03-17-2021, 10:50 AM
|
|
VideoKarma Member
|
|
Join Date: Jul 2010
Posts: 7,562
|
|
Quote:
Originally Posted by Jeffhs
I had an Arvin AC-DC 4- or 5-tube radio, model 540T (I'm not sure anymore how many tubes it had) years ago. It was housed in a green metal cabinet and had an external antenna terminal on the back cover, with a short wire antenna permanently connected to the antenna input circuit. It worked well enough for me (I lived in a Cleveland suburb, 15 miles from the city, at the time), but I was not too pleased with the fact that it was a hot-chassis set in a metal cabinet. The external antenna terminal was isolated from the chassis by a small capacitor, of course, but it could still be a shock hazard if that capacitor were defective (leaky), and could blow the line fuse if said capacitor were shorted. I remember being shocked once (only once) by this radio when I accidentally touched the chassis and a grounded metal gas stove in the kitchen at the same time; believe me, an experience like that will teach you a lesson you will never forget!
However, I now live in a small town some 45 miles from the local AM stations in Cleveland, so this radio probably wouldn't receive many or even most of the smaller ones (5kW or less; there were and still are a few of those in this area) very well during the day, and probably not at all after dark when the stations change their antenna radiation patterns to favor the immediate Cleveland area. This is probably, even likely, why this particular set had an external antenna terminal. However, one had to be very careful not to touch that terminal and a grounded metal object at the same time, for reasons I mentioned earlier. This kind of design could well be a death trap, which is why I am glad AC-operated solid-state radios are no longer designed this way; there is almost always a small transformer used to power the chassis. The only way this arrangement could present a shock hazard would be if someone deliberately touched the AC input terminals on the transformer or, of course, if the power cord itself were frayed or otherwise damaged.
|
Arvin made those radios by the million, many of them badged "Silvertone", Sears private label.
The chassis and metal cabinet was isolated from the line by a .05 cap and a 330K ohm resistor. The isolating capacitor on yours was probably leaky, due to age and it was a paper capacitor.
|
Hybrid Mode
