Restoring a Philco 38-7 code 121. The schematic doesn't show the external antenna which I understand is a one of the early "loop" arrangements inside the console cabinet. The terminals are marked Red, Black, and Grd. Anyone have the Philco instructions or a diagram of the setup?
Thanks, John
The 38-7 never had a loop antenna.
The RED and BLK terminals were designed for use with the Philco High Efficiency Aerial, a special dipole supplied with 1937 and 1938 model Philcos. It used a two-wire transmission line from antenna to radio. One of the two wires - the red wire - connected to the RED terminal; the other (black) connected to the BLK terminal.
In lieu of the Philco aerial, you may use a longwire antenna connected to the RED terminal; in which case there should be a jumper between the BLK and GND terminals.
The answer I was looking for. Thanks Ron.
I'm working on the same radio at the moment and recapped the whole thing. I'm still working through resistors. I finally got sounds out of it, but they're pretty staticky and weak reception. Would not grounding the black to ground make any difference in receiving stations?
Thanks
Bernie
You can try it both ways, but with a long wire antenna, more often than not, grounding the "GND" terminal either makes reception worse or introduces plenty of buzzing noise. A lot depends on the quality of your ground system.
Rob