Today's Mystery Guest (RCA CTC-4)

[Phil Nelson]

I cost just under $180 to FedEx the empty box coast-to-coast. It's the size that made it expensive; the shipper told me it could have weighed up to 200 pounds without increasing that charge. (UPS would have cost even more, if you're wondering). My box was about 2-3 inches taller than it really needed to be. I don't know if making it shorter would have gotten it under some size limit.

I couldn't resist setting the new tube into the cabinet and trying on the retainer ring.



That anode connection is awfully close to the ring. Seems like you're asking for trouble (arcing) if you don't cut away some of the ring.

Looking ahead to when I really install it, the tube has an aquadag coating, so I guess that means fashioning a ground connection.

I don't have any use for the old insulating skirt. I wonder if it would be useful to cut away the bottom of the skirt and retain the rest (the waist, if you will) to go between this ring and the tube's neck and bell? I could even pigtail onto the old ultor connection -- which is built into the skirt -- to make the new aquadag connection. (I already cut off most of the old ultor lead to make my new anode lead.) That would mean cutting a hole in the skirt for the anode lead, of course.

On the other hand, if I butcher the skirt, I couldn't reuse it in the remote event that I run across a good 21AXP22 or have mine rebuilt . . . .

Phil Nelson

[zeno]

Interesting stuff.
For a dag connection use flat braided wire with a spring to pull things tight.
Anode is too close, cut out a large half moon. Insulate with a
piece of plastic with a channel, get from a 70's era Zenith. Others
may have used them, dont remember. They went on the DGS shield.

Use the large brown single wire anode connector from a Zenith tripler
like a 221-141-**. Very common & the heaviest anode I remember.
We used them for all replacements. PN's are 15-276 & 15-276-01
one has 2 holes for HV & focus divider & the other just one hole.
Most had a screw to put them on.

73 Zeno

[stromberg67]

Originally Posted by Phil Nelson

I cost just under $180 to FedEx the empty box coast-to-coast. It's the size that made it expensive; the shipper told me it could have weighed up to 200 pounds without increasing that charge. (UPS would have cost even more, if you're wondering). My box was about 2-3 inches taller than it really needed to be. I don't know if making it shorter would have gotten it under some size limit.

I couldn't resist setting the new tube into the cabinet and trying on the retainer ring.



That anode connection is awfully close to the ring. Seems like you're asking for trouble (arcing) if you don't cut away some of the ring.

Looking ahead to when I really install it, the tube has an aquadag coating, so I guess that means fashioning a ground connection.

I don't have any use for the old insulating skirt. I wonder if it would be useful to cut away the bottom of the skirt and retain the rest (the waist, if you will) to go between this ring and the tube's neck and bell? I could even pigtail onto the old ultor connection -- which is built into the skirt -- to make the new aquadag connection. (I already cut off most of the old ultor lead to make my new anode lead.) That would mean cutting a hole in the skirt for the anode lead, of course.

On the other hand, if I butcher the skirt, I couldn't reuse it in the remote event that I run across a good 21AXP22 or have mine rebuilt . . . .

Phil Nelson

Sylvania published a brochure back in the late 60s about installing rare earth tubes in older receivers titled "Color Fidelity for Older Receivers". The part on CTC-4 showed a small portion of the skirt cut away from the anode area of a 21FB to allow for the connection of a compatible lead and boot. I scanned it, and have it somewhere, but not on this machine. I'll look for it tomorrow and if I find it I'll post it here. Should be an easy job to do, and will prevent arcing. I'm considering putting a 21CY in my CTC-4 but haven't yet made up my mind about that.
Good luck Phil!
Kevin

[Steve D.]

Phil,

When I purchased my CTC-5 Wingate, many years ago, the previous owner had already had the 21AXP22A tube replaced w/a 21FB22. RCA provided a conversion kit that allowed for the installation with a retaining ring that attached directly to the rear of the mask. No struts required and plenty of clearance room for the anode lead. I don't recall ever seeing another kit like this in other sets.

-Steve D.

[Phil Nelson]

Thanks, that is excellent information. I wish I could install the CRT and try to fire it up tomorrow, but with so many things packed up and no suitable place to work, that ain't gonna happen. At least I can try to collect the right materials in the meantime.

Phil Nelson

[stromberg67]

Phil,
I couldn't find the original brochure, but I did find a scanned copy in my CTC-4 binder. The scans aren't too good, but can be read. At least the recommended dimensions are given for notching the flange, along with advise about supporting the bottom of the mask assembly, as the glass tube is much more heavy than the 21AX.
Kevin

[Phil Nelson]

Originally Posted by stromberg67

Phil,
I couldn't find the original brochure, but I did find a scanned copy in my CTC-4 binder. The scans aren't too good, but can be read. At least the recommended dimensions are given for notching the flange, along with advise about supporting the bottom of the mask assembly, as the glass tube is much more heavy than the 21AX.

Yes, I had never lifted a metal tube before and I was startled at how much lighter it is than the glass counterpart.

I might be able to get that article through an inter-library loan (to make a better scan) if I can tell them the desired issue. As I read the first page, it is Sylvania News Technical Section, Summer-Fall 1965, volume 12, no. 2.

Phil Nelson