View Full Version : Stromber Carlson K-1 Color TV

Steve K
01-05-2016, 11:39 AM
It has been a long time since I started a thread on here so I'm not sure I remember how.

It was a year ago today (Jan 5) that my friend and fellow TV collector Ed Reitan passed away. Ed had bequeathed his rare Stromberg Carlson 15 inch color set to me. I helped Ed recap the chassis about 5 years ago. We got a picture on the set but had problems with the color. The color oscillator coil broke and Bob Galanter kindly repaired it for Ed. However, I was never to get back to Omaha and Ed never got the chance to finish it. I was able to pick the TV up this past summer and take to my Wisconsin home. I finally got a chance to work on it a few days ago and was able to get a fairly good picture on it. It has a unique system of obtaining purity and static convergence. There is a color picture but it is missing the green signal. Bob is going to visit next week and we will see if we can fix that. If not, it will have to wait until I can come back to Wisconsin in May.

Here are some pictures (if they load OK!)...


Steve D.
01-05-2016, 03:16 PM

Ed Reitan would be very pleased with your success in bringing the Stromberg-Carlson back to its former full color glory. Great example of this rare early color receiver.

-Steve D.

01-05-2016, 03:34 PM
Looks good !


01-05-2016, 04:23 PM
That looks nice. I have to admit that as a youngster, I was not fond of the round "ancient looking" design. I have a new appreciation for these pieces of history. I particularly did not remember the 15GP22. I have lots of respect for the survivors that still produce a raster.

Good on ya Mate.

01-05-2016, 07:09 PM

You say it's missing green; kinda looks to me like an I/Q set missing Q (both green and purple).

01-05-2016, 09:51 PM
I'm very impressed!

Phil Nelson
01-05-2016, 10:15 PM
What a rare and interesting set. Stromberg Carlson sets are usually well built, in my limited experience. One peek at that dual chassis and you can tell this is not an RCA clone :)

Is a schematic available anywhere online?

I noticed that this page at the ETF website has a little more info about the purity & static convergence gizmos:


Phil Nelson
Phil's Old Radios

01-05-2016, 11:13 PM
Color TV certainly has come a long way since the Stromberg-Carlson K-1, from the 15GP22 round screen to the 21AXP/CYP22 round, to 21- and 23" rectangular, to 12-, 16- and 19-inch portables, to today's flat screens.

Color had to start somewhere, though, and I guess the S/C K-1 (and RCA's own CT-100) were right at that starting point. I don't think there are many of those K-1s in existence today; the one being discussed here could well be the only such set left, so I'd hang on to it and get it working as well as possible.

The number of tubes used in the S/C K-1 is astounding. Thirty-three signal tubes, multiple HV (ultor) and low-voltage (B+) rectifiers . . . I guess multi-section/function tubes hadn't yet been invented when this TV was new, so each tube had its own unique function. I am also sure this set must have cost a small fortune, being one of the first color sets made (aside from RCA's CT-100), so there probably were not many K-1s in use in the US. After all, color TV itself was in its infancy when this set was new, and b&w sets were . . . well, not rare, but not as common as they were to become later in the 1950s and sixties until small-screen color portables and large-screen color consoles from RCA and Zenith appeared.

Again, hold on to that S/C K-1. It is truly one of a kind, and we will likely never see another color TV like it.

John Folsom
01-06-2016, 02:39 PM
Steve, Good work getting that repaired color ctransormer back in and working. Use NTSC color bars to troubleshoot you color problem, it is very diagnostic.

Pete Deksnis
01-06-2016, 08:13 PM
Phil, Ed thought of the K-1 as a close clone of the RCA Model 4. So close in fact that he felt the image on a K-1 would give the viewer accurate insight as to what an operable Model 4 would display.

First, there are differences between the two designs, although examples such as these affect the bottom line more than the picture:

For its power supply, a Model 4 used two selenium rectifiers in a voltage-doubler circuit as did the Model 5 and CT-100. The K-1 uses four 5U4's.

The Models 4 and 5 used a 6CD6 to drive their horizontal output transformers while the K-1 used a parallel-connected pair of 6CD6's.

There are many similarities between the two designs, for example:

The Model 4 and K-1 use a Chroma Phase Amp stage and a pot for Hue adjustment rather than the much simpler variable cap and inductor hanging on the burst amp grid -- that first appeared on the Model 5.

The R, G and B video amplifiers on the Model 4 and K-1 were identical, but then were cleaned up and simplified somewhat for the Model 5.

And yes, There is a K-1 Photofact, the Set 265 Folder 13 dated Feburary 1955.


01-06-2016, 10:18 PM
Great to see these old sets survive with a little help from our friends. :-)

01-08-2016, 06:09 PM
It's nice to see a set displayed that the contrast is not driven up all the way and displays a more realistic image.

01-08-2016, 06:22 PM
It's nice to see a set displayed that the contrast is not driven up all the way and displays a more realistic image.

I agree. If you try to get a picture that's "hard as nails" on a vintage color TV you usually wind up with a poor picture that doesn't really allow the CRT to track correctly. An example for me is my CTC-4. I find if the contrast is driven too hard, the background tint shifts somewhat, and produces a lees than accurate pic. If everything is carefully adjusted, the picture can be very good and satisfying. Still have that nasty blue/green crossover distortion though...:thumbsdn:

01-09-2016, 08:33 PM
I'll send Sams 265-13 to ETF.

01-09-2016, 08:51 PM
I love the color on those early sets. Very impressive!

01-10-2016, 09:05 AM
I agree with dishdude, that color picture, on the early SC, has amazing hues, even as it is right now! So nice to see it at this point.

Electronic M
01-10-2016, 01:31 PM
I think Old_tv_nut's assessment of it missing the Q color axis is correct... The I axis (Orange and Cyan) was used in CHEAP two color film processes, and yields passable skin tones, and enough of the palate as to not easily be perceived as missing something.

Steve K
01-11-2016, 06:34 PM
Here is an update on the K-1. Had to repair the delay line, thanks Bob! A simple adjustment to the quadrature coil brought the green back, thanks John!

Final set up and adjustment will have to wait until I get back to Wisconsin in May. I think Ed would be happy with the progress thus far.

01-11-2016, 08:29 PM
The Photofact has been posted on the ETF site.