CONSTRUCTION GUIDE FOR MONO BAND PANDA 1 SSB/CW TRANSCEIVER SPECIFICATIONS VXO Coverage:7.000-7.078MHz Power Consumption:50mA (receiving mode) Output Power:5W CONSTRUCTION L1 (Optional) 9 MHz trap for conditions where there is a radio broadcast signal near 9 MHz when Panda 1 is used for 40 meter band. L1: 0.1 wire, 16 turns on the can former, C1 151. L2, L3: Band-pass filter inductors. 0.31 wire, 22 turns on NXO-10 toroid core. The wire should spread evenly on the core. Do not overlap the wire. 1
T1,T2: Mixer transformer. Thread a pair of 0.1 wires through the miniature binocular core, 6 turns. Then thread another piece of 0.1 wire from the other direction, 6 turns. See photo (For a clear instruction, a bigger core and colored thicker wires are used). The start of one wire (in the photo case, yellow) is connected with the end of the other wire (in the photo case, purple) to act as a tap. Solder the mixer transformers to the board, and fix them with a tape. The temperature of the solder will remove the lead enamel. T3:Broad-band ferrite transformer, 8 bifilar turns, 0.31 wire, on the broadband core. The wires are twisted. See photo. Pay attention to the phase. 3 and 2 are connected as the tap. 2
T4:IF transformer. 0.1 wire on the miniature binocular core, primary (crystal side) 5 turns, secondary 10 turns. It can be solder directly on the board, or fix it to a former, and then fix the assembly to the board. The temperature of the solder will remove the lead enamel. T5:Use the can former. 0.1 wire, primary (the 3-pin side) 16 turns, counter clockwise, the turns spread in 4 slots. Secondary (2-pin side), 4 turns in the bottom slot, counter clockwise. Wind the 2-pin side first. Pay attention to the start. See the left illustration (Bottom view). The photo on the right shows 4 turns in the slots. T6:Primary (U3 side) 22 turns on NXO-10 core, 0.31 wire. Secondary 6 turns, spread on the middle portion of primary. Pay attention to the winding direction. 3
T7:Can former, 0.1 wire. Primary (3-pin side)18 turns, spread in 4 slots; secondary 4turns. Wind the secondary first. T8:Broad band transformer. 5 bifilar turns, 0.31 wire, on the binocular core formed by 2 sleeves. See photo. Pay attention to the phase. 3 and 2 are connected as the tap. T9: Broad-band ferrite transformer, 10 bifilar turns, 0.31 wire, on the broadband core. The wires are twisted. See photo. Pay attention to the phase. 3 and 2 are connected as the tap. L4:0.31 wire, 21 turns, on NXO-10 core. L5:Can former, 0.1 wire, 31 turns,spread in 5 slots. L6, L7:0.31 or 0.47 wire, 16 turns on NXO-10 core. RFC1:5 turns on the small bead or small toroid. RFC4: 0.31 wire, 3 turns on the small bead or the small toroid ring. RFC5: 0.47 wire, 3 turns on the small toroid ring. The 0.1 mm wire needs not removing the lead enamel. The temperature of the solder will remove the lead enamel. 0.31 mm wire needs removing the lead enamel with a knife and tin them before soldering the transformer to the PCB. Jump R45 with a short thick wire (e.g. a piece of cut component lead). PWR SW is for mounting a power switch. Jump the hol es with a thick wire. C73 is fixed on the back. Insert a piece of paper between the heat sink and the board to prevent short circuit. 4
VXO Module L1:Can former. 0.1 wire, 49turns,spread in 5 slots. T1:Primary 11turns, secondary 3 turn on the broad-band core. Pay attention to the connection( 漏极 stands for Drain of Q2, 电源 power, 地 GND, 输出 OUT). See photo. For better VXO output, use NXO-10 core for T1 instead of the broadband core. Primary 15 turns; secondary 3 turns. Connect an 82P ceramic disc in parallel with the primary so as to tune T1 to resonance. Or use a var cap of 60P and a 47P ceramic disc, and tune the var cap to peak T1. VXO module is mounted on the main board by means of the pins and sockets. L1 can be fixed on the back to lower the height. There should be enough clearance between the module and the main board to reduce the interference. Do not cut the leads of the var cap diode. Bend the leads and solder, so that there is a clearance between the diode and the PCB. 5
Definitions of Main Board Interfaces LO IN:LO input port, connected to the VXO output port via 2 pins SP:AF output port, Connected to the speaker VOL:Volume control, connected to the 10K pot MIC:Microphone port, connected to the microphone AUX:12 V port to supply power to VXO module MODE:Mode switch, connected Mode switch KEY:CW key, connected to the key PTT:Push to talk ANT:Antenna PWR SW:Power switch. Please jump the holes LED: RX indicator Definitions of VXO Module VR1:Tuning port, connected to 10K pot VXO OUT:LO output port 12V:Power port Connecting the interfaces Solder the interfaces with wires. Use a thin screen cable to connect MIC if necessary. MODE is connected as illustrated in the following figure. ANT is connect to the Q9 socket with short thick wires. 6
Adapting some components VR1, VR2, VC1-VC4 need some changes to fit the pads, see photo. The center hole of T5 should be bridged with solder with the lead hole on the right (See photo). Polar of C32 The polar of C32 is as following picture. 7
Alignment BFO Set the mode switch at SSB or CW. Connect a frequency counter to the emitter of Q3.Turnthe slug of L5, until the reading is aro und 8.99778MHz. Check CW mode frequency. Disconnect RFC5 to disable 2078. Set the mode to CW. Short CW key, see if the reading is around 8.99880. In reality the 471 ceramic meets the requirement, and no adjustment is needed. Connect RFC 5. VXO Dot not connect the module to the main board. Supply a 12V to the power pin of the module. Connect a 47 56-ohm resistor at VXO OUT. Connect a frequency counter to the output port. Set the 10K tuning pot to the lowest voltage end (pot center to the ground)adjust L1, until the reading is 16.0000,and turn the pot to the high voltage end, the reading should be around 16.080. Disconnect the 47-ohm resistor. Plug the VXO module to the main board. 8
Receiving Do not connect the antenna. Use a digital meter to measure the voltage of pins 4 and 6 of U1. Adju st VR1 until voltage of pin 4 is around 1.19V, pin 6 around 0.65, or V4-V6 = 0.5V. Now AGC works at the best condition. Never short pins 2 and 3. Another simple way to adjust U1 is to wear earphones, adjust VR1, until you hear a relatively louder hiss sound. Adjust T5. Listen the carefully. Turn the slug, peak the weak hiss sound until until you hear a relatively louder hiss sound. Connect the antenna. Adjust VC1 and VC2 to the position as shown in the below picture. Trim VC1 and VC2 to peak the received signals. Receiving alignment is done. The core in the right picture has 22 turns. LED resistor is 4.7K. Increase R3 can reduce power drain. 9
Transmitting Connect 50ohm dummy load to the ANT (A 2W resistor works fine).use multi meter (250MA range) to measure the current. Press PTT, the reading should be around 100MA. R43 is the bias resistor of 2078. 5.6K works fine. Adjust VC4 to the position as shown in the photo on the right. If your winding is correct (check against the photo), T6 works. Set the mode to CW. Change to 1A range. Adjust T7, until the reading is maximum. 10
Data for 20 meter band: L3, L4 16 turns. C3, C5:47,C4: 3,C2, C6:20 L6 L7 11 turns. C74, C76:221,C75:471 T6 Prim 16,sec 4,C57:47 Adjust VC4 to the position as shown in the photo (Around 30P). T7 2-pin side 4 turns. 3-pin side,12turns. C63:47 L1(VXO) 39 turns. VXO coverage: 14.130 14.330 MHz (or 14.000 14.320 MH z) T1: Prim 12T, sec 3T, on NXO-10 core. Connect a 68P ceramic disc in parallel with the primary. See photo. Note: For 20m, use a 2.2 4.7P ceramic for L5 so that PANDA works at USB. Now BFO works at around 9.0008MHz. A var cap of 1/10P can also be used. Side tone If release the CW key there is a sustained sound can be heard from the loud speaker, then a 47 K resistor is need between the ground and collector of Q11. This resistor can be soldered at the place as shown in the following photo. 11