The AM Forum

Somewhere else in this forum, there were a few comments about wikipedia.    At times I have found this web site useful.    However, just having looked up a town where I have lived and where most people know one another, I found a lot of BS.   The town is Pine Grove Mills, PA.     Under history there is a some BS about some fictitious gang violence and a lot of obviously made up BS.     This town rolls up the sidewalks at night and is so typically small town.    If this is an example of the editing, I don't think I could believe much of anything on this website.

Wikipedia is well known to be very  contentious on social issues, and politics.     One cannot believe anything in either of those issues, due to constant "editing" by activists.    Even scientific entries  are suspect.   

The very fact that it is "Wiki", taints the entries.   They really need objective moderators there, but good luck with that!

Yeah, and sometimes you find stuff on wikipedia about YOURSELF that you didn't even write. ;)


http://en.wikipedia.org/wiki/Junk_box

Did somebody take a clandestine photo of your junkbox box Jason?

Ellen - AF9J

Junk box heck, thats just a junk PILE. ;)  Only the good stuff goes in boxes.

No, its a picture of mine from my web site, that W1GFH snagged when he wrote that page.

Speaking of, has anybody heard from Joe T. after he moved back to 1-land?

73,
Jason kf6pqt

Wikipedia is like asking a question about amateur radio on the QRZ.com Q-A forum.  It can be useful, but you need consider the source, and cross reference the information you receive if you want to be certain of the result.

I recall Paul VJB reporting that he had tried to edit the entry on amateur radio to correct some misleading statements and include some realistic information about amateur AM, but the moderators kept deleting it, saying that AM was too specialised, yet they allowed ample mention of other highly specialised facets that are less used than AM.

"...range in size from small carboard or plastic boxes, to large collections that fill garages and outbuildings."

oh my..
There was a fellow named John E. Long, who lived on Vista street in Plano, TX. His house was a junkbox. There were literally aisles between boxes stacked to the ceiling. One room could not be entered because stuff had fallen down, barricading the door shut from the inside. The hallway was especially treacherous. There was also a 2-car garage out back, with a loft. No cars were in it.

In the wikipedia picture, is that a video delay line from a TV set in the top right corner?

Delay line, huh, is that what those long funny "chokes" are?

What the heck do (did?) those things do? I cut a few of those out from that haul of junkers.

Thanks,
Jason kf6pqt

In an old-skool color TV, there is a slight delay to the color signal as it is demodulated from a phase-modulated subcarrier into the three separate RGB signals applied to the cathodes or grids of the CRT. The delay line makes the luminance (monochrome) component of the video signal take an artificially long path so the luminance and RGB signals all hit the CRT in phase and at once. Assuming a top of the line tube color TV set might be able to resolve 400 pixels horizontally, each pixel could be represented by about 120 nanoseconds. Therefore even a small time delay error such as caused by the propagation of the signal throught the color demodulator could become perceptible as approximately an 8 pixel horizontal misalignment of color versus monochrome images if it were not for the delay line. For simplicity I do not take into account the precise horizontal retrace time, etc so my figures are likely off by a few percent, and I would imagine one would be hard pressed to find a tube TV that could really produce 400 pixels horizontally. In recent transistor-IC based CRT-based color TV's the delay line might take the form of a quartz sheet in a rectangular plastic case about the size of a book of matches. In a very modern CRT-based color TV, there might be no discernable delay line at all due to the high level of integrated circuitry and alternate means of signal processing, some of them still analog. I do not remember exactly how long the delay is, but I believe it is about a microsecond. A www reference http://www.provide.net/~djcarlst/delay.htm claims it is a millisecond, but I think that is an error and I don't recall that kind of delay.

It might be useful as a choke today for low frequencies once any capacitors are removed.
The useful passband when used as a line reaches up to about 4MHz for the ex-TV specimens.