Videokarma.org TV - Video - Vintage Television & Radio Forums - GORGEOUS RCA CTC-16 Console on eBay!!!!

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Videokarma.org TV - Video - Vintage Television & Radio Forums (http://www.videokarma.org/index.php)

- Early B&W and Projection TV (http://www.videokarma.org/forumdisplay.php?f=19)

- - GORGEOUS RCA CTC-16 Console on eBay!!!! (http://www.videokarma.org/showthread.php?t=275667)

bandersen

03-01-2023 03:49 PM

Running the 2.35 volt filament using the 2.68 volt tap would be fine. I was thinking more about all the other stuff like the yoke impedance and connector pinouts.

Chris K

04-13-2023 06:41 PM

Quote:

Originally Posted by bandersen (Post 3249164)

Not really - Predicta compatible CRTs get snatched up quickly.

Are you sure you want a 12JP4? Remember it has no ion trap and will develop an ion burn. I'd suggest going with a 12QP4 to avoid this. 12LP4, 12KP4 or similar might be possible, but they have a different anode connector and are longer.
https://live.staticflickr.com/542/31...0c520182_z.jpg

I have an opportunity to buy a NOS 12QP4 Bob. Is it a direct replacement for the 12JP4? Do I need an ion trap for 12QP4?

bandersen

04-13-2023 07:17 PM

Quote:

Originally Posted by Electronic M (Post 3249183)

ISTR someone on that predicta Facebook group you're part of sticking a debutante head onto a pedestal cabinet, so the reverse should be possible.
As for CRT compatibility the only difference is heater voltage. A series chassis doesn't even notice that, but a parallel heater chassis like the princess can be adjusted to compensate...In the princess and the similar chassis in the continental console all you have to do to compensate for a different heater voltage is swap the heater hot lead between the 2V tap and the 6V tap on the power transformer.

I've ran 17" headshells as test jigs for 21" chassis before so this can be done.

I was thinking about putting a Debutante CRT on a Pedestal set some more. The Pedestal uses 600mA series string tube filament while the 17" CRT is 450mA. You could still do it, but you'd need to add a shunt resistor across the CRT filament.

bandersen

04-13-2023 07:20 PM

Quote:

Originally Posted by Chris K (Post 3250171)

I have an opportunity to buy a NOS 12QP4 Bob. Is it a direct replacement for the 12JP4? Do I need an ion trap for 12QP4?

Datasheet says it needs an external ion trap magnet. Here are the links so you can compare the dimensions.

https://frank.pocnet.net/sheets/127/1/12JP4.pdf

https://frank.pocnet.net/sheets/127/1/12QP4.pdf

Chris K

04-13-2023 07:47 PM

Quote:

Originally Posted by bandersen (Post 3250173)

Thanks so much Bob. Looks like the datasheet for the 12QP4 has an error maybe? It says pin 10 no connection but it's G2, the same as the 12JP4. Looks like things line up well. The 12QP4 might have a slightly larger screen diameter but looking at the chassis and cabinet, it shouldn't be a problem.

Chris K

04-14-2023 06:25 AM

Quote:

Originally Posted by bandersen (Post 3250173)

The seller has the original ion trap magnet and is including it in the purchase. Yaaaaaay! I'll be in the Doghouse for the next couple of months. Sorry Motorola VT71...back on the shelf for you...again. No luck at all with getting the video. No signal and no failed parts.

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