In alt.home.repair, on Wed, 20 Feb 2019 13:02:17 +1100, "Rod Speed"
<
rod.sp...@gmail.com> wrote:
>micky <
NONONO...@bigfoot.com> wrote
>
>> what makes radios drift from the proper tuning?
>
>The thing that does the tuning moves physically. That's
>only with the old radios tho, not modern digital ones.
Digital radios won't work here. They all afaik have a separate
momentary-on on/off switch.
>> I have radios that I tune and after they play
>> a while the tuning needs to be adjusted.
>
>> This is common, I assume.
>
>No it isnt.
I thought I had at least two radios like this.
>
>> What is happening? Does the vibration make
>> the variable condenser shift a little bit?
>
>Shouldn't do unless is much looser than it should be.
It doesn't seem to be loose.
>
>> Or do the parts get warm and some value changes?
>
>Again, it shouldn't happen with a well designed radio.
I wasn't there when they designed it. ;-)
>
>> Is this more common in AM than FM? or vice versa?
>
>In theory its more likely with AM.
That's good to know.
>> FM has AFC but iirc AM doesn't have that.
>
>That's sort of true.
I know some radios have an AFC switch, so you can get weak stations that
are close to strong stations, but if there is no AFC switch, I thought
all FM radios have AFC anyhow.
BTW. that reminds me of another example of drifting. My Hallicrafters
short-wave (plus medium and long wave) radio made in the 30's I got from
my cousin around 1958. A couple times I heard TV sound on it, even
though TV sound in the 50's and until digital is supposed to be FM and
the radio was AM. Nonetheless, I turned on a TV and found the channel
it was receiving.
And I had to retune every 5 minutes or so to a constantly higher
frequency. Finally after an hour or two, I reached the end of the band.
IIRC I switched to the bottom of the next higher band but I couldn't
find the same transmission.
Yes, the thing was 30 years old but it was certainly well-designed. I
still have the radio and I've only had to replace the AC filter
capacitors. Everything else still works, even though it's about 85
years old now.
>> 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.
>
>They arent all like that. Just replace the radio with a better analog one.
I've bought 2 or 3 radios in the last couple years, but in order to get
88.5 in DC in the kitchen, without having to turn on the wireless
speaker from the computer. (no, for others who suggested the computer,
I'm not going to run the computer for 24/7 for 12 weeks when I can just
run a radio 3 or 4 hours a day. I've been plugging and unplugging a
couple of them making sure which one will stay on the frequency it's set
for, but this takes a lot of time and the questions were designed to
speed things up.)