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 Post subject: 10BP4 VS 10FP4
PostPosted: Mar Sun 29, 2020 2:37 pm 
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Joined: Jun Thu 12, 2008 1:05 am
Posts: 150
Location: Detroit, michigan
I want to replace a 10BP4 with a 10FP4. I know I don't have to use the ion trap, Is there any other worries?


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 Post subject: Re: 10BP4 VS 10FP4
PostPosted: Mar Sun 29, 2020 2:46 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 5890
Location: Montvale NJ, 07645
It should be a straight replacement. The FP is basically just an aluminumized version of the BP.
Check that you have a straight gun in the FP because I have heard from some others that sometimes they have a bent gun and need an ion trap.


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 Post subject: Re: 10BP4 VS 10FP4
PostPosted: Mar Sun 29, 2020 3:01 pm 
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Joined: May Sun 07, 2017 11:35 am
Posts: 840
Location: Belrose, NSW, Australia
Looking at the data sheets for each, no real problems that I can see. Pinouts are the same.

https://frank.pocnet.net/sheets/127/1/10BP4.pdf
https://frank.pocnet.net/sheets/127/1/10FP4A.pdf

The 10FP4A (I assume that's what you will be using) is an aluminised tube with an outer aquadag coating that will need to be earthed with a spring-loaded braid or similar. The 10BP4 has this coating so it should already be equipped.

The deflection angle on the newer tube is listed as 54 degrees vs the 50 degrees of the old. That should be well within the range of the chassis' width and height controls.

Bulb dimensions are identical so no problems there.

I'd go right ahead!

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Wax, paper, bitumen, cotton, high voltages - what could possibly go wrong?


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 Post subject: Re: 10BP4 VS 10FP4
PostPosted: Mar Sun 29, 2020 3:36 pm 
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Joined: Dec Fri 08, 2017 5:40 pm
Posts: 324
Location: 44141
In that era that was the demand replacement for the 10BP4. Junk the trap and enjoy a brighter picture.

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Bruce Hagen


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 Post subject: Re: 10BP4 VS 10FP4
PostPosted: Mar Sun 29, 2020 6:13 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2033
Location: Lafayette, CO
Let's see the before and after.... Craig


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 Post subject: Re: 10BP4 VS 10FP4
PostPosted: Mar Mon 30, 2020 12:19 am 
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Joined: May Fri 29, 2009 4:35 am
Posts: 2157
Location: Chicago, IL USA
No, no concerns whatsoever. They are both 54 degrees. Don't know why that datasheet says approximately 50.


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 Post subject: Re: 10BP4 VS 10FP4
PostPosted: Mar Mon 30, 2020 10:43 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 8642
Location: Beaver Falls, PA. USA
A TV collector that I know did the swap in one of his sets, and was very pleased with the brighter picture.

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Tim KA3JRT


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 Post subject: Re: 10BP4 VS 10FP4
PostPosted: Apr Wed 01, 2020 11:06 am 
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Joined: Jan Thu 16, 2020 12:29 am
Posts: 486
It is unlikely to be an issue here because of the size of the CRT (10") and the expected EHT voltages involved.

The EHT is very likely over 6 to 7kV. It was an issue with smaller CRT's trying to go to an aluminzed screen with EHT's under this value.

The electrons in the beam do not have enough energy to penetrate the aluminized coating if the EHT is under about 6 to 7 kV (though it does depend on the exact thickness of the aluminization). So in some cases, fitting an aluminized CRT could result in a dimmer picture.

However, if the EHT is adequate, an aluminized screen produces much higher light output than a non aluminized one. In fact in a non aluminized screen, most of the light output goes backwards into the CRT bulb, where it is wasted.

Aluminized screens were a great improvement for three other reasons too: It prevents the screen surface from charging up, which lowers the effective EHT (making the anode less positive) and the aluminization protects the phosphor to a degree from burns and it protects the phosphor from negative ion bombardment that degrades its light output.

So generally, most CRT's with aluminization don't have or need an ion trap.

Non alminised CRT phosphors are very vulnerable to phosphor burns.

However, you may see an aluminized CRT, with an ion trap, this was an intermediate phase (perhaps to use up the stocks of ion trap electron guns) before they were discontinued


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