Ukw. E. e 1941 RESTORATION WORK
 
Part 3
 
 

 

 

Signal input connected to one of the most difficult places to reach on the receiver: the 1st IF amplifier control grid.

 

 

Front of the receiver with the power on.

 

 

The spectrum analyzer is connected to the control grid of the 2nd IF amplifier tube.

 

 

An input signal of 0.3 mV is amplified to 15mV by the 1st IF stage (50 x amplification factor) (-60 dBm -> -23.45 dBm).

 

 

Now the spectrum analyzer is connected to the input of the detector.

 

 

Special tool to loosen frozen trimmers. Just an insulated wire and the tube of a ball-point pen.

 

 

The whole tool.

 

 

30.3 MHz from the signal generator and a 0.3 mV (-60 dBm ) signal)

 

 

Receiver set to exactly 30.3 MHz

 

 

The detector is receiving the signal, dead-on 3 MHz IF. Very precise tuning.

 

 

 

 

 

 

 

 

Signal input is at the control grid terminal of the 1st IF tube, output reading taken at the control grid terminal of the 2nd IF tube.

 

 

Here we get not a very well balanced resonance curve of the 1st IF stage.

 

 

 

 

 

 

 

 

After tuning the 1st IF stage, the curve improves, but this is the best that it can be tuned.

 

 

Close-up of the new resonance curve of the 1st IF stage after tuning. Central frequency is 3 MHz.

 

 

Input signal is applied to the anode output of the 1st IF, and the spectrum analyzer is connected to the start of the detector tank circuit.

 

 

The receiver sounds EXCELLENT !
 

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