21AXP22A Replacement in CTC-5

[Tim]

Hi Folks:

I have this CTC-5 that unfortunately has a necked 21AXP22A. I plan on installing either a CY or FB and am seeking ideas on mounting from those that have been down this road already. No sense re-inventing the wheel. I know RCA made a conversion kit for this and I have the kit instructions but I am sure there are no kits around anymore. I also know some slight mods need to be made to the drive circuitry and I have the info on that. I think there may be a slight curvature difference in the faceplates of the metal and glass CRTs but that is not a show stopper.

The plastic boot that currently mounts the metal CRT is not going to fit on the glass CRT so my first thought is to locate a metal mounting collar and hardware from a trashed or gutted later style cabinet such as a 9, 10, 11 or 12. Anyone have one I could purchase? I am also interested in what other methods have been used by those who have done this already.

The second part to this is the yoke mounting. The yoke is designed to mount to the plastic boot so a modified mounting method is needed to hold it in place. I imagine I can come up with a clamp arrangement but would like to hear from others that have done this. Thanks in advance for any suggestions.

I know everyone enjoys seeing pictures so one is attached. It is a Chandler in walnut with UHF. BTW - anyone have 4 gold metal 6" legs they don't need? I have some wooden ones that will do for now.

[miniman82]

You need the metal CRT support ring from a CTC-7, which will also have the edge purity hairpin magnets on it. Then instead of trying to keep the stock yoke, you might try using one from a later chassis like a 9 or a 10. Those clamp to the neck of the tube, and it would be a simple thing to crush a useless octal tube to repin it's socket for use with the yoke.

I tried using a glass tube in my CTC-4, but the yoke support was too close to the anode connection of the 21FJP22 I was using and it arced over.

[Mal Fuller]

The RCA metal to glass conversion kits dealt with the deflection yoke mounting/clamping problem by supplying a stock plastic yoke cover of the type used on the CTC-7 and up yokes. Finding a good cover may be a small challenge in itself because the later yoke covers were made of some sort of self-destructing (crumbling) plastic that did not age well.

[mstaton]

This has the conversion done to it years ago. Has a "CYP" glass tube and newer style yoke but missing the hairpins. Hope this helps

[Electronic M]

To stop the arcing (as far as I can tell) on my CTC4 that uses a glass tube I used the anode connector and HV wire of a modern BPC set a neighbor put at the curb, and folded some thicker plastic (that used to be a bag that capacitors were sold in) which I placed between the anode connector suction cup and the yoke frame......So far it seems to work well in preventing direct arcing......

[mstaton]

You need this plastic piece also from the ctc-7/9. Goes between the CRT and support ring. This came from my CTC-9 but was not needed for a FJP/FBP installation.

[Tim]

Thanks very much for the comments and photos so far. That confirms what I was thinking that I need to find a metal mounting collar and hardware from a later model. The RCA instructions for the update kit is only text and no drawings or photos so it is tough to go by. The current black yoke cover has, in fact, turned to dust and I do have a newer one I can use so I think I have the yoke mounting covered. Anyone have a junked cabinet or collar taking up valuable space you want to gain back?

[Mal Fuller]

Originally Posted by mstaton

This has the conversion done to it years ago. Has a "CYP" glass tube and newer style yoke but missing the hairpins. Hope this helps

That's the CTC-5 style yoke with a newer style cover. You can still see the original metal yoke securing extensions on each side of the yoke that once interfaced with the discarded plastic cone.
You won't find any yoke connections inside the cover's holes.