G'day all.

I have a question about the tube configuration of the RCA TK-42/43 cameras. I know the general configuration is three 1 inch vidicon tubes for chroma and a 4.5 inch image orthicon for the luminance. I was wondering with the introduction of plumbicon tubes, were any TK-42/43 cameras modified to use three plumbicon tubes in place of the vidicons for better quality chroma?

Interesting question. I have no idea, but I would guess there was no market for an expensive re-development.

And RCA didn't even see the light on Plumbicon until 1968, when they were developing what became the TK-44A.

I would love to see a chart of evolution...

Since chroma only one fifth the detail/bandwidth/noise of luminance, vidicons probably just fine for the job.

There were NO TK42/43 cameras with plumbicons ever. Plumbicons were a whole new ball game and the cameras could not be modified for them. It would be a big mistake to even try as it would require a total re engineering and would be way beyond practical expense not to mention nothing would fit right as the body was not designed for that format.

And of course, prior to the development of the TK-44A, RCA mandated that all RCA cameras only use RCA tubes. And RCA didn't make no stinkin' Plumbicons. :thumbsdn: :nono: Never mind the high quality of the then-newfangled PC-60's and later PC-70's from Philips/Norelco.

I don't know if you have seen this book:

Inglis, Andrew F., Behind the Tube: A History of Broadcasting Technology and Business, Boston: Butterworth Publishers/Focal Press, 1990.

Mr. Inglis has written some fascinating stories about color TV, including about the whole RCA TK-42 fiasco and the subsequent developments which led to the TK-44.

I don't have the book right in front of me at the moment but I think this is where I read that, in order to combat the plumbicon camera, RCA tried marketing their behemoth with new tubes. In place of the image orthicon, they tried the image isocon, a tube that was very similar to the IO, but developed its signal not from the return beam, but from some other effect going on when the target absorbed the electrons from the main beam. I'm not too knowledgable about this process in detail. Anyway, this tube never caught on with broadcasters. Its main use seems to have been by astronomers.

For the vidicons, RCA tried a tube called the selenicon, another imager I am not too familiar with, except to say that it must not have been much of an improvement over the vidicon.

These efforts didn't help much in the face of Norelco's camera. But many TK-42/43s were sold, just through brand loyalty, if nothing else. But NBC Burbank only had one in a small closet-like studio off of the telecine area. They evidently used it infrequently for network announcements.

I don't know if you have seen this book:

Inglis, Andrew F., Behind the Tube: A History of Broadcasting Technology and Business, Boston: Butterworth Publishers/Focal Press, 1990.

Seen it? I have it!

Well I thought the book reference might help answer Aussie Bloke's question. It's probably not that easy to find but it might be worth the effort.

In looking back at the book by Inglis, he does say, on page 287:

"The 4 1/2-inch image orthicon was replaced with a tube of related design, the image isocon, which produced a picture that was somewhat more noise free. The policy of using only RCA tubes was changed to allow the use of Plumbicons rather than vidicons in the chroma channels."

He goes on to say that this camera was called the TK-44 and demonstrated at the 1967 NAB show, "...where it received a lukewarm reception from broadcasters."

The later three-tube plumbicon camera was, of course, also called the TK-44.

There is a mention of selenicons in a TK-42 at http://www.tvcameramuseum.org/rca/rcathumb.htm.

The later three-tube plumbicon camera was, of course, also called the TK-44.
Actually, the Plumbicon camera was called the TK-44A (followed, in 1971, by the identical-looking TK-44B), to distinguish from the prototypical image-isocon TK-44.

Yes, I know...

Hi all-

An upgrade kit was developed by Amperex to convert RCA TK-42/43 cameras from vidicons to lead oxide (plumbicon) tubes in the color channels.

The conversion kit was promoted in the later years by RCA as an option, or it was at least mentioned in Broadcast News.

I was told that the conversion would result in a 1 F stop increase in sensitivity, and this was confirmed by a CE who updated one of his cameras. However, he so much wanted to replace the TK-42 cameras with TK-44As that no more cameras were converted.

One serious design flaw in the camera was matching the transfer characteristics of the IO with that of the vidicons. The IO in luminance had a knee, but the vidicons would keep cranking out signal after the IO had hit the knee. RCA solved it by adding adjustable knee and slope compression in the three colour channels to match the IO. With these modules, the TK-42/43s became the only RCA cameras with knee and slope controls, which later became common in studio/field cameras.

I believe Andy Inglis saved the division by dumping the 4 tube TK-42/43 and improving on the Philips design. RCA introduced the 4 tube TK-44 with an Image Isocon and 3 vidicons at the 1967 NAB, thinking that the Isocon, with its low noise floor, would be the hit of the show. RCA was stunned at the simplicity of the Norelco PC-60, and secretly decided in May 1967 to adopt the 3 tube lead oxide concept. Back to the TK-41 conceptual design.

Mind you, the Norelco pictures were far from perfect, lacking saturation in the red end of the spectrum, and subjectively poor resolution, which was corrected with the CBS image enhancer. Norelco added a simple linear matrix (red enhancer) and later developed the extended red tube for improved red response.

But the almost total lack of noise, good sensitivity, and simplicity sold the design. It became the automatic choice for broadcasters during the mid 60's , and Philips couldn't make them fast enough. If you couldn't wait, there was GE, Marconi, and RCA.

Inglis sent some RCA senior engineers to Eindhoven, and cut a deal with Philips for use of the tubes, beam splitter, and yokes. A secret development program was begun in Camden, and at the following year's NAB, RCA showed the TK-44A, which became their best selling, top of the line color studio/field camera, ever.

You can see working TK-44s at the Museum of Broadcast Technology in Woonsocket, RI. The quality of components used by RCA has stood the test of time in that camera. However, the vertical coils in the Philips yokes have a tendency to open and the prism may delaminate.

Regards,

JB

Interesting observations,
I know that TK-42's where in use at our local NBC station they became a Sony shop and went with BVP series cameras in the late 80's early 90's. Our local CBS station had TK-42's till the mid 80's and then went with Philips LDK cameras and now Panasonic.

JB - is the Museum of Broadcast Technology in Woonsocket, RI open to the public? Every time I look at their website, it says they are not. I would love to see it since I get to the Boston area several times a year. I recently saw a MBT YouTube video showing them demo a Quad VTR. I even saw an old RCA TRT-1B (although not running) in the background. I would love to visit it. Any news on when they may open? Thanks.

HJi John-

The website hasn't been updated since we started, much to my frustration. Some of us still have day jobs, but there is usually someone there Staurdays. We also host local chapter meetings of the SBE, SMPTE, and once for a ham club. Our mission is to make the gear operational.

We have operational live cameras, 2" VTRs, RCA telecines (26,27,28). The TRT-1 is going to require a lot of effort, as is the VR-1000. But the TR-70, TR-600, and AVR-2s are running.

Our biggest challenge is funding and recruiting competent technicians-ones that can handle a scope, and work on tube gear without getting burned, or worse.

We also are overstocked with certain camera models such as TK-60s and assorted Ikegami models. Contact me off list TK41C@aol.com, or alternatively, Paul_Beck@emerson.edu.

We are always in the market for NIB spares-RCA, Ampex, Conrac, Tektronix,etc.


Regards,

JB