Category Archives: Модули

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:

 

MOSFET LINEAR POWER AMPLIFIER 50 WATTS

Final 50W amplifier is designed using 4pcs. QFET N-MOS FAIRCHILD FQP13N10 transistor. The module consist of three stages: predriver with NXP PD85004, driver in push-pull configuration (2xPD85004) and final unit utilizing 4pcs. (2 by 2 push-pull in parallel) FQP13N10 transistors in easy to mount TO-220 case.

Main reason we chose such a general purpose switching MOSFET’s is that they are cheap and is in current production so can be delivered anytime from a trusty supplier.

Input matching and especially Ciss (~400pF) compensation is performed by input transformer TR2, inductors L3, L7, L8, L9, swamp resistors R7, R16, R26, R39. This group of components increases input drive signal for frequencies over 10MHz and swamps input energy for low frequencies where the overall gain is more than sufficient.

Bias voltage for all transistors is provided by voltage regulator 78L05 (U1) and MPSA13 (T11) which is in good contact with final transistor heatsink in order to perform needed temperature compensation.
In order to minimize voltage drop power supply input and current sensor are also on this board – C58,C59, D1, ZXCT1081E5

PCB component side:

PCB component side (references)

LOW PASS FILTER BLOCK 3.5-30MHz

This board consist of the following modules:

5 sub PCB with low pass filters chebyshev type for all HF bands. There is place where to be nested one optional LPF subboard (for 160m)

High voltage (210V) scheme (voltage tripler)

Antenna RX/TX switching

SWR directional coupler and measurement of Vfwd/Vref

Optional LPF (160m) connector

This module ensures clear harmonic output of the linear amplifier, also fits the components for antenna RX/TX switching. Following the “click-less” concept, there are no mechanical relays in the circuit. After long searching for suitable power switching component I found VISHAY high voltage rectifier diode S07J (S07M) that met all the requirements for reverse voltage capacity, reverse recovery time, forward current and reverse voltage. So S07J were used in the project to ensure good switching of TX power to the antenna via proper LPF and also reliable isolation between each other low pass filters not selected for this band portion.

High voltage generated from input signal polarizes unused switching diodes in reverse direction ceasing the chance for signal leak. Same votage is used in RX/TX switch for completely disconnecting receiver front end on transmit.

PCB layout
Component side (bottom) values:

Component side (bottom) reference names

Top – connector side:

Picture of the ready board with filter subboards on it:

 

 

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