG dn 199138 ON Lk co ia ence de E i mn mm Pt LL Ie ers LLL III AS NISFOHPL NE6EDHAPL ONG ON ONG EE qano QNS ON 0 KE a Do DIE QNS dp ONS ER de dzol 4 dalol qe lt Si lt o SEH 0 E Bu E SS D lt P o oO o Vv Vv AS AG AS ONG ONG ONG ONG ONG sl uoo al nay QNS RETE sr ONE lt ino Ni ki A Ch VOOFNI ed Page 15 of 16 Version 1 8 Cumbria Designs ter v3 0 PCB1 1 Inicoun M Minicounter Component Overlay pg e Ere Deo OAKS ca The Assembled Kit mah mS DD Yee ee LI m A j Ke I A E o E g e 1 os cia PEME um uud dimbr i adesi gn STE S e bei 7 BASSE PAPAS lge PISIS Minicounter v3 0 PCB1 1 Version 1 8 Page 16 of 16 Cumbria Designs
13. isplay will show the difference between the input frequency and Offset A On transmit with the key down and ground applied to GROUP B pin Offset B zero is selected overriding the lower priority Offset A the display will now show the input frequency with no offset On receive Offset B is deselected and Offset A is re applied 7 5 Delta RIT Mode When control input PL 2 pin 8 is grounded the Minicounter captures and stores the current frequency and compares subsequent samples against it The difference in kHz is shown on line 2 relative to the captured frequency END Page 12 of 16 Cumbria Designs Group Programming Functions DOWN GROUP A SEL MODE A COUNTER SEL 2 secs LABELS A MHz kHz SEL 2 secs OFFSET A 000 000 00MHz SEL 2 secs MULT FACTOR A x1 SEL 2 secs UP DOWN Groups C F T to R Hang Delay Restore Defaults Restart GROUP B UP Press UP or DOWN to toggle between Counter and Radio modes Press UP or DOWN to toggle between MHz kHz and GHz MHz formats Press SEL briefly to toggle between steady and blinking cursor With steady cursor use UP DOWN to select decade With cursor blinking use UP DOWN to change decade value Press UP to increase multiplier and DOWN to decrease multiplier Press SEL for 2 seconds to return to top Common Programming Functions Tx gt Rx HANG DELAY Tx gt Rx HANG DELAY 100 mSec Press UP to increase han
14. l Input Diodes Polarity conscious components Make sure that orientation is correct Fit the 8 Control Input blocking diodes D1 D8 1N4148 The diodes are mounted vertically body next to the SIL resistor network black polarity band to the top Fold the top wire over to fit Ceramic Capacitors Minicounter v3 0 PCB1 1 Version 1 8 Page 5 of 16 Cumbria Designs Suggested Installation order C2 10nF 103 C3 C1 22pF 22J C4 100nF 104 C5 s 4 7 Transistors Polarity conscious components Make sure that orientation is correct handling Avoid wearing static generating clothing e g wool man made fibres The J310 is a Static sensitive part Discharge yourself to ground before E etc during assembly a Fit J FET Q1 J310 b Fit Bipolar transistor Q2 MPSH 10 4 8 Variable Resistor The pre formed leads will require to be straightened to fit Note that due to PCB through plating tolerances VR1 may be a tight fit If this is the case work it gently into position or alternatively carefully trim the width of the pins Fit the 10K LCD Contrast Cermet VR1 103 4 9 Trimmer Capacitor Fit the 22pF Trimmer Capacitor TC1 4 10 Regulator and Protection Diode Polarity conscious components Make sure that orientation is correct Fit Voltage Regulator IC5 LM7805 taking care to perform the leads to ensure correct positioning before soldering Fit Power Diode D9 1N4004 4 11 Switches Do not straighten leads Install t
15. marked BL next to VR1 with a small wire link For a switched backlight useful in battery powered applications extend the BL pads to a suitable switch with flexible multi strand wires 4 16 LCD The LCD is static sensitive handle with care The LCD is connected to the board by the 16 way SIL connector To ensure correct alignment the following procedure is recommended a Place LCD face down on a flat surface insert the broad pins of the SIL pin strip into the 16 Way LCD terminal Do not solder at this stage b Plug the 16 way SIL socket fully home onto the exposed narrow pins of the SIL pin strip Minicounter v3 0 PCB1 1 Version 1 8 Page 7 of 16 Cumbria Designs C Locate the assembled Minicounter PCB onto the pins of the 16 way SIL socket d Fit the four 8mm spacers between the two PCB s at each corner e Place a 3mm spacer onto each M2 5 screw and pass through each mounting hole and 8mm spacer from the front of the LCD Secure on the top side of the main PCB by first fitting an M2 5 nylon washer followed by an M2 5 steel washer and finally an M2 5 nut See final assembly picture for detail f Once the LCD and main PCB are correctly adjusted for alignment carefully solder the SIL connectors on the LCD and main PCB Minicounter LCD PCB Equipment fixing PCB point M2 5x20 Screw M2 5 Nut 8mm 3mm M2 5 M2 5 Spacer Steel Nylon Spacer E Washer Washer Hardware Kit Assembly Detail The countersu
16. nk head of the mounting screws are presented at the front of the LCD to support the mounting of the complete assembly to countersunk mounting holes within the chosen enclosure The short nylon spacers provide clearance between the top side tracks of the LCD module and the rear of the mounting surface 4 17 Connector Assemblies Connector shells and pins are supplied to allow connection of power signal and controls to the Minicounter The use of good quality colour coded heat resistant multi stranded wire is recommended To avoid accidents a colour code convention should be chosen to represent function e g Red ve supply Black ground striped colours controls etc The connector assemblies comprise of two components the shell and the pins To terminate a conductor first strip back about 2mm of insulation and tin the exposed wire Place the tinned end of the wire into a pin such that the tinned wire sits inside the inner pair of tabs and the insulation sits within the outer tabs With small pointed nose pliers carefully compress the outer tabs onto the insulation to hold the wire Repeat this with the inner tabs to grip the exposed conductor Very carefully solder the exposed conductor in place taking care not to allow solder to flow onto the locking tab Finally insert the pin into the shell with the small locking tab orientated to the face of the shell with the small cut outs Push Minicounter v3 0 PCB1 1 Version 1 8 Page 8 of 16 Cumbria De
17. o Rx Hang Delay For use in CW break in applications where the Tx Rx transitions are very fast a small delay is built in to hold the Tx configuration briefly during Tx to Rx transitions This in turn holds the format of frequency display in the Tx state during short transitions to Rx avoiding display disturbances The delay is called Hang Time and can be programmed in steps of 100mSec from 100 to 1500mSec To change the Hang Delay from the Hang Delay top menu press SEL to enter the menu and display the current setting The delay can be increased or decreased using the UP DN buttons To save and return to the top of the menu hold the SEL button down for 2 seconds Use the UP DN buttons to move back to the Group functions or forward to the Defaults menu 6 4 2 Restore Defaults To move over the Restore Default menu and restart the Minicounter press the DN button Should you wish to return the settings to their default states once in the Restore Defaults menu press SEL briefly to display the confirmation message D AT THIS POINT HOLDING SEL DOWN FOR 2 SECONDS WILL OVERWRITE THE CURRENT SETTINGS WITH THE DEFAULT VALUES To exit the confirmation screen without overwriting the current settings use UP to return to the Hang Delay menu or DN to exit and restart the Minicounter Page 11 of 16 Cumbria Designs 7 Use 7 1 Installation The Minicounter is designed to be a multi purpose instrument It can b
18. off cuts of Vero board etc make ideal templates that produce consistent results Some parts such as the variable resistors have preformed leads designed for machine assembly These will require straightening to align with the board layout Again a pair of pointed nose pliers should be used to carefully flatten the factory performing to produce straight leads 2 6 Soldering Before applying solder check carefully that the component you have placed is in the right position This is a through plated double sided board Whilst some of the pads are very small the area presented by the through plating is more than adequate to allow good solder flow to form mechanically strong good electrical joints These can be difficult to undo please double check The majority of problems are likely to be caused by soldering faults These can sometimes be difficult to find Here are some basic golden rules that will help you to avoid poor solder joints e Clean Iron Make sure your soldering iron tip is in good condition and tinned A small moistened pad for cleaning tips regularly used to wipe off excess solder and flux will ensure that your iron performs well Remember to tin the iron immediately after each wipe e Clean Leads and Pads All of the component leads and PCB pads in this kit are pre tinned and should not need cleaning before soldering Please ensure that parts are handled so as to avoid contamination with grease or finger
19. prints Minicounter v3 0 PCB1 1 Version 1 8 e Soldering This is the bit that can trip up even experienced constructors For the solder to fuse with the surfaces to be joined it is necessary for them to be hot but not so hot as to damage the parts It s a simple as 1 2 3 1 Place the tip of the iron against the joint hold it there briefly to bring the metal surfaces up to temperature 2 Apply the solder allowing it to flow smoothly onto the surfaces 3 Remove the iron and inspect the new joint The finished joint should have a smooth shiny coating of solder If the joint is dull grey or has formed a spherical blob apply the iron to the joint remove the old solder with a solder sucker and re solder 3 Circuit Description 3 1 General The Minicounter is designed as an easily configurable frequency display for test equipment or transceiver applications This compact module offers many advantages over conventional analogue frequency mechanisms improving accuracy and simplifying the mechanical design of the host transceiver In addition to frequency other basic operational information such as RIT and Tx Rx state can also be displayed There are two types of inputs to the Minicounter RF for frequency measurement and User Controls to instruct the Minicounter to perform specific operations The heart of the Minicounter is a PIC microcontroller This is a pre programmed device which performs all of th
20. rast pot VR1 fully clockwise This sets the appearance of the display Re adjust this later to set contrast 5 2 1 Power With no controls set connect a 12 volt supply to the Minicounter Double check the polarity take a Minicounter v3 0 PCB1 1 Version 1 8 deep breath and switch on After a brief pause the start up message will appear displaying model number software version and the Cumbria Designs copyright message 5 2 2 lnitialisation and Message Checks After a couple of seconds the unit will become active and the start up message will be replaced with the Radio Mode display format With no input and all of the offset control pins high open circuit offset A zero kHz is selected and the display will show Rx 0 00 kHz Grounding each of the five Group control pins will cause the associated IF offsets to be displayed Offset B 455 00 kHz Offset C 9 000 00MHz Offset D 10 700 00 MHz Offset E 21 400 00 MHz Offset F 70 000 00 MHz These initial default offset values are provided for demonstration purposes only The configuration procedure for the Minicounter is described later Grounding the Tx Rx pin PL2 pin 8 will change the Rx indicator to Tx Grounding the Delta RIT control PL2 pin 7 will display the RIT message on line 2 together with 0 00 kHz No Display Try adjusting the contrast pot VR1 If there is still no display check for a 20MHz clock on a Receiver See Trouble shooting section 5
21. signs home until the locking tab snaps into the cut out Should you need to remove a pin gently press the locking tab in with a small screwdriver or the end of some pointed nose pliers The pin will be released and can be pulled out of the shell Assembly complete well done Now carefully check your work for dry joints and bridges before moving on to testing 5 TESTING Before connecting the Minicounter to your power supply for the first time carry out these simple checks just to be safe 5 1 Basic Electrical Tests 5 1 1 12 Volt Input With a multimeter set to resistance place the Red meter lead onto 12v and the Black to Ground and check for a high resistance Note that due to C11 charging the reading will show change providing there is not a short circuit then all is well Carry out the same test on the other side of D9 at the connection with the Regulator IC5 input 5 1 2 5 Volt Rail Carry out the resistance test on the regulator IC5 output to check the integrity of the 5 volt rail Due to the circuitry of the counter a much lower resistance will be measured typically around a few hundred Ohms 5 1 3 Inputs and Controls With the multimeter still set to resistance put the Black lead on ground and use the Red lead to check for shorts on the RF input and the control inputs This concludes the basic electrical checks you are now ready to power up for the first time 5 2 Powering Up Set the LCD Cont
22. the cursor has been placed on a decade to be changed briefly pressing the Select button enables digit change indicated by a blinking cursor The UP DN button will now increment or decrement the decade Once the decade has been set press Select briefly to change back to a steady cursor and use the UP DN buttons to move to the next decade to be changed In this way the new offset value is set up on the display To save the new offset value press and hold the Select button for 2 seconds Multiplier Factors 6 3 4 Multiplier Factors This feature multiplies the measured frequency by an integer value Typical applications would be to correct the displayed frequency when the Minicounter is used with a fixed division prescaler or for representing the output frequency of a VHF oscillator multiplier chain The associated offset is applied after multiplication For example in a VHF transceiver Rx Oscillator 51 9MHz Multiplier x3 Count Value 155 7MHz IF Offset 10 700 00MHz Diff Selected PL2 Displayed Frequency 145MHz The UP DN buttons allow the value to be stepped to any integer value between 1 and 255 To save Minicounter v3 0 PCB1 1 Version 1 8 the new setting and exit to the top of the Group Menu press and hold the Select button 6 4 Common Functions There are two common menu functions illustrated in the Common Programming Functions diagram To move across the common function menus use the UP DN buttons 6 4 1 Tx t
23. utton to enter a group Within each group menu the following functions are available 6 3 1 Mode There are two operating modes Counter and Radio In frequency counter mode the display behaves like a standard frequency counter with a delta frequency feature for measuring frequency change In Radio Mode a Tx Rx indicator is displayed and the Delta prefix is replaced with RIT Note that the polarity of the difference automatically matches the reverse tuning effect when using a high side IF frequency and IF difference measurement The operating mode is toggled between Radio and Counter by pressing the Up or Down UP DN buttons To save the setting and move on to the next function press and hold the Select button Page 10 of 16 Cumbria Designs 6 3 2 Format The display format can be configured as GHz MHz or MHz kHz In GHz mode the input frequency is presented as 1000 times actual For example 40MHz would be displayed as 4GHz This in conjunction with the multiplier function allows the Minicounter to be configured for use with prescalers for use at UHF and Microwave frequencies 6 3 3 IF Offsets Any IF offset in the range 0 00kHz to 999 999 99MHz can be programmed with a resolution of 10Hz A steady cursor indicates that digit selection is active a blinking cursor the digit change is active This will become clear when setting a new offset value The UP DN buttons step the cursor sideways through the decades Once
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