what makes radios drift from the proper tuning?

what makes radios drift from the proper tuning?
I have radios that I tune and after they play a while the tuning needs to be adjusted.
This is common, I assume.
What is happening? Does the vibration make the variable condenser shift a little bit? Or do the parts get warm and some value changes?
Is this more common in AM than FM? or vice versa? FM has AFC but iirc AM doesn't have that.
I am going away for a while and I want to use timers to turn on lights and also a radio, but some radios get so far out of tune, even when I don't touch them, that almost nothing comes out, and I'd like the radio to continue to play the station clearly.
I can't use radios with electronic tuning because with a timer that turns the power off and on, when it comes on, the radio doesn't start until someone pushes a button.
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On 2/19/2019 3:58 PM, micky wrote:

Yep, that's a problem. But you can't do much about it.

You could leave the electronic tuning radio on all the time and use an external speaker switched by the timer.

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On Tuesday, February 19, 2019 at 7:26:40 PM UTC-5, Mike wrote:

Usually the tuning issue is mostly with weaker stations. If the issue is just using it as a source to make it look like someone is home, unless the radio is a real POS, you;d think that you could tune it to a strong local station and it would work. I certainly had all kinds of radios over the years that stayed tuned to all kinds of stations AM and FM without a problem. Micky is in MD too, right? Should be plenty of local, strong stations.
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In alt.home.repair, on Tue, 19 Feb 2019 16:54:36 -0800 (PST), trader_4

I didn't pay much attention until just now, but I think the common one was 88.1, which is pretty strong. I'd leave one radio on and even in the length of time it takes to take a bath, 30 minutes, the sound would get gnarled.
On my 250 dollar radio, 88.1 in Baltimore got lower in volume about a year ago, and 88.5 which is all the way in DC is now louder and probably more clear. (But that one has electronic tuning, have to push a button to get sound.)
BUT, none of the radios I actually use except the car radio can get 88.5, because it's all the way in DC. Yet on the good radio it comes in better.
I guess I figure that if it drifts on a somewhat weak station, it will drift on any station. Is that where AFC will make a difference? On FM only but not AM? (and with enough time it will drift so far it won't sound like a radio station.)

Yes, just for making noise it doesn't have to be a station I would actually listen to. It could even play hiphop. it's a pain for testing however, having to listen to some of that.
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wrote:

Likerly a resistor or capacitor in the tuning tank circuit or PLL is temperature sensitive causing the drift
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In alt.home.repair, on Tue, 19 Feb 2019 16:26:34 -0800, Mike

So are you saying that AM is worse than FM, because AM has no AFC?
Or AM and FM are both a problem?

Maybe for next time. I don't have one of those.
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On 2/19/2019 5:38 PM, micky wrote:

No, I'm not saying that. I'm saying that, if all the devices you have to make noise are insufficient, you need different devices. Fixing ANY of them is gonna be far more time consuming than obtaining a speaker or mp3 player or a computer that can turn itself on whenever you program it...like all of them do...somehow.
Turn on the mp3 player and let it loop 24/7. The switched lights should be sufficient to fool anybody who'd be fooled by such devices.

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@bigfoot.com says...

Usually AM will be worse because there is no AFC. Most FM radios will have AFC.
Just turn the radio on and let it play for half an hour before putting it on a timmer.It may come on off frequency ,but as it warms up it should drift to the station.
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Ralph Mowery wrote: "... but as it warms up it should drift to the station. "
From which 'side' of the selected station?
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snipped-for-privacy@gmail.com says...

My thought was to turn on the radio wait about half an hour and find a station. Then leave it there and put it on the timmer. It will come on and in a short time drift back to that station.
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Ralph Mowery wrote: "
My thought was to turn on the radio wait about half an hour and find a station. Then leave it there and put it on the timmer. It will come on and in a short time drift back to that station. "
Sorry if I was't clear: if the tuning drifts, say on a slide-rule analog dial, it will be to the left or right of the desired station.
Have you noticed a tendency to drift below(to the left of) or abovr(to right of)the selected station?
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In alt.home.repair, on Tue, 19 Feb 2019 23:17:21 -0500, Ralph Mowery

That sounds good.
Thanks everyone.
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On 2/19/19 6:58 PM, micky wrote:

Do you have a TV with cable access ? If so, does the cable service have music only channels ? Our Xfinity/Comcast does.
Have your timer turn the TV on/off. Leave cable box set to music channel.
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In alt.home.repair, on Tue, 19 Feb 2019 20:54:12 -0500, "\"Retired"@home.com wrote:

This is not as bad as some seem to have gleaned. This method will work, I just wanted to shorten the time it would take me to find the right radio, the right AM or FM band, and a a good station

No, I don't.

It doesn't have to be music. Burglars don't know my tastes. It just has to be a radio or tv station.
BTW, I've been on 3 trips in the last 2 years totaling 160 days and no one has bothered my house at all. I just want to keep it that way.

If the timer provides power to the TV, someone has to press the TV's on/off button.
Thanks.
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On 2/19/19 11:27 PM, micky wrote:

Life is a constant battle of keeping burglars out of my house and democrats out of my paycheck. Democrats suck!
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On 2/19/19 10:27 PM, micky wrote:
[snip]

I have found this to be true with larger TVs, but not with smaller ones (the largest I have without the problem is 22-inch). However, they don't put this on the box and any salespeople will probably NOT be able to help.
Possibly a very expensive TV might have an option for this.

--
Mark Lloyd
http://notstupid.us/
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"\"Retired"@home.com Wed, 20 Feb 2019 01:54:12 GMT in alt.home.repair, wrote:

While a timer could be used to turn a modern tv off, it's highly doubtful you can turn it back on with the timer. All tvs I've seen in the past say, ten years have standby modes. If you connect them to AC, they don't just turn on, you still have to press a button. You can't really tape the button down or short it out in most cases either, because it'll most likely do one of two things if you did:
(a) stay off all the time (b) turn on, but go back to stand by a short time later, because you aren't letting go of the button
I seriously doubt it would come out of standby and remain on if you the button remained pressed. You'd need an older tv that had a real power switch that actually did turn it on or off, not one with a standby or sleep mode.
--
Radioactive halibut will make fission chips.

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wrote:

Or a "smart" tv with auto turn on - - - does not need to be a real "smart tv" with internet connectivity - just power saver or timer start - or some that revert to power on on power up. (just like some computers) My ancient Panasonic Viero PT700 has the capability to start and stop by itself
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Clare Snyder posted for all of us...

To OP: As i do see Micky posts.
My Comblast DVR has audio outputs on it. Hook it up to a sound bar and use the soundbar control. The DVR does not switch the soundbar on/off.
--
Tekkie

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Tekkie® posted for all of us...

e

e

Do NOT see Mickys posts.
--
Tekkie

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