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Ranger RCI-2950
Mirage 2950
Sommerkamp 2000DX
Galaxy DX2527


Block Diagram


Adjustment

Reading PointAdjustmentDescriptionValue
OSCILLATOR / PLL
J13L17VCO-Voltage2,2 Volt
IC7 Pin 3L211,2 Volt
L61VC1RX AM10.240MHz
IC14 Pin 3VR21TX AM10.240MHz
D45L27TX AM10.6950MHz
D45L29TX USB10.6925MHz
D45L28TX LSB10.6975MHz
IC17 Pin 13CheckRX AM5.930MHz
IC17 Pin 12L23Maximum on Oscilloscope
IC17 Pin 13L24 L25Maximum on Oscilloscope
D116L19Maximum on Oscilloscope
RECEIVER
L8 L9 L11RF Input
L12 L13 L141st IF
L3 L4 L5 L6AM/FM IF
L7FM Discriminator (Demodulator)
L15 L16SSB IF
TP1L1 L2NB/ANL IF
VR3AM Squelch threshold
VR4SSB Squelch threshold
S-MeterVR2RX SSB
S-MeterVR1RX AM
TRANSMITTER
VR11Bias Driver10mA
VC3Bias Finale
L47TX Mixer input (10.695MHz carrier)
L48TX Mixer input (From PLL)
L45TX Mixer output
L43Pre-Driver input
L34Harmonic output
VR7SSB Modulator Balance
VR16SSB Low Power5 Watt (ALC)
VR12SSB High Power40 Watt (ALC)
VR15AM Low Power4 Watt
VR13AM High Power30 Watt
VR1490% AM-ModulationAMC
Power MeterVR8TX AM

COMPONENTS

RCI2950 Schematic Diagram
Galaxy DX2527 Schematic Diagram
CX7925B PLL and Programmable Divider
HD10551 Programmable Divider (Divided by 10)
TC5081P PLL
TC5082P Reference Oscillator and Divider
NJM234DP Quad Operational Amplifier
TA7222AP AF Power Amplifier
AN612 SSB Modulator
SO42P Balanced mixer
TA7310P Oscillator, Mixer and Amplifier
uPC1028H FM IF Amplifier and Discriminator
2SC2166 Driver
2SC2312 Finale

Improved receive gain

Quieting of AM reception and improving gain of incoming signals is a common request from radio operators. In the first stages of the HF input 2SC1674 transistor can be found. This transistor is responsible for the amplification of a small detected signals. A problems exist if the transistor itself is noisy as is such the case of the 2SC1674 when compared to other low noise packages. Along with the amplification of the incoming signals is transistor noise. Replacement of this transistor with a higher gain, lower noise transistor greatly improves the signal to noise ratio of your receiver.
We will use an 2SC2999 transistor that has higher gain lower noise characteristic. Replace the 2SC1674 (Q18) with an 2SC2999 (or similar low noise and high gain transistor) to achieve this improved signal to noise ratio.
Re-Adjust L8 and L9
The gain will improved with more than 6dB with the same signal to noise ratio.