CurtPalme.com Home Theater Forum

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Oh, just in case anybody was wondering, I did ask and apparently the unique tubes I picked up from VDC for the 9500HR are in fact the only such set ever made. While there were at least two 8500HR machines built, VDC never actually built a 9500HR and these tubes were evaluated but no 9500HR was actually made.

Lexel could probably make you a set of these tubes if you wanted to pay the price.

So, needless to say, I feel both lucky to have them and maybe a little bit guilty, too. A little. But even more, I feel a bit
nervous about even touching them as they are literally irreplaceable short of paying out the nose to have Lexel make up more.

But, that's OK. If a Cine 9 can handle 4K (and actually it's rated pretty close as per factory specs) then it stands to reason that any PJ that also uses LUGs might have similar potential. Every "last model" 9" machine is rated to handle at least 2500x2000 so it's not like 1080p is the real end of the line for ANY top gun CRT projector.

This project is going to be fun to take on but I believe it will be my last CRT experiment. I've seen some pretty impressive digital projectors lately that have managed to impress me with performance worthy of a top-of-the-heap CRT projector only with added benefits of being able to work with higher light output and on a larger screen.

The day's going to come when even I retire my CRTs. But not yet! The fun is far from over.

racerxnet · Joined: 20 Jun 2007 Posts: 362 Location: Illinois

You mentioned on AVS that there were 8 inch tubes made for HR material, and I am wondering what has happened to those tubes? Just curious if they are available.

MAK

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

VDC built two 8500HRs according to Tse. I do not know their whereabouts. Scott told me that they were used for demonstrations but he does not think VDC actually sold them.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

First actual step taken in the project today: Using my spiffy new (to me) Quantum Data 801GP test pattern generator, which I scored off ebay for the appallingly expensive price of 99 CENTS plus shipping, I checked out the projector to be modified (I call it No. 2) and both the generator and the projector are in fine working order. It was checked out at resolutions up to and including 2560x2048 (the limit of the generator) and H scan rates at up to 127 KHz.

The projector is a box stock straight 9500LC from 1997, with red and green C elements that I think will be transferred to the HR tubes. Since it's completely unmodified, it makes a perfect candidate for performing every mod I might want to do, as there will be no worries about having to undo any existing mods to it.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

I lost two LVPS units in a 24 hour period. Had ONE spare. So I just bought another one, it'll be here in a few days. Then I will be able to operationally test the first modified deflection and focus yokes for this project.

Replacing the LVPS in the unit in the home theater worked wonders for improving overall picture quality and especially it helped out a lot with focus stability and resistance to blooming at high contrast levels. It's FULLY resolving 1080p and scan lines are easily counted even in anamorphic squeeze mode. That's on a projector that, other than the MP modded neck cards and VIM, has all stock parts.

The 4K blend thread has made me aware of the fact that UHD range resolutions are available to me without having to wait for the Moome HDMI 2.0 input card. Lots of nvidia video cards can do it, with the custom resolution tool and a DVI to RGBHV BNC pigtail adapter.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Tonight the red HR tube saw "first light" and you just don't realize how sensitive a new tube is until you've dropped into a projector with a couple of "veteran" tubes alongside it. G2 and drive levels on a fresh tube are very low compared to a tube that's got a few thousand hours on it.

Yes, it's SHARP. Oh yes indeed! In a completely stock chassis. It's going to be a while before I start to explore its full potential, though.

I realized, when trying to fit things up, that the Barco magnetics are all equipped with leads that are too short for a Marquee
chassis, so I'm going to have to swap out all the wiring harnesses on the yokes. A minor oversight.

Due to the way Lexel built these HR tubes, the neck cards are rotated by at least a full pin relative to a standard tube. So they
won't be able to fit in the card cages without doing something "different" and I think I have the answer to that problem. An answer that doesn't require any permanent changes to a Marquee neck card. I'm just going to pull the pin sockets out of the neck cards and run them to the card with short wires. As short as possible, and then be able to rotate the neck card to fit in the cage. Some technical details will be addressed as I come to them.

My red 8" LC tube is now known to be a good working tube. When I'm done with my tests, if anybody needs a perfect red for an 8520, it'll be for sale. Hopefully I won't damage it in any way.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Let's see if anybody actually reads this topic.

I've been in contact with Chris Stephens.

And, separately, I've had a meeting with a friend of mine who's a very good RF design engineer, and we are taking a close look
at the feasibility of designing a brand new aftermarket neck card from scratch, with a design goal of 600 MHz of pristine clean bandwidth.

Since the rest of the neck card design is a given, only a new amplifier path has to be developed.

An additional mod to the VIM will be needed as well. This will most likely take the form of a new preamp package that piggybacks
onto the VIM and bypasses the VIM amp circuits entirely.

The best news: Anybody with a healthy 9500LC with Panasonic LCP or LUG tubes will be able to exploit the performance improvements.

Now for the bad news: It's likely that to fully exploit the capabilities of the proposed new video chain, a significant effort to quiet
down and stabilize practically every circuit in the projector will likely be mandatory.

But making the effort to make the projector less noisy (electrically speaking) will have benefits to your picture even if your projector is currently in stock condition.

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4409 Location: Phoenix

Hello

This sounds costly, and I would be surprised if very many people were willing to spend money on hi-band neckboards. Forge ahead and have fun if you must.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Actually we have established a price target. It is quite reasonable.

Because I for one have no wish to step on Mike Parker's toes, I fully intend to approach Mike about this when and if we have decided to push to a prototype stage. I want Mike to be in on this because I have zero desire to urinate in his revenue stream. I respect him too much for that.

In fact, since the subject is up, my goal (if we get this far) is to make Mike the distributor for the package, if he wants, and of course his input on the project will be sought out.

I'm not the sort of person who wants to compete against people I respect. I'd rather work WITH them instead. It's an ethics thing.

haireez · Posted: Thu Mar 31, 2016 1:39 pm Post subject:

Looking forward for this and hopefully affordable to all of us.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

It's a long way from being a sellable product. Right now it's only an idea. Hopefully a good one that can be developed and built economically,
to the point that it'll sell well enough to make it cover its costs.

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4409 Location: Phoenix

Okay

If you are adopting existing beam limit, spot kill or other VDC circuitry there could be patent infringement issues; it would be a good idea to ask about that.

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

mp20748 · Posted: Thu Mar 31, 2016 6:54 pm Post subject:

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Just saying...there is some real "outside the box" thinking going on.

I frankly have no idea if we'll have any success or not.

Interestingly, the MRF 548s and 549s seem to be quite easily available today. Are they Chinese copies? No doubt some are. Are they actually made
to Motorola's specs in a Motorola vendor factory in China? I don't know. But they're VERY available and one thing I am going to do is get a few pairs
of them and see if they work and if they're equal to the "good" genuine ones from years past.

If they ARE good, and are operationally the same as the "real deal" parts, then suddenly we're looking at a simplified project, and it becomes a product
enhancement rather than a complete redesign.

But they may be cheap knockoffs that don't work at all. I don't know.

We're asking questions, NOT promising a product yet. Don't invest too much hope in this yet.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Here, for reference's sake, is a listing of the measured DC and inductance values I've recorded from some unmodified deflection and convergence yokes, both Barco (Kanto-Denshi) and Thomson (from a Marquee) types.

DEFLECTION yoke values and notes:

K-D vertical winding (green-yellow wires) measures 5.4 ohms DC resistance and 4 mH inductance.

Thomson vertical winding measures 15.0 ohms DC resistance and 8.9 mH.

There are four 2.2 ohm resistors incorporated into the Thomson vertical windings, presumably to control current levels. Most of the DC resistance readings per coil (4.4 ohms out of 15 ohms indicated) are due to these series resistance. Actual coil resistance is about 10 ohms per coil.

K-D horizontal winding is two windings connected at a center tap. DC reistance is 2.5 ohms per coil. Inductance is 1.58 mH per coil.

Thomson horizontal winding is two separate windings, not connected to each other. They measure 1.4 ohms per coil. Inductance is 0.27 mH per coil.

Convergence coil values. (Convergence coils are semi-integral to deflection yokes.)

K-D convergence coils measure 1.2 ohms DC per coil with inductance of 0.45 mH.

Thomson convergence coil measures 1.1 ohms DC per coil with inductance of 0.25 mH.

In every case, when comparing the deflection and convergence coils to one another, there are sufficient DC resistance or
inductance value changes to suggest that maybe NONE of the coils will truly be plug-and-play with the projectors that they
are not normally found in. I believe some modifications to the coils, or the driving circuits, or both, will be required to get optimal performance.

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

If I could trust the available MRF548/549s, then we'd modify the heck out of the original design and go for bandwidth.

Those are, if I read the data sheets right, 1.4 GHz devices!

Why a stock set of cards delivers only about 150 MHz of bandwidth is kind of puzzling. Oh, I understand the technical reasons
well enough, I think, but it would not have been so hard to design the card to start with, to maximize its bandwidth potential.

The way those neck cards actually function is pure genius. Basically you end up with two separate amplifiers operating in opposite phase but well balanced to each other. One drives G1, the other drives the cathode.

Panasonic redesigned the LCP tube to create the LUG tube which is optimized for this differential drive setup. Of course they continued to make LCPs as well.

You can find LUGs in some other projectors as well, like the G90 and 909. I wonder if they use the same differential drive amplifier concept?

The difficulty in this propose project is in finding a suitable answer to the question of replacing the MRF 549/549.
Those are a tough act to follow. Which is why the VDC neck card redesign doesn't have the bandwidth of the earlier cards.

But that's why we're trying to think differently. And there are more high power, high bandwidth RF power amp devices to choose from today than ever before. So there's a chance...

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

I'm not the engineer in this, I just deal with one. I'm no designer, but I can fix almost anything you can break.

I do know that the search for a power output device is going to include taking a look at devices built for cellular base station transmitters, among other things.

If we can't get the voltage ratings we need in a single device, there may be ways to do it with multiple devices, but again, that's for the engineer to figure out Hybrid PA modules may be a consideration, too.

All we can do is look for something that meets the requirements.