Total posts : 45366
“I was under the impression that the neon bulb went
out when the final amp was tuned properly. (Somebody
gave me bad info, I guess.) This contradicted the fact
that when I was getting the 6 plus watts out on 860 –
the neon bulb WAS at full brilliance.”
The neon bulb is connected to indicate maximum RF energy at peak resonance and will illuminate fully when the plate is tuned properly. It functions opposite of a plate current meter where we want to see a “dip” in the meter indication.
The traditional plate current meter is looking at the tube’s plate current draw. When off resonance, that current is more, and when tuned to resonance, the current is minimum at the resonance point..hence the “dip” in the meter reading.
The neon bulb looks at the output energy from the tuning tank. It sees nothing but RF energy at that output connector, and just like tuning a 3 meter stick with a grain of wheat bulb, the brighter the light bulb illuminates, the maximum RF energy is passing through that bulb, hence tuned to resonance.
Glad to pass on the info! 🙂