Low Signal Strength?

I assembled the two transistor reflex circuit:

I went with this design as I have built it before and it works.

I did model this circuit in the simulator and the Ge diode can be swapped with a silicon (the diode bias current is about 1.8 uA).

Also the audio output increases as a square of the signal strength (interesting?).

Well the performance was poor, I could just make out a local 720 kHz station.

• Had to ground the tuning coil to the circuit ground to stop audio oscillation.
• Plenty of hum from my soldering iron.
• Plenty of transistor noise.
• All the transistor voltages are correct.
• Not much better than a crystal set with a good antenna?
• Swapped my coil with a MW ferrite antenna coil and it was worse?

So I think the circuit is working properly, just low signal?

• Swapped out the Ge diode (1N34A) for a 1N4148 and the performance is about the same (maybe better).

Here is the reflex:

And here is the DIYLC design:

Th only change was to reduce the 100 uF emitter by pass to to 27 uF (25 uF would have been better) to centre the audio gain at 1 kHz.

AlanX