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Old 29th Oct 2016, 11:07 pm   #10
rambo1152's Avatar
Join Date: May 2010
Location: Manchester, UK.
Posts: 1,437
Default Re: Generating 405 line video using a Windows PC

Bless your heart for saying that Dave, one only tries to do ones best.

As I mentioned, I was cheating because I hadn't built a modulator and I was just feeding the video directly onto the grid of the video output valve.
I have now completed a modulator, well the vision half anyway. Initially the set would not respond to it at all. The RF unit seemed to work OK when I first got the set going as it was picking up interference on vision and sound when I connected an aerial, but not now. The mixer/local oscillator stage was not oscillating and no prizes for guessing the culprit was brown Hunts 100pf
I've now got a bright picture from the modulator but with severe smearing and cogging. I don't have a scope or another 405 line set to see how much is due to the modulator, but for now I'm assuming all the similar condensers have given up the ghost and I am waiting for some replacements I've ordered.

Cheap & cheerful? Well perhaps. Cheap certainly, but cheerful implies a qualitative compromise has been made, and the jury is still out as to how the picture quality compares to (say) an Aurora. I don't see any reason why it should't compare favourably, although I have to say that I don't think I noticed any proper interlacing on my tests. It's something I will look at after I fix the outstanding issues.

Last edited by rambo1152; 29th Oct 2016 at 11:12 pm. Reason: grammar correction
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