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

crackle · 1st Oct 2018, 3:51 pm

Hi Ian
I did swap the L1 L2 coils around and the results were the same bad frequency drift.

However although the frequency stability tests have now proved very good with less than 100hz drift over an hour, that is not the end to the problems.
After the last stability tests I connected the audio to find it is very distorted. I believe there is significant FMing and cant seem to stop it.

I think I may take the view you expressed and donate this to the failed experiments pile.

Unless anyone can come up with a cure to the FMing, I wonder if putting the tuned coil back on the OP would help.

Mike

1st Oct 2018, 3:51 pm	#59
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Building the 'Minimod' AM modulator-questions! Hi Ian I did swap the L1 L2 coils around and the results were the same bad frequency drift. However although the frequency stability tests have now proved very good with less than 100hz drift over an hour, that is not the end to the problems. After the last stability tests I connected the audio to find it is very distorted. I believe there is significant FMing and cant seem to stop it. I think I may take the view you expressed and donate this to the failed experiments pile. Unless anyone can come up with a cure to the FMing, I wonder if putting the tuned coil back on the OP would help. Mike