CTC4 Cheltenham restoration complete

[ohohyodafarted]

I finally completed the Cheltenham restoration that I started 4 years ago.

You can see the write-up and all the photos at the following link

http://antiquetvguy.com/FramesetPage...FrameSet1.html

In the LEFT menu click "Restorations" and then click "RCA CTC4 Cheltenhm"

[NewVista]

That classic looks sensational! Like new showroom condition!

[Pete Deksnis]

Beautiful technical work too, Bob. Your website description mentioned the use of original selenium rectifiers in the power supply. Interesting. "Avoid spreading toxic fumes in case the selenium rectifiers short out and go 'cherry' " has been the gospel truth for years now... but is it accurate?

I switched back to the 65-year-old selenium rectifiers in CTC2 chassis B8000173 I'm finishing up the restoration for that belongs to InfoAge in N.J. It wiped out a bunch of pain-in-the-butt stuff! For example, the design center of the input power for the CT-100 is, according to the label, 115 vac. Yet today -- and for what may be at least a decade or more -- the line voltage in the U.S. runs much higher. Here in MI it's above 123 for much of the day and a little under 123 for the rest.

First of all, I run power to the CTC2 through a six foot extension to a power strip, then through a 50-foot extension cord to the cheater cord. This puts the 123.+ volts at around 117 vac once the tubes warm up.

I have knowingly not added 25-watt power resistors to the equation because of the adjusted ac input voltage. Perhaps a mistake. Perhaps not. But now that the original seniniums are doing the work, much pain-in-the-but stuff is history. Here's the biggy: Been in contact with John Folsom and Wayne Bretl over the high-voltage rising to 25 or 26 kV for a second before the regulator drags it down to the design center 19.5 kV. My experience expected it to be only as much as 23 kV. Now, with the original seliniums in use, its 23 kV. In another case, the 285-volt line ran at 306 volts. Now it's 284.6. The reason for the higher voltage has been the silicon diodes that replaced the seliniums.

So, I'll run the 65-year-old seliniums for a while to see if they're reliable. Or, I'll continue using silicon replacements and buy a bunch of 25-watt power resistors. Maybe both.

BTW. The CTC2 chassis drew around 460 watts with the silicon diodes. Now it's 425.

Pete

[kvflyer]

Thanks for sharing that wonderful restoration. There are only a few of us who appreciate what you have done. I am one of them! I still have a CTC-9 in queue.

I will not hijack your thread and start one on my set!