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  #1  
Old 03-17-2014, 01:09 PM
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bonanzaman bonanzaman is offline
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WTB 12LP4 Double Pole Ion Trap Magnet

Looking for a Jetec #108 or equivalent double pole Ion trap magnet for my
Philco 50-1401 with a replacement Sylvania 12LP4 installed.

Last edited by bonanzaman; 03-17-2014 at 01:38 PM. Reason: typo
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Old 03-17-2014, 08:55 PM
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I have double pole crt magnets, just not sure what kind. It would be an original one pulled out of old set.
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Old 03-18-2014, 01:42 PM
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Are you sure it requires a double ion trap? Forget the specs, if the tube has been rebuilt, it may now only require a single pole IT.
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Old 03-19-2014, 06:43 PM
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Quote:
Originally Posted by John Marinello View Post
Are you sure it requires a double ion trap? Forget the specs, if the tube has been rebuilt, it may now only require a single pole IT.
I am not real anxious to pull off the yoke asm to look at the full length of the neck,
but I can see no other evidence that it has been rebuilt, and the sylvania tube data sheet calls for a double pole magnet and I know the riginal Philco tube used a single. The original Sylvania paper x-ray caution label is still on the tube as well.
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Old 03-19-2014, 07:00 PM
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So if you compare pictures of the different company's tubes, can you see a difference in the gun elements between the two, if you do it with a known tube requiring the double ion trap.....?
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Old 03-20-2014, 12:58 AM
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Quote:
Originally Posted by Username1 View Post
So if you compare pictures of the different company's tubes, can you see a difference in the gun elements between the two, if you do it with a known tube requiring the double ion trap.....?
I've never found a detailed enough photo to "see" the gun elements on any of these vintage CRT's. The mfgr's data sheets only show a "schematic"....which pin goes where, not the physical construction or layout of the gun elements.. I only know that this set has had the original Philco tube replaced with a Sylvania picture tube, and the Sylvania data sheet clearly calls for a double pole Ion trap magnet, positioned at a particular distance and orientation on the neck of the tube. Whoever changed out the tube, simply put the original Philco single pole magnet back on, adjusted it as bright as it would get, and called it good.
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Old 03-20-2014, 08:00 AM
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Yes, I read all the posts on the topic, and from what I understand, the gun is bent, the heavier ions run into the side of one of the gun elements and don't hit the screen, the magnet turns the flow of electrons and points them towards the screen. And all magnets have two poles, or they could not be magnets, so I'm assuming those Sylvania double ion traps must be doing something special, like maybe there is a need for a turn in two spots, or maybe the turn is a little more steep than other tubes, so the magnet needs to be a little stronger..... Just wondering if a difference can be seen, thats all.... Something that may only bee seen with the two tubes compared side by side, or if people post pictures taken similarly and can be carefully compared.

And why are you guys calling it a "double pole" is that the company term...? Or are they calling it a "double ion trap" meaning possibly two in one...? as two magnets ganged together..... Anyone have one and can post picture....? And better yet can identify how it's business parts effect the electron flow....?
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Last edited by Username1; 03-20-2014 at 08:05 AM.
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Old 03-20-2014, 11:13 AM
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Quote:
Originally Posted by radio nut View Post
I have double pole crt magnets, just not sure what kind. It would be an original one pulled out of old set.
I'm pretty sure they're all the same so whatever you have will work. For example, a 10BP4 trap magnet will work just fine on a 12LP4

Quote:
Originally Posted by Username1 View Post
... so I'm assuming those Sylvania double ion traps must be doing something special...
Sylvania isn't doing anything special - all 12LP4s require a double field ion trap magnet. Same goes for 7DP4s, 10BP4s and several other early B&W CRTs. It's two magnets spaced about an inch apart.

Here's an Admiral where the black (stronger) magnet goes towards the base.



Here's an early RCA electromagnetic version.
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Last edited by bandersen; 03-20-2014 at 11:30 AM.
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Old 03-20-2014, 11:18 AM
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Quote:
Originally Posted by radio nut View Post
I have double pole crt magnets, just not sure what kind. It would be an original one pulled out of old set.
Radio nut, please check your PM's.
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Old 03-20-2014, 11:40 AM
dieseljeep dieseljeep is offline
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Quote:
Originally Posted by bandersen View Post
I'm pretty sure they're all the same so whatever you have weil work fine. For example, a 10BP4 trap magnet will work just fine on a 12LP4



Sylvania isn't doing anything special - all 12LP4s require a double field ion trap magnet. Same goes for 7DP4s, 10BP4s and several other early B&W CRTs. It's two magnets spaced about an inch apart.

Here's an Admiral where the black (stronger) magnet goes towards the base.



Here's an early RCA electromagnetic version.
Hey, Bob. Thanks for posting these pictures, for clarification.
Philco made their own OEM crt's and went against the norm.
I would ask the question, why they could do it, when no one else did.
Looking the data on the 12LP4 and the 16WP4, they both show double field ion traps.
I bought a Philco 12LP4, that was pulled from a scrap set and I kept the single ion trap with it, to remind me that, that particular 12LP4, uses a single ion trap.
As a side note, I don't remember, the rebuilder's price lists, having 10BP4's and 12LP4's available as of the early 60's. I guess the demand was no longer there.
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Old 03-20-2014, 11:43 AM
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The RCA data sheet for the 12LP4 refers to North & South poles of the trap magnet in the note for location #4 on the tube neck: "Distance of internal pole pieces. Plane through pin No 6 and the tube axis passes through line joining centers of pole pieces. Direction of principal field of ion trap magnet should be such that North Pole is adjacent to Pin No 6 and South Pole to pin No 12"
It is refered to as a "external double field magnet"
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Old 03-21-2014, 09:06 AM
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Thanks guys for posting all this info, and the great pictures !

I guess this does not apply to the 12KP4 ? Because the chassis for a GE 12C107 I have from my brother seems to not have the same ion trap you guys have pictured....? Looks single to me..... The gun elements are really short, I'm wondering if that is or IS NOT an ion trap, but some other magnet for something else.... Sylvania tube though....

I'm gunna have to take a closer look at it....
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Last edited by Username1; 03-21-2014 at 09:31 AM.
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  #13  
Old 03-21-2014, 12:07 PM
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Quote:
Originally Posted by dieseljeep View Post
Hey, Bob. Thanks for posting these pictures, for clarification.
Philco made their own OEM crt's and went against the norm.
I would ask the question, why they could do it, when no one else did.
Looking the data on the 12LP4 and the 16WP4, they both show double field ion traps.
I bought a Philco 12LP4, that was pulled from a scrap set and I kept the single ion trap with it, to remind me that, that particular 12LP4, uses a single ion trap...
That seems really odd. A 12LP4 should be interchangeable with any other 12LP4 otherwise it's not really a 12LP4

Quote:
Originally Posted by Username1 View Post
Thanks guys for posting all this info, and the great pictures !

I guess this does not apply to the 12KP4 ? Because the chassis for a GE 12C107 I have from my brother seems to not have the same ion trap you guys have pictured....? Looks single to me..... The gun elements are really short, I'm wondering if that is or IS NOT an ion trap, but some other magnet for something else.... Sylvania tube though....

I'm gunna have to take a closer look at it....
The 12KP4 is aluminized and does not use an ion trap at all. So unless yours was rebuilt with a bent gun, it should not have a magnet on the neck.

FYI you can find data on Sylvania CRTs here.
http://www.bunkerofdoom.com/tubes/syl59/HTMLS/CRT.HTM

This is another great source for data from various manufacturers. I don't recall ever seeing Philco specific CRT data. GE, Sylvania and RCA specify a double field for the 12LP4.

http://frank.pocnet.net/sheets11.html
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Last edited by bandersen; 03-21-2014 at 12:13 PM.
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Old 03-25-2014, 05:11 PM
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bonanzaman bonanzaman is offline
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Still looking for one of these. Thanks, Bob, for posting the pic of the black & blue banded
Magnet...I'm guessing that is the style I should try to find.
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Old 03-25-2014, 05:27 PM
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Pretty much any style should work. I didn't realize these were so hard to find. Maybe many got tossed along with dead CRTs ?
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