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

Ian - G4JQT · 26th Oct 2018, 5:28 pm

Just a reminder to anyone thinking of building a Minimod, there are some minor circuit changes since the article was published in the BVWS Bulletin, Winter 2011.

C12 can be reduced to the slightly easier value to source of 470nF rather than the original 680nF, with no signigicant change in bass response.

Q1 FET is now BF256 as it has more predictable performance than the original 2N3819. Note the pinouts are different, although David's layout takes this into account.

R2 can be reduced from 10k to 3.3k or 2.2k for very slighty better signal output with the changed FET.

Ian

26th Oct 2018, 5:28 pm	#69
Ian - G4JQT Octode Join Date: Jun 2004 Location: Reading/Fakenham, UK. Posts: 1,323	Re: Building the 'Minimod' AM modulator-questions! Just a reminder to anyone thinking of building a Minimod, there are some minor circuit changes since the article was published in the BVWS Bulletin, Winter 2011. C12 can be reduced to the slightly easier value to source of 470nF rather than the original 680nF, with no signigicant change in bass response. Q1 FET is now BF256 as it has more predictable performance than the original 2N3819. Note the pinouts are different, although David's layout takes this into account. R2 can be reduced from 10k to 3.3k or 2.2k for very slighty better signal output with the changed FET. Ian