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Old 2nd Mar 2018, 8:07 pm   #11
Graham G3ZVT
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Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,676
Default Re: Modeline problem

Its interesting to note how different set types respond to the non-standard waveform. My Cossor 916 has no problem with vertical lock, it's rock steady over 70% of the travel of the vertical hold pot.

What I don't get however is any interlace.
I don't regard that as a major problem, it might even be considered an advantage when staring at Testcard C at close range, and even with a full spec BBC signal, good interlace was a challenge, due to understandable compromises made by Alan Blumlein et al.

Notwithstanding the above, I did build Peter's logic circuit in order to improve the interlace situation, but didn't have much success, I will revisit it soon, particularly as I now have a cheap PC oscilloscope.
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