Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Aug Tue 14, 2018 11:19 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 23 posts ]  Go to page Previous  1, 2
Author Message
 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Dec Thu 21, 2017 10:04 pm 
New Member
User avatar

Joined: May Tue 24, 2016 2:41 pm
Posts: 10
Location: Scotland
If you are happy to use the normal definition of your old television then any signal that you can play in VLC player can be translated using a PC graphics card and modulator:

http://www.nostalgiatech.co.uk/Baird%20240%20lines.htm

Peter

_________________
http://www.nostalgiatech.co.uk/Vintagetech.htm


Top
 Profile  
 
 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Dec Fri 22, 2017 12:22 am 
Member

Joined: May Sun 07, 2017 11:35 am
Posts: 338
Dare I suggest that you could play such material in CCIR 625 line 50Hz format?

With no chroma, the horizontal and vertical resolution of 625 line 50 Hz approaches the limits of what is possible for most period B&W CRTs. If your TV is currently 525 line 60Hz, you'd have to re-do your vision and sound IF alignment or bypass the RF section of the TV altogether. Your power supply needs to be clean too (new electros, copper flux band on transformer), else you'll see a beat between the 60Hz (power) and 50Hz (TV). But 525 line TVs can be fairly easily adapted to work on 625 line CCIR, the scan frequency differences are minor.

As a kid in the early 60s in Australia, early in the mornings when Ch9 was displaying the Marconi resolution chart, I used to tweak the fine tuning on the family's 23" Pye T20 TV so that the 5MHz resolution grate was resolved. Increasing the contrast and brightness would cause beam spot spread that would blur the 5MHz grate, turning it into a grey block. But with reasonable settings the TV and its CRT would resolve the 5MHz grate, albeit at the limits of its capability.

So, if you want the best possible picture from your old CRT, 625 line is about as far as you can go, and it's practical too. It has the additional benefit that, if your content is from film and was transferred with a digital or a 50Hz telecine, you won't get the 2:1 film pulldown judder you see on 60Hz transfers.


Top
 Profile  
 
 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Jan Sun 21, 2018 5:06 am 
Member

Joined: May Sun 07, 2017 11:35 am
Posts: 338
Your best hope for higher resolution on old TVs would be to use CCIR (PAL) 625 line signals. It's not difficult to modify a TV designed for EIA (525 line) so that it can handle a PAL signal, ignoring the color of course. Even better, use the Y part of a Y/C signal.

It's not hard to get converters that will take HDMI and give you PAL.

Attachment:
PM5544_on_E1.jpg
PM5544_on_E1.jpg [ 48.86 KiB | Viewed 233 times ]


I found a picture I took of a 1956 HMV E1 displaying a PM5544 test card through an RF modulator. This is about as good as it gets.
Note that when this pic was taken the TV still had a fault that "crinkles" the LHS of the picture - it turned out to be a cracked ferrite pole piece in the yoke. But as you can see the resolution goes to 5MHz, not at all shabby and pretty amazing for a 63 year old TV. The CRT BTW is a 17HP4B. It was fitted to the TV within a few months of manufacture and has been there ever since.

Only problem with doing this in a country with 60Hz power is your TV's power supply filters had better be good, else you'll see a 10Hz wobble in your picture.

BTW, this is the technique that's used to shoot film off TV screens when making a movie.


Top
 Profile  
 
Post New Topic Post Reply  [ 23 posts ]  Moderators: 7jp4-guy, Mr. Detrola Go to page Previous  1, 2

All times are UTC [ DST ]


Who is online

Users browsing this forum: Google [Bot] and 4 guests



Search for:
Jump to:  
























Privacy Policy :: Powered by phpBB