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  #1  
Old 09-13-2018, 10:17 PM
grimer's Avatar
grimer grimer is offline
<<721 Porthole ????
 
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12hp4 crt

Picked up a round 12" crt the other day. Assumed it was a 12LP4,but it is a 12HP4..Cannot find any info about it.
Anyone know anything about this tube?
Thanks
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  #2  
Old 09-13-2018, 11:29 PM
WISCOJIM WISCOJIM is offline
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Probably the same as a 12HP1, except that it has P4 phosphor.

https://frank.pocnet.net/sheets/201/1/12HP1.pdf

.
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Old 09-14-2018, 11:23 AM
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Quote:
Originally Posted by WISCOJIM View Post
Probably the same as a 12HP1, except that it has P4 phosphor.

https://frank.pocnet.net/sheets/201/1/12HP1.pdf

.
http://www.mif.pg.gda.pl/homepages/f...3/1/12LP4A.pdf

That tube is ~5" longer than a 12LP4, and uses an 11-pin base instead of the standard 12-pin...Those are obvious enough differences that one would probably notice.

How many pins can the base accommodate, and how many pins are actually populated? (the 12LP4 is a 12-pin but only ~5 are typically populated)
Does the gun look to have electrostatic deflection plates (or leads for them going to the front) in it, or a bend in the lower part of the electron gun for an ion trap? Got pics?

One exceptionally unlikely scenario that would be even harder to mix up is if you scroll down this page: http://www.myvintagetv.com/picture_tubes.htm to the 10HP4 which was a 10" version of the 7JP4 which Raytheon used in some TVs...Maybe the 12HP4 is a 12" 10HP4...If it is that is one rare tube, and one some electrostatic set collectors (myself included) tired of squinting at 7JP4s might want to have.
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Old 09-14-2018, 12:30 PM
dieseljeep dieseljeep is offline
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Quote:
Originally Posted by Electronic M View Post
http://www.mif.pg.gda.pl/homepages/f...3/1/12LP4A.pdf

That tube is ~5" longer than a 12LP4, and uses an 11-pin base instead of the standard 12-pin...Those are obvious enough differences that one would probably notice.

How many pins can the base accommodate, and how many pins are actually populated? (the 12LP4 is a 12-pin but only ~5 are typically populated)
Does the gun look to have electrostatic deflection plates (or leads for them going to the front) in it, or a bend in the lower part of the electron gun for an ion trap? Got pics?

One exceptionally unlikely scenario that would be even harder to mix up is if you scroll down this page: http://www.myvintagetv.com/picture_tubes.htm to the 10HP4 which was a 10" version of the 7JP4 which Raytheon used in some TVs...Maybe the 12HP4 is a 12" 10HP4...If it is that is one rare tube, and one some electrostatic set collectors (myself included) tired of squinting at 7JP4s might want to have.
The data sheet that Jim cited shows the CRT is an E-stat deflection and focusing.
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Old 09-14-2018, 01:04 PM
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Kevin Kuehn Kevin Kuehn is offline
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If the base and envelope really look similar to a 12LP4, I'd plug it into my tester and slowing bring up the filament voltage and see how it tests. I can't imagine the envelope of an electrostatic tube being mistaken for a magnetically deflected. Can you post a picture here?

Last edited by Kevin Kuehn; 09-14-2018 at 01:07 PM.
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  #6  
Old 09-14-2018, 05:58 PM
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<<721 Porthole ????
 
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Thumbs up

Here is a link,the 4th pic is a projector tube from the same place..
https://www.toadstation.com/12hp4

Last edited by grimer; 09-14-2018 at 07:57 PM.
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  #7  
Old 09-14-2018, 08:14 PM
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Polaraligned Polaraligned is offline
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Try testing as a 12LP4 and see what happens.
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Old 09-14-2018, 09:43 PM
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<<721 Porthole ????
 
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Quote:
Originally Posted by Polaraligned View Post
Try testing as a 12LP4 and see what happens.
Well,that was my thought to,I would just start at a lower filament voltage,as
mentioned in one of the other posts....
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Old 09-14-2018, 09:48 PM
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Kevin Kuehn Kevin Kuehn is offline
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I'm going to guess Progressive Electronics was some place selling radio and TV parts to DIY types and that they sold used or rebuilt CRTs and came up with their own tube type designation.
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Old 09-14-2018, 11:16 PM
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Certainly looks like a 12LP4...I think Kevin is right about a rebuilt with a made up number. Some late 60's color rebuilds that would sub for multiple numbers had odd made up numbers assigned by the rebuilder.
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  #11  
Old 09-16-2018, 03:47 PM
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<<721 Porthole ????
 
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I hooked it up to my Beltron,The Beltron meter scale is from1 to 10.
This tube reads 9.75....The highest it has ever gone,Hmmmmm
I have a Garod chassis I'm working on with a bad 12lp, I will try this tube on that
chassis and see what happens...
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  #12  
Old 09-17-2018, 04:28 PM
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Let us know how it works in the set.
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  #13  
Old 09-21-2018, 09:01 PM
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grimer grimer is offline
<<721 Porthole ????
 
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Well,I was greeted by a bright raster.The screen goes dark at a higher brightness setting,as I only have about 9Kv of high voltage now.
This CRT requires an ion trap,just like the 12lp4,but is about 2 inches shorter
in overall length.The face of the screen seems to be just a bit smaller too.
I have more work to do,but its looking good sofar....I do not have a cabinet for this chassis,I plan to use it as is..

https://www.toadstation.com/12hp4a

Last edited by grimer; 09-21-2018 at 09:05 PM.
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