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Old 02-12-2018, 05:35 PM
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R.C.A. TK42 versus TK41. R.C.A. TK42 versus Norelco PC-60 and 70

I've read on the forum some time ago that the operatores preffered "R.C.A." TK41 color studio camera in stad of TK42, throu all that TK42 was more modern... but TK42 had Germanium tranzistors, so it was more instable.
But how the image provided by TK42 was compared to the one provided by TK41?
On this site they are saying that C.B.S. had a feud with "RCA" because of the color televison sistem (the electronic color television sistem of the "R.C.A." won) and when "Philips/Nolerco" camed with color cameras they where glad to get color cameras from them. How the image provided by "Norelco" PC-60 and 70 was compared to "R.C.A." TK41 and 42. "Norelco" used Plumbicon tubes ("Philips" invented them).
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Old 02-12-2018, 09:00 PM
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I'll let someone with direct experience comment on the picture quality of TK-42 vs. TK-41.

The improvement of Plumbicon cameras over image orthicons was particularly in the signal-to-noise ratio. While the Plumbicons had inherently lower detail contrast, their high SNR meant that much stronger image enhancement levels could be applied to compensate. The image orthicon noise spectrum was flat white noise from the beam current shot noise. Plumbicons had target capacitance that was compensated by a feedback arrangement in the pre-amp stage, which meant that the 6 dB per octave roll-off of the target capacitance was compensated by a 6 dB per octave rise in the amplifier frequency response. As a result, the noise spectrum also was triangular, with a 6 dB per octave rise; that is, the low frequency noise (which is most visible to the eye) was much lower than the noise of an image orthicon camera.

By the way, solid state sensors have a flat noise spectrum, but it is much smaller than the image orthicon (since there is no constant beam current, plus the quantum efficiency of solid state sensors is up to ten times better than that of photo-emissive sensors), and generally smaller than an equivalent Plumbicon (since there is no 6dB per octave compensation required).
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Old 02-13-2018, 07:58 AM
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The biggest problem with the 42's (and 43) was the pin board construction. There was even a bulletin out to resolder all the ground connections (the square pads) on the modules.
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Old 02-17-2018, 08:13 AM
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CBS must have had 41's.

Looks like the graphic artists used what they knew for a design for their "please standby" slide.
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Old 06-12-2022, 07:16 PM
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The Norelcos were even favored by NBC in some roles, as the TK-42 and TK-43 were a lot less reliable, harder to repair and maintain. Which is why NBC kept the TK-41 in service for so long, and the TK-41 picture was hard to beat. The Norelco PC-60 and PC-70 cameras were very excellent, reliable and maintainable by enigneers, and made excellent pictures.
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Old 06-13-2022, 03:50 PM
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Here's what happened: RCA had no good comeback for the Philips Plumbicon tube. The TK-42/43 had an odd mix of 3 vidicons for color and one IO for luminance that required lots of light and heavy tweaking at the control unit to even make passable images. This show was likely done on TK-42s. There's some tape degradation but you may still be able to get a feel for the general "look" of the camera, especially against the show's film inserts. Other 4-tubes like the GE PE-250/350 wisely used 4 plumbs.

One other thing was the quirky "handles" on each side for zoom and focus. As temperatures inside the camera rose, the mechanisms seized and chattered, so many stations retrofitted regular controls.

That combination of problems led NBC to keep its TK-41s in the studios and buy Norelcos for the field (and guinea-pigging) until RCA came up with the vastly superior TK-44A...which ended up using Plumbicons just like the Norelcos did.
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Old 06-14-2022, 12:42 AM
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The Plumbicon tube was a game changer for colour cameras. A compact tube, hardly bigger than a vidicon, with the performance close to an image orthicon that was many times bigger.

In the UK and Europe we started our colour services from 1967 so never used anything other than Plumbicons. In the UK we had the EMI 2001 and the Marconi Mk VII, both of which used four tubes, including a separate Plumbicon for luminance. The Mk VII sold well in the USA, though nothing like the numbers of Philips/Norelco PC60/PC80.

The Philips PC60/PC80 were not widely used in the UK. We'd love to have one in the BECG collection www.becg.tv
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Old 07-11-2022, 08:16 PM
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I found this link on ewetube:

https://youtu.be/ZtNIuXHgRlM

I’m curious of anyone knows the cameras and VTR used (quad of some sort, AMPEX?)

Also, why are there gaps in the recording? I’m guessing that’s where commercials were put in (local of the network feed?)

More curiously- why was it “take 1”?

Any comments on the picture quality?
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Old 07-12-2022, 12:02 AM
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Surely Plumbicon cameras.
The video has been through so many stages, including a generous amount of NTSC decoding and digital coding artifacts from YouTube, that it's impossible to tell what (possibly multiple different) tape machines were used.

This was likely originally captured off of network satellite distribution, for syndication across the country on each broadcast station's own individual schedule; thus the built in commercial breaks.

Not sure about "Take #1", but it could refer to taping multiple episodes in succession on the same day.
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Old 07-14-2022, 07:20 PM
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Quote:
Originally Posted by colortrakker View Post
Here's what happened: RCA had no good comeback for the Philips Plumbicon tube. The TK-42/43 had an odd mix of 3 vidicons for color and one IO for luminance that required lots of light and heavy tweaking at the control unit to even make passable images. This show was likely done on TK-42s. There's some tape degradation but you may still be able to get a feel for the general "look" of the camera, especially against the show's film inserts. Other 4-tubes like the GE PE-250/350 wisely used 4 plumbs.

One other thing was the quirky "handles" on each side for zoom and focus. As temperatures inside the camera rose, the mechanisms seized and chattered, so many stations retrofitted regular controls.

That combination of problems led NBC to keep its TK-41s in the studios and buy Norelcos for the field (and guinea-pigging) until RCA came up with the vastly superior TK-44A...which ended up using Plumbicons just like the Norelcos did.
Very true. Seeing that Pilot, shows while the TK-42/43 failed in the marketplace. Tape degradation alone doesn't tell the story. Reliability issues, and all that light needed, and all the issues doomed RCA until the TK44a (with Plumbicons) and RCA's superior overall camera package, loved by cameramen, and engineers alike. Norelco was a much better field camera and RCA alternative, the Plumbicons were so far superior of a camera tube. Those were some of the best TV cameras made in their era.
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Old 07-27-2022, 03:40 PM
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Quote:
Originally Posted by nasadowsk View Post
I found this link on ewetube:

https://youtu.be/ZtNIuXHgRlM

I’m curious of anyone knows the cameras and VTR used (quad of some sort, AMPEX?)

Also, why are there gaps in the recording? I’m guessing that’s where commercials were put in (local of the network feed?)

More curiously- why was it “take 1”?

Any comments on the picture quality?
Cameras were Norelco PC-60s since this was done at CBS Television City (look real quick behind the slate at the start or when her dad runs up on stage at the end and you'll see them). Good guess the VTRs were Ampexes of the 2" quad persuasion. Don't know which ones, though. Gaps are indeed for commercial breaks. This appears to be a network master tape, originally run from a CBS network control room in New York or LA. Since game shows like this are live-to-tape, it's assumed that this would have been the first and only take of that show number, barring any technical disasters requiring an extended stopdown.

Quality-wise, this looks pretty typical for an early '70s videotaped show: little banding on the left, some vignetting that viewers wouldn't have seen then. CBS was most consistent of the networks in quality.
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Old 07-27-2022, 06:05 PM
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Quote:
Originally Posted by colortrakker View Post
.
...
Quality-wise, this looks pretty typical for an early '70s videotaped show: little banding on the left, some vignetting that viewers wouldn't have seen then. CBS was most consistent of the networks in quality.
By "little banding on the left" I presume you're referring to the vertical stripes near the left side, mainly in one camera?

When I saw the word "banding' I immediately went back to see if I could find quad tape banding, and I don't see any. If you can spot any, post the time stamp.

Regarding the image corner vignetting, one of the cameras also has some misregistration in the extreme upper right.

The shading across the image of all the cameras looks excellent.

Did these cameras have a built-in diascope pattern projector and automatic registration?

That was a feature of the first Saticon tube HD cameras that were produced in the early 90s. It would have been impossible to get useful HD resolution without it. The auto setup did both registration and shading.
They also had lens tables that adjusted the scan width and height of the R, G, and B separately according to the lens zoom setting to compensate for chromatic aberration. IIRC, there also was a lookup table for compensating the gradual overall vignetting of the lens at different zooms and aperture settings.
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Old 07-28-2022, 08:42 AM
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Ringing at the left edge of the image was often the first telltale sign of a budding horizontal deflection or power issue in the Norelco PC-60 and PC-70 cameras, e.g. deteriorating filter caps in the camera head, various other problems with horizontal deflection, extremely long or poor condition camera cable, even issues in the horizontal sweep of the viewfinder monitor could crosstalk into the camera head if bad enough.

These cameras did not have a built-in diascope, but an outboard unit was available that could be mounted in place of the lens. It was expensive and difficult to use, so was rarely seen. Various other methods were used to achieve good shading. Basically a somewhat defocused white card could be used, since any variation in lighting could be identified by moving the aim of the camera.

When I see the term "banding" I, too, always think of quadruplex banding. But I've observed that the "younger generation" often uses the term "banding" to describe the pooling of colors caused by quantization steps made visible by not having a sufficient number of bits in the video path.

Last edited by TVBeeGee; 07-28-2022 at 08:48 AM.
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Old 07-28-2022, 06:18 PM
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Optional diascope must mean that registration was done manually on a chart. And the variation in chromatic abberation of the lenses with zoom must have been acceptable.

In HD cameras, my guess (without any evidence, have to try looking it up) is that they went through three stages:
1) Tubes with lookup tables for RGB raster size compensation.
2) Solid state HD sensors with improved lenses
3) Solid state HD sensors with digital lens compensation, once digital video processing became powerful enough

Maybe we have someone here who knows?

EDIT: In (2) and (3) there would be some differences in the case of three (RGB) sensors vs. a single Bayer pattern sensor
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Last edited by old_tv_nut; 07-28-2022 at 06:22 PM.
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Old 07-29-2022, 09:37 AM
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Absolutely correct about manual registration on a chart. The difference in lenses was also apparent. Cheap lenses not only caused varying registration but also a noticeable drop in sharpness, especially when viewing the RBG channels of the camera prior to NTSC encoding. Cheap lenses also had more optical flare, which tended to cause issues with black balance instability. Expensive lenses were usually far nicer in all these areas.

Last edited by TVBeeGee; 07-29-2022 at 09:40 AM. Reason: Some more details.
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