A little bit about the nodes of the transceiver.
The mixer of the transceiver is assembled on the chip multiplexer FST3253, this microcircuit allowed to realize very good parameters. Such as the dynamic range of "clogging", a good suppression of the carrier signal which is more than 90 dB. And in a direct link (without phase-shifting circuits) with a frequency synthesizer on SI5351A, the minimum phase error, in the entire amateur frequency range (1-30 MHz)
At the input of the mixer, the signal from the antenna passes through the bandpass filters (BPF). Then, the signal is amplified from the mixer and goes to a low-frequency phase shifter of the 8th order in which the non-working sideband is suppressed, at least 80 dB.
In all low-frequency paths, film capacitors were used, this allowed obtaining very high characteristics of the device.
After the low-frequency phase shifter, the signal is fed to an amplifier with adjustable gain, which is set by the optocoupler participating in the AGC system circuit. Then the signal passes through the low-pass filter which is implemented on the chip MAX74000, before and after which additional low-pass filters are installed on the operational amplifiers. Then the signal amplifies and comes to the AGC amplifier and low-frequency amplifier, made on the chip LM386.
For transmission, the transceiver operates in the same way, but in the opposite direction, bypassing some nodes that are not involved in the transmission. The generated signal is fed to a high-frequency power amplifier made on the AD8009 chip (driver) and the output transistor RD16HHF1.
The transceiver is controlled by the microcontroller STM32F100. The program part for it was developed by our colleague and my friend Yuri (UT5QBC). Yuri also took a direct part in the development of this transceiver.
What is implemented in it ...
Frequency bands: 1.8, 3.5, 5, 7, 10, 14, 18, 21, 24, 28 MHz.
Operating modes: CW, LSB, USB, DIGI. (You can receive stations working with AM modulation, with a noticeable, better quality than using an amplitude detector).
Manual and electronic telegraph key.
Mode of turning on the transmission by pressing the telegraph key (auto transmission).
Adjustable reception delay (with CW auto transmission on)
Adjusting the speed of the electronic key.
Enable CW self-monitoring mode.
Detuning the receiver relative to the transmitter (CW SHIFT) 0-1500Hz. with a step of 100Hz.
Three modes of AGC: Fast, slow, disabled.
Adjust the brightness of the display. (0-250).
Automatic dimming of the display when idle. (30 seconds).
Scan mode within the same range (Skanner).
For operation in digital communication modes, it is possible to turn on the transmission when an audio signal appears on the line input of the transceiver (Audio VOX).
Turning on the audible confirmation of pressing the control buttons.
Ability to control the transceiver by CAT protocol (Kenwood TS-440) via USB port.
Switching the speed of data exchange CAT: 57600, 115200.
The mode of inversion of the display, which can be convenient in some conditions.
Indication of the received signal level (S-Meter) from S1 to + 60 dB.
Indication of supply voltage.
Characteristics of the transceiver:
Supply voltage 9-14.8V (Rated supply voltage 13.8V)
(It is noted that the transceiver retains its operability when the power supply drops to 6V.).
Consumed current in receive mode and 25% of loudness 120mA. at 100% of the volume to 200mA.
The current consumption is 500-700mA.
The output power of the low-frequency amplifier is 1W.
The output power of the transmitter is 5W. (at rated supply voltage).
Sensitivity of the receiver on all bands is not worse than 0.5μV.
Suppression of the carrier is not worse than 90 dB.
Suppression of the non-working sideband is not worse than 80 dB.
The dynamic range of the AGD system is 80 dB.
The dynamic range for detuning is more than 25kHz, not worse than 120dB.
CW 400-1500Hz. with a step of 100Hz.
LSB-USB 1600-3200Hz. with a step of 100Hz.
Radiation band of the transmitter:
The transceiver is controlled by five buttons, an encoder and a volume control which are located on the front. There is also a small display measuring 0.96 "
On the back side of the transceiver there are 8 connectors ...
Antenna input (BNC).
Power socket (5mm Power Jack).
A jack for connecting a USB cable (Mini USB).
Line input (3.5mm stereo jack).
Linear output (3.5mm stereo Jack).
Microphone (3.5mm stereo jack).
Telegraph key (3.5mm 4pin Jack).
External speaker (3.5mm 4pin Jack).
The entire transceiver is housed in a metal case with a size of 103x100x30mm.
From the inside, in the upper part of the case there is a small loudspeaker.