Category: Netherlands

I few days ago I asked about the significance of the P, E, B, and G markings on my junkbox Toyo CM 455 kc filter (1969 vintage). PA3BCB — in yet another example of the power of the International Brotherhood of Electronic Wizards — was the first to provide the needed info. And in another example of IBEW awesomeness, KA0LDB noted that the markings are explained in the 1971 RSGB Handbook.

P = Plate = filter input
B = B+ = mixer B+ plus if needed or input ground
G = Grid = filter output
E = Earth = Ground

I like the switched filter arrangement presented above (from the RSGB Handbook); the 2.4 kc bandwidth is great for SSB, but a little tight for AM. I might put in a DPDT switch in the circuit so as to be able to go back to the “broad as a barn door” selectivity provided by just the 455 kc IF cans.

Our book: “SolderSmoke — Global Adventures in Wireless Electronics” http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20