CB Radio Ranger RCI-2950 & RCI-2970 Review
Technical Analysis of the RCI 2950, RCI 2970, RCI 2990, Saturn Turbo circuitry
The first striking element of the RCI is the complex frequency synthesizer. As most of the CB rigs use a + 10 Khz step , the RCI uses a 100 times thinner 100 Hz step.
The brain of the RCI is the Microprocessor. The microprocessor is hold by the small board located behind the LCD display. This board rules the rig. It is a double sided board which holds a battery, an alignment of 2.54mm connectors, a voltage regulator (5V - MC7805) on its back. The regulator feeds all the digital components, a network of internal resistors. On the same side of the board, you can find a buzzer and a lithium battery which is here to keep the memories when the rig is switched off. Note that, in the latest versions of RCI rigs, the lithium battery has been replaced by a capacitor.
The other side of the board holds 3 CMS chips, a double Op-Amp (5223), a box containing 6 inversors gates (buffers) CD4069. This last one is controlling the 6 digits of the display. This side of the board also holds a 64 pins CMS chip, driven at 4 Mhz by a crystal, which is a CMOS circuit. It owns a ROM of 2 K, Four 4 bits registers, a 8 bit timer, a serial 8 bits communication interface, 24 Input/Output. Everything is controlled by 10 microseconds cycles. A controller-Driver of Liquid Display Boards is supervising all the needed display cycles on the 24 lines of the LCD segments to display the 6 numbers (7 segments by number) on the orange screen. The microprocessor is having very low consumption characteristics: less than 900 µA.
The programming of the microprocessor is done at factory. All the functions and the frequencies range are stored into the ROM. A jumper allows us to change the frequency range. All the main informations are send to the frequency synthesizer by a limited amount of links: clock signals (CLK), transfers (LAT), serial data (DATA). All these informations are not given by the schematic diagram but were useful to know. Let's pay a visit to the main board.
The Frequency Synthesizer is complex because of the 100 Hz resolution. It owns a dozen of integrated circuits: a programmable divider (IC17:7925 Sony) addressed in serial mode by the microprocessor, a first VCO (IC8: TA7310 Toshiba), two phase comparers (IC5-IC7 TC5081 Toshiba), three mixers (IC9-IC10-IC14: TA7310), an oscillator-divider driven by a 10.250 Mhz crystal. This part of the rig generates 2 different frequencies: in RC mode to get an infradyne pulse of the first conversion (RX QRG - Interm.QRG of 10.695 Mhz) and in TX, the necessary to produce a supradyne ( Interm.QRG of 10.695Mhz + FVCO). Depending of the TX mode, in AM/FM, the Q44 oscillator is controlled by X3 (10.695 Mhz). In SSB and CW, there is a 1500 Hz jump (+ 1500 Hz in USB and CW and -1500 Hz in LSB).
The transmit circuits follow the frequency synthesizer. It has a HF mixer (IC20 : SO42P Siemens). It is adapted in large band conditions by a set of varicaps D93-D94-D95. The result of the mixing is then applied to a band filter (L43-L46), amplifier in voltage by a transistor Q50: 2SC1730L. The output level of this TR is enough to control the pre-driver (Q49: 2SC1973). The pre-driver, via L41, excites two finals in parallel (Q46-Q47: 2SC2312). They are followed by a low-pass filter in PI (L32-L31) and associated capacitors C243-247-251).. And then a hi-pass filter follows (L33/C248-VC3). A line of measurement of the SWR is present in the form of a vertical mini circuitry board, plugged between the TX output and the antenna plug. All the 3 power transistors are biased VR11. In AM and FM, the mixer IC20 adds the VCO QRG to 10.695 (Q44). In SSB and CW, it is the output of the crystal filter that is added.
The receiver is classical: superheterodyne with 2 IF conversions. It is very similar to the one of most cb rigs. There are output stages: HF Amp (Q18: 2SC1674), transfo L8, first mixer Q19: 310), L9-L11 filter, the IF output by L12,L13,L14. What strikes is the presence of varicaps D19,D23,D24 which works to produce a perfect tune in this large band rig. The band filtering is also perfect. It is done by two combined transfos linking the HF amp to the mixer. The ceramic IF filter FL2: 10.995 Mhz is attacked by L14. The a second stage of IF Q8 is feeding the second IF filter FL3 455 Khz. The first following TR loads Q5. Then Q10 & Q11 produce a Hugh gain before the first IF transfo L6. The follow AM and FM demodulators. In AM you have a diode circuit to detect and gain control (D11-D12). The Op-Amp IC1: LM324 follows. IC2, is the discriminator (UPC1028H). It handles the FM.
The noise blanker is very good. It is composed of 6 stages with at least 7 TR and 3 diodes assuming the amplification of HF interference coming from the first QRG changer.
The AM is using a classical and reliable technology: a ballast PNP transistor (Q51).
In FM, we can find the old good MC14558P (IC16) which handles modulation of the mike before exciting the varicap of the VCO to produce frequency excursions.
In SSB, IC16 pre-amplifies the mike signals. It is followed by IC3 (AN612) which produces a double side band modulation (DSB). Once going through the crystal filter, the un-wanted side band is eliminated.
You now know more about the hiddent componentes of your RIG.
·Full Band Coverage - Covers the 10 Meter Amateur Band from 28.0000 to 29.6999 MHz.
·All Mode Operation - Operates on USB, LSB, CW, AM and FM.
·Brightness Control - Four Step LCD brightness control for easy viewing under any condition.
·Repeater Offset Switch - Gives you standard offsets for repeater operation.
·Programmable Frequencies - Allows you to program up to 10 individual frequencies. Includes battery backup.
·Built in Dual VFO - Choose steps of 10kHz, lkHz or 100Hz, manual or scan
·RIT - Receiver Incremental Tuning to fine tune the receive frequency up to +/- 3kHz.
·Squelch - Cuts off or eliminates receiver background noise in the absence of incoming signals.
·Noise Blanker - Greatly reduces repetitive impulse noise.
·RF Gain Control - Reduces the gain of the receiver under strong signal conditions to prevent overloading.
·RF Power Output Selector - Lets you select transmitting output power
·External Speaker Connection - Place a speaker anywhere for convenient listening.
·PA Mode - Use an external speaker for a mobile PA system.
·LCD Display - Large, easy to read backlit LCD display.
·Multi-Function LCD Meter - Indicates transmit power, receive signal strength, modulation, SWR Calibration and SWR.
- ·Frequency Range: 28.0000~29.6999 MHz
- ·Tuning Steps: 100Hz, 1kHz, 10kHz, 100kHz, 1MHz
- ·Emission Types: USB, LSB(A3J), CW(A1), AM(A3), FM(F3)
- ·Frequency Control: Phase-Locked Loop Synthesizer
- ·Frequency Tolerance: 0.005%
- ·Frequency Stability: 0.001%
- ·Operating Temperature Range: 0 to 40 degrees C.
- ·Antenna Impedance: 50 Ohms
- ·Microphone: 400 Ohms, Dynamic PTT
- ·Speaker: 8 Ohms, 2 Watts
- ·Display: Digital Frequency, LCD
- ·Meter Function: RF Output, Receive Signal Strength, Modulation, SWR Calibration, SWR
- ·Power Requirements: 13.8 Volt DC Negative Ground
- ·Antenna Connector: UHF TYPE, 50 Ohm
- ·RF Transmit Modes: USB, LSB, CW, AM, FM
- ·RF Output Power: USB, LSB (25W); CW (8W); AM/FM (8W)
- ·Spurious Emissions: -50dB
- ·Carrier Suppression (SSB Modes): -50 dB
- ·Sensitivity for 10dB SINAD: AM 0.5uV
- ·Sensitivity for 10dB SINAD: USB/LSB/CW 0.15uV
- ·Sensitivity for 12dB SINAD: FM 0.25uV
- ·Image Rejection Ratio: 65dB
- ·AGC Figure of Merit: SSB/CW/AM 80dB for 50mV for 10dB Change in Audio Output
- ·Audio Output Power: 2.5 Watts
new RCI-2950DX & RCI-2970DX
These new DX models feature microprocessor control of not one but two amateur bands. The new RCI-2950DX, rated at 25W PEP and the RCI-2970DX, rated at 150W PEP are perfect for the recent band openings on 10 and 12 meters. Now you can upgrade your mobile Ham capabilities with a radio that is rich in features and reasonable in cost.
The new DX models have retained the operating features of its popular predecessors, including programmable repeater offset and capabilities for a CTCSS tone option — great for increasing repeater activity on 10 meters — and receiver scanning for quick search of active frequencies. The units offer three methods of frequency selection, non-volatile memory to store and scan up to ten favorite frequencies, and front panel frequency selector lockout.
In addition, the DX Series offers an impressive array of design and performance improvements.
What's different in the 2950DX from older 2950?
- An improved receiver: designed for increased sensitivity and image rejections.
- A double FET balanced mixer: for improved receiver inter-modulation rejection.
- New power supply protection: and temperature compensation for improved stability and reliability over wide temperature ranges.
- Surface mount components: for increased resistance to shock and vibration.
- Improved display lighting: for easy reading in a wide range of light conditions.
- Green backlit display (Now Black)
- Frequency range now 12-10 meters.