Newbie would welcome Ferrograph advice - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

silverfox684 · 17th Sep 2019, 3:10 pm

Quote:

Originally Posted by AC/HL

Please raise a separate thread for the Brenell, mixed threads get complicated!

OK sorry

Uncle Bulgaria · 21st Oct 2019, 3:53 pm

My Ferrograph 4A thread https://www.vintage-radio.net/forum/...d.php?t=151194 (lengthy with my many and varied questions) could be of use to you. One 'upgrade' worth doing on the 4A would be worth doing on the 631, as I understand they have fundamental similarities. The user 'Pichacker' on here had the idea which I copied.

I put a 0.1uF capacitor between the grid of V3 and the volume control, with a 470k resistor from the grid to ground so the volume control doesn't vary the grid leak resistance. BillDWVA posted his diagram on the same thread.

21st Oct 2019, 3:53 pm	#22
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,333	Re: Newbie would welcome Ferrograph advice My Ferrograph 4A thread https://www.vintage-radio.net/forum/...d.php?t=151194 (lengthy with my many and varied questions) could be of use to you. One 'upgrade' worth doing on the 4A would be worth doing on the 631, as I understand they have fundamental similarities. The user 'Pichacker' on here had the idea which I copied. I put a 0.1uF capacitor between the grid of V3 and the volume control, with a 470k resistor from the grid to ground so the volume control doesn't vary the grid leak resistance. BillDWVA posted his diagram on the same thread. Last edited by AC/HL; 21st Oct 2019 at 8:53 pm. Reason: Link added