Quote:
Originally Posted by wa2ise
Answer is yes. The pilot lightbulb is wired in parallel with a portion of the 35W4 rectifier heater. Off the hot side of the incoming powerline are connected the pilot light and the 35W4 heater portion mentioned above. Then the pilot light and heater tap in turn connects to the 35W4 rectifier plate. Thru the bulb and heater portion is about 300ma average of current, 150ma for the heater string, and the rest feeds the rectifier and in turn becomes the set's B+. The heater portion will get unhappy with all the 300ma. I think Radio Shack still sells #47 bulbs.
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This is all well and good, but I am much more interested in why the radio doesn't pick up more stations than it does in the daytime (as I mentioned, it only gets two stations, and there is no reception below about 800 kHz). I seriously doubt there's anything wrong with the radio if it gets all sorts of stations after sundown, but if this is the case then I would think I'd be hearing every major Cleveland station in daylight hours as well as the two I mentioned (this area has about a dozen AM stations, not counting small low-power ones, one of which went silent about five years ago, in suburbs and small-town "exurbs" which are not considered part of the metropolitan area). I am thinking just about every paper capacitor in my set is bad, since the H511 series was introduced in 1951, sixty-plus years ago.
I also mentioned a Zenith AM-shortwave battery set (farm radio?), 1952 vintage, similar in appearance to the H511. I spent literally hours last night on Google and even eBay looking for information on it (I am interested in this model because of its similarity to the H511), but couldn't find anything. Were these radios any good on shortwave or just so-so? I would think the latter, since the radio was primarily designed for AM broadcast reception.
Also, what types of batteries did this radio use, and where were they stored inside the set? The cabinet doesn't look anywhere nearly big enough for the large 90-volt B battery needed for the plate supply or the smaller batteries needed for the filaments. As large as the H511 cabinet is, it almost certainly isn't big enough for a combo AB battery pack either. The chassis sits on the floor of the cabinet with no space, that I can see anyway, for batteries underneath it. Unless the battery-powered AM-SW version's cabinet is actually larger than that of the line-operated H511s, I cannot imagine where the batteries would be stored. Having a large battery pack sitting alongside the radio wouldn't settle well with most people, unless the batteries were in a separate case that could be hidden under the table on which the radio sits.
Also, the schematic you included with your response is not specifically for the H511. I realize that diagram is for generic 5-tube AM radios (commonly known as AA5s), but is it close enough to the H511 circuit design as to be usable with the latter? I am asking because the H511 has at least one circuit refinement most AA5s do not have -- namely, a tone-compensation network in the audio stage, before the output tube. This probably has no bearing on the configuration of the power supply (when you've seen one AA5 power supply, you've seen them all, except for those weird series-parallel arrangements sometimes found in high-end sets; I have a Zenith MJ1035 with such a filament configuration), but I mention it as a point of interest.
Thanks much.