Most of the 12XYZ tubes (12AX7, 12AU7, 12AT7, etc.) have a center tapped filament, which may allow for transmit/receive functionality.

Dave Rossetti
410-279-0226 mobile
On Dec 6, 2024, at 8:22 PM, Hubert Miller <[email protected]> wrote:




Sent from my Galaxy
I think maybe the 3A5 is unique in the separate filaments. The 12xyz tubes have the one filament heat both cathodes, isn't that right ? 
The QST article, maybe 1940, used a triode - pentode. Of course, the pentode section becomes the receiver. 
This makes me remember a Hallicrafters novice radio where the ? 35L6 ? switched from audio out to crystal oscillator. Also the "Mighty Mite" another beginner set with a dual use ? 35L6? output tube. I have only heard of one Mite existing. 
-Hue Miller



ARC5 mailing list
Home: http://mailman.qth.net/mailman/listinfo/arc5
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]

This list hosted by: http://www.qsl.net
Please help support this email list: https://www.qsl.net/donate.html