Actually, I found that file directly from Google. I made sure it worked before I sent it, you need to be sure to copy and paste all of it, starting with "file" and ending with "htm". However, I just now went to the file and backtracked to this url: http://www.thevalvepage.com/teletech/teletech.htm With it, you may find additional interesting articles.

Another thought occured to me. Perhaps inadequate high voltage to the anode of the crt would decrease the emission giving the same results as a weak crt.
Donald

Man you need to chill out and thank your lucky stars to be a part of a group of people who at least give a rats a** about your problem. If this were a be perfectly correct all the time forum, what would we have? I love the way many of us simply give educated guesses (some uneducated) just trying to help someone with a clue as to what is going on with a given situation.

Sure now I could see somebody getting steamed if someone led them into physical harm or something. Man, nobody told you to place the HV anode to the crt in your mouth to check for low voltage. Did they?

The craziest part is the fact that we are both using some of the same information and also have some of the same conclusions. AGAIN my info comes from my 4th printed revised edition of the Sylvania Electronic Products Technical Manual-1958

I will state what is clearly said in this very informative manual. The 16RP4 in ANY form is a tube that needs a 35 Gaus, single field ion trap magnet. "The Sylvania type 16RP4A is identical to the 16RP4 except for having an aluminized screen". What I make out of studying this manual is also that "A" does not necessarily mean aluminized. Again case in point the 10BP4A for instance has what is refered to as a "gray filter glass faceplate". No mention of aluminization. Also, I have found out the fact that just because a given tube may be aluminized does not mean that it has a "straight gun" and therefore needs no ion trap.

There is absolutely nothing that says that if a tube has an aluminized screen then no trap is required. Now there are many tubes that were built specifically to NOT require an ion trap. I am fairly certain that ion traps kind of faded out with the 50's. I myself, due to misinformation thought for a long time that if a tube had an aluminized screen than it DID NOT require a trap. I didn't get all bent out of shape about it. Really the person led me toward learning more about the whole ion trap mystery. Double field, single field, needed, not needed ect...

So I think it is an insult to everyone to imply that everyone should refrain from saying anything to try to help anyone unless it is verifyable as being BY THE BOOK. I'm not saying I have never made an incorrect statement on this forum but the Sylvania info is as by the book as it gets. Now there is a possibility of tech books not being completely clear but in this case I doubt it.

So SORRY if my attemt to lend a hand and do some free research did not fix your problem. Evidently some other idiot made the same mistake before me. I think I can speak for both of us and say sorry pal.... I WONT try it again.....

Hey, tube.

Please re-read my comments. I was castigating myself for MY not speaking clearly when I was speaking (i.e. "soliciting advice"). I was a bit angry at myself for not reporting the tube number right in my 333, and also for originally reporting that the "use no ion trap" sticker was in my 325 when it wasn't. I chided myself somewhat and then vowed to "speak more precisely" in the future. At NO POINT did I criticize a single word of yours. At no point did I imply that anyone else should refrain from saying anything. I was only speaking about myself. Please re-read my comments and tell me where I asked anyone (other than myself) not to say anything about anything at anytime, ever. I thought that was clear. If it was not, I sincerely apologize. To you and to the forum.

Please lighten up. I had no ill will whatsoever in any of my writing, I have none now. I clearly appreciated your comments and I believe I thanked you for them in several places. I'm glad you told me what you know about single-field ion traps vs. double-field ion traps vs. no trap at all, and when and where and why you thought each was necessary. I thought that letting you know (and others know) that magnets weren't working in my situation was helpful, informative, and perhaps entertaining information, both to you and to others. Should I have lied and said the magnets worked, just to make you feel good about yourself? Are you so insecure that when I doublechecked your facts against a book (and found your original statement to be wrong) that you have to lash out, call people "idiot", and then refuse to ever lend a hand ever again? This is the behavior of a kindergartner.

Not entirely sure I'm the one who needs to "chill out".

In your rant above, you say that "what you make out of studying the manual" is that "A does not necessarily mean aluminized". Two posts earlier you said "A stands for aluminized". Complete contradiction, both stated as fact. I found out from independent study that A does not mean aluminized. I believe we completely agree on that question now. I don't think we did earlier. I was simply clarifying. Should I have not pointed out your earlier statement? Should I have let a third pary or fourth party or fifth party read the statement and use the information? Or was it so much of an offense to point out the error that I should have just remained silent, so as not to disturb your fragile ego? Really? I'm sorry if pointing out a misstatement caused you such grief that you felt you had to jump all down my throat for doing so. Really, I was just trying to advance the understanding for everyone. I guess that was wrong. Sorry, everyone else, for correcting Tubejunke on a mistake. We should never do that. Ever.

In fact I was just part of the caring group of people who gives a rat's a** about the next guy down the line who might have had the same problem.

I don't think this forum is for children to cry foul and act injured and make silly threats. Please don't call me "pal". Farthest thing from. If you "WONT try it again", don't. Free country. Sorry I bothered you. Really didn't mean to.

Thanks for sucking all the air out of the room. This place was fun, now it's not.

One sign of a tube that needs an ion trap is that the electron gun is angled.
There might be some non-angled that need the trap, but the angled gun tubes always need the trap to bend the electron stream back straight.

Guys, are we both having a bad day?

"I was already misinformed about the "A"-meaning-aluminized rumor before hearing Tubejunke say it a couple of posts ago"

Yes, this could be taken the wrong way but I don't think it was intended as an insult.

Kbmuri you responded with a rant that was equally nasty.

Can we all just take a deep breath and relax a little. it's supposed to be fun. :yes:

kbmuri - I also read tubejunke's reply and agree with you 100 percent. Without going into details, I learned my lesson as to shooting my mouth off in these forums long ago. I have been corrected many times for inaccuracies in my answers to posts--and I took it all like a man. I'm far from an expert when it comes to electronics (just in it as a hobby, not a business) and not afraid to admit it. I know very little about the solid-state technology everything in electronics employs these days, as almost all my experience in electronics, in over four decades of experimenting and 34 years in amateur (ham) radio, has been with tube-powered equipment; if I should make a comment in a post to any of these forums that may be anywhere from a little bit to totally wrong, I will welcome the correction. The longer I read these posts in the various AK forums, the more I learn about electronics, both vintage/antique and solid state. I have made it my business since joining AK not to respond to a post unless I am reasonably certain that my comments will be of some help. If I know nothing about the subject under discussion, I write nothing and read other posts, in hopes of learning a thing or two. Sometimes my answers to threads I do reply to may be a bit off the mark, but if they are, as I said above, I will welcome corrections.

I also agree with your comment that we don't need that kind of childish behavior here (getting all bent out of shape just because someone corrects you or outright calls you out on a comment you make in a post to an AK forum). I think tubejunke would be a lot better off in this forum, and any others within AK to which he may post, if he would adopt the same attitude, i. e. welcoming corrections if information in one of his posts is inaccurate or incorrect, without snapping the respondent's head off. We all goof once in a while; none of us is perfect. Just a thought. :yes:

As I understand it from electronics school many years ago, (44 years ago), plus a recent review: An aluminized crt does not have a gun with an ion trap and does not require an ion trap magnet. The electron beam has ions mixed in with it that will damage the screen phosphors causing a dark spot in the center of the screen. The very thin aluminum coating has many tiny openings in it which will pass the electrons but will not pass the ions which are of a much greater mass. On a non-aluminized crt, an ion trap, (bent gun, tilted gun, or tilted electrostatic field) aims the electron-ion beam towards the side of the crt neck, or in some, the side of the second anode. The ion trap magnet is used to deflect the electron beam back to center but will have little effect on the ion stream which hits the inner side of the anode, or the side of the neck. If you have a spot of light or a raster on the screen without an ion trap magnet, then obviously you don't need a magnet to straighten the beam. You don't need an ion trap with an electrostatically deflected crt, because the electrostatic field will deflect the ions as well as the electrons, and the ions won't be concentrated in the center of the screen and damage it.
Donald

I looks as if we both need to just take a second look at what we are doing. I did go back and look at the comment that sent me into my "rant" and I can see at least that I over reacted in an unacceptable way. I am glad to know that at least one person who read the whole mess could conceive HOW someone might take the statement with my name in it in offense. Still the same my reaction was wrong.

I stick with my guns on my position that this forum should not be thought of as a place where you have to be "precise" in order to be welcome. Also,I may have reacted in a childish way but I didnt make ANY "threats".

I think kbmuri and I have now stood in each others shoes in a way. I will say his very bad reaction was at least more justified than mine. Just as cutting though for what started out as an apologie. I dished out the mess, so I should take it. I will accept my mistake, apologize, take my licks, and hope everyone here including kbmuri can forgive and forget. In my defense I say that I have several hundred posts and never had a bad word with anyone. No excuse, just trying to clarify the whole matter in a fair way for everyone. I think I have been watching the world news too much. There may be a bigger lesson to learn here than we think. Ecpecially if you watch the world news.

Personally, I love to learn the ropes of our hobby, I have MANY times found that I was completely off base. After many years of interest and tinkering I am finally getting to where I am HALF decent at it. The whole aluminized issue is a prime evample. In the few days between some of my posts on this thread I had learned that "A" IS NOT a guarantee that a tube is aluminized. I was wrong if I said anything different. I was given that info here I think. Completely wrong. The thing that I think confuses the issue is the fact that if a tube has NO extended call letter like "A" or "B" then it WILL NOT be aluminized. In other words the aluminized tubes all have an extra call letter, either "A" or "B" or possibly something else. The extra call letter just signifies something other than the plain P4 phosphur, clear glass faceplate. The way the book reads none of this is a decisive factor as to weather or not an ion trap is used.

This is what I make of the whole thing based on my research.

Again folks sorry for my stupidity. I really was an idiot weather kbmuri implied it or not.

We live and we learn by our mistakes.....

Tube out.........

Hey KB, if you're still checking out this thread here's some information from a totally amatuer non-electronically inclined guy whose abilities don't go past changing out tubes (but NOT CRT's--that whole high voltage thing scares me too much) and making adjustments.

My 325 had an ion trap originally and still does after having its CRT replaced many years ago, and I know it's necessary because adjusting it does have an impact on brightness. I think yours probably needs one. Not saying that will fix your problem, but I'm guessing once the problem has been solved, an ion trap will need to be a part of the finished and working product.

I'm considering a re-cap of my 325 by a local vintage TV/radio guy but am thinking even in working condition I probably wouldn't recover my costs when the set eventually goes up for grabs. And there's that open issue around the wrong channel selector knob. . .

Nice to see some team building on the forum. I know, some of us are allergic to letter fungus, but I put together a neat top 10 list I wanted to share. Hey, feel free to modify it. But this one I always find fun to do. Except step 10 gets to be a bit of work. But, at any rate, here goes. So, as another member mentioned glowing white dot after the set is turned off is a good sign that you have (some) emission and (some) high voltage. Here's a few tricks I learned years ago.

1) Examine the neck of the CRT. If the Cathode and G1 are crooked at a noticable angle about 30 deg then you probably need an ION trap.

2) Turn off all lights in the room (do this at night) and let you eyes get used to the dark for about 15 minutes.

3) Turn on the set and let it warm up for a few minutes then turn it off to get the white dot.

4) If an ION trap is needed you need to figure out the best position and what impact it may have on brightness. Need to experiment a bit.

5) With your eyes acquainted to the dark the white dot will appear brighter to you. Slip the ION trap over the CRT socket onto the end of the tube and gradually slide it up the tube. Rotate slowly as you slide. Constantly watch how the brightness of the dot varies.

6) There should be a point where the maximum dot brightness appears on the screen. Leave the ION trap in this position.

7) Turn the set back on. Turn the brightness control OFF. Turn contrast to MID position. Tune in a station, hoepfully you'll get sound. If you can tune in a station then great! But if you can't ..don;t fuss. Just you blank raster for the next step.

8) Slowly increase the brightness and observe the screen carefully for raster. Inter play contrast and brightness controls. Most situations boil down to 2 conditions usually: a) weak HV and b) low emission. If HV is weak then setting the birghtness too high causes the HV to reduce (can't supply enough current) and the picture blooms until you can't see it. In the low emission case, brightness or contrast may bias the tube off. Watch for tell-tale 'negative picture' as the brightness or contrast begins to push the CRT into saturation. In some case you can bias off the CRT if misadjusted.

9) If you still can't get anything then try checking CRT emission with a CRT checker. But a CRT tester may not tell the truth, especially with older ION trap tubes and weak emission. I know some ION trap tube that don't show any emission on my B&K yet still produce marginally weak, but watchable, pictures.

10) All else fails there may be a circuit issue that's causing the CRT to bias off when the set is operating. Roll up your sleeves and get out the 'ol scope probe and start hunting!

Hallelujah!
 

After finishing up the Magnavox, then taking care of a load of non-TV-related "job jar" items, this morning I got the Capehart 325 back out for another go-round with it.

I made an "error-in-thinking" assumption in one circuit. When replacing (and repositioning) the power-supply electrolytics, I pulled a wire from the case of one of the multi-can capacitors, and when repositioning the cap a mile away, decided to just run the wire to an equivalent point elsewhere in the circuit. Turns out it wasn't equivalent. Brain fart. It led to a dead section of TV set in the 6AH6 Video Amp section (among others). I corrected it. Full raster. After some knob turning (agc, focus, vert lin), I have pretty good-looking snow. Good stopping point for the night.

I'm really strongly leery about saying this. I have no larceny in my heart and no ill will towards anybody. Just for the people who were technically interested in technical details about the technical facts of this TV. It's displaying a very nice raster, with no ion trap.

Just the fact. No ion trap. No hidden meaning nor insults. Really.

I'll prolly post one more pic of it all zipped back up and showing a football game or something, just for full closure, then I'll retire from here. It's a fun place sometimes, sometimes not, and I admit I don't fit in very well. Problem's with me, you guys all are great.

Enjoy,

- Kirk

progress...

... success.

Lousy picture is from the Ramsey transmitter (lighter/darker blocks of picture). Will run it with a VCR for final photos.

Bottom-right corner has a neck shadow. Seems like a physical problem with the yoke mounting (too far up? too far down?). Will experiment.

Horizontal-hold had to be turned all the way in to get sync. Maybe an out-of-tolerance resistor in this circuit.

Simple stuff left.

Fantastic! Nice to finally see a pic on your Capehart as i know you've put alot of work into it. Its funny how alot of us resolve a puzzling problem after taking a break away from it once in awhile. Sometimes it just takes a fresh take on things to spot the obvious. Thanks for the update!
-Tony

Done
 

Not 100% perfect, but I'm satisfied.