President Harry CB-Radio

Search: The Web Tripod

# President Harry CB-Radio

## ALIGNMENT PROCEDURE

### RECEIVER PORTION

Test equipment required:

Power Supply: 13,8 V | RF Signal Generator | AF Signal Generator | Oscilloscope
| Dummy Load 8 ohm |  |

Preparation alignment:

Channel: | 19

Step | Condition | Adjustment | Procedure
--- | --- | --- | ---
1 | MODE: AM Mod: 1 kHz, 60% SSG output: 0dB (0.5mV) SQ: Min. | L1 L2 L3 L4 | Adjust for maximum output reading on the Oscilloscope
2 | MODE: AM No Mod. SSG output: 1000uV SQ: Min | RT1 | Adjust so LED 4 lights
3 | MODE: AM Mod: 1 kHz, 60% SSG output: 1000uV SQ: Max. | RT2 | Adjust RT2 so that the squelch just breaks.
4 | MODE: FM Mod: 1 kHz, +/- 1,5 kHz Dev. SSG output: 1000uV SQ: Min. | L6 | Connect 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.

Search: |  | The Web |  | Tripod |

Share This Page

Report Abuse

Build a Site

Browse Sites

|  |  |  | « Previous | Top 100 | Next » |