Category Archives: HF home made transceiver
Front panel CPU Board
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)
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
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
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
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
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
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
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.
PCB component side (bottom)
PCB top
The board
Filters spectrum analyzer plots:
Custom made control knobs
Three types control knobs are used in this project:
MAIN dial knob – for VFO frequency tune
ENCODER knobs – various functions
DUAL CONCENTRIC knobs – AF/RF gain control
FACE PANEL MOLD PLASTICS OR ALUMINUM MACHINED
To bring more professional and stylish appearance we decided to design custom front panel especially for this project.
Next question was: Injection plastic mold or machined aluminum
First, we made one prototype of machined aluminum in order to test if everything in design is right on the place
Then we start building (ordered) our face panel plastic injection mould. It is known that this was pain process and it took almost 3 months to build it .. after three revisions here it is now ready to “SHOOT” our plastic panels
We made some samples of all three materials available: Glass filled polyamide (black colored), Glass filled polypropylene (grey colored), ABS plastics (white colored)
