HF home made transceiver

Front panel consist of two boards. One of them is CPU board with main microcontroller AtXMEGA128A3U-AU, main dial optical encoder BOURNS, mechanical encoders, dual concentric potentiometer AF/RF. This board holds LCD&switch PCB.

Main Board (MB)

March 1, 2019 HF home made transceiver, MAIN board (MB), Modules

RGO ONE Main Board (MB) or so called mother board fits all connectors on the rear panel, power supply, I/O controller (second CPU). MB is also intended to be a chassis for all RF boards and options, as long as “cable harness” and board interconnections.
The board has the following components on it:
– I/O micro controller U5, DAC U7, external fan control – U8, T12, signal multiplexer U9, 3.3V LDO regulator chip U4

– USB FTDI chip F1

– I/O connectors at the back side, daughter board connectors, power on/off switch, level converters, 5V,8V LDO regulators

PCB component side (bottom):

PCB component side (bottom) values:

PCB top:

LO board

February 25, 2019 HF home made transceiver, LO local oscillator/BFO/BEEP/SIDETONES/SSB monitor, Modules

LO board provides all oscillator signals needed for signal conversion and mixing. The board consists of the following components:

– LO first oscillator realized by U2 – SI570 (570CAC000141DG), 3 switchable low pass filters: 10.8-15MHz; 15-24MHz; 24-39MHz. Filter switching is performed by I2C chip PCA9536
– 9MHz generators – U3 (SI5351) BFO, CW sidetone, beeps, U1 (SA-612) balanced mixer which acts as CW/SSB monitor product detector, digital poteniometer – U7 (MCP4018-502E)
– Tone shaping, (tones on/off ) circuitry – T1,T2,T5
– Temperature compensation oven made by thermo resistor R14 and T3,T4

PCB component side

In order to achieve good results with low harmonic content and stability – PCB board is well shielded in two component metal tin can:

RX MIXER

February 22, 2019 HF home made transceiver, Modules, RX MIXER

RX MIXER standard is ADE-1 diode ring mixer. Here described is optional high dynamic range H-mode mixer.

The schematic and original H-mode mixer concept has been designed by Colin Horrabin G3SBI and further developed by Martein Bakker PA3AKE.

PCB component side

RF MIXER

February 22, 2019 HF home made transceiver, Modules, RF MIXER

RF MIXER board does all RX/TX signals on IF and operation frequencies.
On receive the signal comes on CX3 coaxial connector, then passes (or not) through input attenuator R10,R13,R14, then via switches come to BPF board. IF TRAP circuitry consists of L1, C7, C38. Then signal passes through U3 (ERA6SM) RX preamplifier (operator switchable). RX MIXER is on additional subboard and sits over RF MIXER board. 9MHz diplexer follows and then IF amplifier – U12 (ERA6SM). After some switching and attenuation signal comes to the first crystal filter – 2.7kHz then to CX6 coaxial connector and IF/AF board.

On transmit the signal from SSB GEN board through CX7 connector passes through crystal filter and after TX/RX switch to a pin diode D1 attenuator. It is driven by ALC circuitry performed by U16 and T4.
U11 is TX mixer which is fine balanced by R62 and impedance matched by L10,L18 wide band transformers. Output mixed signals are further filtered by BPF board and amplified by U3 and U9. Output attenuator R4,R5,R6 is following then via CX4 signal goes to linear amplifier PA55W board.

Component side PCB

Component side values

IF/AF unit

February 3, 2017 HF home made transceiver, IF/AF, Modules

This unit includes the following:

intermediate frequency IF amplification – MC1350
optional crystal filter (4 pole variable crystal Johnson type filter)
RX product detector – SA612
AF preamplifier – MC33079DG
RX MUTE and sidetone input circuitry
AF final amplifier – SA58631
Fast IF 134kHz Automatic Gain Control scheme – SA612,MC33079DG
Optional AF filter board

PCB component side

MIC amplifier, DSB, CW modulator unit – SSBGEN

February 3, 2017 HF home made transceiver, Modules, SSBGEN

In order to form DSB/CW modulation on TX, a SSBGEN board is used.

It consists of the following parts:

Microphone preamplifier and TX audio amplifier – TL082
Switched input: LINE IN or MIC (MUX 4053)
DSB modulator – SA612
CW drive level and form circuit – ½ of MCP4631 dual digi pot
SSB drive level (mic level) – ½ of MCP4631 dual digi pot

PCB component side

BAND PASS FILTERS

January 25, 2017 Band Pass Filters, HF home made transceiver, Modules

Six band pass filters were built to cover 10-80m bands on RX. Schematic utilizes Skywork solutions AS169 PHEMT GaAs SPDT switches, used in modern wirelless equipments. In order to perform individually “fine tune” a variable coil inductors are used. The module fully meets project CLICKLESS concept as there aren’t any mechanical switching components. MCP23008 serial controlled I/O expander is used to engage needed filter. The board has a provision for two optional filters.