Balun works - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

SteveCG · 12th Aug 2014, 9:59 am

Correct me if I'm wrong but a 75 unbalanced coax source can be connected to a 300 Ohm balanced input with correct impedance matching if the inner of the 75 ohm coax goes to one of the 300 Ohm inputs and the outer of the coax is connected to the earth/chassis at the tuner input. (a 2 to 1 turns ratio giving a 4 to 1 impedance ratio)

G8HQP Dave · 12th Aug 2014, 5:54 pm

Yes, provided that the radio has a centre tap on whatever is implementing the 300 ohm input. This is likely, but not guaranteed.

12th Aug 2014, 9:59 am	#21
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Re: Balun works Correct me if I'm wrong but a 75 unbalanced coax source can be connected to a 300 Ohm balanced input with correct impedance matching if the inner of the 75 ohm coax goes to one of the 300 Ohm inputs and the outer of the coax is connected to the earth/chassis at the tuner input. (a 2 to 1 turns ratio giving a 4 to 1 impedance ratio)

12th Aug 2014, 5:54 pm	#22
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: Balun works Yes, provided that the radio has a centre tap on whatever is implementing the 300 ohm input. This is likely, but not guaranteed.