This review of Carrier Current as an outlet medium has come to these impressions:
The matching between transmitter and wiring is extremely critical and requires careful engineering precision;
Measurement of field strength in the field around power lines is beyond reach, as usual for poor part 15ers;
Filtering AC hum is important, and mixed in with the matching process;
It's fair to say that carrier current radio is intended to reach radios near the house wiring, but not radios out in open space.
But here is one question left un-answered. What is the advantage of Neutral Loading over the normal way of loading?
No need to answer my Neutral Loading question. The subject is fully explained in the Design paper linked by SCWIS.
Talking about carrier current draws attention to the lowest AM frequencies, and a check of 15.219, the rule most referenced for Part 15 installation, covers the frequencies 510 kHz to 1705 kHz. Many radios include 520 as a usable channel. A check of Radio Locater shows no stations licensed for 520.
This may be an important observation here, where 530 has TIS and 550, 590 and 630 are full power. 520 might be the perfect home for a new station.
Except I no one I know can receive on 510 or 520.
There is some sort of station here on 512 kHz which identifies with tone morse code as OS. I am near an airport owned and operated by The Ohio State University and I suspect this is some sort of aircraft navigation signal. I did a quick search and found "The frequencies 30-535 kHz are used for maritime communication and navigation and for aircraft navigation. "
So, if this is the case be very careful operating in the low AM range.
Neil
And yet FCC Part 15.219 is marked - 510 to 1705 kHz
At the same time, Part 15.221 is marked - 525 to 1705 kHz
Could the FCC have made a typo?
Dear Part 15 people. It pays to actually read the FCC Rules before saying too much.
15.219 (510 - 1705 kHz) expressly applies to intentional radiation from the now famous 3-meter antenna.
15.221 (525 - 1705 kHz) applies to carrier current and leaky coax, as well as the special radiation provisions for educational institutions.
Small mistakes lead to big oil spills.
The assumption exists that LPB does not exist. But why can't the story be found?
I checked Radio World and Broadcast Engineering for articles about the end of LPB, but there is no mentioned at all. Perhaps LPB wasn't an advertiser and in that sense was an outsider, but the web has the reputation of knowing everything, so where does it know what happened to LPB?
It Probably just died so slow that no one picked up on it.
I'm not sure that LPB closed. Upon a search it appears they moved locations some time ago and never updated the yellow pages. it pointed to an empty warehouse. I found their new location and it had cars at it. So I think it's still open.
The former President and Chief Executive of LPB Communications, Tom Spadea (~1998-2004), sold his interest in 2004. That move was made after liquidating several of its acquisitions, including Fidelipac tape cartridge company. The remnant of the company appears to be for the purpose of support for equipment sold in the last years of operation of manufacturing. The company has had several addresses and phone numbers since 2004.
The former owner of the company went on to become a franchise consultant and leader in the salad restaurant business and other interests (Saladworks, Rita's Water Ice, Huntington Learning Centers). Mr. Spadea was not a broadcaster and considered the business as an investment from all appearances. His involvement with LPB appears to be building a communications firm that covered a broad spectrum of equipment for broadcast and event/sports venues including audio production, software, AM, FM and studio equipment. LPB was known for its niche low power broadcast transmitters.
LPB Communications, as a manufacturing firm of broadcast and communications equipment, appears to be out of business. It exist only as a parts house and product support business. LPB Communications manufactured broadcast and communications equipment from 1960 to 2004.
I know from my own contacts with LPB that the company was operating in Camden, NJ in 2006, and that the man in charge was Tom Spadea. I wouldn't be surprised if he is still the owner today. My contact at LPB in 2006 was Ed Devecka, who owned LPB before Tom Spadea bought it in 1998. Ed was staying on as a consultant. By 2007, LPB seems to have gone underground. By 2007, I was not able to contact Ed, or anybody else at LPB. I e-mailed LPB in 2007, and I was told that they were having problems with their telephone system ("which should be up and running soon"). In the meantime, I was told to use a Philadephia-area telephone number (Tom Spadea operates from Philadelphia). I called that number a few of times, and the person answering did not identify the company. I asked if I was calling LPB. He said I was, and he wanted to know who I am, and what my business with LPB is. In one call, I kidded around, and said I was calling about 10 kW shortwave transmitters. The guy freaked out, and he had a prepared response, which I didn't understand. He said the real name of the company (apparently LPB is not LPB anymore), which I didn't catch, and he wouldn't repeat it when I asked him to.
I learned on the Internet that, in 2005, LPB lost a civil case in Federal Court in Camden, NJ because they were unable to perform on the delivery of several 10 kW shortwave transmitters to a foreign customer. I suspect that this is the reason that LPB is laying low now. It seems to me that they owe money, and they don't want to pay. Their wesite, www.lpbinc.com , is still in operation, but it still has the old Camden, NJ phone and fax numbers, which have not been in operation for a long time. Their e-mail address has also not worked for some time. They operate a little like a speakeasy: They don't want to talk to you if you are not a known customer.
Sad Ending for what seems to be a once great Company.
Not mentioned in the LPB Technical papers linked earlier is a remarkable "other way" of connecting a transmitter for carrier current coverage of 7 to 9 miles! This interesting method is described in the booklet LOW POWER RADIO BROADCASTING "Missions Edition" by James R. Cunningham, found right here on this site:
http://part15.us/files.p15/melprb.pdf
Pages 34 & 35 describe sending the RF output up a 50-ohm coax direct to the power company ground cable attached by alligator clip right up where the ground cable attaches to the building at the service entrance. No coupler unit is needed.
Transmitter power can be anything up to 50-watts just so long as field measurements comply with regulations.
In the U.S., the scenario Carl refers to re: pgs. 34-35 of "Missions Edition" is clearly not accepted commercial power code or FCC accepted for Part 15 use. LPB sold these 50 watt transmitters exclusively to licensed broadcasters with pre-sunrise and post-sunset authorization, colleges, universities, government agencies and for export. They were never intended to be used for Part 15 use. Another model of LPB transmitter was built for Part 15 use.
The implication should not be made that these transmitters are in anyway legal to use on the Part 15 AM BCB.