UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Marconi TF2431 Counter Service Manual / Schematic

brian_mk · 28th Jul 2020, 4:30 pm

I spoke too soon.

After fixing the AGC detector fault, I am still seeing HF parasitic oscillations / ringing in the wide band amp and the schmitt trigger.
Whatever the problem is, the result is false counter readings.
It appears to depend to some extent on the input signal and the AGC gain setting. Without a service manual I'm not sure how to set the AGC gain trimmer.
I haven't figured out if this is a design problem or a fault condition.
I'm still investigating.

28th Jul 2020, 4:30 pm	#10
brian_mk Tetrode Join Date: Mar 2015 Location: Milton Keynes, Buckinghamshire, UK. Posts: 91	Re: Marconi TF2431 Counter Service Manual / Schematic I spoke too soon. After fixing the AGC detector fault, I am still seeing HF parasitic oscillations / ringing in the wide band amp and the schmitt trigger. Whatever the problem is, the result is false counter readings. It appears to depend to some extent on the input signal and the AGC gain setting. Without a service manual I'm not sure how to set the AGC gain trimmer. I haven't figured out if this is a design problem or a fault condition. I'm still investigating.