UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Building the 'Minimod' AM modulator-questions!

crackle · 28th Sep 2018, 10:10 pm

I think once the correct adjustment point of L1 is found the frequency would be pretty stable, or at least stable within 1kHz of the desired frequency which would probably not be noticed too much.
But the problem is adjusting L1 to try and get the desired frequency is like trying to adjust an old clock with a pendulum on a piece of elastic. The slightest touch of the coil slug sends the frequency rocketing up or down, then you have to wait an hour for it to settle back into its groves.
I know it sounds daft, but I am convinced this is what is causing my problem.
Thanks for the advice everyone, and thanks Nick for doing those tests.
Mike

28th Sep 2018, 10:10 pm	#49
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Building the 'Minimod' AM modulator-questions! I think once the correct adjustment point of L1 is found the frequency would be pretty stable, or at least stable within 1kHz of the desired frequency which would probably not be noticed too much. But the problem is adjusting L1 to try and get the desired frequency is like trying to adjust an old clock with a pendulum on a piece of elastic. The slightest touch of the coil slug sends the frequency rocketing up or down, then you have to wait an hour for it to settle back into its groves. I know it sounds daft, but I am convinced this is what is causing my problem. Thanks for the advice everyone, and thanks Nick for doing those tests. Mike Last edited by crackle; 28th Sep 2018 at 10:19 pm.