I was listening the radio this morning on my stereo when I needed to unplug it to use that outlet. So I unplugged it and plugged it into the outlet directly above it. What was weird was that when to radio came back on it was on a different station. The tuner is analog and changed via a knob. It had not been moved. When I retuned the station I had been listening to it came in clearer also. Can anyone offer an explanation why this happened?
Geeze, I dunno. Do you have ghosts?
The only explanation I can think of off-hand is the following:
- The power supply (and possible some other circuits) remain powered when you turn the unit “off.” Assuming this is so, many components in the radio have been powered for months or even years.
- By unplugging it, and then plugging back in, you inadvertently “reset” a component. This could be anything, but my guess would be a diode, transistor, or even an electrolytic capacitor. (Perhaps the cap was leaking, and powering it down/up fixed the leak.) The “reset” could be due to a hypersensitive electrical and/or thermal characteristic of the component.
Just a WAG.
Is it a clock radio or other small tabletop model?
Many of these use the power cord as the FM antenna, also. When you changed outlets, you changed the position and the shape of the FM antenna, and thus changed its resonant properties.
Resonant properties of the tuning and superheterodyne circuits also change during the transition from off to on. The components aren’t being “reset” - it’s just that the circuit behaves differently when it’s in the middle of being energized. Many components (transistors, diodes, etc.) are nonlinear and their behavior can be completely different at low and intermediate voltages.
These two effects can combine to “fool” the tuning circuit to “lock” onto a station closely neighboring the one that you tuned to when all the components were in steady state. This is even more likely when the new station is a much more powerful transmission than the station you originally selected. And once the tuner locks onto a station, it will generally stay locked on until something causes the resonant frequency of the tuner to change.
Other things besides moving the antenna and cycling the power can change the tuner’s resonance. Most commonly, temperature is the culprit. I have a clock radio that is fairly sensitive to changes in temperature. I listen to a Rock station that is immediately adjacent to another very powerful Latin broadcast on the dial. If I tune into my station during a warm day, and then leave the windows open and let the room cool off at night, the clock radio will “retune” and lock onto the Latin station - even while it’s ON.
So, if you want to avoid the problem in the future, 1) use an external antenna and secure it so it does not inadvertently change shape or orientation, 2) leave it on all the time, and 3) keep it in a temperature controlled environment.