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G8BBZ · 5th Dec 2022, 4:16 pm

Hi Erik,
Synchrodyne is quite correct in thinking that the amplifier in your MCU6 is similar to that in the R499. In fact it is the same 20dB amplifier but with a splitter on the output rather than a direct feed to the mixer and without the tuning elements of the R499 amplifier.
There is an AGC loop but this should not come into effect until the input signal is about 500mV. The controlling device is a diode attenuator which is the sandwich unit in the middle of the board.
If you have any problem finding a circuit diagram let me know. I have a diagram but will need to scan it.
Good Luck
Peter G8BBZ

5th Dec 2022, 4:16 pm	#5
G8BBZ Pentode Join Date: Oct 2005 Location: Hebden Bridge, West Yorkshire, UK. Posts: 200	Re: Redifon MCU6B Hi Erik, Synchrodyne is quite correct in thinking that the amplifier in your MCU6 is similar to that in the R499. In fact it is the same 20dB amplifier but with a splitter on the output rather than a direct feed to the mixer and without the tuning elements of the R499 amplifier. There is an AGC loop but this should not come into effect until the input signal is about 500mV. The controlling device is a diode attenuator which is the sandwich unit in the middle of the board. If you have any problem finding a circuit diagram let me know. I have a diagram but will need to scan it. Good Luck Peter G8BBZ __________________ Peter G8BBZ