Picked up a '65 Magnavox AM/FM radio at the flea market

[radiotvnut]

It looks like the chassis is R254-01-BB and there is a Sams number 850 on that number.

BTW, I'm probably going to open this up again and replace those black electrolytics. I've seen several of those crack and open.

You know, not only are tube radios getting harder to find. These solid state sets from the '60's are not as easy to come by as they were just a few years ago and may become the next "collectible" for younger generation radio collectors. Radios of this vintage (both tube and SS) used to be common at places like the Salvation Army and yard sales. Now, you're lucky (at least in my area) to find anything older than an '80's LED clock radio. I did pick up an early '70's cheap plastic Zenith Korean built AM/FM clock radio at the SA for $1. The boss was going to give it to me when I discovered it didn't work; but, I handed him $1 anyway. I cleaned the controls and it plays about as good as any other cheap radio. I'll probably end up giving that one away.

[wa2ise]

I remember those hot chassis SS sets, usually a hogh voltage audio output stage, with an output transformer quite similar (if not the same, usually smaller) to those in tube sets. The rest of the set ran on the more usual 10V or so found in transistor radios.
typical schematic.
GE used to get that by using the output audio transistor's emitter. They biased this transistor so it would yield about the before mentioned 10V, after the emitter follower audio was filtered out. Mostly an emitter resistor bypass cap. Other designs just dropped the high voltage B+ thru a power resistor to get the 10V, along with some additional filtering caps. I'd estimate that these sets were made from around 1965 to 1973 or so, then digital clock radios came out that used small power transformers for the clock circuit, and might as well use that to run the radio part as well. By then, it all came from Asia...

[radiotvnut]

Originally Posted by wa2ise

I remember those hot chassis SS sets, usually a hogh voltage audio output stage, with an output transformer quite similar (if not the same, usually smaller) to those in tube sets. The rest of the set ran on the more usual 10V or so found in transistor radios.
typical schematic.
GE used to get that by using the output audio transistor's emitter. They biased this transistor so it would yield about the before mentioned 10V, after the emitter follower audio was filtered out. Mostly an emitter resistor bypass cap. Other designs just dropped the high voltage B+ thru a power resistor to get the 10V, along with some additional filtering caps. I'd estimate that these sets were made from around 1965 to 1973 or so, then digital clock radios came out that used small power transformers for the clock circuit, and might as well use that to run the radio part as well. By then, it all came from Asia...

I remember seeing a small GE red LED clock radio with a transformerless "hot chassis" power supply. I know this radio wasn't older than the '80's and it could have been from the early '90's. I was shocked to see such a new radio using this type of power supply. The early '70's Zenith Korean set I mentioned also has this type of power supply.