Elecraft KRC2 Band Decoder and Controller Table of Contents qq001 Introduction qq002 Specifications qq003 Assembly qq004 Case Assembly qq005 KRC2 Test Procedure qq006 KRC2 Final Assembly qq007 K2 to KRC2 Control Cable Assembly qq008 Using the KRC2 qq009 Default Key Behavior qq010 KRC2 Jumper Configuration qq011 KRC2 Power Connections qq012 Connecting the KRC2’s Drivers qq013 Troubleshooting ::: qq001 Introduction The KRC2 is a universal, programmable station control unit that can switch any combination of antennas, filters, amplifiers, or other equipment. It supports analog, digital, and RS232 control inputs, so it's compatible with transceivers from Elecraft as well as other manufacturers. Decoded outputs are provided for all HF bands (including WARC bands and 60m), three transverter bands, and general accessories. High-side (source) and low-side (sink) relay drivers are included. All signal lines are RF bypassed to minimize RFI and noise pickup. Individual driver outputs can be wire-ORed. However, the KRC2 also provides a PC-based command interface, allowing the user to configure the unit. New firmware can even be downloaded via the Internet. Additional features are available when the KRC2 is used with our K2 and K2/100 transceivers. The ACC menu entry can be used to directly control the KRC2's accessory outputs. Four buttons on the top of the KRC2 can be used as "hot keys" for instant access to CW message buffers, fast switching of the RXANT jack, or other functions. ::: qq002 Specifications Outputs 32 (16 sink, 16 source) Output Driver Ratings 500 mA max, 50 V max (sink and source) Analog Inputs 0-5 V (1 input), 0-10 V (2 inputs) Band Decode Formats Elecraft, Icom, Yaesu, Kenwood1 Internal Current Drain Approx. 20 mA (excludes output driver current) Size 5.5" (L) x 3.5" (D) x 1.5" (H) (14 x 11.4 x 4 cm) Caution: Some parts in this kit can be damaged by static discharge. Before handling any transistors or ICs, put on an anti-static wrist strap, or touch a grounded, unpainted metal surface. Firmware Requirements To use the KRC2 with a K2 or K2/100 transceiver, you will need K2 main microcontroller firmware revision 2.01 or later and either the KIO2 or KPA100 options. Note: The main K2 microcontroller is U6 on the K2 Control board. To check your firmware revision, hold any K2 pushbutton when powering up the K2. When you release the pushbutton, the revision will be shown on the LCD (left side). ::: qq003 Assembly - A fine-point, temperature-controlled soldering iron (700-800 degrees F maximum) is required to assemble the printed circuit board. A higher-wattage iron or one with a wide tip may damage components, pads, or traces. We also recommend the use of a Panavise (or equivalent bench vise) and an illuminated magnifying glass to facilitate PCB and connector assembly. Additionally, flush-cut wire cutters are recommended for steps where component leads must be cut close to the circuit board. - To avoid soldering conflicts, install components only in the order described below. Double-check all values before soldering, since removing parts from double-sided printed circuit boards can be difficult. - The leads on small capacitors can be fragile. When handling capacitors in the following steps, do not pull on the leads or bend them excessively. - Locate the KRC2 PCB and identify the top and bottom sides. The side of the board with outlines of ICs U4-U7 and most other components is the top; the side with the "KRC2" label is the bottom. If an assembly step does not specify top or bottom, the component should be installed on the top side. - Install the two 0.1-µF (104) capacitors with 0.1" (2.5 mm) lead spacing on the top side of the board C25,C60 - Solder C25 and C60. Trim the leads of C25 as short as possible, using flush-cutters if available. If the leads are not kept very short, they will interfere with installation of J5 on the bottom side of the board. - On the top side of the board, install the 0.01 µF (103) capacitors with 0.1" (2.5 mm) lead spacing listed below, beginning with C28 in the upper center of the board and proceeding in a line to the end of the board. After installing each capacitor, bend the leads outward to hold it in place. The capacitors line up so that you can solder them in one step after inserting them into the circuit board. You may solder the components in smaller groups if desired. - Note: When multiple items appear on one line in a component list such as the one below, complete all items on one line before moving on to the next, as indicated by the small arrow. (In other words, install C28 first, then C29, C30 and C31, then go to the second line.) C28,C29,C30,C31,C32,C33,C34,C35,C24,C23,C22,C21,C44,C45,C46,C47,C48,C49,C50,C51 - Solder the fixed capacitors. After soldering the leads of the capacitors, be sure to flush trim the leads so that terminals J6, J8, J10 and J12 will seat properly on the bottom side of the PCB when they are installed later in these instructions. - On the top side of the board, install the small 0.01 µF (103) capacitors with 0.1" (2.5 mm) lead spacing listed below, beginning with C36 in the upper right of the board and proceeding to the end of the board. After installing each capacitor, bend the leads outward to hold it in place. C36,C37,C38,C39,C40,C41,C42,C43,C52, C53, C54, C55,C56, C57, C58, C59 - Solder the small fixed capacitors. After soldering the leads of the capacitors, be sure to flush trim the leads so that terminals J7, J9, J11 and J13 will seat properly on the bottom side of the PCB when they are installed later in these instructions. - Install the three remaining small 0.01 µF (103) capacitors with 0.1” (2.5mm) lead spacing listed below on the top side of the PCB: C7, C16, C17 - Solder the small fixed capacitors. - Note: For all remaining assembly steps, you should solder then trim component leads after installing each group of components unless otherwise instructed. Leads can be trimmed before or after soldering, but trim them as short as possible. - Install the two 33pF ceramic disk capacitors on the top side of the PCB. Note that the lead spacing for C1 and C2 may be too wide for the holes in the PC board. If so, use a pair of needlenose pliers to crush the ceramic ‘flash’ which covers the leads up close to the body of the capacitor and then re-bend the leads so they fit the available holes and scrape away the crushed flash debris. C1, C2 - Install the following 0.1µF (104) capacitors with 0.2” (5.0mm) lead spacing on the top side of the PCB: C13, C14, C20, C26, C27 - Install the following 0.001µF (102) capacitors with 0.2” (5.0mm) lead spacing on the top side of the PCB: C3, C4, C5, C6 - Install the following miniature inductors on the bottom side of the circuit board. Then solder and trim the leads. These miniature RF chokes are very fragile. Do not pull on the leads, and keep soldering time to a minimum. L1 100µH Inductor, (brn-blk-brn) L2 100µH Inductor, (brn-blk-brn) L3 100µH Inductor, (brn-blk-brn) - Install L4, a 15µH miniature inductor (brn-grn-blk) on the top side of the PCB. - Install C18, a 120pF (121) capacitor, with 0.1” (2.5mm) lead-spacing on the top side of the PCB. - Install C19, a 56pF (560) capacitor, with 0.1” (2.5mm) lead-spacing on the top side of the PCB. - Install the following 0.01µF (103) capacitors with 0.2” (5.0mm) lead spacing on the top side of the PCB: C8, C9, C10, C11 - Install the following resistors on the top side of the circuit board. R1 47k, (yel-vio-org) R3 1k, (brn-blk-red) R4 470 ohms, (yel-vio-brn) R6 10K (brn-blk-org) R7 10K, (brn-blk-org) R8 10K, (brn-blk-org) R9 100 ohms, (brn-blk-brn) R10 10K, (brn-blk-org) R12 4.7K, (yel-vio-red) R13 47 ohms, (yel-vio-blk) - Install two 1N4007 diodes D4 and D5 on the top side of the board. Make sure the cathode (banded end) of the diodes follow the same orientation as that silk-screened on the PCB then solder and trim the leads. D5 must be flush-trimmed on the bottom side in order not to interfere with J5. Be sure to save these cut leads for later use as ground jumpers. D4, D5 - Install the following 1N4148 diodes on the top side of the board. Make sure the cathode (banded end) of each diode follows the same orientation as that silk-screened on the PCB, then solder and trim the leads. D6, D7, D8, D9, D10 - Before handling ICs and transistors, touch an unpainted, grounded metal surface. - Install voltage regulator U3 (78L05C) on the top side of the board as indicated by its outline. The voltage regulator has a 3-pin TO-92 package, like a transistor. The installed height of the regulator must be no more than 3/8" (9 mm). Use a minimum of soldering time (1-2 seconds per lead). - Locate the four pushbutton switches. One of these will now be installed on the top side of the board. Insert the switch into its mounting holes at S1, spreading the legs slightly so they will properly engage the holes. Press the switch down until it is fully seated on the bends in its leads. When the switch is fully seated, there will be a slight gap between the switch body and PCB. This is normal. Solder the switch onto the circuit board from the bottom side. - Note: The pin 1 end of ICs can be identified by a notch or dimple as shown in Figure 1. This end must be oriented toward the notched end of the component outline. - Install the following ICs on the top side of the board. Orient the notched or dimpled end toward the notched end of their PCB outline (pin 1 end, to the left). Double-check the orientation before soldering. Be sure to flush-trim the leads of each IC after soldering so as not to interfere with cables on the bottom side of the board. U4 UCN5891A U5 UCN5891A U6 TPIC6595 U7 TPIC6595 - Install the rectangular Green LED at DS1 on the top side of the board. Spacing the LED about 1/8” (3 mm) above the board will nicely align the top of the LED with the case top. The dot marked on the PCB next to DS1 indicates the placement for the longest lead of the LED. Visual Inspection: Using a magnifying glass, examine the entire board for unsoldered pins, solder bridges, broken leads, or backward diodes or ICs. Reheat any suspect joints This simple check could save you hours of troubleshooting later. - The following components will be installed on the bottom side of the circuit board. Turn over the circuit board to install the components. - Install 1N4007 diodes at D2 and D3 on the bottom side of the PCB. Make sure the cathode (banded end) of the diode matches the silk-screened outline on the PCB. D2, D3 - Install a 1N4148 diode at D1 on the bottom side of the PCB. Make sure the cathode (banded end) of the diode matches the silk-screened outline on the PCB. - Install 10k, 1/4 watt resistors (brn-blk-org) at R2 and R11 on the bottom side of the PCB. R2, R11 - Install the 40-pin IC socket at U1 on the bottom side of the board. The notched end should be oriented toward the notched end of the PCB outline (pin 1 end, to the left). Solder just two corner pins. If the socket is not sitting completely flat against the PC board, reheat these two pins one at a time, pushing the socket down until it snaps into position. Then solder the remaining pins of the socket. - Install U2, (MAX1406CPE or LT1039CN16) on the bottom side of the PCB. Orient the notched or dimpled end toward the notched end of their PCB outline (pin 1 end, to the left). Double-check the orientation before soldering. There is no need to trim the leads of U2. - Install resistor network RP1, 390 ohms (391), 8 pins, on the bottom side of the PCB. This resistor network is symmetrical and can be installed in either orientation, but for consistency you should orient it with the pin 1 end (black dot) toward pin 1 of the PCB outline (round pad, also labeled "1"). - Install resistor network RP2, 47k (473), 8 pins, on the bottom side of the PCB. This resistor network should be oriented with the pin 1 end (black dot) toward pin 1 of the PCB outline (round pad, also labeled "1"). - Install low-profile crystal X2 on the bottom side of the PCB. This is a short 16.289 MHz device. Make sure it is flat against the board before soldering. Use a minimum of solder so that it does not wick through and cause a short on the opposite side of the PCB.. - Locate the ground pad near X2. Insert a discarded component lead through this pad, then fold it over the top of X2. Solder this lead at the ground pad, then solder it to the crystal can. Avoid overheating the crystal. - Install electrolytic capacitor C15 (10 µF) on the bottom side of the PCB. The (+) lead of C15 must be installed in the hole marked "+". The (+) lead is usually longer than the (-) lead. The (-) lead is identified by a stripe on the body of the capacitor. - Install transistor Q1 (J310) as indicated by its outline on the bottom side of the PCB. The installed height of the transistors must be no more than 3/8" (9 mm). The top of Q1 must be no higher than the top of C15. Use a minimum of soldering time (1-2 seconds per lead). - Install the subminiature DPDT slide switch S5 on the bottom side of the PCB. Make sure the switch is firmly seated against the board when soldering. After installing the switch, move its handle to the position closest to J2. - Install a 16-pin dual-row header at W1-W8 on the bottom side of the PCB. The short pins are inserted into the PCB. The header must be firmly seated against the board when soldering. - Install a 16-pin dual-row header at W12-W19 on the bottom side of the PCB. The short pins are inserted into the PCB. The header must be firmly seated against the board when soldering. - Locate the remaining 16-pin dual-row header. Cut the header into three pieces so that you have one 8-pin dual row header, a six-pin header and a 2-pin header. This is best done using diagonal cutters. Cut the header on the side, then bend the portion to be cut off away from the rest of the header. The two pieces should snap apart somewhat cleanly. Discard the 2-pin header. - Install the 8-pin dual-row header at W20-W23 on the bottom side of the PCB. The short pins are inserted into the PCB. The header must be firmly seated against the board when soldering. - Install the 6-pin dual-row header at W9-W11 on the bottom side of the PCB. The short pins are inserted into the PCB. The header must be firmly seated against the board when soldering. - Locate the shorting headers. Install 14 shorting headers on the dual-row headers W9-W19 and W21-W23 by plugging them onto the header pins. Do not install a jumper at W20 at this time. - Install electrolytic capacitor C12 (220 µF) on the bottom side of the PCB. The (+) lead of C10 must be installed in the hole marked "+". The (+) lead is usually longer than the (-) lead. The (-) lead is identified by a stripe on the body of the capacitor. - Install the DC barrel jack (J3) on the bottom side of the PCB. - Install J2, a male PC-mount DB9 connector on the bottom side of the PCB. This position is next to the side of the PCB. The connector will “snap” into the board as its mounting tabs “grab” the board. Be sure you have installed the MALE connector (with pins) before soldering the connector pins onto the board. - Install J1, a female PC-mount DB9 connector on the bottom side of the PCB. This position is approximately in the center at the end of the PCB. The connector will “snap” into the board as its mounting tabs “grab” the board. Be sure you have installed the FEMALE connector (with sockets) before soldering the connector pins onto the board. - Refer to Figure 3, and install screw terminal connectors at J4 and J5 on the bottom side of the PCB. The opening between the connectors forms a “trough” for control cables to external devices. The terminals must be mounted so their side openings face this trough. Make sure the feet of the terminals are firmly seated against the board, leaving a very slight gap between the body of the terminal and the PCB. J4, J5 - Connect two terminals together end-to end by sliding the tab of one connector into the slot of another. This forms a single 8-pin connector. Form three other eight-pin terminals following the same procedure, then install the screw terminals at the locations indicated in Figure 3 on the bottom side of the PCB. Make sure the terminals are mounted so their side openings face the trough. Also make sure the feet of the terminals are firmly seated against the board, leaving a very slight gap between the body of the terminal and the PCB. J6/J8, J7/J9, J10/J12, J11/J13 - Install crystal X1, a tall, 4.000 MHz device, on the bottom side of the PCB. Make sure it is flat against the board before soldering. Use a minimum of solder to avoid the solder wicking through to the other side, causing a short. - Locate the ground pad near X1. Insert a discarded component lead through this pad, then fold it over the top of X1. Solder this lead at the ground pad, then solder it to the crystal can. Avoid overheating the crystal. - Adjacent to J1, on the bottom side of the board, you will find two pads connected by a white line. Using one of the 1N4007 diode leads previously saved, install a 1/4" (6 mm) tall U-shaped ground jumper between these two pads, on the bottom side of the board. This jumper can be used as a ground point for test instruments. - Locate the remaining three pushbutton switches. These will now be installed on the top side of the board. Insert the switches into their mounting holes at S2, S3 and S4, spreading the legs slightly so they will properly engage the holes. Press the switch down until it is fully seated on the bends in its leads. There will be a slight gap between the switch body and PCB. Solder the switches onto the circuit board from the top side. S2, S3, S4 - Locate the four pushbutton key caps. Making sure the key caps are oriented from end-to-end across the board, press the key caps onto the pushbutton switch stems until they lock into place. - Before handling U1, touch an unpainted, grounded metal surface. - When you install the IC in the following step, always straighten the leads of the IC first as shown in Figure 4. The two rows of pins must be straight and parallel to each other to establish the proper pin spacing for insertion into the PC board or socket. To straighten the pins, rest one entire row of pins against a hard, flat surface. Press down gently on the other row of pins and rock the IC forward to bend the pins into position as shown below. - Carefully straighten the pins on the microcontroller, U1 (PIC16F877A). The two rows of pins must be parallel to each other, with no pins bent. - Press the microcontroller into its socket, orienting the notched or dimpled end of the IC with the notched end of its component outline. The labeling on the microcontroller should read from left to right. - This completes assembly of the KRC2 circuit board. There are two remaining parts locations, R5 and SP1, which are used with the accessibility speaker option. All other component locations should now be filled. - Visual Inspection: Using a magnifying glass, examine the entire board for unsoldered pins, solder bridges, broken leads, or backward diodes or ICs. Reheat any suspect joints This simple check could save you hours of troubleshooting later. ::: qq004 Case Assembly - Locate the case top cover. This piece has three rectangular holes punched into the face. - Locate a 4-40 x 3/16” flat head screw. Push it through the hole on the top of the case, holding it in place with a finger as you turn the case over. Locate two #4 internal-tooth lock washers. Slide both lock washers onto the screw shaft inside the case. Locate the 1/4 x 3/16” round threaded standoff. While holding the screw with a Philips screwdriver, screw the standoff onto the screw. Tighten the assembly. - Insert the circuit board assembly into the case with the pushbutton switches and LED passing through the rectangular holes in the case. Secure the circuit board to the case with a single 4-40 x 3/16” pan head Philips screw and #4 lock washer. - Locate the four #4 male-female hex standoffs. These are used to secure the DB9 connectors to the case. Screw each standoff through one of the mounting holes next to the DB9 connectors in the end of the case into the threaded DB9 assemblies. - Locate the two “2-D” fasteners. These are used to secure the case top and bottom. Note that on the side of the fastener with two screw holes, there is more space to one side of the holes than the other. The side with the most space will face away from the circuit board. - Using two 4-40 x 3/16” flat-head screws, attach one “2-D” fastener to the case top just above the J1 DB9 connector. Make sure the wide side of the fastener side faces away from the circuit board. - Attach the second “2-D” fastener, using two 4-40 x 3/16” flat head screws, to the end of the top case away from the DB9 connectors. Follow the same procedure as in the previous step. Again, the wide side of the fastener should face away from the circuit board. ::: qq005 KRC2 Test Procedure The KRC2 should be powered from its DC barrel jack using a +12 volt supply for its initial power-up. No other connections should be made to the unit. - Connect the power source to the unit. After a short delay while the KRC2 performs diagnostics, the front-panel LED should turn on to its dim level. If this does not happen, turn power off to the unit and refer to the troubleshooting section. Driver Relay Test: You will need a DC voltmeter for this procedure. Connect the black lead (common) to the ground jumper located near J1 on the KRC2. The red lead should be used to measure the voltage on each terminal of J6, J7, J8 and J9. Be sure to check the voltage at the side connector of each terminal. The initial readings should be 0 volts on each terminal. The Tap/Hold Rule: Each of the pushbutton switches on the front panel has two functions, one activated by a TAP (short press) and the other activated by a HOLD (long press, about 1/2 second). To highlight this in the text, we use two different typographical styles to identify switches: TAP and HOLD. - Holding F1 should cause the KRC2 to change the driven band terminal. Only the 60m source terminal should indicate 12 volts. The LED should be alternating between dim and bright. - Holding F1 again should cause the 10m source terminal to indicate 12 volts, and all others to remain off. - Continue this procedure, actuating the F1 command until all HF source terminals have been checked. - The F4 function is used to switch the AC1-AC3 outputs. First, hold F4, then tap F1. The AC1 source terminal should now indicate +12V and AC2 and AC3 source terminals indicate 0V. - Hold F4, then tap F2. The AC2 source terminal should now indicate 12V with AC1 and AC3 at 0 V. - Hold F4, then tap F3. The AC3 source terminal should now indicate 12V with AC1 and AC2 at 0 V. - Hold F4, then tap F4. All three AC source terminals should now indicate 0 volts. This completes checkout of the KRC2. Continue to the Final Assembly section. ::: qq006 KRC2 Final Assembly - Place the case bottom onto the case top, aligning the screw holes at each end of the case. The case may be a tight fit, but the two halves should slide into place without difficulty. - Using two 4 x 3/16” pan-head screws, secure the case bottom to the top. - Locate the four rubber stick-on feet. Remove the adhesive backing from each foot, and place the foot securely into place in a corner of the case bottom about 1/8” in from each side. ::: qq007 K2 to KRC2 Control Cable Assembly - Locate the 8-conductor cable. Note: A shorter cable may be used as long as it accommodates the physical orientation of the K2 and the KRC2. A longer cable can also be used, but it will have to be tested to ensure that it is not subject to RF interference. A more heavily-shielded control cable may be required. A standard shielded male-female DB9 straight-through cable has been tested and should work well with the KRC2/K2 combination. - Remove 1/2" (12 mm) of the jacket from the cable at each end. Be very careful not to nick the individual wires. - Peel back and cut away the foil shield. - Strip 3/16" (5 mm) of insulation from each insulated wire. - Twist the strands of each wire together. Tin lightly with solder. - Locate the male and female DB9 connectors. - Insert the female DB9 connector (KRC2 end) into the vise, with the solder cups facing up. - Solder the wires to the indicated connector pins at the KRC2 end of the cable as shown in Figure 6. It may be helpful to melt some solder into each solder cup on the connector first. Pin 1 Bare wire Pin 2 Orange Pin 3 Blue Pin 4 Red with Black stripe Pin 5 White with Black stripe Pin 6 Green Pin 7 White Pin 8 Red Pin 9 Black - Remove the female connector from the vise (K2 or K2/100 end), and insert the male connector (KRC2 end). Solder the wires to this connector using the same colors and pins as in the previous step. - Locate the connector housing (backshell) and associated hardware. - Note: A single hinged backshell may be provided rather than a two-piece backshell. - Attach a backshell to the male connector at the K2 or K2/100 end of the cable. Figure 7 shows how the backshell appears when assembled. Use the provided cable clamp to hold the cable in position, then secure the clamp with two screws. The jackscrews must be retained by the shells. Secure the backshell halves with the provided hardware (or, if the shell is hinged, snap the backshell closed). Do not over-tighten the two screws which secure the cable clamp! - Attach the remaining backshell to the female connector at the KRC2 end using the procedure described above. ::: qq008 Using the KRC2 KRC2 operation with an Elecraft K2 or K2/100 Transceiver The KRC2 should be connected to the K2 using the Male/Female DB9 cable assembly described in the previous section. The KRC2 derives its operating power from the K2 in this configuration. In the KRC2's factory configuration, the per-band outputs (both sink and source) will be turned on or off based on the K2's selected band. This default behavior will suffice for many amateur station applications. However, the correspondence between selected band and output driver states is fully programmable. Band mapping and other configuration changes are accomplished using the KRC2 configuration utility. (NOTE: At the time of this manual printing, the configuration utility is still in development. Refer to the KRC2 page on our web site for details.) For example, if the station includes a 20/15/10 meter tri-band beam, the 20 m sink output could be programmed to be turned on whenever the K2 is set for 20, 15, or 10 meters. Another alternative for mapping multiple bands to a single antenna or other device is to "wire-OR" the outputs. This is explained in more detail later in the manual. Switch S5, accessible through a small hole in the side of the KRC2 sets the operational mode of the unit. For normal operation, the OP (operate) position of S5 is used. This allows the KRC2 to communicate with the K2 via its AuxBus and RS-232 interfaces. Set S5 to the DL (Download) position for downloading firmware upgrades or device configurations to the unit. Firmware upgrades can be downloaded using the KRC2 download utility. (NOTE: At the time of this manual printing, the configuration utility is still in development.) ::: qq009 Default Key Behavior There are four buttons on the top of the KRC2, labeled F1, F2, F3 and F4. In the KRC2's factory configuration, the F1-F4 buttons have the following TAP and HOLD functions: F1 Sends the contents of K2 CW message buffer #1. F2 Sends the contents of K2 CW message buffer #2. F3 Sends the contents of K2 CW message buffer #3. F4 Sends the contents of K2 CW message buffer #4. Note: Playing messages using F1 - F4 is more convenient than using the K2’s FAST PLAY (1-touch) technique. F1 Selects the next lower HF band’s relay driver output in the KRC2. F2 Selects the next higher HF band’s relay driver output in the KRC2. Note: This is useful in cases where you switch to a K2 band for which no antenna relay has been connected in the KRC2. See next page for details. F3 Switches the K2 receiver to (or from) the RCV ANT jack. This is a toggle operation. F4 Holding this button, then tapping any button, will then cause one of the ACC drivers to be turned on or off as shown in the list below. The KRC2 will illuminate the green LED at full brightness while it is awaiting the key tap. F1 Turn on AC1 driver. F2 Turn on AC2 driver. F3 Turn on AC3 driver. F4 Turn OFF all ACC drivers. Note that holding F4 instead of tapping a key will cancel the function. The F1 and F2 functions change the output terminal for the relay drivers up or down in single band increments. When the highest band is selected, the next hold of F2 will cause the drivers to go to the 160m setting. Conversely, when the lowest band is selected, the next usage of the F1 function causes the drivers to go to the highest band. The band map follows the values indicated in Table 5, which places the 60m band above the 10m band. Thus the sequence will be: …12m<->10m<->60m<->160m<->80m<->40m… While the selected driver is different from the current band indicated by the transceiver, the green LED will flash between dim and bright states. The XVT drivers do not participate in the sequence, and when the transceiver selects a transverter these buttons will not change the driver selection. The behavior of the KRC2’s keys can be modified using the KRC2 configuration utility. (NOTE: At the time of this manual printing, the configuration utility is still in development.) ::: qq010 KRC2 Jumper Configuration There are 21 jumpers in the KRC2 allowing for a wide range of device options. The W1-8 block, located near the front of the case, controls device configuration for different radio setups and driver output logic. Table 1 and Table 2 show the different settings. Table 1 Jumper: W1 Jumper Out (default): Use digital band decoding Jumper In: Use analog band decoding Jumper: W2 Jumper Out (default): Band decode option bit 1 - see Table 2 Jumper In: Band decode option bit 1 - see Table 2 Jumper: W3 Jumper Out (default): Band decode option bit 2 - see Table 2 Jumper In: Band decode option bit 2 - see Table 2 Jumper: W4 Jumper Out (default): ACn drivers use 1 of 3 decoding Jumper In: ACn drivers use binary coding Jumper: W5 Jumper Out (default): Xvtr drivers use 1 of 3 decoding Jumper In: Xvtr drivers use binary decoding Jumper: W6 Jumper Out (default): No auto-report mode Jumper In: Place XCVR in auto-report mode Jumper: W7 Jumper Out (default): Attempt communications failure recovery Jumper In: Recovery not attempted Jumper: W8 Jumper Out (default): Normal key operation Jumper In: Disables keys F1-F4 Table 2 W1: Out W2: Out W3: Out Band Decode Source: AuxBus Mode – K2 operation W1: Out W2: Out W3: In Band Decode Source: Serial Port Mode – K2 or Kenwood operation W1: Out W2: In W3: Out Band Decode Source: Digital Input through J4 W1: Out W2: In W3: In Band Decode Source: Not used W1: In W2: Out W3: Out Band Decode Source: Analog input using ALC input (DB9 pin 4) W1: In W2: Out W3: In Band Decode Source: Analog input using VRDET input (DB9 pin 7) W1: In W2: In W3: Out Band Decode Source: Analog input using 8R input (DB9 Pin 9) W1: In W2: In W3: In Band Decode Source: Not Used Using the information from these tables, the following settings are suggested for each radio: • Elecraft K2: W1 - W8 removed PC log program in use • Elecraft K2 W6 installed, others removed Stand-alone (no PC) operation • Kenwood W3 installed, others removed PC log program in use • Kenwood W3,W6 installed, others removed Stand-alone (no PC) operation • Computer Printer Port W2 installed, others removed • Icom: W1 installed, others removed. Input uses J1/2 pin 4 • Icom: W1,W2 installed, others removed. Input uses J1/2 J2 pin 9 • Yaesu FT817 W1,W3 installed, others removed. Input uses J1/J3 pin 7 W8 may be installed to disable the operation of the KRC2 keys if control features are not needed. The choice of the Icom setting is determined by the input pin for the J1 or J2 connectors. If you connect the input to pin 4, use the first setting. Otherwise use the second setting. Other jumper settings besides those recommended may be used as desired. Jumpers W9-W23 are used to connect or disconnect the DB-9 connectors from the KRC2. Normally these jumpers should be left installed. When used with a K2, the minimum jumpers that must be installed in this block are W16, 18, 19, 21 and 23. DO NOT install jumper W20 when using the KRC2 with the K2. Doing so will cause problems in the K2, including disabling SSB output. If the PC connector (J1) is used to pass K2 information through to a peripheral such as a KAT100, it is important that all jumpers in the W9-W23 block with the exception of W20, be installed. W9 J1 Pin 2 - PC Enables Serial Data to PC from KRC2 or XCVR. W10 J1 Pin 3 - PC Enables Serial Data from PC to KRC2 or through to XCVR. W11 J1 Pin 4 - PC Enables J1 Pin 4 W12 J1 Pin 9 - PC Enables J1 Pin 9 W13 J1 Pin 8 - PC Enables J1 Pin 8 W14 J1 Pin 7 - PC Enables J1 Pin 7 W15 J1 Pin 6 - PC Enables J1 Pin 6 W16 J2 Pin 6 - XCVR Enables K2 AuxBus signal into KRC2. Must be installed for KRC2 AuxBus band decode mode operation. W17 J2 Pin 7 - XCVR Enables K2 VRDET signal into KRC2. W18 J2 Pin 8 - XCVR Enables K2 12CTRL signal into KRC2. This signal normally powers the KRC2. W19 J2 Pin 9 - XCVR Enables K2 8R signal into KRC2. Used to determine transmit/receive activity in K2 operating mode. W20 J2 Pin 4 - XCVR Enables K2 ALC signal into KRC2. DO NOT insert this jumper when using the KRC2 with the K2! W21 J2 Pin 3 - XCVR Enables K2 TxD signal from KRC2 serial port driver. W22 J2 Pin 3 - XCVR Enables K2 TxD signal from J1 pin 3 (PC serial port driver). W23 J2 Pin 2 - XCVR Enables K2 RxD serial port signal into KRC2. When the KRC2 is set to receive band data in an analog mode, the jumpers associated with the selected input should be removed from the J2 connection. The analog input should then be fed into the KRC2 using the PC connector. Use J1 pin 1 for the ground return connection. These settings and connections are listed in Table 4. Table 4 Analog Input: 8R/AN1 Remove Jumper(s): W19 J1 Pin for input: 9 Comments: 0 - 10 volt input range Analog Input: VRDET / AN2 Remove Jumper(s): W17 J1 Pin for input: 7 Comments: 0 - 5 volt input range Analog Input: ALC / AN3 Remove Jumper(s): W20 J1 Pin for input: 4 Comments: 0 - 10 volt input range Using the information from Table 3 and Table 4, the following settings are suggested for each radio: • Elecraft K2, Use with PC: W9, W10, W16-W19,W21-W23 installed, W11 – W15,W20 removed. • Elecraft K2, Standalone or used with Elecraft peripheral: W9-W19, W21-W23 installed, W20 removed. • Kenwood W9, W10, W21-W23 installed, W11-20 removed. • Icom: Icom 0-8V analog band input to J1 or J2 pin 4: W11, W20 installed, W9, W10, W12-19, W21-W23 removed. • Icom: Icom 0-8V analog band input to J1 or J2 pin 9: W12,W19 installed, W9-W11, W13-W18, W20-W23 removed. • Yaesu FT817 Yaesu 0-5V analog band input to J1 or J2 pin 7: W14, W17 installed, W9-W13, W15, W16, W18-W23 removed. For all analog inputs, use J1 or J2 (same connector as the analog input), pin 1 for ground connection. This information is described in more detail in the sections below. Important! Do NOT use the jumper connections to bridge external RS-232 serial port signals. This may cause serious damage to your radio when moving the KRC2 from one radio to another. The preferred method is to provide the bridging in the cable used with the radio needing it. This specifically applies to Kenwood transceivers. ::: qq011 KRC2 Power Connections The KRC2 may be powered from one of several sources. The microcontroller and logic are powered either from the K2 through the DB-9 connector, or from the +12V DC barrel jack. The voltage applied at the DC barrel jack must not exceed 15 volts. Power for the Source drivers can come either from the DC barrel jack or the J5 terminal connector. Voltage applied to the J5 ‘V’ terminal must not exceed +50 volts. Maximum current drain for either source is 1 amp. ::: qq012 Connecting the KRC2’s Drivers There are 36 driver output terminals. The terminals are accessible by removing two access screws on the bottom case. Sixteen of the drivers will source current, and another sixteen will sink current. The remaining four drivers, labeled A, B, C and D, are TTL-compatible inputs or outputs depending on the operating mode. In normal KRC2 or analog modes, the terminals are outputs. In digital parallel input mode, they become inputs, and receive the BCD-encoded band data. An additional four terminals are provided for connecting the KRC2 to ground returns, and to provide a supply voltage for the source drivers as described in the KRC2 Power Connections section. Figure 8 illustrates the connections. A bar over the terminal label indicates the output is a sink driver. Sink driver terminals are located near the front of the box. Source drivers are located toward the rear of the box. Like-drivers may be wire-ORed (connected together) in order to allow a relay to be selected on more than one band. For example, the control line from a tri-band beam would connect to terminals 20, 15 and 10 for source drivers, or /20, /15 and /10 for sink drivers. IN NO CASE SHOULD THE SOURCE AND SINK TERMINALS BE CONNECTED TOGETHER IN ANY WAY! Connecting other Elecraft Peripherals Additional Elecraft peripherals, such as a KAT-100 or XV-Series transverter, may be connected to the KRC2’s PC port in a “daisy-chain” fashion in order to operate with the K2. Simply plug the DB-9 connector from the peripheral into the KRC2’s PC port, and use the peripheral as if it were directly connected to the K2. Be sure to follow the rules outlined in the jumper discussion and insert all jumpers in the W9-W23 block with the exception of W20 when using this configuration. KRC2 PC Connections A personal computer’s RS-232 serial port may be connected to the KRC2’s PC port using the PC connector. Normally the K2 does not automatically report its settings to the KRC2. If you have an alternate KRC2 configuration that needs for the K2 to report its settings, install jumper W6 to enable the K2’s auto-report mode. Using the KRC2 with non-Elecraft Radios The KRC2 is designed to accept band information from radios other than the K2. As discussed in KRC2 Jumper Configuration, setting jumpers W1-3 for Kenwood mode operations allows the KRC2 to interface with those radios in a manner similar to the K2. Other radios that do not use this command set may not be interfaced using this mode. To use the KRC2 with an ICOM transceiver that has analog (stepped voltage) band output, you should set the W1-3 jumpers for Analog Mode using the desired input (8R/AN1 or ALC/AN3), and connect the transceiver’s analog output to the appropriate input pin on J1 or J2. Be sure to remove W19 or W20 as appropriate. Power the KRC2 using an external 12-volt supply connected to the KRC2’s DC barrel jack. The KRC2 should now set its band outputs according to the voltage presented by the radio. The three analog inputs have slightly different characteristics you should consider when choosing which to use. The 8R/AN1 and ALC/AN3 inputs have voltage divider networks on their inputs that divide the input by 2. Thus their input range is from 0 to 10 volts. The VRDET/AN2 input has no divider network, giving it a voltage range of 0 to 5 volts. Each input voltage is filtered through a band selection table that determines the selected band. There are three tables, one for each input. The factory-configured tables are set up for Icom radios with voltage range of 0 to 8 volts for the wide-range inputs, with the third table set for the Yaesu FT-817 transceiver’s analog output. These tables are user-configurable using a Web-based software tool. Check the Elecraft web site for the availability of this tool. To use the KRC2 with a Yaesu radio or computer parallel port outputs, set jumpers W1-3 as follows: W1 OUT, W2 IN, W3 OUT as described in Table 2. You may then connect the radio or computer outputs to the KRC2’s ABCD terminals, with the return ground connected to one of the terminals labeled ‘G’. Power the KRC2 from an external 12-volt supply connected to the DC barrel jack. The unit should now switch the driver outputs in accordance to the digital inputs it sees. Note that in addition to the standard BCD outputs, the KRC2 recognizes additional band codes according to Table 5. Binary coding Hex Band Binary coding Hex BAND 0001 01 160m 1000 08 12m 0010 02 80m 1001 09 10m 0011 03 40m 1010 0A 60m 0100 04 30m 1011 0B unused 0101 05 20m 1100 0C XVT1 0110 06 17m 1101 0D XVT2 0111 07 15m 1110 0E XVT3 ::: qq013 Troubleshooting If you have any difficulty with your KRC2: Most problems in building the KRC2 are caused by poor or non-existent solder joints. Closely examine the PC board for poor solder joints and incorrect, broken or missing components. Problem: The KRC2’s LED does not turn on. Make sure the KRC2 is powered, either from the K2 or from the DC barrel jack. The KRC2 must be powered from one of these two sources. The internal controller circuits may not be powered from J5’s ‘V’ terminal. Problem: Source drivers inoperative. The source drivers require that a DC supply of up to 15 volts be attached to the KRC2’s DC barrel jack, or a DC supply of up to 50 volts be connected to terminal ‘V’ of J5. The source drivers are not capable of supplying voltage from the K2’s power supply. Problem: KRC2 does not communicate with K2. Check jumpers W9-W23. All but W20 must be installed for the KRC2 to communicate properly with the K2. If these are properly installed, check the cable connecting the KRC2 and K2. This must be a straight-through Male DB9-Female DB9 cable as constructed in this manual. Problem: K2 has no transmitter output in voice modes. Remove jumper W20 from the KRC2. The KRC2 adversely affects the K2’s ALC system, causing low voice power output of the transceiver. The K2 works quite well without the external ALC line installed, so simply leave jumper W20 out of the KRC2. Problem: LED Flashing on and off. On/off LED flashing indicates that the KRC2’s microcontroller has not passed its startup tests, and is waiting for a firmware download. This is not to be confused with the slower bright/dim LED flashing which indicates the driver band selection does not match the K2’s band setting. Try turning power off then on to the unit. If the condition persists, contact Elecraft technical support for an upgrade. Included below are complete DC Voltage Tables for all ICs. ::: qq014 Circuit Details Refer to the schematic diagram, Figure 7 on page 29. U1 is a PCI 16F877A microcontroller. This device controls the operation of the KRC2. U1 operates at a clock frequency of 4 MHz, as determined by X1. It communicates with relay drivers U4-U7 using its built-in Serial Peripheral Interconnect (SPI) interface, commanding them to turn their outputs on or off. Which outputs should be on or off is determined during execution of the microcontroller’s internal program. It uses band input from the attached radio or computer to determine which driver output(s) should be enabled. The MCU receives band information from the attached radio through one of six input channels. Three channels are analog, using the MCU’s built-in analog to digital converters to measure band voltages, while the other three are digital in nature. These consist of a BCD parallel input and two serial inputs. One serial input enables the MCU to participate on the K2’s AuxBus channel, while the other uses the MCU’s built-in UART serial port to communicate using the Elecraft serial protocol (similar to the Kenwood serial protocol). Selection of the active input method is made by setting the W1-W3 jumpers. The UART serial port uses industry-standard RS-232 voltages. These are switched in the KRC2 using U2, a MAX1406 (or similar) RS-232 interface. U2 requires a negative power supply for its operation. This is developed using the oscillator and rectifier circuitry of Q1. Q1 and X2 and their associated components form an oscillator running at 18.289 MHz. Output from this oscillator is fed to a voltage-doubling rectifier made up of D6, D7, and C15, then fed to U2’s –12V input pin. The circuit typically provides –7.5 volts, well within the range required by the RS-232 specification. For analog band operation, the input voltage is connected to the microcontroller’s AN1, AN2 or AN3 inputs through divider or isolation networks. The AN1 input comes from pin 9 of J1 or J2, depending on jumper selection. It is reduced by the divider network made up of R6 and R10. The values for these resistors provide a division by 2, giving the input a maximum range of 0 to +10 volts. The AN3 input is identical to that of AN1, with RR8 and R11 making up the divide-by-2 network. This input comes from J1 or J2 pin 4. AN2 comes from J1/J2 pin 7, and is fed directly to the MCU input without a voltage divider. Its input range is 0 to +5V. The KRC2 can communicate with two devices using the RS-232 port, depending on the setting of S5. In S5’s normal operation position, the KRC2 listens directly to the transceiver’s serial output, and also can send directly to the radio attached to the XVCR port. Additionally, the RS-232 signals from a computer attached to the PC port (J1) are ORed with the KRC2’s serial port, allowing it to send, and listen, to the transceiver as well. No protection is provided to keep transmissions from the KRC2 and PC from colliding on this channel, so care must be taken to prevent this in the PC and KRC2 operation. The S5’s Download (DL) position enables the microcontroller to communicate directly with a PC. This is used in downloading configuration and firmware upgrades to the KRC2.