UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

Argus25 · 9th Mar 2019, 2:04 pm

There are plenty of scope tubes out there to make an electrostatic deflection 405 line TV.

There are numerous articles on how to do it. The one UK TV experimenters were keen on was the Argus, that used the VCR97 CRT, these are still available from time to time.

However many American 5" scope tubes with P1 (green phosphors, like the VCR97) can be substituted to make an Argus.

The only problem with P1 phosphor is that it makes everyone look like the incredible Hulk. (Aka Dr. David Bruce Banner who was accidentally overdosed with Gamma radiation and whenever he is angry or outraged transforms into the Hulk. For example, changing his car tire he gashed his hands on the pavement, got angry and tossed his car over an embankment...grrrrr). Pretty cool really, and Marvel are making a big comeback.

Here is an Argus TV I made:

http://worldphaco.com/uploads/ARGUS.pdf

The problem with electrostatic deflection, is that most CRT's suited to it, run from relatively low EHT voltages, 3kV or less for small'ish CRT's. Large electrostatic CRT's become impractical due to the high deflection voltage requirements, though PDA CRT's help a little to ameliorate this problem.

The advantage of magnetic deflection is you can run higher EHT voltages, have higher "screen energy" (contrast and brightness) and generally better results. (the electron energy, or electron.volts are higher)

So I would recommend, if you are building a vintage set "replica" to use magnetic deflection with an aluminized CRT, and an EHT of at least in excess of 7kV if you want a good bright high contrast image.

Most (but not all) modern P4 phosphor CRT's have an aluminized screen, so they need over 5kV to penetrate the aluminium layer to get any reasonable light output from the phosphor. Non aluminized screens can work well down to 2kV EHT.

9th Mar 2019, 2:04 pm	#2
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Re: Build a TV? There are plenty of scope tubes out there to make an electrostatic deflection 405 line TV. There are numerous articles on how to do it. The one UK TV experimenters were keen on was the Argus, that used the VCR97 CRT, these are still available from time to time. However many American 5" scope tubes with P1 (green phosphors, like the VCR97) can be substituted to make an Argus. The only problem with P1 phosphor is that it makes everyone look like the incredible Hulk. (Aka Dr. David Bruce Banner who was accidentally overdosed with Gamma radiation and whenever he is angry or outraged transforms into the Hulk. For example, changing his car tire he gashed his hands on the pavement, got angry and tossed his car over an embankment...grrrrr). Pretty cool really, and Marvel are making a big comeback. Here is an Argus TV I made: http://worldphaco.com/uploads/ARGUS.pdf The problem with electrostatic deflection, is that most CRT's suited to it, run from relatively low EHT voltages, 3kV or less for small'ish CRT's. Large electrostatic CRT's become impractical due to the high deflection voltage requirements, though PDA CRT's help a little to ameliorate this problem. The advantage of magnetic deflection is you can run higher EHT voltages, have higher "screen energy" (contrast and brightness) and generally better results. (the electron energy, or electron.volts are higher) So I would recommend, if you are building a vintage set "replica" to use magnetic deflection with an aluminized CRT, and an EHT of at least in excess of 7kV if you want a good bright high contrast image. Most (but not all) modern P4 phosphor CRT's have an aluminized screen, so they need over 5kV to penetrate the aluminium layer to get any reasonable light output from the phosphor. Non aluminized screens can work well down to 2kV EHT.