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President Harry CB-Radio


ALIGNMENT PROCEDURE


RECEIVER PORTION


Test equipment required:
Power Supply: 13,8 VRF Signal GeneratorAF Signal GeneratorOscilloscope
Dummy Load 8 ohm

Preparation alignment:
Channel:19
StepConditionAdjustmentProcedure
1MODE: AM
Mod: 1 kHz, 60%
SSG output: 0dB (0.5mV)
SQ: Min.
L1 L2
L3 L4
Adjust for maximum output reading on the Oscilloscope
2MODE: AM
No Mod.
SSG output: 1000uV
SQ: Min
RT1Adjust so LED 4 lights
3MODE: AM
Mod: 1 kHz, 60%
SSG output: 1000uV
SQ: Max.
RT2Adjust RT2 so that the squelch just breaks.
4MODE: FM
Mod: 1 kHz, +/- 1,5 kHz Dev.
SSG output: 1000uV
SQ: Min.
L6Connect Oscilloscope to TP1 and adjust L1 for 4.5 V +/- 0.2 V reading on the Oscilloscope



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 (Q1) with an 2SC2999 (or similar low noise and high gain transistor) to achieve this improved signal to noise ratio.
Re-Adjust L1 and L2
The gain will improved with more than 6dB with the same signal to noise ratio.