[98CRI]

I see a few ungodly-expensive RPTV's with 9" CRT's. I see plenty of RPTV's with 7" CRT's over a wide price range. The 9-inchers can do 1080i properly, and 720p easily. The 7-inchers claim 1080i, but really overlap the scanlines so much you just see 540p--and 7" CRT's don't even pretend to handle 720p.


Why don't I see any RPTV's with 8" CRT's priced between the 7" low-end and the 9" high-end? It appears that an 8" gun would handle 720p nicely (and display more of 1080i than a 7-incher).


(9" has about 60% more emitting face than 7", whereas 8" has about 30% more).


I'd really like to buy a 720p capable RPTV for

say $3000 instead of $6000.

 

[[email protected]]

The 7-inchers claim 1080i, but really overlap the scanlines so much you just see 540p--and 7" CRT's don't even pretend to handle 720p.

=========================================


Actually, 7 inch tubes do handle 720P, it is the bandwidth of the

electronics that limit the output to 1080I.

 

[DTC mac]

The simple fact is that 8" is not a standard size amongst CRT manufacturers. Also it is very odd that there such a price disparity between 7" and 9", while more materials go into a 9" tube the manufacturing process should not be all that more complex. The key is demand, RPTV makers use more 7" tubes and since the demand is higher more tubes are made in that size and we all know in mass productionm the more units produced the lower the price.

 

[Ken H]

In industrial video, there is a 8" CRT projector, the Marquee 8500. It's basically the same as a Vidikron Vision One, with 8" tubes instead of 9".


This is a great product and can do any video signal up to 152kHz horizontal, HDTV is a no-brainer.

 

[dkeller_NC]

Uh - Ken, I'm pretty sure the projector you're refferring to actually uses tubes that measure around 7" diagonal (Tim Martin would be able to answer more definitively).


In the CRT proector world, projectors are listed as 7", 8" or 9" units, but this actually a misnomer. In general, a 7" unit is a CRT projector with electrostatic focus and 7" diagonal tubes (all CRTs are 4:3 devices, BTW). An "8 inch" CRT projector actually has 7" CRTs, but with electromagnetic focus - the end result is far superior to a 7" electrostatic tube, since the electromagnetic focus allows a much smaller beam spot size.


A "9-inch" CRT projector actually has 9" diagonal tubes and electromagnetic focus, for a truly superior image that has yet to be equalled by digital products. However, as with most things, it has a truly superior price tag to match. Unfortunately, I cannot answer whether a 9" RPTV actually has electromagnetic focus (I kinda doubt it), but as Ken said, even a mediocre FPTV CRT can best almost any RPTV becasue of the electronics contained therein.


It's worth remembering that the $4-$8k CRT FPTVs that are sold rebuilt by Curt Palme and others on the CRT Projector forum were machines that were $17k-$30k new, so it makes sense that they would have far more adjustments and be able to generate a far better image in the right hands than a $4k new RPTV.

 

[Ken H]

Nope, the 8500 actually has 8" tube faces. Tim can confirm this. It's not a misnomer when referring to 8" tubes, as they do exist. Electromagnetic focus is a function that can be applied to any CRT, for use in a projector.


Here is a link to info on Marquee 8500 products. Christie Digital recently sold their full CRT product line to VDC.
http://www.vdcdisplaysystems.com/Products/MARQUEE.pdf

 

[VideoGrabber]

98CRI, please check your Private Messages. Thanks.


- Tim

 

[dkeller_NC]

"Electromagnetic focus is a function that can be applied to any CRT, for use in a projector."


Sure, but it seems to be a "convention" when referring to Sony products at least.


That's interesting about the E-home Marquee - I suppose that explains why Tim is able to drop 9" tubes into an 8500LC chasis and make it work....

 

[Grosse Fatigue]

Actually Barco and Electrohome use to make RPTVs with removable projectors. They could accomodate any of their 7", 8" or 9" projectors, whatever. Those were the only kind of RPTVs I know of that were actually retubed. HiRez use to have some used models about five years ago. They are now impossible to find. None were 16.9 widescreen, by the way. I believe that some of the early Runco RPTVs were just modified and simplified Barco and Electrohome RPTVs. GF.