Ranger RCI-2950
Mirage 2950
Sommerkamp 2000DX
Galaxy DX2527

Block Diagram

Adjustment

Reading Point	Adjustment	Description	Value
OSCILLATOR / PLL
J13	L17	VCO-Voltage	2,2 Volt
IC7 Pin 3	L21		1,2 Volt
L61	VC1	RX AM	10.240MHz
IC14 Pin 3	VR21	TX AM	10.240MHz
D45	L27	TX AM	10.6950MHz
D45	L29	TX USB	10.6925MHz
D45	L28	TX LSB	10.6975MHz
IC17 Pin 13	Check	RX AM	5.930MHz
IC17 Pin 12	L23		Maximum on Oscilloscope
IC17 Pin 13	L24 L25		Maximum on Oscilloscope
D116	L19		Maximum on Oscilloscope

RECEIVER
	L8 L9 L11	RF Input
	L12 L13 L14	1st IF
	L3 L4 L5 L6	AM/FM IF
	L7	FM Discriminator (Demodulator)
	L15 L16	SSB IF

TP1	L1 L2	NB/ANL IF




	VR3	AM Squelch threshold
	VR4	SSB Squelch threshold
S-Meter	VR2	RX SSB
S-Meter	VR1	RX AM
TRANSMITTER
	VR11	Bias Driver	10mA
	VC3	Bias Finale

	L47	TX Mixer input (10.695MHz carrier)
	L48	TX Mixer input (From PLL)

	L45	TX Mixer output
	L43	Pre-Driver input
	L34	Harmonic output


	VR7	SSB Modulator Balance
	VR16	SSB Low Power	5 Watt (ALC)
	VR12	SSB High Power	40 Watt (ALC)
	VR15	AM Low Power	4 Watt
	VR13	AM High Power	30 Watt
	VR14	90% AM-Modulation	AMC
Power Meter	VR8	TX 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.

Ranger RCI-2950Mirage 2950Sommerkamp 2000DXGalaxy DX2527

Block Diagram

Adjustment

COMPONENTS

Improved receive gain

Ranger RCI-2950
Mirage 2950
Sommerkamp 2000DX
Galaxy DX2527