Note: The MOS field effect tube 2N7000 in the kit should be soldered as the last component. In order to prevent electrostatic breakdown, the soldering iron power supply should be disconnected and soldered with waste heat.

 The welding of this kit requires a certain foundation of electronic technology. It can recognize components and welding. Basically, the entry machine does not need to be debugged. As long as it is assembled carefully according to the kit manual, it will succeed.

main indicators

Power supply: 12V-13.8V (linear regulated power supply is recommended)

Antenna: 50 ohm, unbalanced

Transmitting power: 12V /5W (using 12V power supply, long-term transmission will be slightly reduced, use D882 output)

Frequency: transmitting local oscillator frequency: 7023kHz; receiving local oscillator frequency: about 7023-7026KHz

Working mode: CW

Circuit principle

       The core of the receiving part is an NE602, which includes a balanced mixer inside. The signal from the antenna passes through two crystal filters and then enters the mixer. The oscillator circuit composed of 9018 sends out the local oscillator signal at the same time. Mixing, the SSB/CW signal is directly converted into audio, and the audio output from NE602 is sent to NE5532 for active low-pass filtering and audio amplification, thus completing the entire receiving process. Therefore, a receiver that directly mixes the RF signal into audio is called a "DC receiver", and DC means direct conversion.

The mute circuit formed by the 2N7000 field effect tube in the circuit is used to turn off the reception when transmitting, and the audio oscillator formed by the internal timer of STC12C4052 generates sidetone, which is output to the earphones, so that the earphones follow the shooting to produce "tick" Audio.

The transmitting part uses 9018 as an oscillating circuit, and then 8050 as a buffer and amplifying. The 8050 is also used as a transmitting key to control the switching of the receiving and sending circuit and the signal. The final stage is a class C amplifier composed of D882, which is amplified by a 1:4 output transformer The matched high frequency signal is filtered by LPF and then connected to the antenna.

The magnification of 018 is about 130, and the magnification of D882 is about 200. T1 is a 1:4 transmission line transformer. Use 0.51 mm enameled double-twisted wire on the ferrite core of FT37-43 and wind 6 turns), and then connect the head of one coil and the tail of one coil.

T2 is a high frequency transformer. It uses 0.51 mm enameled wire to wind on the ferrite ring of FT37-43, with 8 turns on the primary and 2 turns on the secondary (due to the poor consistency of the analog characteristics of the transistor, if the experiment finds that the output power is slightly weaker, You can change the number of turns to 9:3). L1 and L2 are high-frequency filter inductors. Use 0.51 mm enameled wire to wind 16 turns on the iron powder core magnetic ring of T37-2, about 25cm, and the inductance is about 1uH. All capacitors less than 1000pF are high-frequency ceramics, capacitors greater than 1uF are aluminum electrolytic capacitors, and all resistors are 1/4W 5% fixed resistors.

package:

1x kit package

1xcase