Vladimir Zworkin's 21CT55 Restored and On Display

[Kirk]

An amazing find and restoration of this very special 21CT55:

https://www.vrcmct.org/exhibits-collections

Scroll down to film and Television- there is a video and a button that will bring to an Essay that explains the acquisition and prominence of the set.

Just goes to show that they are still out there- hiding and waiting to be found-the donor was an off the grid 87-year-old RCA Engineer from the early 1960's whose Father was an Engineer fro RCA from the 1930's to his retirement in the late 1960's- He saw it all- All of the players were at RCA Princeton in the 1950's.

Enjoy!
Kirk

[old_tv_nut]

Thanks!

[kf4rca]

He died in 1982. I was working at CNN at the time. He probably had several rectangular sets as well. What ever happened to them?

[etype2]

Originally Posted by kf4rca

He died in 1982. I was working at CNN at the time. He probably had several rectangular sets as well. What ever happened to them?

Would be interesting to track them down.

[etype2]

Thanks for posting this, found it interesting.

[kf4rca]

There's even a book about him:
https://books.google.com/books/about...d=tyurXyEBPxkC
I often wondered if he worked on his own sets.

[Electronic M]

Originally Posted by Kirk

An amazing find and restoration of this very special 21CT55:

https://www.vrcmct.org/exhibits-collections

Scroll down to film and Television- there is a video and a button that will bring to an Essay that explains the acquisition and prominence of the set.

Just goes to show that they are still out there- hiding and waiting to be found-the donor was an off the grid 87-year-old RCA Engineer from the early 1960's whose Father was an Engineer fro RCA from the 1930's to his retirement in the late 1960's- He saw it all- All of the players were at RCA Princeton in the 1950's.

Enjoy!
Kirk

I'd like to see a scan of the schematic of that 6080 regulator circuit. Both my 21CT55 CTC-2B and CT-100 CTC-2 (which the 21CT55 was modified from) live on 1KVA voltage regulating isolation transformers so that variations in utility voltage do not disturb the horizontal current level. It would be nice to add a tube regulator to eliminate the need for a 60lb external regulator.
I have not seen reference to that 6080 circuit in any of the 21CT55 service literature publicly available.

[Penthode]

Originally Posted by Electronic M

I'd like to see a scan of the schematic of that 6080 regulator circuit. Both my 21CT55 CTC-2B and CT-100 CTC-2 (which the 21CT55 was modified from) live on 1KVA voltage regulating isolation transformers so that variations in utility voltage do not disturb the horizontal current level. It would be nice to add a tube regulator to eliminate the need for a 60lb external regulator.
I have not seen reference to that 6080 circuit in any of the 21CT55 service literature publicly available.

How much is your supply varying? Do you have aluminum house wiring?

If your supply varies so much that you need a regulating transformer, maybe you should contact your electricity utility.

[Kirk]

I have the one they built to plug in where the ballast tube goes- its the same circuit as the one that is "built in" to the 21CT55 that we have running. It came with a hand-drawn schematic, done by David Neegard, the 87 year-old Engineer from RCA.

I will dig it all out and hook it up to a working CT-100 chassis that I currently have on the Test Jig.

Once I know it's OK, I would be happy to share the info with whoever wants it.

Stay Tuned!

Kirk

[Electronic M]

Originally Posted by Kirk

I have the one they built to plug in where the ballast tube goes- its the same circuit as the one that is "built in" to the 21CT55 that we have running. It came with a hand-drawn schematic, done by David Neegard, the 87 year-old Engineer from RCA.

I will dig it all out and hook it up to a working CT-100 chassis that I currently have on the Test Jig.

Once I know it's OK, I would be happy to share the info with whoever wants it.

Stay Tuned!

Kirk

Thank you.

Originally Posted by Penthode

How much is your supply varying? Do you have aluminum house wiring?

If your supply varies so much that you need a regulating transformer, maybe you should contact your electricity utility.

It's probably more than 10V throughout the year (sometimes throughout the day) but the main reason for the voltage regulating transformer is voltage dips. There's a big industrial park about 3 blocks away. When we moved in several times a minute the grid would have sharp instantaneous dips (reminded me of welding) that would cause SUBSTANTIAL blooming in all my tube era TVs. I used to think something was wrong with my sets until I ran 3 sets at once and watched them bloom in sync with each other.
It's not as bad as 10 years ago, but on 4 figure sets with unobtainium flybacks that the H output cathode current is very sensitive to B+ variations caused by line voltage changes I 1.) don't want to risk damage, 2.) don't want distracting Blooming.

I think it's all copper, but everything is backstabber (which is kind of trash IMO), and this is a 1970s Belinski home (the home inspector had some choice words for some of the non-electrical construction choices to give you an idea of their standard level of craftsman ship here) and it went through a significant change order mid-build, and the previous owner was a small engine mechanic that modified some stuff. I don't own the place so I don't have a say in the matter. At least if it burns down it's more likely to be mice chewing the wiring than what's here.

[Electronic M]

Originally Posted by Kirk

I have the one they built to plug in where the ballast tube goes- its the same circuit as the one that is "built in" to the 21CT55 that we have running. It came with a hand-drawn schematic, done by David Neegard, the 87 year-old Engineer from RCA.

I will dig it all out and hook it up to a working CT-100 chassis that I currently have on the Test Jig.

Once I know it's OK, I would be happy to share the info with whoever wants it.

Stay Tuned!

Kirk

Any updates on this?

[consoleguy67]

He was a spy for Sarnoff. He tried to screw over Farnsworth!!

[Kirk]

PM me- your box is full-

Thanks,
Kirk

[Electronic M]

Originally Posted by Kirk

PM me- your box is full-

Thanks,
Kirk

When one's PM box fills both send and receive stop working. I was able to clear some space so it should work now. I try to avoid using PMs for anything other than exchanging private contact info, and discussing sales to avoid clogging my inbox with technical/restoration discussion that could be done publicly and be of benefit to the community as a whole rather than just 2 people.