YouKits TJ2B Instructions for use

CONSTRUCTION OF TJ2B HANDHELD SSB TRANSCEIVER
The TJ2B is a high-performance QRP portable multi-band SSB transceiver using DDS as
the LO, and offering wide frequency coverage and fine tuning rate. The Doubly Balanced
Diode Ring Mixer makes strong signal handling capability possible. The TJ2B is a
pre-assembled kit. You need only assemble a few parts and connect some cables to be
qrv.
Operating Frequency: 3 - 18.2 MHz (Kit A)
Mode: LSB, USB, CW (RX)
Tuning Rate: 1Hz, 10Hz, 100Hz, 1KHz, 10KHz, 100KHz
IF: 9 MHz
Sensitivity: 0.3uV
Current Drain: 260 mA (RX)
Operating Power: 10 - 13.6V
Output Power: 5W
40 Memories
Dual VFO
Memory-VFO Transfer

Tuning steps of 1 Hz are available. Pressing the TUNE knob selects the tuning rate.
Included Hardware: Buttons, switches, DC sockets, earphone socket, pot, and encoder. A
miniature speaker is packed in the bottom cover of the enclosure.

Cables for internal connections
Components package

Toroids Note: FB-43-2401 may be supplied in the kit. This core is larger than FT-43-37.
Can Inductors

Pre-assembled Miniature Transformers (Packed in a separate plastic bag)
Brass Stand-Off Parts

Included DC cable as a free gift.
All the SMD have been assembled in the factory. However, some bulkier components,
such as the buttons,switches, can transformers, toroids, electro caps., have not been
assembled. Thess components prone to damage in transpiration if they were
pre-assembled. The users are required to solder them onto the PCB.
Let's start step by step.

1. DDS Unit
Assemble the following components: (C34 has no component)
1) Assemble Y1, the 2MHz crystal. Bend the leads before soldering. Otherwise it will be
too high.
2) Assemble MIC. Notice the Ground pin (the pin connected to the casing). Solder the
GND pin of the MIC to the GND pad of CN6 (the square pad on the left), and solder the
MIC pin to the MIC pad (the round pad). It is suggested to extend the leads so that the
MIC is closer to the MIC hole on the case. See illustration.

3) Assemble the 3.5mm stereo socket to J1. This is the external MIC and PTT socket.
Because of the manufacturing process, the top cover opening for J1 cannot be lower. It is
suggested to modify the socket a little so as to align with the opening better. It takes only 2
or 3 minutes. First, cut off the 5 tiny plastic stands-off on the socket. Second, flatten the
plastic rim with a file. See the illustration below.
Assemble the modified socket to J1. Push the socket to the MIC side as much as possible
until the side aligns with the silk line before soldering. See the illustration below.

4) Solder a 220uF electrolytic capacitor to C7 pads. (C7 may have been assembled).
5) Solder a miniature transformer to T1 pads. Six such transformers are supplied in the
bag. Use one of them here.
6) Insert the LCD cable to the FFC socket (CN3). Do not assemble the buttons until the
LCD is assembled. Bend the flexible cable before inserting it into the socket.
Pull the lock bar to release the lock of CN3.

How to insert the LCD Cable
Never bend the cable end soldered to the LCD!

Now carefully insert the flat cable into the socket. When the cable is inserted into position,
press the lock bar down to lock the cable. Never bend the cable end which is soldered to
the LCD PCB. This will break the cable at the end, because the thin tracks have no
protecting plastic at the end. Always push the bent part (the "U" part) to insert.
Another method of inserting the LCD is to insert the LCD with a slanted angle.
Fasten two 6mm-brass stands-off (the two brass stand-offs without a tail) to the mounting
holes with 2 flat-head screws.
Solder the four function buttons onto the DDS board.
7) Solder the 7-wire cable to CN1.
First, split the end leads to fit CN1.

Now, solder the 7-wire cable.

Supply 12V from the 7-pin cable, negative to "GND", positive to “+12V". Voltage ranging
from 10.5 - 13.8V works. Never connect the wrong polarity! When the power is connected,
the backlight is on. There may be nothing seen on the LCD screen at first. Don't worry.
Adjust the contrast control VR1, until the display appears. The 51 ohm resister controls
backlight brightness.
Now push the LCD window through the LCD frame. Fasten the frame with 2 flat head
screws. A little glue can be applied along the contacting edges of the LCD PCB and the
frame. However, even without the glue, the LCD assembly will work fine, because the
LCD is backed by connector CN3, and there is only around 1mm clearance between CN3
and the back of the LCD.

8) Solder the 5-pin socket to CN2. This is the encoder and tuning rate port. Assemble
CN2 at the other side of the PCB, making it easier to run the cable.
Pins 1 - 3 are soldered to encoder pins 1 - 3 respectively. Pins 4 - 5 are soldered to the
two encoder switch pins.
The encoder pins are numbered as shown above. The center pin (Pin2) is GND. The
lower two pins are switch pins used as tuning rate selection.

9) Solder the MIC cable to CN5. Use the yellow connector. Note: The square pad (on the
right) is GND, the round pad is the MIC pad. They are routed to the MIC pad and the GND
pad of Main board CN4 respectively.
10) Assemble the SETUP switch which is on the PCB back.
Now, the DDS Unit is ready. You may test this assembly separately.
Apply 12V to CN1 to test the DDS Unit.
Supply 12V DC to +12V and GND. Connect + to +12V pin, - to GND. Never connect the
wrong polarity! Power supply range is 10.5 - 13.6V.
If there isn’t any display after adjusting VR1, please check the LCD cable. The cable may
only be half way into the connector. Insert the cable properly. For the first test the DDS
works best at the lowest frequency of BAND 1 (3.000.000), LSB, VFO A.
Press MOD, the mode changes, press A/B, the VFOs switch, press V/M, VFO mode is
switched to the memory, press MEM, the frequency is ready to save to the memory. Turn
TUNE, the frequency changes. Press the TUNE knob, the tuning rate changes. All the
functions work! Let's check the DDS output.
Check the DDS output with a frequency meter. Connect the frequency probe to CN4, the

GND clip to GND of DDS Unit. The reading should be 12.000.000. This is the display
frequency + IF (9.000.000). If there is no reading, check T1 for a cold solder joint.
The reading may be not accurate, around 12 MHz, because of the 100 MHz crystal
tolerance. If the measured frequency is not accurate, please calibrate the clock value
through SETUP.
If you don't have a frequency counter, ignore the clock calibration. You may calibrate the
clock later with the aid of beacon signal at 5 MHz, 10 MHz, or 15 MHz.
Let’s setup the DDS unit.
Press the SETUP button, IFS appears on the screen. Setup IFS later
Press again, DDS information appears.
The top line indicates the clock value. The default clock value is 100000000 (100 MHz).
Use the TUNE knob to alter the value. If the 1 Hz tuning rate is too slow, use a faster rate.
Tune while watching the frequency meter, until 12.000.000 (or 11.999.999) is measured
on the frequency meter. Press the MEM button to save this value. You can ignore this step
if you don’t have a frequency counter.
Press SETUP again, USB appears on the screen.
The default value is 3000, indicating USB and LSB are 3 kHz apart, i.e., both the LSB and
USB is 1.5 kHz from the XTL filter center frequency. Turn TUNE knob counter-clockwise to

alter the value to 2800, so that LSB and USB are 1.4 kHz from the center frequency. Press
the MEM button to save the modified data. Press SETUP to exit.
Monitor the frequency meter. Tune from 3 - 18.199999 MHz using LSB mode, the reading
is always 9 MHz higher than the DDS LCD displays. If the frequency is not very accurate
at higher band frequencies, re-calibrate the clock. Press MOD to enter USB mode, the
measured frequency is 2.4kHz higher. Now, let's calibrate the IF.
Press the SETUP button, IFS information appears on the screen. "0" indicates the default
IF value which is 9 MHz. In this kit, the BFO frequency at LSB mode is 8.998400 MHz, not
9.00000 MHz.
(900000 –8998400) = 1600, i.e., 1.6 kHz. The DDS should be 1.6kHz lower to match the
LCD display. Please turn the TUNE control counter-clockwise until -1600 appears on the
LCD screen. Press MEM to save this modified data. Press SETUP or other function keys
to exit SETUP.
Now let's move up to the main board.
2. Main Board
Note –there are no components at C21
A few bulkier components should be assembled:
1) Two DC input sockets
2) Power switch
3) PTT switch (Do not put on the push button until the whole kit is completed.)
4) Phone socket (3.5mm stereo socket. Do not cut the stand-off and file the rim like J1 of
DDS board.)
5) Connectors: CN3, CN4, CN5, CN6, CN7 (Note: CN7 is assembled on the back to
shorten the leads from the battery pack.)

6) Two TQ2 relays (Notice the bar printed on the relay. There is also a bar printed on the
PCB.)
7) 220uF electrolyte caps. Note: The longer lead is "+". Solder them to C28, C30,C80,C82
pad. Find “+”on the PCB. Never mistake the polarity.

Notice "+" symbol.
8) Solder the 9 MHz crystals on main board Y1 - Y5 pads.
9) Solder the can inductors to the main board. The can without any number is for T4; the
can labeled (3) is for L2; and the can labeled (2) is for L3.

10) Solder T1, T2, T3, T5, T6. These are miniature transformers. One of them is used on
the DDS Unit.
11) Assemble the 10k trimmer on the CN2 pads. Adjust the leads so that they fit the pads.
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