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Title: Overmodulation gadget Post by: WA4WAX on January 16, 2023, 04:31:31 AM From the old days.
https://worldradiohistory.com/Archive-All-Amateur/XTAL-for-the-Amateur/XTAL-1949-02.pdf Title: Re: Overmodulation gadget Post by: K9MB on January 16, 2023, 12:18:03 PM From the old days. https://worldradiohistory.com/Archive-All-Amateur/XTAL-for-the-Amateur/XTAL-1949-02.pdf I used to like magic eye tubes on equipment . My 20A had one. I like Don Chester’s Over mod sensor. It uses an 866. Simple and the blue glow of an 866 is cool! http://amfone.net/Amforum/index.php?topic=27557.0 Title: Re: Overmodulation gadget Post by: Opcom on January 20, 2023, 12:42:24 AM Some very old versions of 866 and 872 have an unshielded filament so that the beautiful flashing glow can be better enjoyed. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
If using a standard HV recitifier of any sort, other interesting gas-filled devices can be put in series with the rectifier for a brighter or more unique flash on overmodulation. The 0A4G octal gas triode tube is one. It usually has a clear top, looks like a fully lit eye tube when on, and is either orange or violet depending on the gas. A small fluorescent lamp can also be used in series with the HV rectifier. No filament power required by the lamp. A phosphorless one (UV) is hard to find but a regular 4 watt (F4T5) white flourescent tube gives a bright flash that's easily seen. A voltage bias similar to keep-alive is needed because gas tubes have a 100-150V striking voltage. Not saying it's efficient but it is pretty and worth a few experiments. |