Technology ConnectionsFeb 26, 2024

If you've been watching my videos for a while, you may have noticed this Silvertone radio in the set. It's an AM/FM set from 1952.

I restored it when I was in high school (I think) by replacing its capacitors but never got into the habit of using it since its FM reception was a bit spotty.

Well I finally hooked up a decent antenna to it and while it's still not able to tune in perfectly well, it's been a pleasure to use this again!

Show threadTechnology Connections

Note that the dial is separated between "Standard Broadcast" and "Frequency Modulation" - 1952 is quite early for FM radio and it was a new and weird thing. I've seen slightly-earlier sets which don't even use the same band!

Also interesting, like any tube radio it take about 10 seconds from power-up to produce any sound but on FM, it takes about 5 minutes for it to fully settle in. It's got a whine and lots of distortion at power-up which gradually improves.

Feb 26, 2024 at 5:32pmWeb
Show threadScott JensonFeb 26, 2024
@TechConnectify That's so fun! Thinking about improving the FM reception: if the FM frequency dial is a potentiometer like more modern radios, swapping the old one out for a new one (which would be hidden from view) might give it finer control? Cheating a bit but could be a simple fix...
Show threadTechnology ConnectionsFeb 26, 2024

@scottjenson Looking at the schematic it appears it's using a variable-capacitor just like AM.

There are some notes on FM alignment using a signal generator and scope, but truthfully I think the bigger issue is just that there are two stations very close to each other on the band and they're fighting. Other stations which come in stronger have less of an issue, so I'm guessing that the only *real* fix would be a proper antenna on the roof which... well, not going that far!

Show threadJonny ClarkFeb 26, 2024
@TechConnectify Did you align it properly after re-capping?
Fiddling with the coils could make a world of difference.
Have a look at “Mr Carlson’s Lab” on YouTube for many demonstrations.
Show threadPaul EvansFeb 26, 2024
@TechConnectify Possibly because FM is much more sensitive to local oscillator frequency stability than AM is, so it needs that extra time to really settle into stable temperatures all over. It'd be interesting to see if it still behaves that way after being on a while then a brief off for maybe 30 seconds.
Show threadTechnology ConnectionsFeb 26, 2024
@leonerd Oh, this I already know from unplugging it to move it. It lost its good lock pretty quickly, with the whine coming in as if it had been cold. It cleared up faster than if it truly were cold but it still took a while.
Show threadPaul EvansFeb 26, 2024
@TechConnectify Ahh exciting investigations there. I don't know radio in much more detail but it could make a fun topic for a video with radio folks - Mr Carlson comes to mind.
Show threadSean Boyer 🇵🇸 FREE PALESTINEFeb 26, 2024

@TechConnectify

A fresh set of valves would "fix" that "problem" for you, though, where's the fun in that?!

Show threadMike JohnstonFeb 26, 2024
@TechConnectify Ouu you should film a cold start. I don't think I've heard a tube radio start up like that
Show threadWesFeb 26, 2024
@TechConnectify is it because of how early in the life of FM that it has not so great reception? Or is that something could be improved with better a antenna or powered external antenna?
Show threadPaul McGraneFeb 26, 2024
@TechConnectify The design is quite handsome. If its vacuum tube(s?) needed to be replaced would it be at all possible to find the part?
Show threadTechnology ConnectionsFeb 26, 2024
@pmcg Oh yeah, there's tons of new-old-stock tubes available still. And they were manufactured long into the solid-state era so there are huge stockpiles.
Show threadbillatqFeb 26, 2024
@TechConnectify I’ve noticed that with one of my old tube radios too. There is a feature on (slightly) newer tube radios that compensates for this problem, called Automatic Frequency Control.
Show threadBenjamin WoodringFeb 27, 2024
@TechConnectify I have a Zenith radio from 1946, and it has two FM bands. The 88-108 MHz we all know and love, and 42-48 MHz!