UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

kalee20 · 20th Mar 2008, 2:11 pm

Hi Dom,

Well, the modulation looks good and linear, even if you're not up to 100% yet.

One thing that bothers me, is the Negative Feed Back loop from the detector diodes goes to the cathode follower cathode, which is a low impedance point (I'm assuming that the circuit diagram in post 82 is correct here). So, the feedback to the cathode of the first triode will be dominated by direct AF feedback from the cathode folloer, with the detected AF having negligible effect. That said, the linearity being good is due to you having it inherently right, rather than being 'corrected' by the NFB.

As for naming that tune, sorry, no! (though I did hear one of a man who could name which Beethoven symphony was on a record just by looking at the grooves, with the label covered up)

Thoughts on step-up coils will follow sometime...

20th Mar 2008, 2:11 pm	#85
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,088	Re: AM Micro Transmitter Hi Dom, Well, the modulation looks good and linear, even if you're not up to 100% yet. One thing that bothers me, is the Negative Feed Back loop from the detector diodes goes to the cathode follower cathode, which is a low impedance point (I'm assuming that the circuit diagram in post 82 is correct here). So, the feedback to the cathode of the first triode will be dominated by direct AF feedback from the cathode folloer, with the detected AF having negligible effect. That said, the linearity being good is due to you having it inherently right, rather than being 'corrected' by the NFB. As for naming that tune, sorry, no! (though I did hear one of a man who could name which Beethoven symphony was on a record just by looking at the grooves, with the label covered up) Thoughts on step-up coils will follow sometime...