CT-100 as shipped from RCA

[julianburke]

A color CRT does have some issues with the earth's magnetic field but nothing that can't be solved with a tech with experience. However, I have never heard of and never experienced any problems with that issue with any color camera. That's a (technicians') wives tale. A properly set up TK41 delivered great color in any position. For that matter, if it were true it would also bother B&W cameras because they used the same basic circuits, pickup tubes and magnetism doesn't bother the color dichroic lens assembly.

[old_tv_nut]

Originally Posted by julianburke

A color CRT does have some issues with the earth's magnetic field but nothing that can't be solved with a tech with experience. However, I have never heard of and never experienced any problems with that issue with any color camera. That's a (technicians') wives tale. A properly set up TK41 delivered great color in any position. For that matter, if it were true it would also bother B&W cameras because they used the same basic circuits, pickup tubes and magnetism doesn't bother the color dichroic lens assembly.

The image orthicons are mounted in a metal tube, which I'd guess acts as a magnetic shield, sufficient for protection from the Earth's field, but not necessarily from man-made fields. The Ed Sullivan theater in NY backed up to a subway transformer station (maybe still does) which caused problems if cameras were too close to the back wall. This was still the case in the early 90s when we shot the first US HDTV tests there on tube cameras (Saticons). Don't know if the substation is still there, but CCD cameras make it a moot point for the Letterman show that is staged there.

[julianburke]

You are talking about a well and overdone subject about a rotary converter near the theater. Rotary converters are no longer used but are still in place. Although I have seen no evidence of that effect, this is an extreme circumstance that would bother anything.

We were talking about the earth's magnetic field, and NOT extreme man made circumstances like that.

As far as the Letterman Theater is concerned, the threat was never much of a problem:

"When the Ed Sullivan Theater was built next door to IRT Substation #13, Lobenstein said CBS made a deal with the IRT; since the extreme radio-frequency energy emitted by the station would make the network’s cameras behave oddly, the IRT agreed to shut down the substation each Sunday evening while Sullivan’s show was broadcast. After CBS moved David Letterman’s show there in 1993, the network inquired about the possibility of doing the same thing for Letterman’s nightly tapings. The MTA balked that time around, since shutting down a working substation each weekday in the middle of the evening rush hour wouldn’t have worked as well. CBS wound up surrounding the entire Letterman stage in a Faraday cage of quarter-inch plate steel to block the RF emissions. The rotary converters were finally de-energized in December 1999, when they were replaced by new solid-state rectifiers, which are much smaller, quieter, cooler, and easier to maintain."

[old_tv_nut]

Originally Posted by julianburke

You are talking about a well and overdone subject about a rotary converter near the theater. Rotary converters are no longer used but are still in place. Although I have seen no evidence of that effect, this is an extreme circumstance that would bother anything.

We were talking about the earth's magnetic field, NOT circumstances like that.

I agree, and I think that's what I said.

[Steve D.]

Originally Posted by old_tv_nut

I agree, and I think that's what I said.

Julian, You do recall the content of previous posts before you post? You also repeated my comments on post #15 re: the TK-40-41 color camera setup. Just checking.

-Steve D.

[julianburke]

Sorry Steve,

I do type alot and just slipped my mind. I was looking under "Rotary Converters" and there was that paragraph with no reference. I was making a reference that the Sullivan Theater was not bothered much after they worked out a solution. Someone started this thread saying that the color cameras were affected by the earth's magnetic field for which they are not really bothered (practical sense) if any and they got off on that tangent about the rotary converter house off Broadway in NYC which has nothing to do with the earth's field, an isolated incident.

[Phil Nelson]

I scanned the RCA CTC2 manual loaned by reeferman and added it to the reference portion of my CT-100 design article:

http://antiqueradio.org/RCACT-100TelevisionDesign.htm

Here's a direct link to the 16-megabyte manual:

http://antiqueradio.org/art/RCA_CTC2...ce_Data_T3.pdf

Sure enough, this manual tells the dealer how to install the 15GP22 CRT, which was shipped in a separate carton. As Charles noted, another carton in the lower cabinet space contained the yoke, purity coil, & whatnot.

This 40-page manual has more content than the shorter RCA Field Service Manual section for the CT-100. I haven't yet compared the two to look for little differences in material that's duplicated (the schematic, for instance).

Thanks, reeferman. I'll send the original back in a day or two.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html