03-07-2006, 09:16 AM
This aerial system is a dipole with a matching transformer to a twited-pair (balanced) lead-in to help eliminate local noise pickup. See my site: http://www.philcorepairbench.com/mystery/40-6112.htm
The "Foreign Tuning System" is an antenna switching arrangement (part of the bandswitch) for selecting either a balanced feed (SW, All-Wave) and unbalanced (local BCB), depending on which band was selected on the radio.
With the Philco High-Efficiency Aerial in place, SW bands enjoyed less noise pickup (due to balanced lead-in). In BC mode the antenna looks like a longwire for local pickup. Today, there is more ambient and household electrical noise than in 1937-38, so an un-shielded twisted-pair lead-in used today would not totally "cure" interference pickup by the antenna system. Back then only motors and "electrical machinery" and an occasional passing streetcar were the major sources of noise.
The "Foreign Tuning System" is an antenna switching arrangement (part of the bandswitch) for selecting either a balanced feed (SW, All-Wave) and unbalanced (local BCB), depending on which band was selected on the radio.
With the Philco High-Efficiency Aerial in place, SW bands enjoyed less noise pickup (due to balanced lead-in). In BC mode the antenna looks like a longwire for local pickup. Today, there is more ambient and household electrical noise than in 1937-38, so an un-shielded twisted-pair lead-in used today would not totally "cure" interference pickup by the antenna system. Back then only motors and "electrical machinery" and an occasional passing streetcar were the major sources of noise.
Chuck Schwark,
The Philco Repair Bench
[Image: http://www.philcorepairbench.com/images/philog3tiny.gif]
http://www.philcorepairbench.com
