Looking for a flyback for a RCA CTC 15

[nasadowsk]

There was an rca tech note that said you seat the 3A3 into its socket with 1/8 th clearence. Then put the top on, and make sure its bolted down tight. Dumb design.

The focus stick I guess wasn’t ready either - they went back to a tube…

Didn’t Zenith just use a rectifier with a conventional setup? RCA seemed to make things stupid at times…

[jsandlin]

With it out of the set and on the bench the resistance from the core to the connection for the rectifier plate (3A3) measures about 200 Ohms. one side has a burn from the plate wire.

luckily one of the other members has a NOS RCA he is willing to sell.

Will post pictures when I get it in and hopefully working.

[zeno]

IIRC all Zenith rectangles with high focus used a stick rect. Later
roundies also I think but it has been a loooong time.
I like sticks myself. No more reliable but easier to fix. Always hated doing
filament winding & sockets on tube jobs.

73 Zeno
LFOD !

Originally Posted by nasadowsk

There was an rca tech note that said you seat the 3A3 into its socket with 1/8 th clearence. Then put the top on, and make sure its bolted down tight. Dumb design.

The focus stick I guess wasn’t ready either - they went back to a tube…

Didn’t Zenith just use a rectifier with a conventional setup? RCA seemed to make things stupid at times…

[damen]

I transfered the tire from a CTC15 flyback to the frame of a burned CTC16 flyback and kept the original pulse winding assembly. Worked fine, just need to remember the short plate cap lead when lifting the cage cover!

[Jon1967us]

Originally Posted by damen

I transfered the tire from a CTC15 flyback to the frame of a burned CTC16 flyback and kept the original pulse winding assembly. Worked fine, just need to remember the short plate cap lead when lifting the cage cover!

How did you get the tire off? Does the core come apart in the middle? I don’t see how you can get the tire off the core

[damen]

The RCA ones come apart quite easily. Straighten the one tab at the top of the frame above the stamped numbers and pull. Sometimes there are spacers between the 2 core pieces, have to be careful to put them back.

[bhegges]

Question on using a new silicon diode for the focus rectifier vs original tube diodes. I like the idea of removing the heater current from the flyback, is there any concern around an increased focus voltage or the change in reverse resistance?

To further "lighten" the load on the flyback is there any reason not to use a silicon diode for the HV rectifier too? Note I understand there is a line to where you should just get a modern TV, but flyback transformers are getting hard to find.

I have also seen they use to make solid state devices that plug into the tube socket but I had thought I read they are prone too fail and it is just better to keep using a tube, not sure if that is because they were selenium, wrong ratings, or just 50+ years old.

[nasadowsk]

Originally Posted by zeno

IIRC all Zenith rectangles with high focus used a stick rect. Later
roundies also I think but it has been a loooong time.
I like sticks myself. No more reliable but easier to fix. Always hated doing
filament winding & sockets on tube jobs.

73 Zeno
LFOD !

My only experience with a tube Zenith rectangular set was one we got from a friend, that started arcing badly one day. When you're 10 and that happens and you're alone, you don't think much beyond yanking the cord out of the wall...

ISTR peeking in the back and seeing a TALL HV box. Beyond that, I don't know what was in there...

[dieseljeep]

Originally Posted by zeno

IIRC all Zenith rectangles with high focus used a stick rect. Later
roundies also I think but it has been a loooong time.
I like sticks myself. No more reliable but easier to fix. Always hated doing
filament winding & sockets on tube jobs.

73 Zeno
LFOD !

When the HV rect winding arced out, I used to just cut away the winding and use, what they referred to as a "Solid Tube".
I assured the customer that it was less expensive to do it that way.