BCB Antenna Ideas - Printable Version
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RE: BCB Antenna Ideas - RodB - 08-01-2022
I remember seeing "standpipes" downtown. Thats a long wire!
RE: BCB Antenna Ideas - Chas - 08-01-2022
https://en.wikipedia.org/wiki/Standpipe
RE: BCB Antenna Ideas - Simon Wa3uay - 08-02-2022
I'm thinking the Standpipe referred to would have been a plumbing vent, like the modern PVC vent from the bathroom. Or perhaps from a boiler furnace steam system?
RE: BCB Antenna Ideas - mikethedruid - 08-02-2022
The "standpipe" in old houses was the main plumbing drain, usually 4" iron in those days, which went from up above the roof as a vent, to the basement, and then connected to the sewer or septic system. The various plumbing drains in the house connected to it, from toilets and sinks. These days they use PVC for this.
RE: BCB Antenna Ideas - Simon Wa3uay - 08-02-2022
I would imagine that the Standpipe may have attracted lightning, but back then they also used lightning rods on the roof, which may have been the reason.....POW!&$** there goes the radio Martha!
RE: BCB Antenna Ideas - mikethedruid - 08-02-2022
Up until this century, virtually all house plumbing was done with either iron or copper piping. Many homes also used either hot water or steam heat with radiators. It was common to use a copper plated steel strap clamped around a radiator valve as your radio ground, or, to clamp the ground to one of the cold water pipes in the cellar. One could also buy ground rods from the hardware store, and drive them into the ground close to where your antenna lead would come into your house, and use that ground for the lightning arrestor as well as continuing on to the radio. My own outdoor antenna is connected just that way.
RE: BCB Antenna Ideas - GarySP - 08-02-2022
I remember as a kid my dad converting our home to 3-wire grounded outlets. Fishing 14 gauge copper wire from the boxes through the walls to the closest cold water pipe and a strap clamp. Take care and BE HEALTHY! Gary
RE: BCB Antenna Ideas - RGK20m3 - 08-02-2022
I don’t see how the 38-690 antenna input is balanced; although it has the 3 terminals (red, black, and ground), the black and ground are connected together and are connected to chassis ground. This is how my unit is wired, and is confirmed on the schematic. The chassis is grounded for RF purposes through the Bakelite block line condenser to whatever side of the line that is the neutral (or external ground).
So explain how any balanced antenna would work (including the Philco) without a balun.
RE: BCB Antenna Ideas - RGK20m3 - 08-02-2022
According to the NEC, if you have a ground rod for your antenna system, it needs to be bonded to the service entrance ground rod. This may save your receiver (and residence) in case of a nearby lightning strike, as a considerable potential difference will exist between unbonded ground electrodes.
RE: BCB Antenna Ideas - Chas - 08-03-2022
https://en.wikipedia.org/wiki/Dipole_antenna
RE: BCB Antenna Ideas - RGK20m3 - 08-03-2022
The Philco 40-6112 kit photo that I found online appears to include a balun, so I guess that answers part of my question.
https://www.worthpoint.com/worthopedia/1938-philco-high-efficiency-aerial-3762728747
RE: BCB Antenna Ideas - Chas - 08-03-2022
Quote:From what I found on the internet..."This aerial system was a simple 1/2-wave dipole with a balanced feed-line. The kit included all wire and lead-in parts and a lightning arrestor. The aerial was designed for Philco radios that had balanced antenna terminals. The balanced feed system helps eliminate local noise and interference."Balun", where?
RE: BCB Antenna Ideas - mikethedruid - 08-03-2022
For a BCB antenna, 1/2 wave (for 900 kilohertz, the middle of the range) woulds be 333 meters / 2, or about 167 meters, even 1/4 wave would be about 84 meters, both pretty long. If the antenna was a "simple dipole" I would like to know what the length of each side was, because that would tell what the antenna was actually tuned to. To tune it for BCB, but keep it to a reasonable size, I would imagine a loading coil for each leg was probably used.
RE: BCB Antenna Ideas - RGK20m3 - 08-03-2022
Picture shows a silver can (balun?), lightning arrester, insulators, and the cloth covered lead in. My understanding is that a balun is best placed at the mid point of the antenna run on a dipole, but happy to be corrected if wrong.
Not a balanced antenna input on the 38-690 as far as I understand, so would make sense that the kit would include a balun. The lead in would act like a 75 ohm coax.
Silver can could be a loading coil for each leg.....
RE: BCB Antenna Ideas - RGK20m3 - 08-04-2022
Philco 40-5922 kit includes “Aerial, aerial transformer, and lead in assembly “- transformer being a balun I assume.