I have a clock-radio on my nightstand that, 365 days a year, is tuned to the same public radio station. Except that in the middle of the summer, for some reason, the tuning goes all wiggy, and changes without human intervention.
This is a problem, because it’s my alarm clock, and the gentle hiss of static between stations is not as effective at waking me up as the Morning Edition fanfare.
I think it’s actually changing during the day, because I checked last night before bed and I was getting static, and tuned it to a station that was playing something orchestral . . . which turned out, this morning, to be a Christian station. Ugh. What a way to wake up.
It’s the kind where you turn a knob, not a digital tuner or anything.
I have a couple half-assed hypotheses:
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This is the time of year when the bedroom experiences the greatest temperature swings. We don’t have air conditioning, so in the day it gets into the 80s, at least, and at night it gets down into the lower 70s or (blessedly) upper 60’s. Perhaps thermal effects are changing the properties of the resistors, capacitors, etc. in the tuner so that the resonant frequency drifts, or thermal expansion and/or contraction are making the knob to move physically.
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Another, nearby station (99.7 MHz) does weird stuff in the summer. I listen to it often in the car, and I think they turn their transmitter (or something?) this time of year, because suddenly my reception gets really bad. It comes back around October. The station I tune the clock-radio to is at 100.9, so maybe there’s some kind of interference thing happening with the other station? I dunno.
For completeness’ sake, I should probably mention that this is one of those “atomic” clocks that recieves the signal from the atomic clock in Boulder and automagically sets itself to the right time, but I don’t think that has anything to do with it.
however, if that’s the whole story, then shouldn’t the frequency be directly relatd to temperature, e.g. if it’s 70 degrees in my room this morning, I wake up to stack, so tune to 100.9, even if frequency drifts through the day, when it’s 70 degrees in my room tomorrow morning, shouldn’t the radio be tuned again to 100.9, instead of off in la-la land between stations? That’s what makes me suspect that part of the problem might be mechanical, so that in the heat of the day, the parts expand, and something gets out of whack somewhere.