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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#2
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If ya still have the thing, I have all sorts of parts.
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"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" |
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
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Also, I am into vintage test equipment, but I'm getting quite the pile of that stuff. My big wish is a black face Hickok 209A. Anything Hickok is worth consideration. I need a meter movement for a 209C which seems to be some rare bird.
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"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" |
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Had one of those years ago. Mine was a vertical chassis console. I hate vertical chassis sets :/
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Audiokarma |
#6
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"Ion burns" on tubes without straight guns are not in fact "ion burns" in the sense some people still seem to believe:
http://www.videokarma.org/showpost.p...20&postcount=8 http://antiqueradios.com/forums/view...16871&start=40 Thank you Kevin! |
#7
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In that case the burn on my 12JP4 is an Ion burn because it has a straight gun, but the spot on the 8AP4 would be from vaporized metal from the gun. I once had a 17" bent gun CRT from a Setchell Carlson (This one in fact http://www.vintagetvsets.com/setchell.htm) that had several flea bites on the inside of the screen that looked like micrometeorites had stuck the phosphor and blasted it off. These weren't large fuzzy spots but more like how a windshield gets pitted when a small stone hits it, only the Phosphor was affected though, not the glass itself. Possibly the beam had hit the screen when there was no sweep but these were off to the the side, not dead center. |
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Also note that WeekendHacker's analysis of ion deflection/ion burn size is incorrect. An ion is NOT deflected by 10% of the deflection angle the electron beam undergoes. He's completely missing the fact that the ions in a magnetic focus tube are NOT being focused before undergoing the minute degree of deflection they experience. Well, they are being focused, but again, the magnetic field has such a minute effect on the ions, that they are essentially unfocused in comparison with the electron beam. If you had a 'static focus tube like a 12AP4 or a 9AP4, you should see a MUCH smaller ion burn because the ions are focused along with the electron beam, and then deflected to a marginal degree by the magnetic field. The ion burn on a 12JP4 is comparatively large because the ions are essentially unfocused. The large burn is NOT a product of deflection; his assertion that the ions are undergoing 10% of the deflection experienced by an electron is absolute hogwash.
Does anyone have a photo of a 12AP4 or 9AP4 with a really bad ion burn? Edit again: The issue of focus is actually what has prevented fast neutron beam therapy from taking off. For certain tumors, especially tumors that are extremely hypoxic, neutron beams do more damage to the rogue DNA than proton beams, X-ray photons, etc. There's a problem with a neutron though: they are both relatively massive, and chargeless (well it may have a charge around 10^-22 e, so essentially chargeless). Because they are changeless, we can't focus them electro-statically or magnetically, so we must resort to collimating a "beam" from the neutrons produced. This is incredibly inefficient, and shaping the beam can be a bit of a challenge. The ion beam in a magnetic focus, magnetic deflection tube is analogous in some respects to a neutron beam: you'd better produce it with the direction you prefer, because you can't do anything to deflect/focus it later. Last edited by benman94; 04-21-2017 at 11:46 AM. |
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#10
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The 12QP4 on my Hoffman 601 apparently has a ion burn spot and I'm trying to make sure it doesn't get worse (not too noticeable when images are moving on the screen and probably even less with the easy vision screen in front of it)
Looking in the Riders, the instruction for "beam Bender" adjustment are confusing. It says to point the arrow forward, toward the 2nd anode and away 180°! I have no clue what this contradictory statement means. Does that mean point the arrow toward the 2nd Anode and then rotate the trap 180°? I just adjusted it for maximum brightness. Seams like that would be sufficient? https://youtu.be/bKE7tG01_xo Last edited by Jon1967us; 10-10-2020 at 12:01 PM. |
Audiokarma |
#11
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My bakelite and wooden 49-701 and 702 7" Philco's both have the same mild ion burn. It's suprising because I never saw it on a 7" model before. The only other set I ever had with it is a Dumont "doghouse", but it's common with them. The burn is hardly noticeable watching something and hardly distracting. I figure if I was 70+ years old I'd have some dark spots too!
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#12
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Forward meaning the arrow is pointing towards the face of the CRT. Rotate the trap magnet around the neck so magnet is on the opposite side of the anode cap.
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I think thats more or less where it landed for the brightest picture.
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If you find a set with X burned into the screen that's from a pirate who left the treasure map with x marks the spot up on the screen for too long
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#15
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In extreme cases the glass can even be melted!
Peter |
Audiokarma |
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