A RCA TK-41C restored to working condition!

[Aussie Bloke]

G'day all. I've recently found out on the Eyesofageneration Facebook page a RCA TK-41C camera chain has successfully been restored to working condition by engineer Charlina Johnson and it is making a fantastic picture!!! For those who have Facebook jump onto Eyesofageneration page https://www.facebook.com/eyesofageneration . For those who don't here's the postings and some pics:

May 15:
IT'S ALIVE!!! RCA TK41C MAKING PICTURES AGAIN!!!
BUT, your help is needed to find a few replacement parts and more about just what is needed is on the individual photo pages so please look there.
CONGRATULATIONS to Los Angeles area engineer Charlina Johnson for accomplishing a feat that many had sought to do, but didn't...yet.
I and all my friends believe this is THE FIRST RCA TK41 to ever be successfully revived, as very few of the camera control units were left and those that were (and the camera heads too) had big capacitor problems. Charlina has managed to totally recondition her unit, BUT...is in need of an Optical Lens and a Prism Block.
Her Optical Lens is missing and the Prism Block has some deterioration in the red and blue channels. She's been in contact with "all the usual suspects" trying to find this stuff, but if you have it (and there are pix of what she needs) please call her at 213 407 5151. More on the photos. WAY TO GO CHARLINA! 🥳🥳🥳

June 16:
RCA TK41 C ALIVE AND WELL IN L.A.!
Last month, I posted the first batch of pix from engineer Charlina Johnson showing her TK41 crackling to life. Here are a few more pix that came in over the weekend. The colorful baby chair looks pretty good in the monitor! CONGRATULATIONS Charlina! 🥳🥳🥳

[old_tv_nut]

Thanks for posting this!

This is amazing, as the two restored image orthicon cameras I've seen in person (Chuck Pharis's monochrome camera and the ETF's field-sequential Vericolor) seemed touchy as heck with regard to setup conditions, and the TK41 must be touchy cubed.

This should give some encouragement to others working on TK41s.

[Telecolor 3007]

That camera is in Australia?

[Aussie Bloke]

Originally Posted by Telecolor 3007

That camera is in Australia?

No. It is in California.

[BBTV]

Yes, I realize this is an ancient thread. I believe there are a few other TK-41 cameras that have been caused to breathe again in the interval.

And now, here I am, trying to restore one for a museum in Ohio. I'm not terribly concerned about the electronics... that can be done but will take time. However, I've got two of them, one with Dichroic optics (trashed) and one with prism optics (a lot less trashed but still defective).

I know better than to ask for parts. But does anyone have a recommendation for an optics house that might be able to repair, or at least in the case of the Dichroic block, replace optical parts?

Second question, and again I know the answer but ... is it possible that someone might have the optical specifications RCA was using? I doubt it, because I'm sure it was a closely guarded house secret .. .but never hurts to ask.

And now back to the past.... ;-)

[old_tv_nut]

About halfway through and following you can find plots of the individual optical components, the image orthicon, and the overall responses.

http://www.bretl.com/Viewing%201950s...lor%20pptx.pdf

Edit - be careful not to confuse the earlier responses with the wrong green curves with the later dichroic and prism responses.

[old_tv_nut]

More:
Slide 146 shows the overall measured responses in October 1949, with improper green. This is the camera that resulted in complaints of unnatural color (faces too red).

Slide 147 shows the measured responses from the corrected design in November 1949.

Any slides labeled March 1953 are from measured cameras with proper responses. Of the four measured, I chose the two with the most difference between them to analyze.

Subsequent slides show calculated responses based on the information on dichroics in Widdop's paper, plus published specs for the trimming filters and image orthicons. These calculated curves are not as smooth as the measured ones. It is not known if the difference is due to differences in the measuring instruments.

Slides referencing the prism optics are based on measurements of a prism by Jay Ballard plus published image orthicon specs. The overall result including orthicons, if measured, may be smoother than calculated, but that is unknown.

[BBTV]

Thanks so much! I had actually seen that somewhere, but did not read far enough into it. I will also contact Jay Ballard again. He's been quite helpful with the restoration so far.

Next stop, optical houses I guess. The dichroic block is pretty much useless, although probably could have the individual elements replaced. The prism block has some separation with the outer filters, so it probably depends on whether they can "un cement" those elements without damaging the rest of the prism block. What to do what to do..

[old_tv_nut]

By the way, when I say overall measured responses for 1949 and 1953, that includes the orthicons; I haven't seen any measurements of the optics by themselves. They must have pointed the camera at a spectrum and measured the video signals with the gamma correction turned off.