Radio won't stop playing Christmas music

Also, the noise stops when I unplug the radio.

Jimmy

Get a 1:1 transformer and isolate the power with that.. That will get red of the ground.. Shouldn't effect reception that bad.. The transformer will act as a filter.

Another trick you can do that may work, at radio shack, they sell a iron core you can wrap your electrical wire around. This may do the trick, or try coiling your cord up now with something iron in the coil.

Jamie.

Thanks, but I'd need a more detailed explanation.

What do you think the problem is? How would these two proposed solutions deal with it?

And where would the 1:1 transformer go -- on the incoming AC power cord?

Jimmy

The rf voltage is developed over the length of the lamp. The facility was built during W.W.II, and was in the middle of an upgrade when I visited. They had a small screend RF tight chamber for some repairs, but the control room and engineering areas were being updated and included sheilding. This was around the start of 1970 and they were replacing the original '40s hardware. The original transmitters had large windows in the doors, and other 'features' that were no longer used in broadcasting.

You do know that there were a number of lawsuits over brain cancer in broadcast & microwave communications engineers over the years?

Jeff, I have used slope detection for FM for about 40 years. My Sadelco TVFSM had a built in audio monitor that was slope detection. You tuned to the aural carrier, and pushed the 'audio' button, then detuned it to hear the Aural signal. As long as the FM signal is wider than a tunable AM receiver's bandwidth, you can recover the modulation.

You obviously are getting RF (Radio Frequency) that your electrical cord is helping with, as ground point of the radial, maybe..

By taking the zip card (assume it is), and wrapping it around some form of iron or ferrous metals, it will give you what is called a common mode choke. Actually, you may be able to buy a noise filter from places like the shack that plugs into your outlet and then you plug the radio into that..

Some better types of power strips come with noise filters in them.

You may want to check on that.

Something like the above..

The difference between those that know, and those that claim to know, is in the numbers. I dunno, let's do the math.

Let's start with an analogy. The voltage difference between the ground and a passing lightning storm is about 120 volts/meter. Therefore, a 2 meter tall person would have about 240 volts DC between their head and their toes. Why are they not instantly electrocuted? Ben Franklin and his wet string kite experiment should have been fried with about 10 Kv. Connecting a wire between your head and foot does not throw a spark. Hint:

Let's grind the VOA transmitter numbers. I need a review of field strength calcs anyway.

Note that the field strength calcs do not require knowing the frequency. I'll assume 50kw, that transmitter building is about 600ft away from the antennas, and that the antennas about 6dB gain.

At 3 meters (the FCC's favorite distance), the power density for an isotropic radiator is: Pd = Power / Surface-Area = Power/4*Pi*r2 and the field strength is: V/m = sqrt(377*Pd) = sqrt(377*Power/(4*PI*r^2)) = sqrt(377*Power/(36*Pi)) where 377 is the impedance of free space = 120*Pi Plugging in: V/m = sqrt(377 * Power/(36*Pi)) = sqrt(377 * 50*10^3watts / (36*Pi)) = 408 V/m at 3ft.

A 1 meter long fluorescent tube is not going to light up with 4 volts between the end terminals. However, if you hold onto one end, or attach some building wiring to one end, the antenna formed is much longer than the 1 meter tube, and picks up much more voltage. To light the lamp, one needs about 90v, which would require 22 meters of antenna wire.

With just the fluorescent tube as an antenna, 90v can be achieved at: meters = 2 * 3m * 408 V/m / 90V = 27 meters

By holding onto one end, raising the total length to about 3 meters it should light up at about 54 meters.

The accuracy of such field strength calcs at HF frequencies are horrible. Ground conductivity, ground reflectivity, reflections, and other oddities can result in huge variations. I've seen corona discharge in the fog off the building rain gutters with a bootleg BCB transmitter, so I know that it's possible to generate considerable voltage across a conductor. I've also lit up fluorescent tubes on broadcast mountain tops, but not reliably. I had to pick my place carefully.

More on field strength calcs:

Call me crazy, but when I was a kid I could occasionally hear a local AM radio station in the springs of my boxspring/mattress. The antenna was about half a mile from my house.

A whole bunch of math formulae...

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If you really want fun.. work at one of those 50KW BCB sites (I did, at the

The old TX site was in the back room of a preschool. I still wonder who thought of THAT brilliant feat of engineering..

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How about a CATV headend in a 5 KW AM transmitter site?

I'd have thought a ferrite ring would be better.

A nice big ferrite ring can be had from the scanning yoke from a scrap CRT TV or monitor, some are cast as a solid ring but more often 2 halves held together with spring clips.

You can put quite a few turns of mains lead through a ring that big.

My uncle used to make radios that worked on navy ships off hot pipes with no electricity.

THere also used to be such a design in my 1969 World Book Encyclopedia, too.

- = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist

I used to be able to hear local cab CB radios thru my closed stereo as the cabs passed my house. I think if you have high enough power you can broadcast to speakers whose poeer is turned off. I seem to remember someone once played a gag and broadcast messages to someone he was trying to spook.

- = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist

Some have argued the Biblical Ark of Covenant was in fact designed to receieve radio signals.

- = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist

My uncle used to make radios that worked on navy ships off hot pipes with no electricity.

THere also used to be such a design in my 1969 World Book Encyclopedia, too.

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I remember when I was young there were radio circuits in books that used one or two transistors and ran off of thermocouples. The description used a candle for a heat source, probably because they were/are cheap and easily available, but I don't see why one couldn't use heating pipes or other heat sources for power as well.

I used to be able to hear local cab CB radios thru my closed stereo as the cabs passed my house. I think if you have high enough power you can broadcast to speakers whose poeer is turned off. I seem to remember someone once played a gag and broadcast messages to someone he was trying to spook.

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I know for certain that early solid state audio systems (stereos, etc.) could be "turned on" by high power RF. A shop I worked at in Astoria, OR had a solid state Motorola console stereo sitting in the showroom. Whenever one of our local hams (just a few blocks away) used high power, the signal would be picked up by the speaker wires, and fed back through the negative feedback circuit and detected by the output transistors and fed into the speakers... and voila!.. audio!

Presumably, this was so that an advanced civilization of extraterrestrial visitors could communicate with Moses, presumably using some form of amplitude modulation. Just one problem... no advanced alien civilization would stoop to using AM modulation for anything useful. More likely, they would use the much more efficient digital modulation modes. Unless the flying saucer also contained a few museum pieces, I doubt if they even had a method of generating AM.

ng

It's is a known phenomena by radio technicians, and many others of us.

Only John Winston knows for sure.