6BJ6 tube in Zenith C845 - AM and FM RF amp?

[Jeffhs]

I have a Zenith C845 radio with a 6BJ6 tube, which is identified on the schematic simply as an RF amplifier. The AM Wavemagnet looks as if it is connected (through a section of the band switch) to the grid of this tube when the band switch is set on AM. Is this amplifier tube used on both AM and FM or just FM? As sensitive and selective as the C845 is on AM (I can hear a 5kW oldies station 35 miles from here, and next to another 5kW station 40 miles distant to boot, fairly well during the day on this set), it wouldn't surprise me if that tube is doing double duty as an AM and FM RF amp.

[wa2ise]

I looked at the schematic in Beitman's 1960 edition, and yes, the 6BJ6 is used for both AM and FM. Also it has two IF stages for Am and FM as well. Should be quite sensitive.

[Jeffhs]

Originally Posted by wa2ise

I looked at the schematic in Beitman's 1960 edition, and yes, the 6BJ6 is used for both AM and FM. Also it has two IF stages for Am and FM as well. Should be quite sensitive.

Thanks for the info. No wonder this radio pulls in stations like a magnet at night on AM and FM (I can hear stations 70+ miles distant on FM just using the built-in antenna, and the AM reception is fantastic as well, day and night, as I mentioned in my post; this set gets AM stations from Cleveland my other sets won't touch--I'm in a weak-signal area for Cleveland radio, AM and FM, especially the former). I have only one other radio with an RF stage on AM (a Zenith TransOceanic Royal 1000-1) and it, too, is every bit as sensitive on all bands as my C845. You can be sure I'll hold on to every one of my Zeniths; as I have mentioned here many times, these radios represent a standard for quality we will never see again, certainly not from Zenith. I knew I became a Zenith aficionado 35 years ago for a reason.

[Chad Hauris]

Most of the older (40's and early 50's) FM radios seem to share the RF amp (and sometimes the converter too) between AM and FM.
Even when Zenith went to the cheaper 12DT8 FM RF/convertor tube they still kept the limiter stage in FM, making for 3 FM IF stages.